Solar Power Minus the Light

An anonymous reader writes "Popular Science is running a story about a small company trying to take advantage of all the global warming hype. Matteran Energy uses 'thermal-collection technology to heat a synthetic fluid with a very low boiling point (around 58F), creating enough steam to drive a specially designed turbine. And although a fluid-circuit system converting heat into electricity is nothing new, Matterans innovative solution increases the systems efficiency to a point where small-scale applications make economic sense.' Notably, this comes during a record breaking heat wave here in the US. So has the day finally arrived where I can run my AC off of all that heat outdoors?"

Comments

Only solves 50% of the problem

[chriss]

Hm, looks simply like a small sterling engine or mini gas turbine used to drive an AC. They managed to make it cheap so it will be applicable in small installations, but both the sterling engine and the gas turbine (using a fluid in a closed circuit) require a temperature difference, so the machine would not be driven by heat alone. You'd have to cool down the steam after it had passed the generator to make it condensate to a fluid again and pump it back into the thermal collectors. The article does not mention how this should be done or where the energy for this should come from.

Power stations using closed fluid circuits (e.g. nuclear plants) use a secondary circuit to cool the first one after the steam passed the turbine. They are usually located near rivers for this. Larger installations for sterling engines can store heat during the day in a water tank and use the difference in temperature between the water and the surrounding cooler air during the night to drive a sterling engine. This obviously works best in areas where the difference in temperature between day and night is significant, i.e. deserts. I don't think it to be realistic to turn 1/4 of your apartment into a heat/cold storage just to drive the AC.

So in the end they made it cheaper, but inefficient (5%) even compared to solar panels (20%) without offering something that could replace a conventional AC. To achieve this you'd still have to build houses in a smarter way, e.g. isolate the walls from the inside and outside and use them as thermal storage. More energy efficient construction has been done for cold regions (where houses require almost no heating during winter when isolated well, the inhabitants' body heat is sufficient) and warmer regions (traditional buildings build with clay and wind-traps and smaller windows to the sunny side). So it is possible, but do not expect too much from our current architecture.

Re:Only solves 50% of the problem

[NightRain]

Presumably however, you'd at least be able to use the existing temperature difference to at least offset the cost of running the airconditioner? Obviously it's not a perpetual energy machine, so you'd lose out in the end, but it seems to me that at least it could use some of the cooled air that is otherwise just going to be wasted.

Re:Only solves 50% of the problem

[lordcat]

You want cool? bury it! The temperature underground tends to stay nice and cool, even during the heat of the summer... If you've ever lived in a house with a full basement... you'll know that during the summer, that basement is the coolest part of the house... Similarly, in the winter time, that basement doesn't get as cold as the rest of the house can... (obviously heat rises so if you heat the house the upper levels will get warmer quicker, but if you didn't heat the house the basement would be the warmest part from the radiant heat in the walls vs the radiant cold upstairs)... Either you should get a nice difference in temperatures between the surface and 10-20 feet underground (maybe less... and you should get a nice difference both durring summer and winter)... or you don't need the ac!

Re:Only solves 50% of the problem

[thealsir]

yeah it could use some of the energy from the air, key point. The machine doesn't have to be near 100% efficient, but the big question will be if it is efficient enough to be worth the added cost of purchase installation. That must always be factored in when piggybacking machines that take advantage of ambient energy onto fuel-driven machines.

Re:Only solves 50% of the problem

[MichaelSmith]

Hm, looks simply like a small sterling engine or mini gas turbine used to drive an AC

Summer power consumption by aircon units determines max peak load on the power grid here in Melbourne, Australia. I think aircons should run primarily on photovoltaics because that way you get the highest power when it is needed the most.

Re:Only solves 50% of the problem

[z0idberg]

Perhaps this could be integrated into the hot water system so incoming cold water can be used to cool the condensate back to fluid and you get hot water out the other end.

Obviously you can only do this for a limited period (i.e. until your hot water storage limit is reached), unless once your hot water storage limit is reached you let the excess escape as steam. This wouldn't be ideal as you are losing fresh water out of the system but the benefit might outway that cost.

Re:Only solves 50% of the problem

[chriss]

It's stirling engine after Rev. Robert Stirling, not sterling engine.

Re:Only solves 50% of the problem

[Alioth]

Radiant COLD? No such thing.

Re:Only solves 50% of the problem

[Jedi Alec]

this very principle is currently being put to use in a part of the Netherlands that used to be mined for coal. The water in the now abandonded mine-shafts will be used to provide heating in the winter and cooling in the summer.

Re:Only solves 50% of the problem

[Schraegstrichpunkt]

What's the thermal conductivity of the ground? Even though the overall temperature of the ground might be cooler than the air, the area around the buried pipes will just heat up and reduce your temperature differential. The poorer the thermal conductivity of the ground, the larger the apparatus needed to exploit the temperature differential.

Re:Only solves 50% of the problem

[Alioth]

It would be nice, except for the cost. I bet a 120 watt solar panel costs around AU$1000 in volume. Even in a sunny place you're going to want at the bare minimum 10 of those panels per kilowatt you need, so by the time you're done you're going to be spending $200,000 on solar panels to run your house.

Re:Only solves 50% of the problem

[bhima]

"I don't think it to be realistic to turn 1/4 of your apartment into a heat/cold storage just to drive the AC."

I see you haven't met my ex-wife.

Re:Only solves 50% of the problem

[MichaelSmith]

by the time you're done you're going to be spending $200,000 on solar panels to run your house.

I am thinking more about office buildings with unused roof space. If you write the building regs to require solar cells to run the aircon systems you will increase the economies of scale in solar cell manufacture and drive costs down overall.

Re:Only solves 50% of the problem

[Smidge204]

I beg to differ; If you make an object cooler that the surroundings, there will be a net radiative heat transfer from the surroundings to that object. It's been done.

The catch is, if you're going to use an existing radiant heat floor/wall/ceiling system, you have to keep the temperature of the surface above the dew point or things will get wet.
=Smidge=

Re:Only solves 50% of the problem

[squoozer]

It will never happen and for one very good reason. There just isn't enough energy hitting the roof of even a moderate office block to power the aircon irrespective of the price of solar cells. Energy from the sun totals about 1kW per sq m. Look at amount of unused space on the roof mostoffice blocks. The amount of power you can generate simply isn't enough to power the aircon even if solar cells were 100% efficient. Even the best solar cell is 20% efficient and that drops with time (not counting the fact that huge amounts of power go into making a solar cell int he first place).

Solar cells have a loooooong way to go before they are worth it. Wind turbines on the other hand are nearly there.

Re:Only solves 50% of the problem

[Smidge204]

Photovoltaic panels get hot because they absorb all that sunlight with only ~20% efficiency. Install the heat exchanger in close proximity to the back of the solar cells to make use of this high temperature and take advantage of the shade it provides (prevent the heat sink from being heated by the sun as well. Now your microturbine may be only 5%, but that's effectively ~25% overall for the PV-turbine system combined.

Make that a concentrating PV and your efficiency increases for both systems.

Every little bit helps.
=Smidge=

Re:Only solves 50% of the problem

[B2382F29]

Wow, that would be expensive. Here (germany) you get 2kW (10x200W) for 9000 EUR

Next time please don't pull prices out of your ass.

Re:Only solves 50% of the problem

[kfg]

you will increase the economies of scale in solar cell manufacture and drive costs down overall.

"Economies of Scale" is not a magic wand you can wave to simply reduce cost to some level you would prefer.

We already make photovoltaics at or near the limits of economies of scale. They are just . . .plain . . .expensive to make. Innately.

If you're losing money per unit you can't "make it up on volume" either.

KFG

Re:Only solves 50% of the problem

[kfg]

warmer regions (traditional buildings build with clay and wind-traps and smaller windows to the sunny side)

I've never lived so comfortably as when I lived in a traditional adobe house in a high desert region . . .at about 17 degrees north latitude. Simply lovely. Cool in the day when it was hot. Warm at night when it was cold. No heating, no airconditioning, but nearly always perfect for comfort.

Adobe, but built in a modern fashion, at sea level against the rainforest, not so nice at all; and the scorpions liked to hide in the tile roof during the day, and then drop down on you when when it got cold at night.

Location, location, location. Plus a bit of native engineering.

KFG

Re:Only solves 50% of the problem

[ozmanjusri]

There just isn't enough energy hitting the roof of even a moderate office block to power the aircon irrespective of the price of solar cells.

Except that energy hitting the solar cells now isn't hitting the roof. You should be able to turn the aircon off...

Re:Only solves 50% of the problem

[cheater512]

Yay now I can use the spare heat generated by my cpu, gpu, hard drives, etc... to power my computer!
Ok yes I know it wouldnt work but it could at least recycle part of that excess energy back in to running the computer.

Re:Only solves 50% of the problem

[Aceticon]

Actually as you go deeper underground the temperature of the soil gets closer and closer to the average yearly temperature in that area as shown here

How fast the temperature approaches the yearly average as depth increases depends on the type (and moisture content) of the soil, but as a rough guide, at 8m depth the temperature is very close to the yearly average.

Note that this is not valid for extreme depth (or vulcanic areas) for the obvious reason ;)

BTW, the graphic was taken from here - if you want to know the depth at which the yearly variation of temperature has 1% of the amplitude of the variation outside, look for "Table I. Depth of Penetration of Diurnal and Annual Temperature Cycles" (sorry, no anchor in doc) and check the column "Depth Year (m)"

Re:Only solves 50% of the problem

[fomhoire69]

Yep well the ausis get stuffed http://www.solaronline.com.au/cgi/index.cgi/shopfr ont/view_product_details?category_id=1107143921&pr oduct_id=1107358708

Re:Only solves 50% of the problem

[bhima]

Radiant cool: think like the floor and the walls of a fully underground basement

Re:Only solves 50% of the problem

[asc99c]

Hm, looks simply like a small sterling engine or mini gas turbine used to drive an AC.

Well it's nice to know all those anonymous cowards are environmentally friendly at least.

Re:Only solves 50% of the problem

[Alioth]

Why so hostile? The prices were "not pulled out my ass" but sample prices from a supplier of panels. You could have said something a little bit less rude such as "I think you're incorrect, we can get panels in Germany for this price here" instead of making a mindless flame that makes you look like an asshat.

Re:Only solves 50% of the problem

[Alioth]

Additionally, before you flame also check your maths. EUR9000 per 2kW is still EUR 90,000 per 20kW - converted to AU$, that's still over $150,000 for 20kW - which I maintain is ruinously expensive for that much power.

Re:Only solves 50% of the problem

[Alioth]

But that's still not radiant cold. You can't have a radiant cooler. If radiant heating is being done then it's the surroundings heating the cooler parts - the warmer surroundings are doing the radiating, not the thing that's cold.

Re:Only solves 50% of the problem

[hort59]

Of course it looks like sterling technology. Look at the name that patents are issued to - Jeffery Sterling. :)

Re:Only solves 50% of the problem

[12WTF$]

Except that energy hitting the solar cells now isn't hitting the roof. You should be able to turn the aircon off...
Yes the solar panels will shade the roof, but they will radiate heat onto the roof. Solar panels are 14-17% efficient. Some of the other 80% of the light energy is converted to heat, enough so they run about 25C above ambient temperature. Solar panels are mounted at least 10cm (a few inches) above the roof so that air can flow freely to help cool the panels.

Re:Only solves 50% of the problem

[AndersOSU]

Yes, and when transfering heat away from the object we're concerned with we typically call that cooling. Sure the heat goes somewhere but we don't care if it isn't our house.

For instance, if you park your car in a car port (no walls - ambient temperature,) and your neighbor parks his car outside on a cold clear night there is a fair chance that your car won't have ice on the windshield, but his will. Why? because the net radiation your car sees (Tcar^4 - Troof^4) is near zero - no heat transfer, while the net radiation your neighbors car sees (Tcar^4-Tspace^4) is negative. His car is being cooled through radiation. It is more convienient in some cases to think of radient cooling, rather than heating something like space. Technically it is all heat transfer - it makes exactly the same amount of sence to think of radiative heating as is does rediative cooling.

Re:Only solves 50% of the problem

[Smidge204]

For fight pedantic with pedantic: unless the object's temperature is 0 Kelvin, it's radiating heat.

Similarly, a hot object is also receiving radiated heat from other, cooler objects that surround it.

"Radiant Cooling" simply means you are removing heat energy from a space via radiation absorption by means of a surface of object that you are actively keeping at a lower temperature than the surroundings. In other words, the space is being cooled by radiating the heat, not by some magical device that emits "anti-heat" radiation.

This contrasts traditional HVAC systems that use convection as their primary means of removing heat from a space.
=Smidge=

Re:Only solves 50% of the problem

[vhogemann]

Well,

There is a lot of options:

* you can build a simple radiator and expose it to wind, on a area protected from sunlight

* you can put it near your house's water pipes, so the running water would absorb the heat.

* or increase the temperature differential, put the engine on your rooftop, directly exposed to the sunlight, paint it black, etc... And the ambient temperature will be cool enought to make this engine work.

* combine all the options above :-)

Re:Only solves 50% of the problem

[12WTF$]

You aren't trying hard enough.
I got 12x125W (1500W) for AUD10,800 less AUD4000 Commonwealth Photovoltaic Rebate, equals AUD4.50 (US3.40) per watt.

Re:Only solves 50% of the problem

[Anonymous Coward]

20kW is a shitload for just a house. Even half that would be a pushing the limits of a very big energy consuming house.

In some situations it is cheaper to get solar... such as when the property isn't connected to the grid.

Re:Only solves 50% of the problem

[elvum]

If your air-con is over-efficient, you will save twenty times as much energy by turning the thermostat up than you could ever reclaim with this process - it's only ~5% efficient, remember?

Re:Only solves 50% of the problem

[tomstdenis]

You obviously didn't pay attention in grade 9 science.

For instance, when you sweat, you "cool down" because you're taking the excess energy and TRANSFORMING it into something else. You're not "radiating cool" onto yourself. You're losing heat. You can't transfer "cold" to something, you can only lose heat [energy] to something. The net effect is you cool down, but only because you're losing energy.

Without sweat, for example, even a nice breeze [of higher pressure, i.e. cooler air] won't really be cool because you're not losing as much energy as you would if you did sweat.

Tom

Re:Only solves 50% of the problem

[Rhett's Dad]

That cost estimate is pretty accurate. I went through getting a quote on installing solar panels on my $160k house, to just replace 50% of electric usage, and it priced at >$270k. It calculated out as "pays for itself after 42 years".

Contrast that with considering replacing a traditional electric heat pump with a geothermal system. About twice the cost to install, but electric costs associated with using it drop tremendously, as in $225/month summer dropping to $80/month. This calculates out to paying for itself after only about five years.

Re:Only solves 50% of the problem

[gatzke]

And they are getting more expensive. I think a lot of the PV solar industries use off-spec or lower grade silicon (refuse?) from the high end CPU / RAM chip fabs.

With chip demand increasing, the supplies are getting tight on silane in some cases, so the lower cost PV that operates closer to margin gets the shaft.

http://renewableenergyaccess.com/rea/news/story?id =45235

Re:Only solves 50% of the problem

[josecanuc]

That's still convective, not radiant. Radiant heat is essentially a specific wavelength range of electromagnetic waves (light). There is no equivalent negative-energy "ray".

Re:Only solves 50% of the problem

[jcr]

There just isn't enough energy hitting the roof of even a moderate office block to power the aircon irrespective of the price of solar cells.

There's probably enough energy to drive a ground-loop heat pump. There's more than one way to cool air.

-jcr

Re:Only solves 50% of the problem

[grub]

It's not radiating "cool", though. The walls and floor are drawing the heat energy from the warmer air.

Re:Only solves 50% of the problem

[It'sYerMam]

In other news, subtraction doesn't exist, you can only add negative numbers. Language is a convenience tool, and sometimes it's just more convenient to say that something sucks air, or radiates cold, or whatever.

Re:Only solves 50% of the problem

[MindStalker]

Most homes use between 1 and 3 kW at any one time. Generally a 1 kW solution is considered good enough for most homes. Sure thats still 20K but when your talking about home prices at 300-500K in many places its a fairly small difference.

Re:Only solves 50% of the problem

[tomstdenis]

Yeah but by saying "you radiate cold" you fundamentally don't understand what's going on.

Energy cannot be destroyed but transformed or relocated. You don't "get cold air" and all of a sudden the heat disappears. You transform the heat into something (e.g. work, or in this case evaporation of water) and in turn "feel cooler".

Tom

Re:Only solves 50% of the problem

[ocelotbob]

I don't think it to be realistic to turn 1/4 of your apartment into a heat/cold storage just to drive the AC. You'd be surprised on how easy it is to find that 1/4 of the space if you start thinking about areas such as the attic, and under the house. I imagine that one could fairly easily get a good amount of the area they needed for cooling reserves from just those areas. If not, then there's always going down; sinking an underground storage tank for energy purposes isn't horribly expensive, all things considered.

Re:Only solves 50% of the problem

[Alioth]

It's not a shitload for an *air conditioned* house though (the original purpose for the solar in this thread was to run air conditioning). AC is extremely power hungry, and you generally need with solar a good deal more capacity than the power draw of whatever you're running due to passing clouds and hours of darkness, storage losses, inverter losses etc.

Re:Only solves 50% of the problem

[Hyecee]

I saw another article about the same thing on Technocrat.net yesterday. They make the distinction that it's not related to the Sterling Engine:

"This is a thermodynamic cycle invented in 1995 by Jeff Sterling, It should not be confused with the unrelated Stirling engine invented in 1816."

There is some other info in the article that explains things from a different perspective, as well, so it might be good for compare and contrast.

"Solar Powered Air Conditioning Getting Real" via Treehugger

Re:Only solves 50% of the problem

[Ohreally_factor]

I think the point he was making is that cold does not radiate, despite appearances. Radiation has a specific scientific meaning. While it might make "sence" to you, it will lead to all sorts of problems and misunderstandings should you want to, say, build something that needs to be cooled. That and you might get hauled into court for attempting to break the second law of thermodynamics. =)

Re:Only solves 50% of the problem

[It'sYerMam]

That's as maybe, but by refusing to understand "radiate cold" as inverse radiation of heat, you just being willfully ignorant. Technically, there's no such thing as sucking - "negative" pressure is just positive pressure acting in the other direction. But we still understand the phrase, and don't actually care.

Re:Only solves 50% of the problem

[Ohreally_factor]

I know what you're saying, but I still side with Alioth on this. Radiation has a specific meaning in science. Is this being pedantic? "Radiant Cooling" sounds like something someone in marketing would come up with. It describes the effect, but at the expense of communicating what is really going on. If you want to say "cooling through heat transfer", then just say it.

Re:Only solves 50% of the problem

[Fordiman]

I don't get how this works without bleeding the efficiency of the systems it draws from.

I don't see what's wrong with having a parabolic mirror concentrate sunlight on the hot side, and running the cool side through a finned radiator, and blowing ambient air through it (mounted under the mirror to take advantage of its shade would be most efficient, I think). You could go stirling (more efficient, lower speed) or turbine (less efficient, higher speed) that way.

I wouldn't be worried about night-time or cloudy-day stuff. Electrical use is highest when the sun is beatin'est.

Re:Only solves 50% of the problem

[tomstdenis]

Suction is the creation of a negative pressure. Blowing the opposite. You can "cool" something, that is, to cause it to have the senstation of being cooler than its surroundings [or more technically to cause it to lose energy], but you can't "radiate cool".

It'd be like saying "that wind is really sucking me around."

Tom

Re:Only solves 50% of the problem

[jbb1003]

2kW @ 9000EUR means 120W comes in at 540EUR, or 900AU

The OP said it would cost 1000AU. So "Next time please don't pull prices out of your ass" feels a bit harsh - and who's to say that panels aren't cheaper in Europe?

Re:Only solves 50% of the problem

[Brickwall]

In Toronto, a recent project takes cold water (4 degrees C) from Lake Ontario, and uses it to provide air conditioning to downtown office buildings. According to the news reports:

Buildings that have joined the grid no longer need to use electricity to run chillers and save nearly 90 per cent of their power costs. The amount of coal-fired electricity required to run air conditioning in those same buildings would produce 79,000 tonnes of greenhouse gases the equivalent of 15,800 cars on the road, the company estimates. http://www.canada.com/topics/news/national/story.h tml?id=7dcd955a-d69f-4bc7-a553-9a4798d388ed&k=8946 7/

Re:Only solves 50% of the problem

[DigitalLogic]

I am glad you pointed out the temperature difference, that was what I was going to do. The temperature difference is extremely important, you do not have a system with just heat.

Re:Only solves 50% of the problem

[Ana10g]

You're actually thinking of this backwords... yes, you are still doing radiant heat, but instead of using the radiator to gather heat, you're using it to dissapate heat. Cars do this all the time, and it works very well. It makes a lot of sense to have a dual purpose system, as the layer of the planet to which the GP is referring (or was it GGP?) is very consistent, and, if you're sending the air from in the house through the "diffuser" (or radiator, whatever) buried deep down in the dirt, physics will take care of the determination of if it should make it hotter or colder (if the house is colder than the dirt, the air will warm up, and if it's wamer than the dirt, it'll cool down). Oversimplified example, but the physics definately apply.

Re:Only solves 50% of the problem

[deficite]

Give it a rest! I'm pretty confident that these guys know about heat transfer either as well as you do or perhaps even better. You're beating a dead horse here because you aren't addressing their argument at all, you're just blasting the same crap over and over. An argument is not even taking place here because you keep repeating the same crap like a broken record.

Re:Only solves 50% of the problem

[drsquare]

Australia. I think aircons should run primarily on photovoltaics because that way you get the highest power when it is needed the most.

Air conditioning is of most use at night. Unless you live in the arctic circle your proposal means everyone will roast in their beds.

Re:Only solves 50% of the problem

[rk]

'but you can't "radiate cool"'

Speak for yourself, buster!

Re:Only solves 50% of the problem

[jank1887]

But in the initial post he didn't say radiate cool. he said "radiant cold". if you're nitpicking semantics, stick to the right ones.

starting with a response to the validity of the term radiant cooling, it is just as valid as any other type of cooling. As said before, you never create "cold", i.e., destroy energy. You move it. Thus calling an effect heating or cooling is a relative term, and it is relative to the desired end temperature of the item of interest. your conventional room air conditioner doesn't create cold within your house, it heats the outside air by transferring energy to it from inside your house, leaving net less energy inside. Cooling just describes the end effect of that energy transfer on the interior condition of your house. Radiant cooling just means you've used the process of radiation to achieve a more comfortable personal heat transfer steady-state in your house.

Heating or cooling is a relative term. In either case your are just transferring energy from a hot item to a cold item. Even the terms hot and cold are relative. You are transferring energy from the item with more to the item with less. That item with less may seem hot relative to another item. If you say something is 'cold' you actually mean "it's colder than something else (your skin, etc.). If it 'feels cold' that means thermal interaction with it creates a transfer of heat from you body to the item.

So, radiant cooling exists as much as radiant heating, as either is just transfer of energy via radiation. The person stated originally, "if you didn't heat the house the basement would be the warmest part from the radiant heat in the walls vs the radiant cold upstairs". Radiant cold, being a relative term, means it is a colder radiant source than the comparative hot item, meaning it will be a net absorber of energy. It is an item which primarily transfers heat via radiation yet primarily absorbs energy from the other radiative participants.

He didn't say "thermal sink" or anything that involved the "injection of cold into the system" which wouldn't make sense. He never sugested violating physics, and didn't even invent the radiant cooling terminology (Google radiant cooling or radiant cold). Technically he was not incorrect in that respect, and this whole argument/thread about radiant cold is rather silly. But then, it's slashdot. What else should we expect :)

Re:Only solves 50% of the problem

[QMO]

Great!
-Change the temperature of Lake Ontario.
-Inadvertently weaken a few species that like cold water.
-Accidentally give a little advantage to a few (non-native?) species that prefer the water a little warmer.
-The ecosystem of the lake is destroyed.
-But maybe the swimming will get better.

Re:Only solves 50% of the problem

[edunbar93]

Air conditioning is of most use at night. Unless you live in the arctic circle your proposal means everyone will roast in their beds.

Huh? Around here, it just so happens that the lack of sunlight at night cools the surface of the earth, so miraculously, just pumping air from outside to the inside results in a living unit that gets cooler too.

Just as miraculously, if you keep the temperature of said living unit cool during the day when the sun is shining, it doesn't take a lot of energy to make it cool after the sun sets.

Moreover, who says you have to get all your power all the time from solar? If you're hooked up to the power grid, you can use your solar panels to generate power that goes into said grid, and makes your meter run backwards. You're then producing power for other people to use, and as such reducing the amount that the power authority has to generate. You win because your bill goes down. They win because their bill goes down. Everyone's happy.

Of course, silly ideas like CF lights and high efficiency refrigerators might help that too.

Re:Only solves 50% of the problem

[edunbar93]

Next time please don't pull prices out of your ass.

He's not.

Re:Only solves 50% of the problem

[Anonymous Coward]

Wow, that would be expensive. Here (germany) you get 2kW (10x200W) for 9000 EUR

Next time please don't pull prices out of your ass.


Your solar panels are also artificially subsidised by your government.

Next time, consider /all/ the variables.

Re:Only solves 50% of the problem

[Mr. Slippery]

Yeah but by saying "you radiate cold" you fundamentally don't understand what's going on.

It makes every bit as much sense to speak of something "radiating cold" as it does to speak of "hole flow" in a semicondutor, or indeed "conventional current" in any electric circuit. Relax.

Re:Only solves 50% of the problem

[Dun Malg]

Huh? Around here, it just so happens that the lack of sunlight at night cools the surface of the earth, so miraculously, just pumping air from outside to the inside results in a living unit that gets cooler too. Just as miraculously, if you keep the temperature of said living unit cool during the day when the sun is shining, it doesn't take a lot of energy to make it cool after the sun sets.

In very hot climates, nighttime doesn't result in significantly cooler temps. The "miracle" of thermodynamics dictates that when the sun heats up millions of tons of dirt and rock, that material stays hot even after the sun has gone away. By morning you're lucky if the air has cooled to 80 degrees. What this means is that your air conditioning system has to run 20-22 hours a day to keep the living space cool.

Re:Only solves 50% of the problem

[nsayer]

"Look! There's footprints in the snow ahead!"

Reference hint: A. A. Milne.

Re:Only solves 50% of the problem

[nsayer]

Where do you think the money for all those mandated solar panels actually comes from?

Raise the cost of the office building and you raise the cost of the office space. Raise the cost of the office space and the owners of the business will have to charge more for their services. And so on. You might as well simply tax everyone and buy the panels that way.

Re:Only solves 50% of the problem

[AnotherBlackHat]

There just isn't enough energy hitting the roof of even a moderate office block to power the aircon irrespective of the price of solar cells. Energy from the sun totals about 1kW per sq m. Look at amount of unused space on the roof most office blocks. The amount of power you can generate simply isn't enough to power the aircon even if solar cells were 100% efficient. Even the best solar cell is 20% efficient and that drops with time (not counting the fact that huge amounts of power go into making a solar cell int he first place).

Solar cells have a loooooong way to go before they are worth it. Wind turbines on the other hand are nearly there.

The colo facility my servers are in has about 5,000 square meters of roof space, of which more than 50% is unused.
2,500 square meters = 2.5 megawatts at 100% efficiency, or more than twice the power used.

Data centers aren't typical though, a more typical business uses less than 100 watts per square meter of office space.
Without bothering to post the details, the breakdown point is about two stories, buildings taller than that don't get enough sunlight to completely power themselves, though if all you wanted to run was the air conditioning you could probably go taller.

All of which is irrelevant.
Solar cells on the roof are worth it when they generate more electricity than it costs to put them there.
Whether that's 100%, 50%, or 2% of the total amount of electricity consumed by the building doesn't matter.
You don't have to run all the air conditioning off solar, you can have a mix of conventional and nonconventional technology.
The "magic" price point is a dollar a watt, which we aren't at yet, but we are close. ($3 a watt is the cheapest I've seen)
And more importantly, it's likely that we will have some fundamental improvements in solar cell technology, like cheap Gratzel cells.
Wind turbans on the other hand are are very old technology.
There have been some improvements, but they nearly as cheap today as they will ever be.
The only real "improvement" is that the price of alternatives is going up.

-- Should you believe authority without question?

Re:Only solves 50% of the problem

[bhiestand]

It would be nice, except for the cost. I bet a 120 watt solar panel costs around AU$1000 in volume. Even in a sunny place you're going to want at the bare minimum 10 of those panels per kilowatt you need, so by the time you're done you're going to be spending $200,000 on solar panels to run your house.

Nice to know you pulled a nice round number out of your ass. I know a small CNC machine shop (think several large computerized cutting machines constantly running), complete with air con at 74 degrees and several computer workstations on 12+ hours per day that runs entirely off of solar. The whole system cost around $40,000 before tax rebates, if I remember right. During the summer months the meter actually rolls back (it's on the grid), so that the net electricity bill is essentially nill.

Re:Only solves 50% of the problem

[dajak]

This guy is quoting a price of a little over EUR5/Wp, which is about the same price as in Europe. If you buy a larger system, the price can drop to EUR4.5/Wp, EUR4/Wp, but little less.

Whether this is very expensive depends on the price of energy where you live. In the long run you will probably get a better deal than you thought when you bought them, as energy has been getting more expensive in most of the world the last decade.

Re:Only solves 50% of the problem

[bhiestand]

My apologies. 40,000 USD. That's about 53,000 AUD last I saw.

Re:Only solves 50% of the problem

[Intron]

If you can get the cost down to $1.85, then its a sterling engine.

Re:Only solves 50% of the problem

[Anonymous Coward]

More energy efficient construction has been done for cold regions (where houses require almost no heating during winter when isolated well, the inhabitants' body heat is sufficient)

Hey! Would you like a job in Finland, because we haven't figured out yet how to heat our houses with just the heat from making love or farting.

Re:Only solves 50% of the problem

[chgros]

In very hot climates, nighttime doesn't result in significantly cooler temps.
You mean in very damp climates. Desert nights are cold.

Re:Only solves 50% of the problem

[Brickwall]

"Change the temperature of Lake Ontario"

RTFA. The water that is drawn out of the lake is used in a heat exchanger, and then is passed to the pumping station for treatment before going out as the local water supply. This water was coming out of the lake before; they're just drawing from a slightly cooler source. No hot water is being passed into the lake.

And even if the entire 61 MW was being passed into the lake, 24/7/365? It works out to about 500 trillion calories, which is not enough heat to raise 1 cubic km of water 1 degree C. Considering Lake Ontario has some 1639 cubic km of water, the net effect will be zero.

Who modded it up?

Re:Only solves 50% of the problem

[Anonymous Coward]

The prices were "not pulled out my ass" but sample prices from a supplier of panels.

Then cite your source with a link next time. Also, you used the phrase "I bet" which indicates that you were not sure. Use clearer language next time to say what you mean.

Re:Only solves 50% of the problem

[LouisZepher]

Ditto. I'm so cool you can keep a side of meat in me for a month...

Re:Only solves 50% of the problem

[drsquare]

You mean in very damp climates. Desert nights are cold.

Bullshit. Try going to Egypt in June and tell me it's cold at night.

Re:Only solves 50% of the problem

[Anonymous Coward]

20kW electrical power is an enormous amount of power for AC in a house - the AC will probably have 60kW cooling power, and if you need that, you really should invest in better isolation, or just try keeping your windows closed or at least the shades down. The solar constant is just above 1kW/m^2, so you would have to have the sun shining into your house through 60m^2 of glass apropriately slanted to let in essentially all of the light, and none of it shaded.

Re:Only solves 50% of the problem

[QMO]

I guess if I should have used the joke tags. Sorry for the confusion.

Re:Only solves 50% of the problem

[chgros]

I don't mean "Egypt" I mean "desert". Egypt is not just desert you know (especially places where people are are usually not desert)

Re:Only solves 50% of the problem

[Alioth]

But 20kW of solar photovoltaics is not 20kW due to the intermittent nature of sunlight (none at night) so if you want to run your airconditioner off solar photovoltaic - unless you want sweaty nights, you're going to need at least twice the solar photovoltaic capacity that the air conditioner actually needs (probably more if you want to account for partial cloud cover) - and a shedload of electricity storage.

If all you want to do is make a dent in the power consumption of the AC, then sure - you need less than 20kW of solar capacity. (It also depends on how big the house is of course). However, if you want to run all your AC needs of solar panels you will need significantly more solar than the AC's average power draw.

Re:Only solves 50% of the problem

[AeroIllini]

Wind turbans on the other hand are are very old technology.

Is that like a turban with a built-in fan? 'Cause that would come in really handy in the hot Saudi Arabian desert.

Re:Only solves 50% of the problem

[griffix]

I don't know if this is correct it has been awhile since I took physics. If the gas is compressed before it hits the turbine and uncompressed as it hits it. The uncompressing of the gas cools it, and that might be enough to recondense the liquid. It probably depends on the properties of the liquid/gas they are using. Does that sound right?

Re:Only solves 50% of the problem

[bhima]

OK *fine* anti-radiant cooling... is that OK?

Re:Only solves 50% of the problem

[amerinese]

The good thing is that the Taiwan thinks that solar energy is one of the next big things and is investing heavily in growing their solar panel industry. If Taiwan is making it, don't worry, it will get to below $1 per watt.

Re:Only solves 50% of the problem

[Eccles]

We already make photovoltaics at or near the limits of economies of scale. They are just . . .plain . . .expensive to make. Innately.

What makes them expensive to make?

Seriously. I assume they're not hand-crafted. Is it the raw materials? The manufacturing? Silicon is cheap, pure silicon probably much less so, but still tolerable; what makes solar cells expensive to make?

Re:Only solves 50% of the problem

[mambodeath]

you actually are a side of meat. two of 'em.

Re:Only solves 50% of the problem

[LadyLucky]

In such climates with low humidity you can use a much simpler system - you simply blow outside air over a pool of water. The water evaporates, absorbing energy from the air, cooling the air down. This uses far less energy than an aircon unit.

Re:Only solves 50% of the problem

[WatchTheTramCarPleas]

What about cooling underground? There are probably a few places where this isn't possible, but most of the time deep in the ground, it is a lot cooler. I don't know if the ground could easily absorb the heat necessary though, and obviously would require different setups depending on the soil type at the installation site.

Re:Only solves 50% of the problem

[Anonymous Coward]

you just being willfully ignorant.

Welcome to the wonderful world of Tom St Dennis. And by wonderful, I mean "sucktastic."

Re:Only solves 50% of the problem

[evilviper]

I wouldn't be worried about night-time or cloudy-day stuff. Electrical use is highest when the sun is beatin'est.

So, you're spending all this money on setting up a power generator, which is really only useful a tiny percent of the time (summer, peak power usage hours). In the winter, you'd probably be better served by using those water-heating panels to heat your home (and water) directly.

I think I'll put my money in the bank, and use the earned interest to pay (more than) the difference of my electric and gas bills.

Re:Only solves 50% of the problem

[AK Marc]

Bullshit. Try going to Egypt in June and tell me it's cold at night.

Certainly cooler than the day. Summer days *always* draw more electricity than summer nights. The more sun, the more electricty that is used. Conveniently, more electrivity from the photovoltaics.

Re:Only solves 50% of the problem

[kfg]

What makes them expensive to make?

Well hey, you try turning sand into a semiconductor and not spend a lot of money in the process.

http://www.facsnet.org/tools/sci_tech/tech/fundame nts/clean.php3

http://www.eere.energy.gov/RE/solar_photovoltaics. html -- Scroll down to the bottom of the page for cost issues.

There is one factor that isn't addressed directly, only indirectly in terms of cost; and that's the incredible amount of energy required to make semiconductors (and you have to include the energy costs of creating the facilities in that) and that energy does not come from the solar cells the fab puts out. The whole affair would grind to a halt if you tried that, like a "free energy" machine unplugged from the wall. At which time the cost per any "excess" units would be phenomenal.

The whole thing runs on . . .oil. No oil. No solar cells. Ironic, innit?

And as the cost of oil goes up, the cost of manufaturing solar cells goes up. The break even point is an ever moving target proportional to the cost of what we're trying to replace with something cheaper, and/or compelled to consume its own output in a vain attempt to keep going.

There's a hole in the bucket, dear Liza, dear Liza.

This is the Renewable Dilemma, that it takes energy to make usable energy and without a source external to the system it feeds on itself. It isn't about cost, it's about energy. To follow the money you need to follow the energy, because over the short run the money can be used to disguise what's really going on(investment, tax incentives, etc) at the energy level, but when the energy runs down, so does the money; and costs skyrocket.

So you grow biofuels to replace oil, which means you have to use your biofuels to grow your crops and refine them into fuel. How much fuel is actually left over when you've finished this and - at that point how much is the "excess" going to cost per gallon to the consumer - assuming there is any?

That is your true cost of renewables as an oil "replacement." What you have to pay when the oil is gone and no longer driving the process. Using solar cells to make solar cells.

You won't like it.

But are you starting to get it? Solar cells are expensive because it takes energy to make them.

KFG

Re:Only solves 50% of the problem

[njh]

We bought solarex polycrystal 85W panels for $550AU, excluding rebate, 8 years ago. But I agree, PV is probably not the cheapest way to cool your house - better insulation, smarter ventilation policy, decent thermal mass in the house and growing pumpkins on the roof would give much the same cooling effect for less than the price of a bottom of the range installed wall unit. Indirect cooling is a better choice too.

Re:Only solves 50% of the problem

[njh]

Your solar panels are also artificially subsidised by your government.

So is the petrol, electricity, natural gas, diesel, heating oil, biodiesel etc.

Next time, consider /all/ the variables.

Re:Only solves 50% of the problem

[njh]

The technical term for this is EROEI (Energy returned on energy invested) (http://en.wikipedia.org/wiki/EROEI). Every energy source has this. For fossil oil it is currently around 5:1, for PV it is at least 6:1 (http://www1.eere.energy.gov/solar/clean_energy_pa yback.html). Converting oil into solar panels is thus a sensible thing to do - certainly better than burning, which is what you seem to be advocating? The same is true for biofuels - biodiesel produces 2l of fuel for every litre invested, so it is a good investment if you want to multiply the value of that fossil energy. Clearly once bootstrapped any net positive EROEI can be self-powering, as long as the energy is in a suitable form.

Solar panel manufacture needs chemical energy to convert SiO2 into Si (electrolysis is not cost effective AFAIK) and oil/gas/coal is a reasonable way to achieve this. In a solar power future the reduction might be done by solar-thermal electrolysis of water to hydrogen, and use the hydrogen to produce silane.

The reason people don't solar panels everywhere is simply because they are too expensive. There are many reasons for this, but from a purely energy physics point of view there is nothing wrong with the current production.

Re:Only solves 50% of the problem

[njh]

Probably should just use it for hot water - people demand enough hot water that a rooftop combining PV and SDHW will offset a large chunk of the total energy demand of the house. (And much cheaper than some complex mechanical system)

Re:Only solves 50% of the problem

[BlackSabbath]

OK - I'll bite. Where?

I'm in the market and the best price I can get is a little under $12K for a 1KW setup AFTER the rebate.

Re:Only solves 50% of the problem

[kfg]

The technical term for this is EROEI (Energy returned on energy invested)

Yes.

Every energy source has this.

Of course. That is innate. Even in just lying in the sun. Fossil Oil simply has the advantage of being a "found" concentrate. The disadvantage of being "irreplacable" (within a timespan relevant to the human lifetime) initial capital.

Converting oil into solar panels is thus a sensible thing to do -

Of course. Often times the optimum solution. You won't find many cruising sailboats these days without a solar panel somewhere about. Some also drag generators.

. . .certainly better than burning, which is what you seem to be advocating?

Hardly. In fact I haven't advocated anything at all. What I am doing is noting that the burning is part of the process of converting oil into solar panels.

Clearly once bootstrapped any net positive EROEI can be self-powering, as long as the energy is in a suitable form.

Clearly. But net yields go down. Scarcity goes up. Crop fuels and photovoltaic power are also proportional to acerage and weather, something oil isn't. So you'll need backup at full capacity for those times when the crops fail or the sun goes down. Less oil also means you need more acerage for the same return in crops. Have you tried self sufficient farming? Certainly it's a good way to leverage oil, but leverage and replacment are two different things.

The reason people don't solar panels everywhere is simply because they are too expensive.

Of course. And they will remain so. In fact, as oil becomes more expensive they will become more expensive in real dollars, as a proportion of what you have available to spend. Dearer. Because we will be using energy obtained at a higher EROIE to make them; and thus increasing their own EROIE as well. It's a feedback system, although damped.

. . .from a purely energy physics point of view there is nothing wrong with the current production.

Of course not. Just add oil. Easy. In the abscence of oil, just add. . .something else, from . . .somewhere.

Again, not advocating, just noting.

If I were to advocate anything it would be contraception. Scarcity is relative to the population. Fewer people, more "stuff" per capita. Not too little oil. Too many damned rats in the cage. "Spaceship Earth" and all that.

KFG

Re:Only solves 50% of the problem

[Anonymous Coward]

I'm so hip I have trouble seeing over my pelvis.

Re:Only solves 50% of the problem

[njh]

Again, not advocating, just noting.

If I were to advocate anything it would be contraception. Scarcity is relative to the population. Fewer people, more "stuff" per capita. Not too little oil. Too many damned rats in the cage. "Spaceship Earth" and all that.

The other two ethical/political things would be improve everyone's standard of living (which will require a change in energy usage patterns) and encouraging frugality.

Re:Only solves 50% of the problem

[Fordiman]

Possibly. I'm not exactly chomping at the bit to build one myself. I can think of much simpler ways to utilize a parabolic reflector (stamped aluminum polished to an automotive finish would likely have the best cost/efficiency ratio) than putting it through a near-goldbergian heat-transfer device.

No, seriously. This is little more than a retrofitted air conditioner - and it wouldn't do bollocks even if you coupled the turbine directly to the compressor of another AC.

Re:Only solves 50% of the problem

[kfg]

You're going to have to seriously redefine "Standard of Living." :)

KFG

Re:Only solves 50% of the problem

[njh]

Well my house is already using less than half national average footprint, and we're comfortable, so we can certainly make some progress. I agree there are lots of problems. My big gripe is that outside technical forums like this nobody is willing to talk about the problem carefully.

(Thanks for the chat)

Re:Only solves 50% of the problem

[kfg]

I guess my own rule of thumb for a good standard of living is, "Enough, but not too much to dust."

But then I like to dress in "bedsheets" too. I'm not exactly typical.

KFG

Re:Only solves 50% of the problem

[Anonymous Coward]

The same intermittent natuer of sunlight also reduces your power requirements for the AC. Not in the same degree as it will reduce the output power of the photovoltaics, but the point remains that a AC with 20kW electrical power will be way too much for an average house, and instead of investing in photovoltaics to keep the AC going, you'd better insulate the house, invest in double glasing, or consider a geothermal exchange heat pump, all of which will not only reduce your demand in airconditioning power, but also the heating requirement in winter.

Re:Only solves 50% of the problem

[Eccles]

Well hey, you try turning sand into a semiconductor and not spend a lot of money in the process.

Iron ore into steel and bauxite into aluminum takes a lot of energy, but those metals aren't particularly expensive. Is making silicon from sand that much more energy intensive? Look at one of those linked articles, and what does it say?

"Photovoltaics are expensive to produce because of the high cost of semiconducting materials. Cost reductions can be achieved by reducing manufacturing costs. As manufacturing capacity increases, costs of manufacturing decrease."

I.e., from that last sentence, it is at least in part a matter of relatively small production lines.

You need fairly pure silicon, but nowhere near the purity needed for IC production. You have to dope the materials, but again, no ultraclean room needed.

As for oil to produce solar, that's because solar cells are expensive; but that's circular logic. "They're expensive because they're expensive."

Re:Only solves 50% of the problem

[drsquare]

You don't need air conditioning during the day, it's when you're trying to sleep you need it.

Re:Only solves 50% of the problem

[AK Marc]

You don't need air conditioning during the day, it's when you're trying to sleep you need it.

So, you are in places without air conditioning from 8 a.m. to 5 p.m. every day and do not enter an air conditioned area until after 5 p.m.? That would not be how the vast majority of the US spends their time.

Re:Only solves 50% of the problem

[macdaddy]

The obvious solution to this is geo-thermal cooling. I've had about a dozen conversations about this over the past month (100+ temps here in Kansas tend to prompt discussions about keeping cool). The constant 55 degree temps of the Earth are more than enough to cool the steam. This sounds like a nice pairing of technologies.

Re:Only solves 50% of the problem

[kfg]

Iron ore into steel and bauxite into aluminum takes a lot of energy,but those metals aren't particularly expensive.. . .

Steel and aluminum are not equivilents. Iron and aluminum are. Aluminum is more expensive than iron, even though the ore is less scarce, because it requires more energy to refine it than does iron.

Of course cost itself is a swimmy issue. It depends on what units we use to measure it, which depends on what we intend to use it for.

Dollars per volume/pound/tensile strength/electrical conductance/purity . . .etc.

Simply saying "cost" is meaningless.

Is making silicon from sand that much more energy intensive?

Look at one of those linked articles, and what does it say?

"Photovoltaics are expensive to produce because of the high cost of semiconducting materials."

This is largely due to the amount of energy it takes. We also produce it at or near the limits of economies of scale, so that cost is not going to be coming down much for that reason (once upon a time aluminum was a rare and expensive metal. Now its price is not going to drop dramtically due to economies of scale. We've achieved them).

"Cost reductions can be achieved by reducing manufacturing costs."

Well of course they can. I've never denied economies of scale.

"As manufacturing capacity increases, costs of manufacturing decrease."

Indeed, but what percentage of the price does that represent and what are its limits? Economies of scale are not an arbitrary factor you can invoke to arbitrarily reduce prices. What's more, as you approach the limits the cost reductions become more and more of interest to the manufacturer, but of less interest to the consumer.

Have you ever found yourself thinking:

"What the hell did they do that for? It would only have cost them an extra penny per unit to make it ten times better!"

Aha!

Economies of scale can fuck the consumer as they approach the limit, because that extra penny means nothing to the consumer, but a great deal to the manufacturer. Price reductions due to economies of scale are not always a simple issue, because cost depends on the units you measure it with; and the scale you measure those units on.

. . .from that last sentence, it is at least in part a matter of relatively small production lines.

Is it? There are solar cells in wrist watches, pocket calculators, novelty hats. Solar cells are pumped out by the godzillion. At what scale do you expect prices to take some sort of relevant nose dive? The ultramegagodzillion?

Let's take a look at the obverse of the solar cell. The LED. Do you think there's going to be some sort of real reduction in cost to LEDs through economies of scale? They already make those by the ultramegagodzillion.

And they're cheap. As are solar cells. In fact, they are, effectively, the same price, because they are, effectively, the same thing.

But how do we measure the cost of solar cells?

Aha!

You have to dope the materials. . .

i.e., make steel from the iron.

As for oil to produce solar, that's because solar cells are expensive; but that's circular logic.

Huh? What I said was solar cells are expensive, that's because oil is used to produce them. Something that takes two gallons of oil to produce is going to innately be more expensive than something that takes one gallon of oil to produce, assuming equality in other factors.

And the cost of oil sure as shit isn't going to be coming down due to some economy of scale or other. We've already squeezed that puppy so hard that people are shooting each other over margins of a penny.

People are funny critters.

Anyway, now you've got your solar cell; and it's cheap.

What good is it?

Aha!

We're back to the units thingy again. :)

KFG

Re:Only solves 50% of the problem

[drsquare]

Why would I need air conditioning during the day? I only need it to sleep, I don't need to be comfortable when I'm awake do I?

Re:Only solves 50% of the problem

[Eccles]

Steel and aluminum are not equivalents.

Chemically, sure. In practical terms, however, they're both generally made with high-temperature smelters. And I think you missed my point: iron, steel, and aluminum, despite needing these high-temperature industrial processes, are all fairly cheap. They need energy, but that energy doesn't increase the price that much. And raw silicon metal? Less than a dollar per pound. ( http://minerals.usgs.gov/minerals/pubs/commodity/s ilicon/760397.pdf ) The cost of the silicon in a 120 watt solar cell is probably less than $20. (Evergreen's $600 model weighs 28 lbs. ( http://www.affordable-solar.com/evergreen.ec.120.g d.120.watt.cedar.solar.panel.htm )

So if it's not the raw metal, and clearly it isn't, what stage(s) of turning sand, etc. into a solar cell are expensive? *That's* what I'm trying to figure out. It doesn't seem you know specifically either; your (reasonable) point is generally "if it could be made cheaper, it would have already." And you may be right, I'd just like to know what in the process is the tough point or points.

Re:Only solves 50% of the problem

[AK Marc]

Why would I need air conditioning during the day? I only need it to sleep, I don't need to be comfortable when I'm awake do I?

Yes, you (generic) do need it during the day to remain comfortable. The energy usage in the US shows that energy use spikes during the day when people are up and about and in air conditioning. Energy use is greatest when the sun is up and least when the sun is down, and that's why solar is a good thing to have to suppliment the other power sources.

Re:Only solves 50% of the problem

[kfg]

And I think you missed my point: iron, steel, and aluminum, despite needing these high-temperature industrial processes, are all fairly cheap.

But iron ore costs less than iron costs less than steel; and always will. No amount of scale can ever reduce the price of steel to that of iron. Aluminum costs more than iron, despite the ore being in greater supply. The differences in the costs are energy costs.

If you want to build a bridge you do not buy ingots of pig iron (singularly usless stuff in and of itself, except maybe as a doorstop). Nor do you even buy steel. You buy steel beams. A steel beam costs rather more than steel ingots of the same weight. For starters, of course, it needs a good deal more energy put into it to form it into a beam.

Even iron ore costs vary by purity. Purity costs energy.

They need energy, but that energy doesn't increase the price that much.

Think not? Go buy some iron ore. Now go buy some 4130 steel. In point of fact you could simply go find some iron ore. You're not going to go find some naturally occuring 4130 steel. You're going to need a furnace.

And raw silicon metal? Less than a dollar per pound.

Here's where the root of your confusion seems to lie.

That price is a commodity price. What you would pay to have your computer screen tell you you own it.

I build bicycle frames. Pig iron goes for about ten-fifteen cents a pound (I didn't bother looking up today's price) . By the time it reaches my door it is twenty five dollars a pound of steel, as delivered.

That is my cost of "raw materials." There's nothing weird or inexplicable about this, the stuff has been traded, processed, shipped, formed, shipped, traded some more. . .and that's the way it is. And all of it represents use of energy (not that some of the trading represents useful energy).

By the time I processes it and ship it to you you're paying fifteen hundred dollars for ten cent a pound iron.

The price you quote is also 10 years old. What's more that's metallurgical silicon. The equivilent of pig iron. You might want that if you're making aluminum alloy, the equivilent of steel, which will sell for rather more than raw aluminum. Solar cells aren't made from metallurgical silicon. They're made from cryastalline silicon, the same as any other semiconductor. You're going to have to . . .purify it. Crank up the "furnace."

Metallurgical silicon is 98% pure. Purifying energies are logarithmic. 90% pure, piece of cake, but 99% (just a tick more than that metallurgical stuff) costs just as much again. 99.9% pure, just as much again, talking in crude, round numbers.

We're looking for polycrystalline silicon, just to make things easy. The "low grade," cheap stuff of "consumer grade" solar cells.

Purity of one part per billion.

Formed into a bar.

This is the pig iron of the semiconductor industry. The real raw material. What you have to buy and have delivered to your factory if you want to work from raw materials, like a blacksmith. The stuff that article was talking about manufacturing.

And the cost of it doubled last year. It seems there's a shortage of the stuff, because the people who produce it are now working at capacity, but the demand keeps rising. The cost of solar cells is going to go up.

It's important to note that this doubling is a scarcity price of the raw material. More production will bring the cost down, but will not bring the manufaturing costs down. Manufacturing is already being done at maximum scale per production facility, at the maximum possible economy. More capital will need to be invested, but that capital will need to be amortized all over again.

So, anyway, now that we have had our raw material (a dominant factor in the cost of our goods) dropped off at our loading dock we can

Re:Only solves 50% of the problem

[Eccles]

And by the way, your solar panel is nearly useless. You're going to need more stuff if you actually want it to keep the light in your house on at night.

That's for the nuke plant to handle, or utility-run reservior "batteries" (raise the water when you have excess, drive a gravity turbine when you need more), or even some coal. I'm not trying to escape the grid, just trying to turn the solar energy hitting my roof into useful energy and reduce coal usage.

And even with these shortages of polysilicon, 120 watt panels are $600. They don't have to go down that much to become cost-effective, esp. with my local utility planning a 75% rate increase. If average power need of a house is on the order of 1000 Watts, that's 8 of those panels; if they drop to $300, that sounds quite affordable if installation and wiring doesn't vastly increase the cost.

Re:Only solves 50% of the problem

[kfg]

I'm not trying to escape the grid, just trying to turn the solar energy hitting my roof into useful energy

Ok, I'm about as green as they come without having to have a lobotomy, but, if you've got a nuke plant . . .why? Sounds like a job for a solar water heater, not solar cells.

raise the water when you have excess, drive a gravity turbine when you need more

I like cement blocks on a rope and a pully. The pendulum clock model of power.

They don't have to go down that much to become cost-effective. . .

Payback in about 20 years at current current (ain't English grand?) and panel prices. The higher current (there's that English again) prices go after install, the quicker the payback. Not taking into account what you might earn if you just invested the money. A good panel is expected to last about 40 years, but they aren't maintanence free. I hope you like climbing up on the roof. If you pay someone to do it for you, add that to the payback time.

From the article linked:

the soaring cost of fuels burned to make electricity.

Well there ya go!

If average power need of a house is on the order of 1000 Watts. . .

Don't turn on your A/C and your desktop at the same time.

. . . if they drop to $300. . .

I wouldn't bet on it. Besides the shortage, increases in fuel prices increase solar panel prices. That's just the way it is. Food, clothing, movies, action figures, lumber, iron, aluminum, paper . . .all going up. Salaries won't be. It's crunch time.

. . . if installation and wiring doesn't vastly increase the cost.

You're going to need batteries (or cement blocks and a generator), a charge (or cement block) controler and an inverter. Labor to get the panels on the roof and an electrician to hook it all up. The permits of course. The permit people might not like the cement blocks. People are funny critters. If you want to run your house just as you do when drawing from mains (doing a load of wash without turning off the A/C) figure $30,000.

A third to half that if you just want to save some coal.

If you radically change the way you run your house things change, but the permits people don't always like that.

KFG

Re:Only solves 50% of the problem

[Eccles]

Gads, an actual long-running discussion on /. What a concept.

Ok, I'm about as green as they come without having to have a lobotomy, but, if you've got a nuke plant . . .why?

Me personally? No. My assumption is that we're discussing what an average homeowner can do to go green without major lifestyle changes and without going broke. Ideally, we're hoping that we can spend a bit more up-front but actually save money in the long-run. As such, I assume that I'm not going to change the grid overnight, and that I plan to stay connected to it unless that really pays off.

Based on that assumption, I can use The Grid as a battery, selling excess power back to the power company. It makes a lot more economic sense than to try to rig up my own storage system.

So yeah, in the end what we're really arguing about is whether the amortized cost of a solar panel system could be as low or lower than the reduction in my electric bill. I think we'll just have to wait and see. One of the thin-film approaches may achieve the up-front cost lowering, or perhaps a cheaper doping process will appear. If it does, solar could be cost-effective even you're as environmentally conscious as the average Hummer driver.

One could even create a spreadsheet or little app to compute the crossover point based on assumptions about inflation, investment returns, cost/watt installed, local solar levels, and local grid energy costs.

Thermo

[LesPaul75]

So has the day finally arrived where I can run my AC off of all that heat outdoors?

Ok... I'll be the first to admit I wasn't paying close attention when this was discussed in my college physics class, but something having to do with the laws of thermodynamics feels wrong here. :)

Re:Thermo

[Umbral Blot]

What's specifically wrong is this: to condense the steam back into a liquid you need something colder than its boiling point. Thus on a hot day you couldn't get it to condense, and thus it wouldn't work. What you really need is a a large heat sink, like the ocean or a big peice of ice, and then you could turn the tempertature differential into energy using this device (at the cost of heating up whatever cold thing you were dumping heat into).

Re:Thermo

[Fred_A]

Well, you could put the condensing coil in your fridge. Problem solved !

(I know, just being silly)

Re:Thermo

[warewolfe]

Energy is being extracted from the fluid circuit system and being converted into electricity. Steam re-condenses into fluid because it has lost it's energy to the turbine.

No perpetual motion or violation of the laws of thermodynamics involved, just energy transfer.

Re:Thermo

[stunt_penguin]

How about using the ground, which stays cool even during hot summers. Geothermal heating/cooling systems draw heat from or sink heat in the ground or a body of water depending on whether they're being used for heating or cooling. In this case, you'd run the system underground and deposit your heat there. Obligatory Wiki

Re:Thermo

[smittyoneeach]

to condense the steam back into a liquid

Hm. PV=nRT, right?

Why not have a compressor somewhere removed from the thing you're trying to refrigerate?

With the right engineering/business model, that work could come from people on exercise bikes.

Attack power generation, fat, and unemployment problems in parallel.

This idea is too good to work in practice.

Re:Thermo

[Firehed]

What you really need is a a large heat sink, like the ocean or a big peice of ice

I'm sure Al Gore will love you for suggesting that.

Re:Thermo

[Timmmm]

That's just plain wrong. You need a temperature difference to generate electricity*. I.E. if he wanted to run AC from the heat outdoors, you would need a cooler (or hotter) place too in order to generate electricity. Using a hotter place is just a conventional power station, and if you *have* a cooler place, why do you need AC? Just connect your house to the cold place with pipes.

*If you don't believe me, read this: http://en.wikipedia.org/wiki/Carnot_cycle

Especially: efficiency = 1 - (t_cold / t_hot)

Re:Thermo

[Anonymous Coward]

You might want to reread your thermo book. The effeciency of a turbine is related to the temperature differencial and thus without a temperature differencial it would have zero effeciency. The fact that there is a gas is not enough to turn the turbine there must be a flow which is a close system only comes from temperature differences causing high and low pressure differences thus causing flow.

Re:Thermo

[tradiuz]

Gyms should be tied into the grid...

I've gone to the 24 Hour Fitness to see over 50 people on the exercise bikes, and thought, "Gee, I wonder if enough of these endurance machines (exercise bikes, stairmasters, eliptical machines, treadmills) could be converted to power generation, and would it be possible for the gym to generate a fraction of it's electricity by hooking up the bike farm."

Re:Thermo

[Anonymous Coward]

Thank you! Precisely.

The Carnot cycle guarantees that your energy production depends on the ratio of hot to cold temperatures available to you - and there is mathematical proof that you can't build a heat engine that's more efficient than an idealised Carnot engine. So this gadget can't take advantage of global warming for long because if the atmosphere heats up by a few degrees, so (eventually) will all sources of cooling water, underground ice/water, etc. You can perhaps earn a living while the planet continually increases in temperature - but once it stabilises, you're screwed.

Re:Thermo

[hey!]

Turbines aren't run by heat, but by pressure differential. To be sure some of the kinetic energy of the gas goes into turning the blades which will cause some condensation. But without some kind of condenser on the low pressure side, in any closed circuit the pressure will soon equalize and the engine will stop running. Otherwise, you'd have a perfectly efficient machine, which does not exist.

And, if you're talking about a system that runs on ambient tempertaure, how do you establish the pressure differential to start with?

Fortunately, there is a pretty good heat sink out there: the Earth. You could create a well into which you pump excess heat. Perhaps later you could extract the heat. Either way, a temperature difference can be used to extract usable work.

Everything old is new again. As energy prices climb, ideas for new energy sources are put on the table and attract VC money. Back in the 80s, a friend of mine went to work for a company that developed a system that worked this way. It was conceived in the energy crisis of the 70s. However, energy prices collapsed in the 80s, and the company went out of business. The same thing with many fuel efficiency technologies.

And that's the problem with most alternative energy schemes. There are plenty of physically feasible was to get energy, the question is what is economically feasible. Energy prices are volatile, and private investors don't have the decades long perspective it takes to stay the course and bring the technology to market when it's needed. In time, rise of the smoothed average of energy prices, combined with continued technology advances, will make some alternative energy scheme viable. This might be the time. But probably not.

The present always feels exceptional.

Re:Thermo

[smittyoneeach]

Well, you'd need some clever engineering.
No, it would never work. Better to stick to circuit-switched networks and proprietary licenses. Other possibilities are sheer madness.

Re:Thermo

[Brandybuck]

So basically you're pumping all that heat outdoors into your home.

Re:Thermo

[Lord Ender]

Your sig is seven lines long. Please leave slashdot and don't ever return.

Celsius

[jakuis]

That would be around 14,5 degrees for the rest of the world.

Carnot efficiency.

[Anonymous Coward]

58f = 14.4C or 287.6K

Now lets be generous and let our panel "superheat" the stuff up to 80C or so, and put the cold reservoir in a bucket of ice.

That gives us a heat source at 353.15K and a sink at 273.15.

Efficiency = 1.0 - cold/hot = 1.0 - (273.15/353.15) = 0.226, or about 23% efficient.

Not great.

Re:Carnot efficiency.

[FuzzyDaddy]

A direct comparison of thermodynamic efficiency to solar cell efficiency is not immediately relevant, as you are tapping into different sources of power.

In order to get power from heat, you correctly point out that you need a cold reservoir. Now, for this working fluid, the reservoir needs to be below 58F. The hot reservoir is unlimited (if the air cools down enough, we don't need the AC anymore). So our available energy to run our AC is limited by the cold reservoir.

You could compute, for a given size of cold reservoir, how much cooling you'd get. So what's your cold reservoir? Here's where TFA (and website) are a little hazy. If you have a large reservoir at 58F, why wouldn't you just use that to cool the air directly? So even if you had a large efficiency, I don't think this would make much sense!

Re:Carnot efficiency.

[mdielmann]

Do you mind telling me where you're getting this free ice? I think I'll cool my house with it. Of course, if you're paying for that ice, whether you buy it at the store or make it in your refrigerator, that needs to be taken into the efficiency of your circuit, too.

Re:Carnot efficiency.

[Anonymous Coward]

Efficiency does not matter if you are not paying for the energy input.

Re:Carnot efficiency.

[MADnificent]

A. Mind you, that the carnot efficiency can never be reached in real-life applications.

B. The efficiency of 23% just means that from the 'absolute heat' (~energy) you take from the high reservoir, you can only convert 23% to pure power (as in usefull energy), the other heat (Q_l) is lost to the low energy reservoir. This is quite nice actually... :-) Just means you have to get enough energy from the high reservoir...

C. I'm currently learning this, so the parent post (and this one) is quite fun/usable...

Re:Carnot efficiency.

[Shadowlore]

58f = 14.4C or 287.6K

Now lets be generous and let our panel "superheat" the stuff up to 80C or so, and put the cold reservoir in a bucket of ice.

That gives us a heat source at 353.15K and a sink at 273.15.

Efficiency = 1.0 - cold/hot = 1.0 - (273.15/353.15) = 0.226, or about 23% efficient.

Not great.

Well gee whiz wally anyone can just make up numbers to plug into the formula and "make a point". But how about we use numbers actually commonly acheived, rather than some feel good alleged "generosity"?

80C is not a difficult target for flat-plate collectors, so there is no generosity in assuming it. It's actually a "bottom end" figure. Concentrators such as dishes and troughs routinely achieve 200C+, with some reaching 3+ times as high.

So assuming you had the capacity for cooling to handle the concentrator produced 150C steam heat, with a cold temp of slightly above freezing (we added water and salt to the bucket of ice) we would be in the mid-thirties range for carnot efficiency. If you used geobanking (subsurface thermal transfer using the earth at depth) for a 52 degree cold temp, you would have about a 32.8% carnot efficiency. Much better. Naturally, increasing the temperature up to say 250C brings the carnot efficiency to about 46%. Still not too shabby.

But why talk about the solar heating aspect? Because you want to talk efficiency of the cycle. That said, I have a stong suspicion that the Carnot efficiency here is a bit of a canard. After all it is only one peice of a much larger pie. The key issue for these folks appears to be about making low temperature economically viable by doing it for much cheaper. If "traditional" solar thermal systems have a payback period of 5-10 years (they do - the payback on mine w/o incentives is just under 5 years on the NG reductions alone), and the low temp route could offer a graduated implementation with shorter paybacks it could lead to more adoption.

If it only takes (hypothetically) say 1000 dollars to get in the door with a payback time of two years, you can scale up every two years. Bringing the initial cost down will open it to a larger market. If the carnot efficiency is low but is good enough to meet the needs (using "renewables" such as sunlight) and lower carbon emissions and grid load, reducing rolling blackouts, etc. then the carnot efficiency isn't all that important. This is particularly true if the process supplants even less efficient methods. Local generation reduces infrastructure costs and losses, and these must be taken into consideration of efficiency as well.

If your central system is 80% efficient but it and the distribution infrastructure can not deliver to the whole user base at the same time, it's not that great either. If there is no distribution system, the cost and embedded energy costs of building the infrastructure may well overwhelm any effeciency gains over local generation.

Re:Carnot efficiency.

[Anonymous Coward]

"80C is not a difficult target for flat-plate collectors, so there is no generosity in assuming it. It's actually a "bottom end" figure. Concentrators such as dishes and troughs routinely achieve 200C+, with some reaching 3+ times as high."

You can achieve 150C inside vacuum tube solar thermal collectors without the need for mirrors and in theory you could heat a working fluid up to something approaching this. See www.positiveplanet.co.uk, for example.

I also agree that the Carnot efficiency is a bit of a red herring. The important thing to most people is not the theoretical efficiency but the potential financial savings and payback period. (Although it is worth keeping an eye on any pollutants, CO2 or otherwise during manufacture too). Increased efficiency may help to drive down the payback period (smaller units for lower cost, perhaps) but as you say, it's the bottom line that matters most. Also the idea of using modularity to mean you have a continuing cycle of relatively short payback periods is interesting.

it aint that great

[hamburger lady]

~5% efficiency.

what's wrong with a reflective dish and a stirling engine, anyways? much higher efficiency, materials aren't as expensive as solar panels and not nearly as bad for the environment.

Re:it aint that great

[chriss]

The main problem with stirling engines and reflective dishes is that they consume a lot of space, most of which is the empty area between dish and engine. While they may be more efficient and their production be less hazardous to the environment, they cannot compete with solar panels which can be put on roof tops or basically any flat surface. Newer PV technology even promises "paint on" solar cells. They are simply less invasive and therefore can be put into more places, leveling their lower efficiency. For rural areas this may be different, but for cities PV wins.

Re:it aint that great

[hamburger lady]

i'd say you'd have the same problem with the system in the story, with a turbine and all.

as for a stirling dish-solar system, they would work alright in the city; one would easily fit on the roof of my rowhouse (since a satellite dish would fit just fine). it actually has a smaller footprint, per kwh, than solar cells. however, if you're talking about the suburbs, you're right; solar roof shingles etc are a much more usable option.

Re:it aint that great

[dbIII]

they cannot compete with solar panels which can be put on roof tops or basically any flat surface

There is the issue of scaling. If you double the area of photovoltaics you only get double the power output. If you double the size of a thermal power generation method you usually get more than double the output - which is why the idea is to build really big solar thermal power installations on bits of land no-one wants. This happens because you can use bigger turbines and more of them to get more out of the same temperature difference, and because losses such as friction become a lot less of the total percentage generated. This scaling up of thermal power as distinct from the additive output from photovoltaics is why the nuclear power industry always use it as a comparison - a really big thermal source doesn't have to be very cost effective to come out ahead of thousands of acres of photovoltaics (which would be a stupid use for them - there's plenty of other ways to use them). About the only nuclear power plant that didn't even come ahead of this ridiculously skewed comparison was the fast breeder Superphoenix - hundreds of acres of photovoltaics would have been cheaper per MW.

Solar powered Air conditioning

[Hal_Porter]

Notably, this comes during a record breaking heat wave here in the US. So has the day finally arrived where I can run my AC off of all that heat outdoors


I guess you're making a perpetual motion joke, but the strange thing is it's not a daft as it sounds.

You could have an electrically powered heat pump to pump heat into the ground in summer, and back out again in winter.

http://www.igshpa.okstate.edu/geothermal/geotherma l.htm

Very popular here in Sweden.

If you insulate your house enough, the energy required to heat or cool it is pretty minimal, so you could generate it from solar panels, at least in the summer. And heat pumps are 3 to 4 times more than resistive electric heaters.

As wikipedia puts it

http://en.wikipedia.org/wiki/Heat_pump

When used for heating on a mild day, a typical heat pump has a COP of three to four, whereas a typical resistive electric heater has a COP of one. That is, one joule of electrical energy will cause a conventional heater to give off one joule of warmth, while under ideal conditions, one joule of electrical energy can cause a heat pump to move more than one joule of heat from a cooler place to a warmer place. Sometimes this is expressed as an efficiency value greater than 100%, as in the statement, "XYZ brand heat pumps operate at up to 400% efficiency!" This is not quite accurate, since the work does not make heat, but moves existing heat "upstream". This does not violate the second law of thermodynamics, because it takes less work to move the heat than to make the heat.

Kind of reminds me of the hurricane tower story

[Antony-Kyre]

We all remember http://science.slashdot.org/article.pl?sid=05/05/2 5/2227215 from back in 2005, right?

Just use solar already...

[drgonzo59]

Solar pannels might just work better. Besides with solar if you have an excess you can pump it back into the grid which is just the perfect cure during the high power demand scorching heat weather.

Re:Just use solar already...

[Alioth]

The trouble with solar is it's ruinously expensive. The surface area required generally isn't a problem for a house (use the roof), but when a solar panel costs £450 (about US $700) for a 120 watt panel, to actually get enough solar panel to do something like run your home becomes fantastically expensive. You'd need at least twice (preferably three times) the solar capacity that you actually use in many places, so you can store enough during the day for the night, and not be without power on a cloudy day. Just to run your desktop computer and monitor, realistically you'd need three of those 120 watt panels to avoid frequent power shortages. Even if the panels were half the price they are now, it would still be so expensive it would never actually pay back (monetarily - apparently the energy payback for a solar panel is about 6 years, and solar panels are typically guaranteed for 25 years) compared to just buying power from the electricity company.

Re:Just use solar already...

[plantman-the-womb-st]

Um, so? Pay a lot once and forget about it -or- pay a little at a time over th course of years and constantly worry if you'll be able to get enough.

Seems a simple choice to me.

Re:Just use solar already...

[Alioth]

I'm afraid it's a bit naive to think you can pay a lot for solar and forget about it.

The panels eventually do fail/wear out. They do last a long time - most are guaranteed to still produce 80% of their rated output when 25 years old. Cells will fail and will need replacing from time to time, and will be expensive to do. So you have to *keep* paying a lot time and time again. Also, you need somewhere to store the energy for later - home energy usage is pretty much the exact inverse of when the most solar radiation is available - where I live, you need the most electricity in the winter when it doesn't get light till 9am and is dark by 4pm - so you need to store the power during the day for your peak night time usage. The most cost effective way of doing this currently is deep cycle lead acid batteries (since you don't care about weight as it's in a building). Try pricing up enough lead acid batteries to be able to get you through a week of shitty, dark, rainy winter weather just when you need the power the most. Then realise you'll probably have to replace the whole set of batteries every 8 years (and that's optimistic). And factor in the energy cost to make and (preferably recycle) those batteries.

Solar is fine for running small things; I am considering it for running outside lighting and things like the pond pump - the whole thing only needs one 120W panel and a leisure battery, inverter and controller - and in the winter time when the solar energy isn't very abundant, I'm hardly going to need the power anyway. However, for serious microgeneration, at the current time the only halfway practical and affordable renewable energy source is wind, which is vastly cheaper - and when you need the power most, it also tends to be windy, so the energy availability actually matches domestic energy usage much better. Wind also has a much better energy payoff. The energy to make a typical wind turbine is generated by the turbine over a period of six months - it's more like 6 years for solar. Unless photo voltaic solar becomes vastly cheaper, it's simply a non-contender except for novelty value, even if you live in the desert.

Re:Just use solar already...

[Ohreally_factor]

You're talking about getting off the grid entirely, it seems. Where I live, the power company is required by law to purchase any excess electricity you put back on the grid. So, no need to store your home generated electricity with batteries.

Depending on how expensive electricity gets in the near future, solar panels to supplement what one takes off the grid might make the whole thing economically viable. Combine this with tax credits and suddenly it doesn't seem so expensive.

Not all places are equally windy. Where I live, we get a good deal more sunshine than we do wind. Wind power wouldn't work for me.

Re:Just use solar already...

[Anonymous Coward]

Unfortunately feeding back into the grid doesn't give the same value of credit as your usage from it. Your area might be different, but here, you're only getting a discounted rate. To go PV for our house, I was getting quotes of $35-40,000 after tax credits. That's just too expensive, especially when the average stay in a house is roughly 5 years. In comparison, it cost around $3500 to install our solar domestic water heater.

Re:Just use solar already...

[RockModeNick]

not to mention wind turbines take up tons of space, slaughter birds, and are eyesores, while solar panels are relatively low-key.

Re:Just use solar already...

[Alioth]

A roof mounted wind turbine would take a lot less roof space than roof mounted solar panels (and be far easier to mount), and in the case of office buildings, make a much larger contribution (multi storey office buildings tend to have comparatively little roof space compared to floor space).

It's a common myth that wind turbines "slaughter" birds - a very small number of birds are killed by wind turbines: http://www.treehugger.com/files/2006/04/common_mis conce.php . Building microgeneration schemes are highly unlikely to be in bird flight paths - birds of prey don't generally congregate in urban areas!

Re:Just use solar already...

[chriss]

They neither take up tons of space nor do they slaughter birds. There have been a number of studies to determine if they have a negative impact on birds by either killing them when they accidently fly into the wings or disturb and drive them away by the noise they make. Both claims have been proven to be completely wrong, birds aren't stupid enough to fly into the wings and get as easily used to the noise as they get to street noise. If they are an eyesore is a question of personal taste. I prefer their sight compared to highways or the towers of overland power lines. And I guess that nobody will notice them any more than any other structure humans place in the landscape once one generation has passed and they have become "normal".

Re:Just use solar already...

[Ana10g]

Actually, in addition to roof mounted wind turbines, wouldn't it make sense to mount them on the sides of buildings as well? IIRC, Tall buildings produce a lot of wind shear down the side of a building (especially in places like chicago (any chicagoans confirm this?)), which can produce a lot of wind. Anyone else confirm this (or, prove yet again, that I'm talking out of my arse?)

Re:Just use solar already...

[Mr. Slippery]

Also, you need somewhere to store the energy for later

Only if you're off the grid. Intertie systems with net metering (run your electric meter backwards when you're producing more than you're using) look very attractive.

Re:Just use solar already...

[winnabago]

Hey, do you know any of those short-sighted folks who live on Cape Cod? I keep waiting for them to show up on /.

Re:Just use solar already...

[Mr. Slippery]

not to mention wind turbines take up tons of space, slaughter birds, and are eyesores, while solar panels are relatively low-key.

Wind turbines take up little more space than radio towers or high-tension power lines, and are much more aesthetically pleasing. Think of them as giant mobiles.

We do need to learn more about how to make them safe for birds, but smokestacks and pollution from other forms of generation also kill wildlife; well-placed wind turbine may well be safer for birds than the forms of generation they displace.

Re:Just use solar already...

[Venik]

While you guys are still playing with windmills and solar panels, I already have a small lead-cooled reactor in my garage. And enriched plutonium is not as expensive as everyone thinks.

Re:Just use solar already...

[bill_mcgonigle]

We do need to learn more about how to make them safe for birds, but smokestacks and pollution from other forms of generation also kill wildlife; well-placed wind turbine may well be safer for birds than the forms of generation they displace.

Good point. From what I've read the birds are killed near the hub where the blades are hardest to get out of the way of (they like the view from there). The easy solution I've heard is to put a spire with a perch on top of the hub to let the birds sit up there where the blades are more slow moving. There's a technical term for such a bird perch/nest which escapes me at the moment.

Re:Just use solar already...

[Dr Caleb]

" but when a solar panel costs £450 (about US $700) for a 120 watt panel,"

Where the hell are you shopping?

Link

Re:Just use solar already...

[RetroGeek]

Ok, but remember that you put power in when everyone else is also putting power in (assuming wide-spread use).

Then when the weather turns, you (and everyone else) now needs to draw power. So you STILL need massive power plants for those times when no one can put power in.

Re:Just use solar already...

[mutterc]

On-grid solar also has an advantage: You can just use a grid-tie inverter, instead of a regular inverter, charge controller, and batteries. Not having to buy (and maintain, and replace) batteries is quite the money savings.

Downside: Your solar isn't giving you any power while the grid is down, even if it's sunny.

Re:Just use solar already...

[Anonymous Coward]

Anyone else confirm this (or, prove yet again, that I'm talking out of my arse?)

I don't know about that, but I've just thought of a great place to put a wind turbine.

Re:Just use solar already...

[Bryansix]

Solar obviously does not make sense for everyone. However it makes complete sense for people in the Los Angeles area of California. The reasons are various. First of all most energy usage is in the Summer when solar energy is abundant. Secondly there is plenty of time when the sun shines here and we have many more sunny days then overcast or stormy days. Thirdly, Southern California Edison has a program to interconnect solar panels to their energy grid. In essence wehn you generate electricity you spin your meter backwards. This means they have to buy less power from outside sources and this saves them money too and no batteries are involved. If you need power at night, you are still connected to the grid. Most estimates say that it will take about 19 years to pay off a solar panel installation. However power prices have risen since those estimates where made and they will most likely rise again. The point is that solar not only pays for itself but it adds clean energy to the grid and bypasses most of the distribution associated with large power plants thereby cutting those costs as well. All of society as a result benefits. Solar is not just a novelty.

Re:Just use solar already...

[EvilMagnus]

You're right about usage patterns being wonky for residential consumers - that's why California has a 'net contributer' law; you can feed the juice you generate back to the utility company, and get credit for it later (up to 12 months after generation), at the price you paid in at. This is key, as PGE has just announced their intention to start time-of-da y rate variations for residential customers.

The idea is that if you contribute energy during times of peak demand (say, at 35c/KWh) you can tap it back when demand is lower and you actually need it - during the evenings or winter months.

And if you happen to be home during a hot day and there's a blackout, you have solar power to run your airconditioners. :)

It's still not cheaper than getting all your electricity from the utilities (but it's getting closer, thanks to several tax rebates), but if you have external factors (like you want to be a net generator of green electricity, or want to have AC during a blackout) it's great.

Re:Just use solar already...

[rainman_bc]

not to mention wind turbines take up tons of space, slaughter birds, and are eyesores, while solar panels are relatively low-key.

Modern wind turbines move quite slow actually. Google for it. What you're saying about the birds is a myth.

And if you have a large agricultural area, wind turbines aren't very invasive to their land; a farmer can probably grow around it with virtually little loss of space.

Re:Just use solar already...

[tzanger]

You linked to a 15W panel for US$179, or approximately $12/W. 120W would be $1440, all else being the same.

Re:Just use solar already...

[Eccles]

Unfortunately feeding back into the grid doesn't give the same value of credit as your usage from it.

Our assumption, though, is it is better than trying to set up your own energy storage, which would add significantly to costs and complexity.

Re:Just use solar already...

[WeAreAllDoomed]

buckminster fuller suggested putting a windmill on basically every existing high tension line tower.

they're an eyesore already, and the generated electricity can be transferred directly to to grid. (supplementally, of course).

Re:Just use solar already...

[WeAreAllDoomed]

Hey, do you know any of those short-sighted folks who live on Cape Cod? I keep waiting for them to show up on /.

just put the windmills over the horizon. problem solved. while you're there, harvest some tidal energy.

Re:Just use solar already...

[winnabago]

I would rather be fighting against a few vocal NIMBYers than trying to drop what is essentially a skyscraper foundation into 1000 feet of water sitting over 200 feet of muck. Oh, and then I need to repeat it a few hundred times. This is why the sound was chosen, I believe, because of its stable bedrock and relatively shallow water far enough offshore to keep it away from view. Apparently it's not enough for a select, wealthy few.

Tidal energy is intriguing, though. I thought it was only useful in shallow water, where a plenum effect could be achieved. Is there new tech in this area?

Re:Just use solar already...

[Screwy1138]

Don't forget... this is something I often see not mentioned, is that once you pay to install the panels, they (usually) increase the value of the house. So if you install them, get the payback in 19 years, then you sell your house, you've likely made money off the effort.

Re:Just use solar already...

[jargonCCNA]

not to mention wind turbines ... slaughter birds

Have you ever actually seen a contemporary wind turbine in action? They move extremely slowly; the probability that a bird is going to be struck is low enough to begin with, but to be struck fatally is even lower yet. The only way that they're going to have a decent chance of killing birds would be in a hurricane, but even birds are smart enough to stay the hell inside during one of those.

Re:Just use solar already...

[Cecil]

That's a 15W panel, not 120W. Nice try, though.

Re:Just use solar already...

[rahrens]

You are right - I was visiting Germany a few years ago, and in their heavily agricultural areas, they have a lot of very big windmills (very big - you can see them for MILES) and they move very slowly. The design was modern, slick, and not at all displeasing. My wife noted to me (she's German, and this is in her home area) that not all area residents were delighted with the view, tho.

Re:Just use solar already...

[tylernt]

Where I live, the power company is required by law to purchase any excess electricity you put back on the grid.

While this is true, the cost of grid-tie inverters is astronomical. $2,000 for a bargain basement model, and they go way up from there. (The power companies have stringent specifications and requirements for what it will let you hook up to the grid.)

It'll take a long, long time for that little piece of hardware to pay for iteself. Good for the environment but not so good for your ROI.

Not that batteries are much better, of course.

Re:Just use solar already...

[Fallingcow]

Is there a reason that this is not done? It sounds like a great idea.

Re:Just use solar already...

[AlphaLop]

Yes, but once again you are overlooking the hidden costs... Lube and hemorrhoid cream are not free you know....

Re:Just use solar already...

[Maxo-Texas]

They are more expensive than that.

120 watt panel is at 12 volts.

So you need multiple panels to make 120 wall current.

Whenever I do the numbers so far, it makes more sense to put the money into a 5% CD and use that to pay the electric bills except for...

1) Power Failure- no power available at any price-- be really nice to have 8 4'x1' panels pumping out 110 watts of wall current.
2) Big War. Prices go insane.
3) Period of high inflation (buy solar at $45k now.... but after 10 years, you are making $25k per month minimum wage and your electric bill is $18,000 a month).

A modest system to run a small window AC was estimated at $8000 if I used batteries and $17000 if I did not. This is for an estimated annual usage of $130 worth of electricity at current prices.

Re:Just use solar already...

[gr8_phk]

you need to store the power during the day for your peak night time usage. The most cost effective way of doing this currently is deep cycle lead acid batteries

No. For now the cheapest thing to do isn't to store the energy but push it onto the grid. Now in many states they screw you either disallowing this practice, or allowing the power company to pay you less than you pay them for the energy. That's more a political issue than practical though. Long term there is a problem - if everyone did it, there would be no place for the peak power generated to go because all homes would be sources not loads. In reality we are a long way from having to solve this energy storage issue. At present, the most efficient place to put the energy is on the grid.

Re:Just use solar already...

[mikeydb]

I use a small solar panel to charge a 40aH lead acid battery which I will use in the next 50MHz amateur radio contest, which will potentially save me £10 in fuel which would've been used running the car engine to keep the battery voltage up and there will be less waste and emissions as a result, when I say waste, I mean using fuel to turn an engine that isn't doing any real work, so the waste is generated as heat from the engine as the engine is not 100% efficient.

Re:Just use solar already...

[Anonymous Coward]

Where I live, the power company is required by law to purchase any excess electricity you put back on the grid.

Unfortunately, since they're forced, they don't have to pay market rates--true market rate as in what it's actually worth to them to have the electricity, as opposed to a mandate to pay you the average prevailing market rate or some such. Think about it; if they actually could make money doing this, they wouldn't need to be forced. As a result, other customers who don't do this are subsidizing your activity. And of course, the tax credit is an outright subsidy.

But hey, at least you get to feel good about yourself and pretend you're making a difference, and we all know that's what really counts.

Re:Just use solar already...

[Anonymous Coward]

You take a hit when running the inverter to get you up to 120 VAC, sure, but 120W @ 12V isn't less power than 120W @ 120V. Supposing you got 80% efficiency, your 120W/12V panel puts out 96W at 120V, not 12.

Re:Just use solar already...

[Alioth]

A correction: with a grid tied inverter (i.e. what you need to feed power back out to the grid) if there's a blackout, you won't have power either - so if there's a blackout, your're still SOL if you want to sell the power back.

Re:Just use solar already...

[Anonymous Coward]

"Unless photo voltaic solar becomes vastly cheaper, it's simply a non-contender except for novelty value, even if you live in the desert."

You are assuming that photovoltaics are the only useful form of solar energy usage. Solar thermal can be anything up to 90% efficient, and hot water generated from solar thermal can be a useful storage medium to store solar energy during the day for use at night even in winter. In winter when daylight hours are shorter then the amount of incident energy per day is less, so it will heat less, but it is worth remembering that the important factor is incident energy NOT ambient temperature. With some additional devices and a bit lower efficiency you can use solar thermal to also run air conditioning. Solar thermal, of modest sizes, is even viable in northern Europe or Canada. In Northern Europe combine solar thermal with underfloor heating and some roof insulation and the pay back period on the capital cost based on average conditions can be as little as 4 years for a retero fit to an existing build, less in new builds. In terms of technology, it is essentially the collector, and plumbing. I.e. it is well designed, but not particularly any harder to maintain than any other form of home liquid-based heating system such as water heaters, radiators, water-based underfloor heating, and so on. Some of the specific plumbing skills for dealing with the solar radiation collection and particular installations are new, but could be learned relatively easily.

Combine solar thermal with wind and decent insulation and energy-saving appliances, and you can probably save a fair proportion of your energy bills at a competitive rate (i.e. net benefit) if you ameliorate the capital cost and maintenance costs over an anticipated lifetime of the major systems of around 25 years.

Re:Just use solar already...

[Dr Caleb]

That's what I want to know. $149 * 8 = $1192. Per watt, $700 is a good deal. Where?

Re:Just use solar already...

[Anonymous Coward]

If you are using PV to create 110V to run an AC then you are doing so in a way that is sure to reduce the efficiencies. Better to use an AC unit that can use direct current. Many household appliances (e.g. LCD TVs) convert the AC back to DC before they use it, adding more conversion losses. Better to simply run them via DC from the PV cells in the first place. New forms of lighting and computers can also run on DC. Even 12V DC washing machines and A/C units are possible.

Solar thermal energy can be efficiently used to create an AC system, so you don't have to use PV cells for A/C.

8 4x1 panels is approximately 3500kW incident radiation. At current PV conversion rates this is 0.8kW usable. Assuming 8 hours of sunlight at this level per day on average that's the equivalent of about $5 per day at typical current costs. Let's assume that this isn't achieved every day, and halve it, then scale it up by 365 days - so that's $900. Then let's assume that half the time this is not at the time of day you want to use the A/C and you aren't using storage technology, and halve it again to $450. However many power companies will allow you to sell back the energy you don't use at about half the cost to buy it at, so the other $450's worth you can't store is still worth $225 to you, and so your total saving is $675 in total. [This also assumes an A/C working on direct current with no losses in conversion.]

5% interest on an account is really about 1.5% after taking into account inflation, and probably only 1% after account charges and other costs. So on a principal of $8000 that is $80 a year. This will not change with increases in energy costs, and is less than saving from using the panels. The advantage here is that you still have access to the capital.

So with current prices you could be saving $595 a year over and above using the capital. The pay back period on your $8000 would be 8000/675 or 12 years.

If energy costs went up by 10% your current costs would rise to $1320 but with solar you would save $495 plus your sale of electricity by $248, to a total of $743, for a total bill of $577, so you'd only see a rise to you of 9%. Now at a saving of $743 per year your pay back period for the $8000 is cut to just over 10 years.

If grants are available, then the pay back period can be cut.

To get general acceptance, a payback period of about 5 years is the right sort of length.

New generations of PV cells being worked on may double PV efficiency and be potentially cheaper too. A simple increase in efficiency probably wouldn't halve the payback period as you'd be generating more power at times when you don't use it, so you'd mostly be selling more back. But that still saves you money. But combined with the possibility of cheaper installations (which would also be the case with better economies of scale) and a 5 year payback period might well be achievable.

Re:Just use solar already...

[Maxo-Texas]

1) Would love a link to DC air conditioning.
2) Our state allows you to roll your meter back but that requires
    a) a new fairly expensive meter (About $1500) that does reverse metering.
    b) the current electrical system of the house brought up to code (About $4000-only a L.E. can do it))
3) My other figures are based on a quote from an actual solar power company.
4) I think you are being selective about the way you apply inflation.
5) 5% on 8,000 is $400 per year. Electricity for the window unit is $71 (by the tag on the unit).
      So my 8,000 grows by $300 a year which accounts for inflation fairly nicely.
      I have platinum savings and checking so I have no service fees.
6) After 7 years, I have to pay for all the batteries again (including disposal fees here).
7) There are no grants here except in Austin. B(

At the current time, I'm waiting until I build a new house or we get an order of magnitude drop in panel costs (say from Nanosolar or a similar companie's advances).

Re:Just use solar already...

[Anonymous Coward]

Safety Dog Says: Don't forget to keep open flames away from your room full of batteries. There is the possibility of a hydrogen gas buildup in poorly ventilated battery enclosures.

Re:Just use solar already...

[EvilMagnus]

You can cut that off, you know. There's switchs that'll do it. :)

No good if the blackout is at night, though - that's where the batteries and backup generator comes in handy.

Re:Just use solar already...

[Cecil]

Sorry, I misunderstood your tone. Google suggests Affordable Solar among others.

Re:Just use solar already...

[WeAreAllDoomed]

Apparently it's not enough for a select, wealthy few.

well, to be fair, the cape cod coastline could be considered national treasure material. would you put windmills all along the edge of the grand canyon, or on top of the washington monument?

i've always viewed the "see how the rich people like it" thing as a vindictive swipe at those who favor wind power as an alternative to fossil fuels.

Very inefficient

[Cyberax]

This turbine can't be very efficient. Efficiency of any heat engine is limited by the Carnot cycle (http://en.wikipedia.org/wiki/Carnot_cycle).

Basically, you can estimate it with this formula: e=(T2-T1)/T1 where T2 is the highest temperature of the working body and T1 is the lowest temperature. For such a small temperature drop as in this engine we'll get a very minuscule efficiency.

Re:Very inefficient

[KiloByte]

Yet, you're forgetting that heat is exactly what we have too much of. It's for all practical purposes free, so efficiency energy-wise doesn't matter.

What matters, is the efficiency time-wise, space-wise or monetary cost-wise. Having twice as much power from the same heat would be nice, but it isn't the point.

Re:Very inefficient

[IcePop456]

I thought we only worry about efficiency when the energy supply is low? Granted I wouldn't want a huge piece of equipment, but considering how much thermal energy is in the air during the summer, cost is what I'm worried about more than efficiency.

Re:Very inefficient

[Cyberax]

The only problem: you'll need a lot of these devices to generate usable amount of energy.

Re:Very inefficient

[Cyberax]

You need a temperature differential, not just a high temperature. I see that one can use water from a river/lake/sea in which case this device might very handy.

But in most places such device will be less effective then solar panels (which are not limited by the Carnot cycle, BTW).

Re:Very inefficient

[KiloByte]

The only problem: you'll need a lot of these devices to generate usable amount of energy.

Exactly, that's what I meant with "space-effective" and "cost-effective". If these devices can be cheap and compact, efficiency isn't really a concern.

Re:Very inefficient

[Waffle Iron]

If these devices can be cheap and compact, efficiency isn't really a concern.

The laws of thermodynamics essentially dictate that for a given power output, the size of the working parts of a heat engine must get larger as the temperature differential between heat source and sink gets smaller. Therefore, at power outputs greater than toy demonstration levels, devices like these will not be compact.

Didi I really read ...

[Anonymous Coward]

... all the global warming hype? I guess in the US of A the hype warms you.

Re:Didi I really read ...

[Anonymous Coward]

I was gonna post the exact thing but you beat me to it. Thanx mate. Let them stew in the heat waves and clam its ONLY a hype. And let me quicxkly add: it doesnt matter if it is made made or if it is natural. Once ithe global warming begins to affect our food supply EVERYONE WILL get concerned. Untill then, keep on hiding your collective heads in the sand.

Re:Didi I really read ...

[Anonymous Coward]

The hype seems to be related to the source and/or the degree of global warming occuring...

I just got back from Banff, Canada and had a day trip up to the glacier area. I heard more than once that the glaciers had been retreating for around 175 years and in the next breath that this was caused by human activity (with automobiles being implied as the principal cause.) As far as I know, there weren't too many automobiles running around 175 years ago so perhaps it was all the leaked freon from the air conditioners being sold in the early 1800's.

Why?

[Ogemaniac]

It is just cheaper to add a new gas or coal plant and update the grid. As long as this is true (and it will not be forever) people are going to choose the dirty way. PV costs several times what dinofuel does. This isn't what you want to hear but it is the truth.

Re:Why?

[Tatarize]

Nuclear Please.

I want to breathe.

Re:Why?

[Anonymous Coward]

you don't mind if I store that nuklear waste in your backyard do you? Thanks.

Re:Why?

[QMO]

I don't mind at all.
Especially since I'd get paid pretty well for it.
Unfoutunately:
1- My backyard isn't big enough for nuclear waste disposal/storage.
2- Some laes restrict what I can do with my back yard.

Re:Its still a heat engine

[Anonymous Coward]

Carnot efficiency isn't the only metric here, however. Economic efficiency and thermodynamic efficiency, though correlated, aren't the same thing.

If the heat source is free (as opposed to having to buy oil, coal, or uranium) and the engine itself costs less to manufacture than high-purity semiconductors with equivalent power output, it's quite possible for something like this to make economic sense (others have mentioned heat pumps, woefully inefficient in the Carnot sense, yet still perfectly sound from the economic perspective).

Solves almost 100% of the problem

[Yetihehe]

Main innovation here is that they removed feed pump, which makes whole thing more efficient at low temperatures. If their fluid boils above 58F, then it condensates below 58F. If it condensated just above outdoor temperature, then thermal collectors could heat it and normal outdoor temperature could make it condensate back. With such low temperatures however it's very inneficient to run a feed pump. They however have plan:
1. Eliminate feed pump
2. ??
3. Profit.

Re:Solves almost 100% of the problem

[plague3106]

Only problem is that when you want an AC on, the outside temp. is way more than 58F... so I don't see how you'd use outside are to 'cool' the fluid.

Re:Solves almost 100% of the problem

[Yetihehe]

I would use fluid with higher boiling point, better suited to desired temperatures.

Re:Solves almost 100% of the problem

[plague3106]

Right, but I thought you were talking about the fluid from the article.

Re:Solves almost 100% of the problem

[njh]

By compressing the gas.

MOD PARENT UP (n/t)

[Schraegstrichpunkt]

no text

Deep in the earth... well not that deep.

[IBitOBear]

On the average, the underground temprature at ten feet below ground level is something like 52 degrees. (I am looking into geothermal [q.v. ground-sourced] heat pumps.) If the fluid boils at 58 degrees and you put a reasonably large ground loop you would have your temprature differential.

Toss a solar collection array on the hot side, and if the latent heat of vaporation of the mistery fluid isn't too high you should be able to get a pretty flow.

You might need to pull-start it (8-) to get the initial pressure differential, but once the system was running the cost of using some of the energy to replenish the boiler from the condensate coils should be low enough.

It mostly comes down to a matter of surface area.

In a steam/turban plant the energy to move the turban doesn't _really_ come from boiling the water, it comes from super-heating the steam. You have to move the steam through the turban energetically enough to move the machinery (which cools the steam as the pressure is relieved (etc). So it isn't so much the boiling temprature, its how much energy the media can carry _after_ boiling. A lot of volatiles do an incredibly poor job as a (relatively, in this case) super-heated fluid because of crosiveness or viscosity.

ASIDE: If I were trying to build a solar-powered air conditioner I'd use basically the same material and design as a propane-fired refridgerator and a Clever Arrangement(tm) of concentrating mirrors. The whole system is low pressure and has no moving parts. The mirros would have to track, but those moving parts wouldn't ever have interract with the volatiles.

Re:Deep in the earth... well not that deep.

[Max von H.]

in a steam/turban plant the energy to move the turban doesn't _really_ come from boiling the water, it comes from super-heating the steam. You have to move the steam through the turban energetically enough to move the machinery...

Steam-powered turban?? There's a few pakistani taxi drivers who might be interested ^^

Re:Deep in the earth... well not that deep.

[gatzke]

Problem in these methods lies in maintenance. How long do pipes in the sea or underground last? Depends on how you install them or what they are made of. If you have to dig up your backyard 10 feet down every ten years, is it worth it? Maybe, maybe not.

Solar hot water is fairly easy to do and not too complex.

PV Solar would be great, since you have no moving anything (liquid and turbines lead to failures). Stick them out, keep leaves off them, and out comes power.

There are new advances in manufacturing coming online as well. PV cells on flexible material printed like a printing press, leading to half the efficiency but at 1/10 the cost... We should get there, especially if the middle east keeps oil up.

Re:Deep in the earth... well not that deep.

[Technician]

The whole system is low pressure and has no moving parts. The mirros would have to track, but those moving parts wouldn't ever have interract with the volatiles.

Low pressure is news to me. An absobption cycle RV refrigerator does use low vapor pressures to evaporate ammonia to create cooling. However to keep the water where it belongs, the system is under high pressure. Water and ammonia are the working coolant. Water is the absorbant. However the ammonia is not boiled. It is evaporated. To seprate the water and ammonia, it is heated in a boiler under pressure to force off the ammonia and condense the water back into a liquid. The entire system is under a single pressure. Remember it is run without a compressor.

If interested in the continous cycle absorption cycle refrigeration, pick up a copy of Modern Refrigeration and air contitioning.

Re:Deep in the earth... well not that deep.

[Shadowlore]

n a steam/turban plant the energy to move the turban doesn't _really_ come from boiling the water, it comes from super-heating the steam. You have to move the steam through the turban energetically enough to move the machinery (which cools the steam as the pressure is relieved (etc).

Errr .. I don't normally correct or point out typos or incorrect words on /. but there is a huge difference between a "turban" and a "turbine". The latter is the correct word here. A steam turban won't really produce much electricity. That said, applying super-heated steam to a turban in use will definitely cause an energetic movement of the accompanying machinery.

Re:Deep in the earth... well not that deep.

[IBitOBear]

While I have no informed opinion about whether the mystery fluid is compatable with the current underground technology, the underground loop for a geothermal heat pump are essentially 40-year (e.g. unknown but unbounded) installations. In the existing technology the pipes are some sort of flexible plastic arrangement and only carry a mixture of water and anti-freeze, but it _is_ an established technology. (Check out climatemaster.com for a decent set of brocures on the topic.)

Providing the underground loop can survive the mistery fluid, or provided that the mistery fluid can be second-staged to water from the underground loop, the repeated diging is a straw-man objection.

Re:Deep in the earth... well not that deep.

[evilviper]

On the average, the underground temprature at ten feet below ground level is something like 52 degrees.

Maybe in Canada...

The depth you need is around 30 feet to get to a stable tempurature (not 10), and you need to spend energy circulating the antifreeze through the very long loop of heat-exchanging pipes (which you need for enough surface area). And the tempurature down there is around 68F degrees, not quite enough for this.

Meanwhile, if you were to just buy and install a ground-source heatpump unit for heating and cooling your home, your heating and cooling bills would fall to almost nothing.

Re:Deep in the earth... well not that deep.

[IBitOBear]

My point was that if you _don't_ super-heat the steam the turbine doesn't spin (at least not with sufficent torque to produce useful output). We have been told of a mistery fluid that boils at 58F but we havn't been told how much energy it takes to make it change state. [for the viewers at home, if something "boils" at temprature X, it still takes a spesific amount of added energy to turn the liquid at X-degrees into the gas at X-degrees; which is why the whole pan of water on your stove doesn't swoosh into a cloud of steam all at once.] We also don't know how well it can be super-heated...

But even with any of that, energy in == energy out so the useful work output is still constrained by the surface area and conductivity of the vaporator and condenser if you want this thing to work at ambient tempratures.

Re:Deep in the earth... well not that deep.

[shadowbearer]

The new crosslinked poly pipe (pex) being used more and more for plumbing in the US should be able to survive most anything provided it's not too acidic, plus it last virtually forever.

  I'd love to correspond with you on this - it's an interest of mine as well. Don't live somewhere where it's used currently, but hopefully in the next couple years I'll get a start ;-) meanwhile I do correspond with other people trying to be self-sufficient.

  Munged addy: snarkthster.nonsensecrap@gmail.com

  remove the dot nonsense

  Cheers
SB
  ps sorry for the short reply, carpal acting up again

Re:Deep in the earth... well not that deep.

[skinchin]

When they installed our Geo-thermal heat pump, the installer told me the ground loop coils had to be 5 to 6 feet below the frost line. At our location in western Oregon, that is ~5 feet. At that depth, the ground temp here is about 52 degrees year round. Our ground loop is 1500 feet of 2" PEX coiled in four "slinkies" that are layed in four 125 foot by 2 foot wide by 5 foot deep trenches. The fluid is a 15% ethyl alchohol/water solution. The ground loop can also be done in vertical wells (even in your domestic water well) or in a pond or lake. Thought you might be interested.

-

If it's too hard to do, you are most likely doing it wrong. (Melvin Hill)

Depends where you are, but very inefficient

[Flying pig]

In many places in the world the deep soil temperature never reaches summer air temperature maximum. In such cases it is theoretically possible to use the Sterling cycle to obtain energy by, effectively, transferring heat from air into the soil. However, eventually this is going to stop working as the soil around the heat exchanger warms up. There is also the problem that the efficiency of a heat engine cycle is limited to 1- the ratio of output to input temperature. Since the ratio is rarely lower than about 0.95, and you need power to drive the fluid through the soil circuit - do the math. It would be much more effective to grow sunflowers or sugar beet and use the product in your bio-Diesel or bio-ethanol engine.

Re:Depends where you are, but very inefficient

[bloobloo]

Except of course you would have to pump the warm vapour down to allow it to condense out. This would take energy. The reason geothermal power is good is because the heat source is at the bottom so the system can act as a thermosyphon and so no pump is needed.

Good idea.

[Meor]

Not that I've been duped in to believing human caused global warming, but we need more passive/green energy sources like this. Geothermal is one of the most abundant, constant sources of energy that doesn't generate any waste. You don't have to worry about using exotic materials for the cycle of storage as with wind and solar.
I would recommend looking at some pictures of geothermal power plants, I was very impressed with the first one I saw. They don't even really need buildings.

best solution to global warming

[zimsters]

best solution: pop more holes into the ozone so we can get the absolute zero temperatures of outer space cooling the earth ;) come on everybody, act now to save the planet! Buy the biggest SUV money can buy!

Re:best solution to global warming

[Anonymous Coward]

How would buying or driving an SUV pop more holes in the ozone layer?

Re:best solution to global warming

[snoggeramus]

Better still, do a few more shuttle launches. I'm sure that flying fuel tank punches some neat holes through the ozone layer.

Funny, never hear Nasa talking about it, though.

More flies in the ointment ...

[JumpingBull]

First, the refrigerant used in their independent calculation is R-22, a cloroflorocarbon that kills the ozone layer, implicated in crop failure due to high uv exposure.

Second, the cooling cycle uses water. Considering that potable water is in short supply, this is a problem...

Third, the thermodynamic Carnot cycle is a cap on the efficiency. Higher working temperatures do give a better efficiency, but you still have to cool them!

A different working fluid can be used. unfortunately, organic fluids tend to be flammable. Methanol might be a candidate. It is less toxic then ammonia.

Before the advent of mechanical refrigeration, some AC was done with evaporative air coolers. (for cinemas at the start of the 20th century). This might mitigate the second point.

Perhaps we are missing an important use. The humidity usually makes an environment uncomfortable. This system might find even more effectiveness driving a dehumidifier.

Finally, it might be equally effective to use a two stage boiler. A flat plate to get the fluid up to working temperature, and a solar concentrator to superheat the fluid to drive the system to a higher efficency

Re:More flies in the ointment ...

[Lord Bitman]

"It uses water" ... "Potable water is in short supply"
If all water was Potable, it wouldnt be in short supply ;)

Re:More flies in the ointment ...

[cnelzie]

Potable means drinking.

    You don't need drinking water to use for cooling something.

    There are plenty of places with water that isn't potable, thus such a system would have no problem being used in places with undrinkable, yet available, water sources.

Re:More flies in the ointment ...

[asuffield]

First, the refrigerant used in their independent calculation is R-22, a cloroflorocarbon that kills the ozone layer, implicated in crop failure due to high uv exposure.

This one is not a big deal because R-22 can almost always be replaced one of the common modern refrigerants (I'm not sure which offhand, might be R-409c), which has extremely similar properties and is often used to replace R-22 in old air conditioning units. It's a little bit less efficient though (and most equipment can be redesigned to use more modern chemicals that work better). I have no idea why they used R-22 here.

Your other points are more significant problems.

(Incidentally, R-22 is an HCFC but not a CFC, and is not a major threat to the ozone layer, you're thinking of the banned R-12 which was both a CFC and a major issue. However, R-22 is being phased out anyway because there are better choices available which are even less harmful and no particularly compelling reasons to use R-22 any more)

Re:More flies in the ointment ...

[Anonymous Coward]

Evaporative air coolers fail to work well in areas of high humidity - precisely where air conditioning is needed most.

Re:More flies in the ointment ...

[Farfromlosin]

"Before the advent of mechanical refrigeration, some AC was done with evaporative air coolers. (for cinemas at the start of the 20th century)."

And to this day. 'Swamp Coolers' are still in use, still sold and installed and still used every hot day in the southwest US, namely NM and AZ where it is hot, but low humidity. Medium to High humidity causes them to be ineffecient and will make you more miserable than the heat, but in places with humidity averages in the low 20%, they work extremely well. Ater all, it might be a 105, but it's a DRY heat.

Re:More flies in the ointment ...

[WeAreAllDoomed]

Potable means drinking.

i went to basic training at fort benning, georgia when i was 17. i remember seeing "potable" written on the side of a water truck, and thinking "wtf, is that the southern spelling?"

Re:More flies in the ointment ...

[njh]

Well you could just use an indirect evaporative cooler, which apparently work well everywhere in the states, use minimal water and electricity and push fresh air into the house.

Not a chance it will work, or ever break-even.

[Ancient_Hacker]

Ahem, this thing won't work.

The diagram shows 10 PSI gas being condensed. Then somehow, without a pump, the 10PSI liquid "flows" into a 65 PSI boiler. No way, Jose. And no, you can't use the height of the condenser to supply "gravity" pressure. There is no free lunch.

Then there's this dang thing called the Carnot Cycle, which is impossible to violate, and dooms all these low-temp difference heat engines to extremely low efficiencies. So low, in most cases, you can't even keep up with paying the interest on the investment.

I didnt see a single numeric calculation for the loop efficiency, a really bad sign. These calculations have been basic, simple, and mandatory for upwards of a century and a third.

Re:Not a chance it will work, or ever break-even.

[Van Cutter Romney]

They do show a simple solution to this. The temperature increases in the heat exchanger from 80F to 160F and as that happens the pressure increases from 10 PSI to 65 PSI. When the pressure in the heat exchanger reaches 65PSI, the pressure in the boiler reaches below the same. QED

Re:Not a chance it will work, or ever break-even.

[Ancient_Hacker]

>When the pressure in the heat exchanger reaches 65PSI.... ... you have a boiler. Which:

• Has to be at a slightly higher pressure and temperature than the downstream "boiler".
• Which means it has to siphon off the hot water FIRST before the second boiler gets it.
• Which means you've jsut moved the pressure problem back a stage.
• And the second boiler is running at even lower temp and worse efficiency.
• And you lose lots of heat heating up the first boiler from scratch every cycle.

This Carnot thing has been extensively studied for over 130 years. Is it likely some Joe-Schmoe can improve it without the slightest math or even graphical analysis? Nope.

If he gave us a few hints, like the actual temps and pressures and volumes, we could begin to calculate its efficiency

Re:Not a chance it will work, or ever break-even.

[Anonymous Coward]

Sure it will work. It works for me. I'm a venture capitalist. The diagram has lots of little floaty balls in it and they go round - thats all I need to invest a couple of million.

Have you thought that the aim of the machine was to work in a different way to the way you think? You're only an engineer - what do you know about sitting in a board room?

Re:Not a chance it will work, or ever break-even.

[Anonymous Coward]

The world also used to be flat, 512k should have been enough for anybody, and on and on ad nauseum. Look, to assume something isn't possible just because it goes against conventional wisdom is naive.

Reading through your previous posts it's quite clear you're a chronic naysayer. Lighten up, free your mind and your ass will follow.

our galactic stone-age

[uioreanu]

Solar energy is yet expensive, but it's easy just to look at the effects of the crisis in middle east over the fuel price to understand that we need to start thinking differently when we're talking about energy consumption. Most of the house devices we have could work just slower and consume half of what they do now; but this is a lesson we were not yet trained to learn.

Our story resembles more and more with some Age of Empires game where we start on an island, burn out everything there is to burn over there, and then have no more resources to build transporting ships.

Re:our galactic stone-age

[antoinjapan]

The middle east will own the solar age like they do the oil age now, they have the sand and the sun, and huge deserts to coat with panels. They're just waiting for the oil to go before they get started.

Re:our galactic stone-age

[El Torico]

The middle east will own the solar age like they do the oil age now...
Last time I checked, there was sunshine and open spaces in a lot of places other than the Middle East.

Re:our galactic stone-age

[CreatureComfort]

Well, there's lots of oil in other places also, so why does the middle east still control the world energy market? Easy, for the same reasons they will control the solar market.

1) Cheap labor
2) All their open land doesn't have any NIMBY neighbors to complain
3) No environmental restrictions/regulations
4) The open land cannot be used for anything else, especially crops.

The big downside they face is how do you transfer all the energy collected to the markets that need it? The great thing about oil is that it is extremely portable. Direct electrical transmission over power lines is hugely ineffecient and unreliable over even multi-state regions, let alone continent-wide or global distances. If only there was some ubiquitous power storage and transport system with high efficiencies to help the big middle east oil barons keep making money... hmm.. what's that.. GWB (Halliburton) is now supporting moving to a hydrogen based economy? Remember kids, hydrogen isn't an energy source, just an energy storage medium.

Is anyone still naive enough to think that all of this hasn't been thought about, researched, and planned for years? The global cartels know to the year, possibly to the month, when oil will be too expensive in recovery to maintain a strong global economy, i.e. current levels of comfort for the ultra rich. Spending large amounts of money on researching alternatives too soon just wastes current year investment income, and results of such research would interfere with pulling every last cent of profit from the current system. As soon as the money/lifestyle/economy equation balances you will see vast changes in the energy landscape, almost overnight. And the same people making huge profits now will still be making huge profits then.

Re:our galactic stone-age

[B3ryllium]

America's largest supplier of oil is ...

wait for it ...

Canada.

Re:our galactic stone-age

[LWATCDR]

Yes most people don't seem to get that the US gets most of it's imported oil from Canada and Mexico. Notice how the middle eastern countries have not tried an Oil Embargo to influence the US. Europe and Japan depend a lot more on Middle eastern oil then the US does.
Of course I vote for nuclear. And yes I have on in my back yard. Right now we have 10+ years of nuclear fuel left over from old weapons more if we use the plutonium for fuel. I say the sooner we burn up the weapons grade stuff the better.
It produced 0 CO2, light water reactors with containment buildings have been very safe, and they really are cheap and reliable.
I also think we should use solar as well. Wind? I think it is a bit iffy at best but it has it's uses.
The trick is diversity.

Re:our galactic stone-age

[Anonymous Coward]

I have a dumb question. Won't the solar panels trap a lot more of the sun's heat on the Earth that would normally be reflected?
And won't that add to global warmng?

Re:our galactic stone-age

[Anonymous Coward]

Please take 10 seconds to calculate the total amount of area for all solar panels combined and compare it to the area of the Earth. Then please jump into a lake (to cool off, I mean).

Re:our galactic stone-age

[iminplaya]

Solar energy is yet expensive...consume half of what they do now...

Oh jeeze. So now we'll have to flush four times to get everything to go down. Instead of us doing the sacrificing, how about telling the corporations to sacrifice a little profit? In reality, the resources are nearly infinite. All we do is move them around and combine them with others. Our management of them is the problem. Our present business models create the need for shortages and "crises". Let's work on that to see where we really stand. We're still trying to sell refrigerators to the Eskimos.

Our story resembles more and more with some Age of Empires game where we start on an island, burn out everything there is to burn over there, and then have no more resources to build transporting ships.

Ok, and that too.

Re:our galactic stone-age

[rainman_bc]

America's largest supplier of oil is ...

wait for it ...

Canada.

And the won't believe you unless you provide a link

Only 4% even know it.

Re:our galactic stone-age

[chris_eineke]

Ich bin ein Canadian!

Re:our galactic stone-age

[operagost]

GWB (Halliburton) is now supporting moving to a hydrogen based economy?

Now the president runs Halliburton... hahaha. You guys just keep cracking me up.

Re:our galactic stone-age

[stonecypher]

And Canada buys 2/3 of their export oil from ... wait for it ...

Re:our galactic stone-age

[Sethb]

Regarding the flushing, we just redid our bathroom with a low-flow toilet, but our new one flushes 10X better than our old high-flow toilet ever did. Get yourself a Kohler Class 5, it's rated to handle 100 feet of toilet paper, and I haven't even had a single second-flusher on it. As the plumber said when he installed it, "this will handle quite a load". Efficient equipment doesn't have to be inferior, just properly designed.

Re:our galactic stone-age

[WeAreAllDoomed]

Now the president runs Halliburton... hahaha. You guys just keep cracking me up.

other way 'round.

Re:our galactic stone-age

[tntguy]

Hope they opt to pay extra for the scratch-resistent coating.

Re:our galactic stone-age

[Captain Splendid]

That's Canuckistan, you unpatriotic clod!

Re:our galactic stone-age

[iminplaya]

Yeah, well, that bowl had better be pretty deep too. There are few things worse than the unexpected "touch" of cold porcelain in the morning.

Re:our galactic stone-age

[thealsir]

I have an idea: Peer to peer power. The power company subsidizes some of the cost of installing a solar panel on people's homes, and in turn, power can be shared home-to-home. The power company wins, because they do not have as much load on their plants and can power more area with fewer plants. The people win because they have a more stable energy supply (not reliant on one/few sources). Financially, I'm sure it could be made so that people pay less for power bills and get more reliable power. The company will still have more money than they did before to invest in new plants and power more area with the same number of plants.

Re:our galactic stone-age

[evilviper]

The middle east will own the solar age like they do the oil age now, they have the sand and the sun, and huge deserts to coat with panels.

They have the sun? Really? I though I had the sun locked up in my garage, so nobody else could get at it.

And sand... Yeah, that's great for solar panels. You want lots of sand blown across them for peak effeciency.

Solar is only effective if it can be generated near where it is needed (which it can). You can't bottle up electricity (without SERIOUS conversion losses) and ship it to where it's needed, nor are transmission lines effecient enough to send it across countries.

If the middle east can meet all their energy needs with solar, good for them. It won't hardly affect the rest of the world.

Re:our galactic stone-age

[evilviper]

Wind is a lot like hydro. It has an upper-limit, but other than that, it's cheap enough, and should be utilized as much as possible. Solar has even more potential, but wind gives a better return on investment right now.

Re:our galactic stone-age

[iminplaya]

It's already being done in some states. I forget the official name. When you generate more than you use, the meter runs backwards. Been around for a few years now.

Re:our galactic stone-age

[evilviper]

America's largest supplier of oil is ...

wait for it ...

The U.S.

A) You didn't say "foreign" or "imported" anywhere.
B) "America" isn't a country, it's two continents. The "of America" part of USA is almost always left out.

Re:our galactic stone-age

[evilviper]

1) Cheap labor
2) All their open land doesn't have any NIMBY neighbors to complain
3) No environmental restrictions/regulations
4) The open land cannot be used for anything else, especially crops.

Sounds exactly like most of AFRICA to me... And Africa is a hell of a lot bigger than the middle east.

Re:our galactic stone-age

[LWATCDR]

Unlike hydro you can not throttle wind. You can not save it up and control how much you use when. I say yea use it. Use it all.

Re:our galactic stone-age

[Anonymous Coward]

A) The two continents are generally referred to as the "Americas" .
B) Mexico's full name being "The United Mexican States", U.S. isn't really any less ambiguous than America.

Re:our galactic stone-age

[Anonymous Coward]

4) The open land cannot be used for anything else, especially crops.

The big downside they face is how do you transfer all the energy collected to the markets that need it?

It seems that it'll have to be the crops, after all... a biofuel, produced by GM algae in shallow, sunny, covered against evaporation tanks.

Using carbon-based fuel is OK as long as the carbon in it comes from present day atmosphere, not from fossile sources. It is preferable way to go over the "hydrogen revolution" for at least two major reasons:

First, switching from "pumping from the ground" to "raising on the ground" would spare the world from complete infrastructure rehaul and if it is done in the areas which used to "produce" mineral oil, the savings would be even greater (pipelines, oil tanker terminals in ports are already in place). Enormous collection of knowledge and engineering expirience in design and maintanance of ICE and virtually all transportation means would not be just thrown away.

Second, it is effective way of excess atmospheric carbon recall and sequestration: we can pump the "bio-oil" back into the depleted oil wells, or bake it into sooth, press it into blocks and dump deep underground (or use it up in carbon-based nanotech devices and materials) untill we lower the atmospheric CO2 concentration to the level we want.

Third: you get to keep your SUV's, Hummer's (and your jets, aircraft carriers and tanks as well) after all...

Fourth: the upkeep of Israel continues to pay out, as its strategic importance continues, and furthermore, Israel becomes active, leading producer of fuel as well (however, Kishon's "No Oil, Moses" will not be read less because of that change).

Re:our galactic stone-age

[CreatureComfort]

Actually most of Africa is good arable land, perfect for farming. If you could get the neighbors to stop killing each other, Africa would be the breadbasket of the world. The famines there have nothing at all to do with poor climate or soil. In addition, Africa is still a major source of biodiversity and the target of western environmental protectionism. Once again, the only reason more enviro-nuts aren't protesting and putting a stop to uranium mining, diamond mining, and other polluting and destructive practices is because the locals are likely to kill them when they show up. The locals are too undereducated, underfed, and poor to have time or knowledge to do anything about the poor conditions. If the lifestyle was upgraded, you would find NIMBYism very strong through most of the region. Throw in the fact, that because it really is pretty easy to survive (find minimal food, water, shelter necessary for the climate), there really are a lot of people scattered throughout Africa.

Aside from the Sahara region, Africa has much less to offer for massive solar installations than the middle-east. And I personally tend to loosely define "middle-east" to include Egypt, Libya, and Algeria, all major oil producing nations. Those three are much more closely aligned, culturally, religiously, environmentally, and economically to the rest of the "middle-east" than they are with any other African nations.

Actually, the area other than the middle east that is well suited for this type of installation is western China, but it is so isolated with so little infrastructure and transportation that it would be way behind in developing these kinds of facilities in a cost effective manner. One of the nice benefits of most of the middle eastern region is that it is very accessable by road and sea.

Re:our galactic stone-age

[macdaddy]

I agree. We should use every renewable method available to us. I also agree with the nuclear. Why are we building more coal-burning power plants? I can't believe we continued building them about the 60s or 70s. It should have stopped long ago.

Re:our galactic stone-age

[evilviper]

The famines there have nothing at all to do with poor climate or soil.

No, actually droughts (climate) are the most common cause of famines in Africa.

Aside from the Sahara region, Africa has much less to offer for massive solar installations than the middle-east.

Oh, gee, ONLY the Sahara region, eh? ONLY an area of 3.5 MILLION square miles? ONLY an area more than 3 times the size of the middle east?

And that's not even bothering to mention the large Kalahari and Namib deserts.

Actually, the area other than the middle east that is well suited for this type of installation is western China,

The Gobi desert (Mongolia and China) is only 0.5 million square miles all together. The Taklimaken desert (China) is only an additional 0.14 million square miles. Together, still less than 1/5th the size of the Sahara.

Re:our galactic stone-age

[CreatureComfort]

No, actually droughts are not the most common cause of famine in Africa. If the social and political climate were stable, and modern farming methods and seeds could be imported and grown, there would be no famine in Africa. With the antiquated farming techniques, and instability in the region, the local farmers need perfect conditions just to feed themselves, so it gets blamed on drought.

Yes, only the Sahara, which, as I said, if you bothered to read my post, is mainly contained in the countries of Algeria, Libya, and Egypt. All countries much more closely aligned in any manner you choose to investigate, with the "middle-east" than with any other ideological or political block. So, you might as well include those as part of the "middle-east". And if you bother to look it up in World Fact Book, you'll find that Saudi Arabia, Iran, Iraq, Afghanistan, Pakistan, and the smaller countries such as Kuwait, Syria, Lebanon, Oman, Yemen, etc. have far more land area than even the largest estimate of the Sahara. If you then include the additional three I mentioned and move their area from "Saharan Africa" to be included in "middle-east" there is no comparison.

As I said, the next largest area even comparable to Middle-east or Sahara is China's deserts. Every place else is far smaller.

So we are back to my original contention. The "middle-east" (including the three Saharan countries) are far better poised to rule any new solar based energy economy than any other area of the world. Coincidentally, these countries, including the three Saharan countries, also control the world oil based economy.

Re:our galactic stone-age

[thealsir]

Wish I had mod points sir. It's good that this is in use already...I should've done research. But the fact that I haven't heard about it and not many people use it says something about its need to be advertised/implemented more.

Re:our galactic stone-age

[evilviper]

the local farmers need perfect conditions just to feed themselves, so it gets blamed on drought.

This is nonsense, but it's clearly not worth the effort arguing the point with you.

Yes, only the Sahara, which, as I said, if you bothered to read my post, is mainly contained in the countries of Algeria, Libya, and Egypt.

I tried to read your post, but it's more a collection of unrelated sentences put together in a big block, with no coherency. So, you start talking about those countries producing oil jump off onto some other subject without warning, and I'm supposed to somehow know what you were actually trying to say?

[...] have far more land area than even the largest estimate of the Sahara.

This is just completely arbitrary nonsense. Yes, the WHOLE of the middle east is slightly larger than the largest DESERT on earth. The problem is, not ALL of the middle east is desert, and the DESERT isn't covering all of Africa.

As I said, the next largest area even comparable to Middle-east or Sahara is China's deserts.

Mongolia isn't in China.

Re:our galactic stone-age

[dbrutus]

We could create plants that convert coal to gasoline via very well understood Fischer-Tropsch processes (WW I invention). Sasol in S. Africa does this for about $32/bbl. The crushing financial losses associated with FT plants started during the Carter oil spike has delayed the plants and environmental protests (CO2 is associated with the process) are likely to delay them yet more.

The companies are willing to provide the solution for cheaper energy. Are we willing to let them?

Re:our galactic stone-age

[dbrutus]

Actually, you can bottle electricity, it's called electrolysis and you ship the resulting hydrogen. The current price is about $6/gge (gallon of gasoline equivalent) though the DOE projects that price to drop below $3/gge by 2010. Coincidentally (or not), 2010 is when the DOE has projected we're going to have hydrogen cars that can run the standard 300 miles to the tank with a fuel cell system that is all weather and costs and takes up the same amount of space as a conventional gasoline engine. Try taking a look at the GM's Sequel. It looks like they might make their announcement of a few years back of 2011-2012 timeframe to ship a practical hydrogen car.

Re:our galactic stone-age

[iminplaya]

The power companies are unlikely to promote it. Until some laws were passed(reinvigorates my faith in government...to an extent), there was quite a bit of trouble getting it set up and connected to the grid(about half way down the page). And I finally found out the name, "net metering". Spread the word.

Re:our galactic stone-age

[evilviper]

Actually, you can bottle electricity, it's called electrolysis and you ship the resulting hydrogen.

I specifically said: "You can't bottle up electricity (without SERIOUS conversion losses) and ship it to where it's needed,"

What part of that didn't you understand?

Re:our galactic stone-age

[LWATCDR]

Why. Because of people like my ultra-liberal co-worker. He is so worried about global warming yet, he drives an SUV, just put in a heated swimming pool, and didn't use solar to heat it. Yes WE LIVE IN FREAKING SOUTH FLORIDA!
His comment is. The government should provide more tax credits for solar...
Way too many people want somebody to do something about global warming... Not them of course but somebody needs to do something.

AC??

[AcidLacedPenguiN]

So has the day finally arrived where I can run my AC off of all that heat outdoors?

I thought you just had to log out to run AC.

See Einstein's Ammonia Refrigerator

[Anonymous Coward]

Right here: http://en.wikipedia.org/wiki/Einstein_Refrigerator

Reichstag, Berlin

[D4C5CE]

Here's another "tiny, little-known building" that uses the method. Involved quite a bit of drilling, but then again we're talking several GigaWatt-hours of heat transfer per year... (Web site only partially in English)

The day came 100 years ago

[dbIII]

So has the day finally arrived where I can run my AC off of all that heat outdoors?

Early refrigeration used heat sources such as kerosene to expand the working fluid - so there are such things as the kerosene fridges with no moving parts used in remote areas. A big curved mirror reflecting the sun could have been used as the heat souce a century ago, but is a bit inconvenient. It would make far more sense to use solar heating to drive your airconditioning than have a not paticularly efficient way of converting solar energy to electricity first and then a not paticularly efficient way of using electricity to move heat about. Doing other stuff that can only be done with electricity is a different story and solar thermal scales up - but doing stuff with heat when you already have a heat source is not the best way to do it.

Re:The day came 100 years ago

[kfg]

Early refrigeration used heat sources such as kerosene to expand the working fluid. . .

Don't be silly. I've been told right here on Slashdot that you can't make things cold by applying heat to the system. Anyone can see that doesn't make a lick of sense.

KFG

The Kalina cycle

[Richard Kirk]

It is a pity about the chlorofluorcarbons. There is a good alternative process that uses ammonia and water that has been around for some time. It is more efficient than the straight water cycle, and the system is closed so the water isn't going anywhere. See for example http://www.geothermie.de/gte/gte46/geothermal_powe r_plant.htm

One small problem: You need a heatsink....

[gweihir]

Thermodynamics allows you to convert a temperature differential into mechanical energy. Heat in itself is basically worthless as enegry source. So if it gets warmer everywhere, this does not generate the possibility to produce energy.

One thing that usually can be done is to have heat/cold storage and to radiate the heat into space at night. Ironically deserts are best suited for that.

You already have thermal energy

[dbIII]

I think aircons should run primarily on photovoltaics

Run them on heat instead - instead of having water in a rooftop solar hot water system you could have your airconditioning working fluid (eg. ammonia) getting hot then expand it through a nozzle to give you cooling. This gives you cooling with no moving parts and would use a lot less roof space than the photovolatics required to run an electric airconditioner. Electricity is not the answer to everything - it's a way to get energy from one place to another.

Re:You already have thermal energy

[Diamondback]

That's so crazy it just might work. I always marveled at the propane refrigerators my parents had at our cabin - you boil something to make something else cold! Wow!

Solar-powered air conditioning, using no electrical conversion at all... brilliant.

Re:You already have thermal energy

[Anonymous Coward]

As to heating something near an object to get that object cool:

An very old, now deceased, friend of mine used to tell me they would bury a six-pack in sand, pour fuel on it, and light the fuel, during WWII. The beer would then be cool enough to drink(for Americans who like cool beer). This always sounded a bit nutty to me, but I guess it worked.

If you try this and it works, make a toast to Carmine Mangano!

Re:You already have thermal energy

[gatzke]

Take a class in engineering thermodynamics, or just read up on the topic. Amazing stuff.

IC/Diesel/HVAC cycles are neat to see.

And remember, don't open your refrigerator to cool your house.

Re:You already have thermal energy

['nother poster]

Don't light the fuel! You don't want it to burn, you want it to evaporate. Use gas, not diesel, it has a lower vapor temp/prerssure, and flame off any resude before you drink it. I'm betting that is where the set it on fire part came in. This will get you several degrees below ambient, which beats the hell out of 97F 3.2% ABV pissy lager. Now if they just served a nice beer that benefits from being warm, like some belgian ales, this wouldn't have been a problem.

Re:You already have thermal energy

[PeterChenoweth]

http://en.wikipedia.org/wiki/MythBusters_(season_2 )#Episode_29_.E2.80.94_.22Cooling_a_Six_pack.22

Re:You already have thermal energy

['nother poster]

But, the ammonia won't condense at the ambient temp. It's boiling point is -33.5C. It would cost a lot more to keep putting ammonia in your system than the cost benefit of the cooling. If you use a compressor to condense the ammonia you're just back to a standard AC unit that needs outside power. Secondly as far as I can see your system would cool the water, not the air, and you just heated the water with solar energy. You would need to heat the water with the heat from the building. The problem comes from the fact that you want to have the temp of the inside lower than the outside. That means that you have to concentrate the heat in the building into the water to raise it above the ambient and that will take more energy than the cooling system saves.

Re:You already have thermal energy

[QMO]

Then there's the old jet powered beer cooler.

Re:You already have thermal energy

[lubricated]

In this house we do not violate the laws of thermodynamics.

Re:You already have thermal energy

[njh]

to be honest, all he was really doing was using LPG evaporation to cool the beer. The jet engine was just an excuse for pyrotechnics :)

ACTUALLY, MOD PARENT DOWN

[Anonymous Coward]

Because he didn't explain shit, exctracting heat energy from a system doesn't work without a heat sink of lower temperature

Sig

[Poromenos1]

People replying to my sig annoy me. That's why I change it all the time.

Well, one can always quote it :P

no, it solves 100%, it clearly states ambient air

[_Shorty-dammit]

it very clearly states in the animation at the company's website that ambient air temp is sufficient to cool it back down. You seem to be forgetting that those big black panels on rooftops that heat water using the sun's solar energy heat the water up to a much higher temperature than the ambient air is. What exactly would be the point of a solar water heater if it only gave you water that was the temperature of the ambient air? Anyway, so, you use that heat source to boil the liquid in the closed circuit. Don't forget, it ain't water. It's some liquid that boils at a pretty low temp. And then you use the ambient air for the heat exchanger to cool the 'steam' in the closed circuit back down, condense, and start all over again. So, from what I gather the only requirement for this to work is that the boiling point of the liquid in the closed circuit needs to be higher than the ambient air temp, and lower than the temp you can achieve from a device similar to / same as those rooftop solar water heaters. Then you should have no problem boiling or condensing that liquid, since you have the capability of getting the substance up to the boiling temp, and back down below that temp so it condenses again.

cooling water needed

[Anonymous Coward]

"Steam re-condenses into fluid because it has lost it's energy to the turbine....
No perpetual motion or violation of the laws of thermodynamics involved,"

Yes, perpetual motion or violation of the laws of thermodynamics involved. Plus, if you look at their website, that's not what they are claiming.

If you put the steam through the turbine, you now have lots of low-pressure steam that you can't get any more useful work out of. They are condensing the steam back into liquid using copious amounts of cooling water (see the condenser and motorless pump in their animation). You don't get energy for nothing.

Also, keep in mind that the article summary is a little misleading by mentioning that the liquid boils around 58F. They are actually heating the system up to 150F - they are _not_ running this at room temperature. They are simply arguing that it's easier to get 150F temperatures from natural sources (geothermal, solar) than the higher temperatures required for more traditional steam engines.

You're not using your head

[Anonymous Coward]

The Mid-Atlantic has always been brutally hot in summer.

DC always has a month of weather than is 90-100 degrees with 80-100% humidity. Makes you wonder why we were stupid enough to build a city here.

And in Pennsylvania we always had 1 week fo 105-110 degree weather (accompanied by 4 weeks in january/february of 0 degree weather.

This is not a symptom of anything other than brutal weather in eastern US.

Re:You're not using your head

[Gryle]

In terms of heat nothing beats Texas. Daily highs routinely reach into the 100s during the summer. In Dallas, the heat kills old people. Houston, being so close to the water, is damn near unbearable. Texas has four season: summer, summer, still summer damn it, and Christmas.

Re:You're not using your head

[Don853]

I don't know where in Pennsylvania you live. I grew up in the middle of the state (out in a podunk town past Gettysburg, if it makes any difference), and for the 21 years I was there, 100 degrees happened an average of maybe twice a year, and 0 degrees less often than that. Granted, 0 is a lot more common in say, the Allegheny forest, but 100 isn't. In terms of temperature change, the Mid-Atlantic is far less extreme than the plains states.

And this is totally trivial, but it's a peeve of mine: 90 degrees and 80% relative humidity is an 83 degree dewpoint, which never happens in this area of the country. Maybe the Amazon basin. The hyperbole scales badly from there.

Re:You're not using your head

[Anonymous Coward]

I always heard they put Washington DC somewhere so miserable in summer it would force politicians to go home and do something useful for part of the year.

I doubt it is true, but I like the story.

Jeff

Re:You're not using your head

[bmalia]

Here is Kansas, we have a saying. "If you don't like the weather, wait 5 minutes."

Re:You're not using your head

[Fallingcow]

I think that they say that in all of the states around here. Certainly, they did in Missouri when I lived there.

It does always weird me out a bit when we have more than 2 days of the same kind of weather/same temperatures. The 3-day super-hot period we just had (in S.E. KS, anyway, I don't know about the rest of the state) was starting to piss me off, glad it's over and we're back to just regular-hot. Now if we can get some damn storms, I'll be really happy. The last 2-3 years have been practically devoid of good storms, it seems.

Solar Roof Powers the H2o Pump, Steam Engine

[digitaldc]

How about recycling the gathered water back to the steam engine with energy collected by solar roof shingles, then you have both heat and light-powered A/C.

This house would be the best of both worlds.

sure it will, it's not 10PSI

[_Shorty-dammit]

Link to animation Page 7 explains how it works. The liquid is heated by an external source, such as solar water heaters on a rooftop, to a temperature much higher than ambient air temp. This heat is transferred to the liquid, which boils and gets pressurized, and goes through the turbine. After which it is condensed in the condensor, which is cooled via ambient-temperature water. Then the second heat exchanger comes into play. This second one is isolated by valves at both ends. Before the condensed liquid is released into the second heat exchanger, the empty HE is cooled by the same ambient-temperature water as the condensor was. Once the HE is roughly the same temp as the condensed liquid, the top valve opens and the condensed liquid enters the HE, and then the valve closes. Now it is isolated by both valves inside the HE. And the HE is then heated by the same solar heater, bringing the liquid up to the same temp and pressure as it is in the boiler. Then the bottom valve is opened, and the liquid moves into the boiler. The valve is then closed. Then the HE is cooled again, so it can receive more condensed liquid. And on and on. The animation, and their more clear explanation, shows the entire operation rather well. Click it, I say! Click it!

Re:sure it will, it's not 10PSI

[Ancient_Hacker]

There's no free lunch.

To heat the liquid so it will flow into the boiler requires you to use slightly hotter source water than that you feed to the boiler. So you have just LOWERED the efficiency of the boiler even more, in an attempt to get rid of the pump. Not a good tradeoff.

The Carnot cycle has been studied intensively for over 140 years. Is it likely soime Joe-schmoe is going to come up with a breakthrough, without using even a smidgen of engineering math?

Re:sure it will, it's not 10PSI

[geekoid]

"The Carnot cycle has been studied intensively for over 140 years. Is it likely soime Joe-schmoe is going to come up with a breakthrough, without using even a smidgen of engineering math?"

Do you relize how many people have ended up with egg on there face by saying similir things?
Yes, you make a good point, but when Ir read that it made me laugh.
It's almost a garentee this guys product will work.

Re:sure it will, it's not 10PSI

[Alsee]

You seem to be saying the system is claiming to beat Carnot, and then criticizing them on that basis. I see no suggstion anywhere except from you that this is supposed to beat Carnot.

I think the claim is that this system is better than the current pump design, at least for some applications. Note that efficency is merely one factor in defining "better".

(1) In the usual system the pump appears to be a signifigant physical cost element. The new system should simply be less expensive to produce and thus less expensive to buy.

(2) In the usual system the pump is a primary point of failure. Eliminating the pump should increase reliability.

(3) In the usual system the pump is a primary factor in maintenance costs. Eliminating the pump reduces maintenance costs.

(4) According to their website, this design can more easilly be run at higher pressures (they cite 450-500 PSI). Higher pressures mean improved efficency compared to the usual pump design. I expect it would also mean smaller size - which would also mean less expensive .

Which brings us to (5) overall efficency. Everything you said about this appears to accidentally assume that the energy cost and thus the efficency cost of the pump is zero. You neglect that you are taking the heat energy and transfroming that by boiling into energy of vaporization, transfroming that into linear motion of the vapor, transforming that into into rotary motion, likely going through an extra step converting it into electricty, then transering that to the pump, which then then finally converts it back into into pressure and heat to inject the fluid back into the boiler. Each step or energy transformation in that sequence represents a subtraction from efficency.

The new design takes the heat energy and directly transfers it into pressure and heat to reinject the fluid back into the boiler. That is the direct and most efficent usage of your heat energy source to do the work you need to do to run the system.

Any reduction you claim in the efficency of the boiler itself would be more than offset by the amount of energy you need to bleed off from the boiler in order to run the pump.

This is obviously not any earthshattring violation of the laws of thermodynamics. They do not appear to make any such claim. It does however look to me like a very interesting and useful design. It looks cheaper and likely more efficent than current pump designs. It may indeed make it cost effective to open up at least some more applications harnessing ambient low level heat sources like the sun and geothermal and hydrothermal and waste heat.

-

Re:sure it will, it's not 10PSI

[Ancient_Hacker]

>It looks cheaper and likely more efficent than current pump designs.

There's not a smidgen of numerical evidence for this, and plenty of indications otherwise: Heating and cooling that chamber is going to cost a lot, especially since it has to get first dibs on the hottest water.

Let us know when the system can pay back its interest costs. Not likely to be anytime soon.

Re:sure it will, it's not 10PSI

[McCaliber]

We can't tell if its a good tradeoff because they don't give us hard numbers. The engine as a whole was already less efficient because it was using its own electricity to run the pump. Changing that to using the boiler's heat directly is no different. The purpose of this design is to remove the inefficiency of transforming energy from heat to electricity to pressure, and just use the heat to generate pressure directly. The assumption they seem to make is that the loss in efficiency from the electrically powered pump is significant, more so than the energy loss from a less than optimal Carnot cycle involving small temperature gradients. Since the efficiency for a small temperature gradient Carnot cycle is already so low, they may be right. For the CS majors out there, the constant factors in this application outweigh the asymptotic behavior. They're working on removing constant factors.

Re:sure it will, it's not 10PSI

[shadowbearer]

  Arguments about whether it will work or not aside - and they claim to have built working prototypes, so the market will decide;

  well, that's easily the best use of flash animation I've ever seen. nice and nicely done :-)

SB

take a bath in the heatsink

[hogghogg]

If you have something cold to work as a heatsink, eg, cold water, why not just take a bath in it? A one-minute cold bath beats hours of AC any day!

Re:take a bath in the heatsink

[Kadin2048]

Because people don't want to get wet?

Lots of people have swimming pools, and yet still have air conditioners...the presence of a liquid heat sink doesn't make air conditioning any less attractive.

Personally, I've always thought that people who have swimming pools that are heated with fossil fuels or electricity, and also have air conditioners, are wasting a lot of energy: why not just use the air conditioner to pump the heat from the house (which you want to cool) into the swimming pool (which you want to heat)?

Even a medium-size residential swimming pool has a pretty large heat capacity, particularly if you leave it uncovered (so that heat is constantly lost to evaporation) and even moreso if it's an above-ground pool.

Re:take a bath in the heatsink

[Anonymous Coward]

I'd imagine the main reason is the larger pump necessary to circulate the refridgerant from the central AC unit to the heat exchanger in the pool and back. Also, you'd have to insulate the long length of piping pretty well to avoid major heat transfer losses to the air/ground before it reaches the pool.

Re:take a bath in the heatsink

[Kadin2048]

I'd imagine the main reason is the larger pump necessary to circulate the refridgerant from the central AC unit to the heat exchanger in the pool and back. Also, you'd have to insulate the long length of piping pretty well to avoid major heat transfer losses to the air/ground before it reaches the pool.

True, but there's a lot easier way to do it than piping the refrigerant all the way to the pool; you can always just install an extra loop in the pool filter's piping that runs over to the A/C compressor. Then you're just moving water around, rather than Freon, which is pretty simple. If it's in PVC, it's also fairly well-insulated.

Sure, you'd need a slightly bigger pump, but probably not much more than you'd need to pump water through a conventional fossil-fuel fired heater.

I think the problem is more that there aren't air conditioners that are designed to work with pools or to be water-cooled (residential ones, anyway; industrial ones are frequently water cooled, and combined with an evaporative cooling tower). The common design is the barrel-shaped, periperhal-intake/axial-exhaust one, and it's tough to figure out a good way to water-cool it, I expect.

I actually found online that there is at least one company around that does this, by adding an additional heat exchanger to the cooling circuit and then running the pool water through it. It has the downside of apparently making it impossible to run your air conditioner without the pool pump being on (I don't understand quite why -- wouldn't this just make it work like a normal air-cooled system, without the benefit of the water-cooled exchanger?), but it's otherwise pretty neat.
http://www.toad.net/~jsmeenen/pool.html

And then there are standalone heat pumps for pool heating, which just move energy from the air into the water in order to raise the latter's temperature; I wonder if you could just redirect the (cool) exhaust air from one of these and use it as air conditioning, for example in an outdoor patio room or something.
http://www.centralsolar.com.au/pool_heat_pumps.htm

Too little

[bWareiWare.co.uk]

Even if you assumed that the 5% efficiency was constant at any absolute value (it is highly likely that it is 5% peek at some specific temperature) and the solar panel did not reduce the efficiency of your heat collector (it is also likely that a solar panel reflects and radiates more energy then a dedicated collector) then you would only get a combined efficiency of ~24% as the collector can't get the 20% the solar panels are converting
Either way solar is very rarely constrained by size, but rather cost of installation. I expect that in most situations installing a solar cell with 120% of the service area is more cost effective then installing another complex system that would need additional maintenance.

obligatory Austin Powers

[Anonymous Coward]

Swedish heat pump?

"Honestly, it's not mine!"
"This sort of thing ain't my bag, baby!"

heat to make cold, cold to make heat

[nitz7978]

http://en.wikipedia.org/wiki/Peltier-Seebeck_effec t this doesnt sound like a new idea to me.

there is a heatsink

[_Shorty-dammit]

and it is dumping the heat into the ambient air. Solar water heater = much higher than ambient air temperature. Much higher than ambient air temperature = ambient air will cool it. Nobody is trying to say this is defying thermodynamics. And it doesn't. It's not even terribly effecient. But it would work, provided you had a suitable liquid in that closed circuit that powers the turbine. Suitable meaning, the solar heat source's temperature is sufficient to boil it, and ambient air temperature is low enough to condense it. I'm guessing a working device/system would be pretty bulky. But, you could indeed build a working device/system.

OT please do not moderate

[Red Flayer]

Just wanted to mention that your sig is fantastic. Scary, but true.

Re:OT please do not moderate

[Tim C]

If you don't want a comment moderated, I'd suggest using the guy's email address next time. Anything posted here is fair game (yes, including this - karma is irrelevant anyway).

Re:OT please do not moderate

[Red Flayer]

I'll have to set up a dummy email account then -- guess I was being lazy. There's no way I'm sending an email from any of my normal accounts to someone I don't know who frequents slashdot :)

Re:OT please do not moderate

[Anonymous Coward]

That's not a bad idea. In fact, I'm posting from my dummy account right now!

Re:OT please do not moderate

[bhima]

Oh damn the moderation!

Glad you like it

I've emailed some random dude off slashdot and it went OK

I've gotten email from some random dude off slashdot over my last sig... I was looking for a way to use Intous input devices on a self made OS X powered iTablet sort of thing. Actually I still am but I've given up on slashdot as a source of information on that fools errand

Solaring

[SouledOut]

Me and my mate tried solaring for the first time at the weekend... tokin' bud in a pipe and lighting it with the suns rays through a magnifying glass is the way to go, I tell thee!

Re:Solaring

[Anonymous Coward]

Just use the earth as your heatsink, because it is colder than the above ground temp most days of the year. Caves are what 50~60 degrees year round right? Tap a well, and force the fluid down and up again from the earth to cool it. It would work anywhere it's hot right? And during the winter you could generate energy the opposite from the differential between ground and air temp!!! Just chew on that for a minute!

Re:Solaring

[Anonymous Coward]

Now THAT would be a deep hit! Watch out for buried caves full of [insert toxic gas here] though...

Re:Solaring

[internewt]

He's right. It's a much better use of the sun than this "air conditioning" or electron generation BS.

Heat outdoor?

[Anonymous Coward]

So has the day finally arrived where I can run my AC off of all that heat outdoors?

You probably mean energy outdoor. Heat is the transfer of energy by means of temperature difference. If you can't move what you call heat to a cooler place, you can't make much use of it. You are actually trying to move that heat of your from hour house (the colder place) outdoor (the warmer place). This is not easily done, and you certainly can't expect to use the flow of enery in one direction (heat) to power a flow in the oppsite (your AC).

Assumptions are way off

[brunes69]

Why do you make any assumption that the liquid needs to be heated anywhere near 80 degrees? I see nothing saying that at all on the company website.

If the boiling point of the liquid is 58f then you only need to heat it to a range of 65f and condense it at around 52f. Thats 284.26 to 291.48. Quite a difference.

Re:Assumptions are way off

[Don853]

You're correct, he was being extraordinarily generous in both directions. You've now gotten the effeciency down to 1-(284.26/291.48), or about 2.48%.

Re:Assumptions are way off

[brunes69]

You guys are both seriously missing some steps here.

The efficiency of the system is basically irrelevant. The energy being used is already wasted energey, ambient heat from the air. The system could be 0.01% efficient and it would still be a huge boon to the environment, assuming you could harness enough enegergy from it to use.

Heat the liquid to 65 degrees, heat it to 70 degrees, even higher for more efficiency, who cares. The important thing is that because the boiling and condensation points are so close (and low), you can derrive useful work from the thing with low ambient temperatures. Note that temperature != heat input. It may take a lot of heat input to heat this substance to that 65 or 70 degrees, but because that is the ambient temperature that will be the equilibrium point.

Re:Assumptions are way off

[Don853]

If you don't mind something the size of an automobile that makes a few hundred watts, you can get as low of an effeciency as you want. If you want it to recoup the investment costs in a reasonable length of time and not take an incredible amount of space, the efficiency is still relevent. And you need a heat sink, though you can use the ground. This increases initial costs as well.

And I'd hope that the boiling and condensation points are close. That'd be one mighty strange substance if they weren't.

And while you're at it, mod parent *wacko*.

[Anonymous Coward]

Sure, the adiabatic expansion of the gas in the can of air will definitely make for some nice cooling, but you seem to have missed the point. In a closed system, you have to get the gas "back in the can", so to speak, and any diver can tell you how much heat you'll feel then. (Don't get me started on the short fills I got this weekend from the dive shop. Their unacceptably fast fills consistently gave me 2800 psi or less in my 3000 psi cylinders.)

The wonders of popular science?

[dud83]

Despite using a liquid with a low boiling point, the basic laws of thermodynamics still applies.

The energy which needs to be absorbed for turning a liquid into gas can be X. A turbine cannot utilize all energy because of friction, slowness etc. So the energy which the turbine produces would be X - delta X, which could be Y.
Then you'd like to use that energy Y to power air condition to lower the temperature inside?

Did it ever strike these people to think about something called "Solar Photovoltaic Panels", commonly named "Solar Panels", the efficiency of using the photovoltaic effect is indeed much higher than relying on heating a liquid.
Anyone even slightly familiar with thermodynamics and physics will tell you that a large part of the energy to heat up a liquid into a gaseous phase will be lost to the enviroment (owning to the rather amazing "Second Law of Thermodynamics"!).

To summarize, heating a liquid into steam to harvest energy, and then attempt to convert the energy into electric energy, INSTEAD of putting up a solar panel array... Is a fantastically stupid idea. It doesn't matter that the liquid has a lower boiling point, what that means is that less energy has to be absorbed for it to leap into a gaseous phase. In plain english, by using such a liquid you collect less energy than if you were to use good old water.
Also, lets not get into the whole aspect of the fact that the boiling point of a liquid is not only dependent on temperature, but pressure as well... No matter how you twist and turn, you end up with X energy and you will loose energy in every single step and conversion.

Solar Photovoltaic Panel is much more efficient, in every possible way you look at it.

This whole idea reminds me of when you're a kid and you try to lift yourself off the ground by pulling your own legs hehe.... ;)

Re:The wonders of popular science?

[Anonymous Coward]

Actually, you would be correct only if the Photovoltaic panels were very efficient. At the current efficiencies, using the sun's rays to heat a fluid to drive a heat engine is way more efficient. Google solar sterling engines and you'll see that the record for solar efficiency is >30% using mirror concentrators and a stirling engine. Solar panels have not yet crossed the 20% efficiency barrier. The main reason is that the solar panels only use a small portion of the wavelengths while a heat engine system can use far more.

But, as with everything, the cost is still pretty high, no matter which way you go.

Re:The wonders of popular science?

[david_594]

Their whole selling point though is that their system is simple and cheap! Didnt you read to the end of their presentation where they said it would cost $9600 for photovoltaic soler cells(and batteries) to power your laptop? Thats why there system is such a better option.

Im serious, thats what it says! Read to the end

Re:The wonders of popular science?

[david_594]

Correcting myself: They say it would cost them $9760 for a photovoltaic system to power their $800 laptop 24/7.

Re:The wonders of popular science?

[Anonymous Coward]

"Did it ever strike these people to think about something called "Solar Photovoltaic Panels", commonly named "Solar Panels", the efficiency of using the photovoltaic effect is indeed much higher than relying on heating a liquid."

It is possible to get solar thermal panels that will convert 90% of the incident solar radiation into energy within the panels themselves. The question is what proportion of this can you then harvest in a form that is useful to the particular application. I'd suggest that converting it into electricity to run an A/C unit is probably the wrong way to go about it as you can harvest it more directly (using the working fluid directly to drive the A/C process) with fewer efficiency losses, to run an A/C then going through a conversion to electricity. Current photovoltaic panels convert at most 25% of the incident solar radiation into electricity, but then you don't have to go through an additional conversion cycle if the A/C unit works on DC current. You do if it is A/C only.

Ultimately, as others have mentioned, the important thing is amount of air conditioning per $ spent on the system and operating costs, i.e. a financial efficiency. Even if the system described in the article has lower total thermodynamic efficiency it might have higher financial efficiency. I'd suggest that using the working fluid more directly to run an A/C unit, once such units are available and economies of scale have worked their way through, would probably be much more financially efficiency than using current PV tech. Future PV tech might change the balance, of course.

One advantage of converting the energy in the working fluid to electricity, though, is that is can be used of a common energy transfer medium for a whole series of energy inputs (PV cells, wind power) to be delivered to a whole series of power drains (A/C, washing machine, TV, etc). So there is something to be said for doing it this way for the ability to take your inputs from a variety of sources to a variety of drains, even at the loss of overall efficiency.

Use it to recharge electric cars

[s_p_oneil]

I wonder how well it would work to use a fluid that boils closer to 100 degrees F, and use the temperature differential between the roof/interior and the underside of a car. Combine it with flexible thin-film solar panels on the roof (which are usually black and tend to get very hot), and you might be able to generate quite a bit of power when the car is sitting in the sun. ;-)

For a house, it shouldn't be that difficult to create a temperature differential. Have a black surface soaking up the sun (i.e. on the roof) and a white surface perpetually in shade (i.e. under the house). The black surface could even be a solar panel, boosting the energy output even more. Under the house, ventilation could be set up to blow most of the transferred heat outside during the summer, and inside during the winter.

Re:Use it to recharge electric cars

[PermanentMarker]

Hmm thinking about my car, let's make it airthight as my whole car is quite hot,
and creating a seccond gas chamber on the roof on my car.
A sterlin engine can be used to transfer the heat differences to power my car.

The faster i drive the faster my roof cools, the faster i will go.
Altough then i think i'll requires some rocket engines as brakes.

:)

Use Nature's Solar Panels

[giafly]

... by planting Trees nearby. Their shade keeps your house cool, all trees produce fuel for the winter, and if you choose the right varieties they deliver free organic fruit. You'll save power by not having to run your air conditioner so much. Why must some engineers make things difficult for themselves?

Re:Use Nature's Solar Panels

[The_Mr_Flibble]

Because it's their job.

Re:Use Nature's Solar Panels

[robertjw]

Yeah, all you have to do is wait 30 years for the trees to get big enough to shade your house. Great plan Poindexter.

Re:Use Nature's Solar Panels

[adolf]

Having recently been forced to cut down an 80' elm tree which died and was threatening to wreck my home, my neighbor's garage, the local power grid, and an above-ground swimming pool, I can say exactly why it is that people don't plant big trees next to their houses:

Because they're fucking expensive.

HTH, HAND.

Re:Use Nature's Solar Panels

[Anonymous Coward]

Feh! Not in MY back yard!

Re:Use Nature's Solar Panels

[njh]

Trees are slow to grow, potentially damaging to your house and block sunlight in winter making the house colder. A better solution is to grow fast growing annual creepers such as pumpkin and watermelon each year. I believe Kudzu is popular for this in some areas ;).

I've grown pumpkins on my greenhouse roof for this purpose.

Re:Use Nature's Solar Panels

[ArtStone]

Can Australian cane toads eat Kudzu?

Re:Use Nature's Solar Panels

[njh]

There is no such thing as an Australian cane toad. Bufo marinus might eat kudzu, but more likely it would go for idiot internet trolls.

Eyesore solution

[aplusjimages]

I bet you wouldn't mind looking at the windmills if I put some porn on them. Eh. You like that. I bet you do. You so dirty.

If you actually visit the company's website...

[RebornData]

There's a link in the article to the company's website. They've developed a motorless feedpump system, and there's a rather elaborate flash animation that describes specifically how it works, and several possible sources of energy... solar water heaters, sub-boiling geothermal sources, or even wood stove waste heat. The point is that they think it can work efficiently with a 50 degree temperature differential above ambient temperatures, which is pretty easily achievable without a lot of elaborate heat/cold storage.

The point of their system is not to be more efficient than solar panels, but to be MUCH CHEAPER. We don't have a shortage of energy from the sun... we have a shortage of cost-effective ways to harnass it.

-R

Um, no, mod the parent down...

[chaboud]

My apologies to those who modded the parent of the parent up, but you're all wrong.

First off, that's not what these people are claiming.

Secondly, if the turbine alone were enough to cause condensation, and were all that was required for operation, these guys would be violating the second law of thermodynamics.

Take a read.

Oblig. Futurama

[Zerbs]

"What's this layer of Ozone? That was never there before", Prof. Farnsworth

the secret

[PermanentMarker]

the secret ofcourse is ... the bubles!!!

Is it Coca Cola or Pepsi?


Or a nice cooled glas of beer ?
By these temperatures i prefer the latest ( 30 degrees Celcius netherlands ).

Cooling by burning gas.

[MarkusQ]

I can't tell if you're being sarcastic or not, but the GP is correct. In fact, you can still buy appliances with a cooling cycle based on this system.

The basic idea is

1. You burn the gas to make a hot, compressed exhaust
2. You let this cool by contact to the environment (e.g. down to about "room temperature")
3. You let it expand, which cools it much further
4. You use the now cold, expanded exhaust to cool your load

--MarkusQ

Re:Cooling by burning gas.

[kfg]

I can't tell if you're being sarcastic or not . . .

I am.

. . .you can still buy appliances with a cooling cycle based on this system.

Sure. There are still lots of places on earth, and even in America, where such a refrigerator is your only practical choice if you want something "conventional."

Apropos to the article the heat source I was talking about using to cool things that drew said criticism was. . .the Sun. It may not seem intuitive that placing something in the Sun can cool it, but if instead of thinking of it as "heating" that something you think of it as adding energy to the system it may become more obvious that such might be possible; if you have a sink available to absorb the heat, say, the air.

In this case by the sacrifice of a heated fluid when it changes to vapor, expands and carries its heat away into the air, which means you have to manually add more fluid. It's not "set and forget." Anyone from a native desert culture that has progressed to pottery making (I learned it from the Zapotecs) should be able to show you the system working; and show you that it works faster with direct exposure to the Sun, but to try a simple version simply wrap a damp towel around a water bottle.

And please note that while a portion of the towel (and the water saturating it) is being heated by the Sun the water bottle (and hence its contents) is entirely in the shade.

KFG

Re:slaughter birds,

[N Monkey]

not to mention wind turbines take up tons of space, slaughter birds, and are eyesores

Excuse me for being a devil's advocate, but I've often heard that claim that wind turbines are giant poultry food-processors and wondered about it. Birds also fly into windows and kill themselves (presumably the reflection confuses them), yet you don't hear complaints calling for the building industry to stop installing windows* **.

(* computer industry, maybe)
(**Of course, if they did, that would half-solve your "eysore" problem 8-P )

Patented

[sgt scrub]

Cool! Someone has patented it!

From the web site: http://matteranenergy.com/

An independent scientific analysis of the patented cycle indicates theoretical efficiencies slightly higher than comparable Rankine cycles.

This is all wrong!

[Anonymous Coward]

I'm too smart for all this fancy science. Give me time, I will figure out why this doesn't work. I'm an avid /. armchair engineer.
 
Would you like fries with that?

Typo

[QMO]

Oops.
"laes" should be "laws"

The second law of thermodynamics called...

[Guysmiley777]

It said to stop surfing the net and get back to work.

Issues can be overcome...

[D4C5CE]

the refrigerant used in their independent calculation is R-22, a cloroflorocarbon that kills the ozone layer, implicated in crop failure due to high uv exposure.

This would only be an insurmountable problem if everyone considered disposing of it in irresponsible ways all the time. Collection of hazardous substances by responsible experts can be organised, and even paid for to an advance fund to make sure it will be used. The refrigerant supposed to circulate and only leak in case of malfunction, so compared to hundreds of casulties in each heat wave (many just because they can't afford the cooling), and to the environmental impact of burning fossil fuels (or using nuclear power) to drive air-conditionings instead the environment, I think we should be able to handle that.

The patent seems about to expire (unless they managed to hire an experienced attorney playing the more elaborate tricks in IP law - that do not usually grow in avocado groves, despite some similarity in name ;-)), there are claims of a working prototype - so every tech school should get a team of budding and experienced engineers out there, have a real close look, and build a couple of these things, preferably creating detailed, open and reproducible documentation ASAP...

Quick fix

[glaserud]

Just turn off all of the AC's out there, and the temperature should drop by, like, 10 degrees.

Bemused eratta:

[kfg]

It may not seem intuitive that placing something in the Sun can cool it . . .

I'm having a little trouble with this concept myself.

KFG

Large Stirling Dish Contracts

[babanada]

Yes. This is real, and being deployed: http://www.solarpower.org/art11.html

At least it was the DIFFICULT 50%

[WebCowboy]

They managed to make it cheap so it will be applicable in small installations, but both the sterling engine and the gas turbine (using a fluid in a closed circuit) require a temperature difference, so the machine would not be driven by heat alone.

Well, this new development solves the difficult part of the equation--it provides a low-cost way to capture that heat. The cold-side of the operation is the easy part. You are onto the solution already:

Power stations using closed fluid circuits (e.g. nuclear plants) use a secondary circuit to cool the first one after the steam passed the turbine. They are usually located near rivers for this.

Well, any residence, office or industrial space with electrical service would have water service as well. This water is brought in through underground pipes and is significantly cooler than the ambient temperature in the summer. This serves a dual purpose too--even in the summer we need hot water so after the vapour in the generation circuit releases its heat energy to the water in the cooling circuit the heated water can actually be used.

Of course, this isn't a total solution to our power needs for the most part, unless you live close enough tho the equator that it is always warmer outside than the temperature of the water brought in. Of course, up here in Canada half the time the situation is reversed--it is below freezing outside and the cold water coming in is warmer, so you could use a heat pump of sorts in reverse fashion. However, the technology described here wouldn't work passively in the winter becasue you couldn't boil even this low-boiling-temperature when it is 20 below freezing. Perhaps natural gas would work and still be quite efficient (cheaper than heating your water anyways).

I think this sort of research is exactly what we need to solve our energy consumption and environmental problems. Right now, there is way too much focus on a few huge projects to solve a few huge problems. Witness the ineffectiveness of Kyoto--yes most of the signatory nations will meet their targets but at what cost? France is permamently addicted to nuclear power generation, Germany didn't even have to try because their 1990 target included dirty, antiquated, cold-war-era east-german industry that needed to be modernised anyways. Russia has not been consistent in its commitment and also has a low hurdle to jump given that it had a period of economic contraction starting around 1990. Canada signed on then did nothing at all--its GHG emmissions increased at a rate twice that of the US--a country that didn't even ratify the accord. China, India and pretty much all of Africa are exempt and are massive polluters. So what was gained out of all the time and expense and bureaucracy? Absolutely nothing--and Kyoto only addressed one single environmental issue--greenhouse gasses. In the meantime there are polluted and improperly dammed waterways, acid rain, an ozone hole, asthma-causing smog, oil-dependency, etc. that have not been adequately addressed.

Instead of dismissing these small innovations they should be embraced. Whether it is solar energy, thermal-collector-powered heat engines or fuel-cells or whatever, being able to equip houses and other buildings with "personal power generators" would have a profound positive impact on the electrical grid and power consumption. Right now the grid is like the early internet--a huge network of unreliable connections with content (electricity) delivered from a small number of large, centralised nodes. Personal generators would make it like the internet--a large, unreliable network but with an equally large number of smaller nodes providing power. This would make the grid hugely more reliable. In the event of a network/grid failure a node/generator could still provide a certain level of content/power to its local network/building electrical system. In the event of a node/generator failure, the network/grid could provide content/power to the LAN/building. Also, less overall power would

Re:At least it was the DIFFICULT 50%

[evilviper]

Well, this new development solves the difficult part of the equation--it provides a low-cost way to capture that heat.

Umm, no. Cheap heatengines have been around for a very long time.

This water is brought in through underground pipes and is significantly cooler than the ambient temperature in the summer.

Cooler? Yes, at least for a few hours of the day. Significantly cooler? No!

Besides, water is ANYTHING but free. If it was, we'd just blast water from the hose into a small turbine, and generate electricity from that.

You're dangerously close to describing perpetual motion machines.

The very fact that almost all large-scale solar power plants aren't price-competitive with non-renewables should tell you there is something wrong here. If this was so great, they would buy up 20 square miles of desert and put it to work, powering the grid.

Home windmills and solar panels are only around because people:

A) Accept a loss (compared to bank-rates) on their money, to help "save the planet".
B) Have remote homes that are off-grid.
C) Pay extra for more reliability than the power grid provides.

Flat lenses/filters/holograms (for maximising the use of P.V. cells) is the only home power generation technology which even sounds like it really has promise, without having to resort to crackpot physics.

This is just some VC money-grab.

Solar cost analysis

[GreenSwirl]

Indeed, the current state of photovoltiac (PV) technology and economics make it hard to justify even solar-powered streetlights, let alone homes. In a recent analysis, the Lighting Research Center at Rensselaer Polytechnic Institute found that it is possible to use PV lighting -- if you're off the grid in a remote area, and fairly low light levels are acceptable (or desirable, to reduce light pollution, for example). But if you are anywhere near the grid, a PV parking lot fixture, for example, might never pay for itself, since maintenance costs may outstrip any energy cost savings.

Life cycle costs for this and several other possible PV lighting applications are detailed in the new report, Lighting Answers: Photovoltaic Lighting, available free at their web site: http://www.lrc.rpi.edu/publicationDetails.asp?id=1 271

Other Types of Solar Energy Use

[the hesper]

It's pretty well known that photovoltaics are very cost-ineffective. Its likely that efficiencies in materials and production will increase enough to eventually make it cost-effective, but that is some time away. Therefore, people commonly discredit PV and thus discredit all solar energy use as too expensive.

The reality is that solar hot water heating and passive solar design are very cost-effective. As part of a "Design of Solar Thermal Systems" course at NCSU, I designed a 2200 sq.ft. house located in Boulder, CO. We implemented a solar hot water system that accounted for 70% of the hot water and paid for itself in 8 years. We also used radiant floor heating with a water/glycol fluid mixture tubed beneath the floor which was on average capable of providing 90% of the heat need during the coldest time of the year (of course it would be less for houses that are not well insulated and have large amounts of infiltration).

Besides those active systems, we designed the house with an imbedded sunspace that was capable of annually providing 47% of the heat needed for the house.

Although these systems are not directly able to produce electricity, they are certainly cost-effective systems capable of significantly reducing electricity use in one's house and should be considered more.

Welcome to the 1980s Jackass

[Anonymous Coward]

Dennis Lee has been doing this for over 20 years.

http://www.lightworksav.com/index.asp?PageAction=V IEWPROD&ProdID=2405

A realistic alternative

[E 99]

This concept depends upon the ability to perpetually cool the liquid to below 58 degrees F, which presumably means putting some pipe down a hole in the ground. (Unless it happens to be located next to a cold mountain spring) I'm actually digging such a hole for an improvised cooling system, and the research I've found shows that at around 20 feet down, depending on soil composition, the anual temperature fluctuation will be 180 degrees out of phase with the surface temperature, making it the coolest depth in the middle of summer, and the warmest depth (until geothermal depths are reached) in the middle of winter -- a typical result being maybe 3 or 4 degrees F below, and 3 or 4 degrees above average surface temp, respectively. This is in a typical temperate climate. Of course, in a tropical or sub-tropical climate, you're completely screwed (barring the cold mountain spring). So say you have 50 degree F water you can circulate out of your hole in the ground. Which makes more sense, use it to cool your 150 degree fluid down to 80 degrees, so you can heat it back up again to turn a turbine, to generate electricity, to compress freon into a hot liquid, and pump it outside to cool, and then back inside and evaporate it to cool it more, and send it through a radiator and blow a fan across it? Or just send the 50 degree water you already have through a radiator, and blow a fan across it? Personally, I'm trying the latter.

Even if their system could produce enough power to run an AC, suppose it was air conditioning all of manhatten... how long do you think the ground layer at 20ft under manhatten would stay at 50 degrees with all that 80 degree water being circulated through it??

And only generation costs

[bill_mcgonigle]

Your area might be different, but here, you're only getting a discounted rate.

And when I last looked at it you could only offset the generation part of your bill - taxes, recovery costs, transmission costs, etc, all weren't eligible against net metering.

So, if my electric bill is $120, I can start net metering against maybe $30 of that, at the discounted rate you mentioned. Max savings: $360 a year.

article summary has error

[Anonymous Coward]

The temperature is 158 F, not 58 F (from the website). That may have led to a lot of conclusion about how it works....

1970's Technology

[Ronin Developer]

If the system described in the article used a slight vacuum in the flash-boiling process, he may get more steam to drive his engines.

The use of a low-boiling solution for cooling is nothing new - especially in the real of solar powered cooling systems.

In the late 70's (I'll say 1978-79), there was an article in Popular Science that described a system that used liquid lithium under a slight vacuum that was used as a refrigerant. Pipes passed through the refrigerant were used to draw heat from the building. As the refrigerant flashed-boiled, it removed the heat from the pipes - thus chilling the water passing inside. The refrigerant was then condensed by passing it through pipes that ran through cool sea-water.

Similarly, the Navy uses flash-boiling to desalinate sea-water during the production of fresh water. The vacuum was provided by the ship's steam engines. The problem with the system comes about when you have a slight spill of DFM (Diesel-Fuel-Marine) in the water near the intakes. The DFM flashes around the same temperature as the water. You get rid of the salt and minerals just fine - but the tast of DFM in your drinking water really sucks.

Is it hype ...

[Anonymous Coward]

Wrong - it's worse than hype. It's downright lies. See Mann, et al.

in order to keep their jobs climate scientists have prostituted science, and turned the modest natural warming cycle we have been in since the Little Ice Age into a mega-world disaster (won't somebody think of the children - la-la-la).

At least Global Warming is a lot more fun, and safer than their earlier lies in the 1970s - Global Cooling and the beginning of the next Ice Age. More sun is a lot better for life on Earth than 3 km thick ice everywhere.

Make up your minds, morons - what are you going to lie to us about next? How about man-eating fog?

Re:Is it hype ...

[Anonymous Coward]

See Mann, et al.

Whoa! You are implying there's more than just one crackpot global-warming-denial apologist? Maybe they could buddy up with "there was no holocaust" folks. Their sense of reality is similarly warped around and about information/space continuum.

Not that it matters.... but it does...

[CodeShark]

But 58 Celsius is 136 degrees fahrenheit. My attic temperature (house in the central Midwest US, (it has insulation above and below, by the way, and is ventilated, which is pretty normal for most houses nowadays) -- which I monitor for experimental purposes, hovers around 120 on the worst days. So I don't have enough heat to boil the fluid, and would presumably have to use some type of fuel or power source to match pressures and boiling points.

Also, another key item is what point the fluid condenses at. If it takes power to condense the fluid (via pressure, etc.) then the net power output is lowered as well.

Finally, if their experimental rig can't be turned into a production unit that mass produced for lower than the cost of the power savings over 7-10 years, most homeowners, etc. will pass on it. TCO vs. savings for a business may be longer of course.

So my question isn't whether it works...it is whether or not it is economically viable even if it does.

AC's grill could do the boiling?

[SoopahMan]

The one efficiency I see in this system over others is that perhaps if this were to drive the compressor/pump on an AC, that perhaps the hot grill on an AC that normally just exhausts heat could actually be heating the boiling process for this cooling system. The AC could theoretically ramp up its cooling factor and efficiency as it ran in this way... and perhaps power itself, though that's not something you can determine from the general statements available.

I certainly don't know enough about thermodynamics to say whether you're removing heat overall (upconverting it in a sense), or just making better use of the heat that's already there... but it's about time somebody sucked in heat and put out electricity in a window-sized unit already. I'm tired of the power outtages in Cambridge.

I've thought about this before

[baudbarf]

I've thought about this before, and come to the conclusion that you need a thermal GRADIENT in order to harvest thermal energy, which is the hard part. If you have a cold temperature next to a hot temperature, then it's easy to capture the heat energy and convert it. But if everything is hot, there's no way to capture it. But I could be wrong.

Re:Deep in the earth...doesn't help much.

[Anonymous Coward]

The problem is that the ground 10 feet below the surface won't *STAY* at 52 degrees. Your gizmo will be heating it up. Pretty soon it'll be at almost the same temperature as your incoming gas and the machine will stop working. Unless you are in an underground river or something, you are relying on the heat being conducted away efficiently - and it won't be...at least not indefinitely. You know this is true because the heat from the surface didn't get conducted down the 10 feet to where you believe the temperature to be more or less constant. If the temperature doesn't change much at 10 feet - then that means that many months of solid summer heat and many months of winter cold didn't propagate through 10 feet of soil well enough to change the temperature enough for you to measure. This means that the ground must be a pretty good insulator. So once you have heated up the ground around your heat sink to the point where the heat engine won't work anymore, it's going to take something of the order of YEARS before it'll cool off enough to be usable again.

You can't have it both ways.

Birds and windows

[Zatar]

yet you don't hear complaints calling for the building industry to stop installing windows

Well, only because windows are a lot more indispensible than wind turbines. There are quite a few people complaining about the various things that kill birds and estimates of birds killed by windows go from 100 million to over a billion a year, much more than the number killed by windmills. There's even people developing special glass to try to stop birds from hitting windows.

Re:A/C on solar cell?

[Anonymous Coward]

A stupid question: would it make sense to have an A/C being charged by a solar cell?

Yes it would, as you would be our first fried Anonymous Coward.
*rimshot* ;)

wow...

[YesIAmAScript]

You're saying that in the summer you can cool your house in Sweden with nothing but solar panels.

Incredible!

Move to Lapland and you don't even need the solar panels.

I am a fan of heat pumps, for the efficiency reasons you mention, but measuring a cooling system by its performance at 59' N latitude is not doing much.

Re:wow...

[Hal_Porter]

They use actually use them to heat in the winter, which is more challenging.

The most important thing to remember is that caves and the like have a fairly constant, bearable temperature all year round and at any latitude, and your house can too if you have lots of insulation and a heat pump. If you do it right, you should end up just needing to pump liquid around to get a ultra low thermal resistance to a cave like environment, and lots of insulation to get a ultra high thermal resistance to the too hot/too cold outside.

Actually, I looked it up, and caves have a temperature close to the the mean surface temperature, which is probably quite good for people, certainly much better than outside which has +-25 degree Celsius swings.

If you live somewhere like California, you'd be more interested in cooling in the summer of course, but in the long run you have the advantage over the Swedes that solar power is more practical at the time of year that you need to run the system on full power, which is definitely not true for them. Even if you don't have solar panels yourself, you should still see a drop in electricity spot prices caused by solar electricity flooding the market. In Germany (not sure about Sweden), they have a law that forces electricity companies to buy power back at the same price they sell it to encourage this sort of thing. Solar power is too expensive at the moment for any of this to matter much and none of these countries have particularly open markets for electricity, but I suspect that won't be the case for much longer.

Re:Not that it matters.... but it does...

[cyanics]

58 F. not C.

Radioisotope thermoelectric generators (RTGs)

[ElliotLee]

Can we harness a technology similar to RTGs for the consumer market? RTGs last for a long, long time: 10 to 20 years or more. They're currently used in spaceflight, and have been used by the Apollo lunar landings, the Viking Landers, the Voyager explorations, and, of course, Cassini. RTGs are not nuclear reactors, have no moving parts, and use neither fission nor fusion. The heat generated by the natural radioactive decay of plutonium, mostly Pu-238 (a non-weaponsgrade isotope), is changed into electricity by solid-state thermoelectric converters. Would it be possible to generate electricity from other sources of heat, too (such as the sun, described in this article)? On Cassini, Power and Pyrotechnic Subsystem (PPS) provided a regulated 30V DC electrical power to the spacecraft, derived from the three RTGs onboard. It is then conditioned and distributed to the powered spacecraft components. RTGs don't provide a lot of power at once, but they provide it for a long time. But they're designed to last for many, many years. If the timespan were shortened, could they generate more power?

Re:Not that it matters.... but it does...

[geekoid]

Maybe they could make micro units and attach them to CPUs?

good idea

[Anonymous Coward]

it all depends on to have a "fluid" that can go
to gaseous form below the hottest place available
in the machine. obviously water won't work with
normal roof-top hot water collector.
if one could improve these collectors (one way glass,
black tubings, etc.) to say ~90 C, then the "fluid"
needs to be able to turn gaseous (at 1 bar) below
90 C.
of course this works, it's just like steam engine
but with another "fluid".
the part that gets patented is prolly the "no pump"
part. acctually the two valves solve this problem.
some smarts there!
question is if these valves are "smart", and do their
opening and closing "autonomous" or if they are
controlled thru some electronics. another question
is if the whole setup is "matroschka"-able. like
the russian doll, a smaller inside the bigger etc.
the animation shows a (i'll call it) one depth
setup; question is if one could put one into another etc.
not going into details here, think for yourself :)
maybe it is also possible to have instead of one "barrel"
with a valve on each end, but two "barrels" with total
four valves etc. one would be cooling, the other one being
heated then swap?
another question :P how compact could one make this?
nano scale anyone?

War porn

[rholland356]

So, Popular Science took a break from its glut of war porn and crackpot energy generation schemes to write a story about yet another impractical energy scheme.

Why am I not surprised? Then again, I guess the answer is in the name of the magazine, and it is just more popular to try to wish your way out of a crisis, rather than sacrifice consumption and promote significant change in the way we live.

At least they still have the BEST artwork in the trade...

Efficiency ?

[sfm]

While it is true the efficiency of this system is lower than for PV panels, I would also expect the cost per watt to be significantly less.

Efficiency of PV panels becomes important when you are limited on space. Most PV installations are of limited size due to cost considerations. Even if the efficiency of this Rankin cycle system is lower, with a larger solar collecting area the same total power can be produced.

I'm convinced the problem with solar (in general) is $/Watt and not efficiency.

and in Portugal..

[Anonymous Coward]

http://www.theregister.co.uk/2006/06/08/solar_plan t/

makes sense to me! do it all on a large scale for the people..

Absorbtion cycle cooling?

[lotho brandybuck]

There are HVAC systems that use a heat source to create cold.. I don't know exactly how they work, but they've been around for awhile. An example of a small system is a propane powered RV refrigerator. See http://www.southerncompany.com/gapower/energy_know how/absorption_chillers.asp?mnuOpco=gpc&mnuType=co m&mnuItem=ed You can get solar collectors with a very high discharge temp... vacuum tube collectors or anything with a concentrator. So why aren't we using solar powered absorbtion cooling in small applications, and why aren't we using deep ocean water to cool our major cities?

It's neither a stirling nor a turbine.

[Medievalist]

If you actually read the website, what it's about is allowing the use of existing low temperature differentials by obviating the need for a power-robbing recirculating feedpump (as in the Rankine cycle). It's not a stirling engine, and it's not a mini gas turbine, although you can theoretically combine either of those in various ways with the Matteran system.

It's all about getting rid of the pump that makes low temperature differentials impractical to use for doing work. AC is just one sample application among many - you can drive any load you want, within the limitations of your available environment.

The flash animation is pretty straightforward, if you can stomach flash.

cool extractors and dark absorbers.

[irenaeous]

How about this:

• Lights are not really lights -- they are dark absorbers.
• The sun is one of many white holes that suck in all the surrounding darkness.
• So called central heating actually consists of a set of cool absorbers.
• A/C units are really cool extracters. They commonly operate by compressing heavily cool laden freon gas to squeeze out the cool which is in turn transferred to cool deficient air used to "cool" a house. Later, the freon is permitted to expand again via evaporation during which it extracts and concentrates cool from the outside.

Works for me :)

Total energy equation?

[c0d3h4x0r]

Matteran Energy uses 'thermal-collection technology to heat a synthetic fluid with a very low boiling point

And just how much petroleum-based energy does it take to produce this special synthetic fluid? Hrmm? My guess is a lot -- more than this generator produces over its lifetime.

Record breaking

[Brandybuck]

I wish people would stop treating "record breaking" temperatures and other day-to-day thermometer readings are relevent to global warming. I've been seeing "record breaking" temperatures at least every other year since I can remember. I remember as a kid decades ago hearing on the news about old ladies dying in a New York heat wave. Doesn't someone die of the heat every couple of years in New York City?

How many days are there in a year? How many years have we been tracking temperatures? How many locations track temperature? How many of those record temperatures in a year are record lows? Think about the statistics. Also consider that a "record" temperature last Saturday might have been the mean temperature on Sunday, but only Saturday's weather report induces panic. And what does it mean when a town has a record temperature, but another town twenty miles south doesn't, even though it was one degree hotter?

It may have a "record breaking" weekend where you live, but it wasn't where I live. Yes, it was a scorcher where I live, but it wasn't unusual. We neared record electricity usage from all the air conditioners running, but that's simply because there are more people here this year than last year.

Re:Record breaking

[Anonymous Coward]

Agreed. The huge amount of scientific data showing a change in global climate is much more convincing.

Re:Record breaking

[Anonymous Coward]

But absolutely ZERO scientific data that turning my air conditioning off on a hot day will do anything about it.

Re:Record breaking

[Anonymous Coward]

sure there is http://www.gdrc.org/uem/co2-cal/co2-calculator.htm l

Re:Record breaking

[fnurb]

Sigh.

There is now a 720,000 year record from the Antarctica ice-core correlating CO2 levels and global temperatures. It agrees with earlier extracted cores that "only" go back a few hundred thousand years, as well as one going back about 120,000 years. Furthermore, more recent climate changes and CO2 levels track closely to the most recent parts of the cores. Finally, the results from the past 100 years of recorded global temperature records fall right in line.

Fact: CO2 levels are off the charts and rising so fast they'd make your head spin - along with global temperatures, which are starting to pick up steam (pun intended) - *if* you bothered to look at the actual *data* rather than read the anti-intellectual denier propaganda, or rely on your local anecdotal subjective experience.

The records from the past 720,000 years of global temperatures are freely and openly available online, if you just dared to check it out - the actual scientific data from the original source, that is, not the creationist deniers or, for that matter, the advocates of science and reason. Just look at the actual source information. If you dare, which I doubt.

'Cause then, you'd have to face an inconvenient truth. Better to blather on about how it used to be worse in the ol' days, when you was a youngun' - probably in the 1990's.

For the first time in human history the facts are freely available for any citizen to check out, unrestricted and unfettered by government, business or advocacy. Including, incidentally, answers to all the foolish questions you just asked above, but can't be bothered to research for yourself.

So, with all this raw data and sourced analysis available, what do most folks like you do? Parrot talk radio and reminisce about the good ol' days. Wow. We truly are fucked.

Re:Deep in the earth...doesn't help much.

[DougWebb]

I think the idea is that this kind of system works in reverse during the winter, pulling that stored heat out of the ground and using it to heat the house. This way, you're taking advantage of the insulating properties of the ground more than its normally contstant temperature.

Here's a detailed description of the technique: http://mb-soft.com/solar/saving.html Once you have the basic concept down, it's basically just a matter of doing the math and figuring out the system dimensions, and then figuring out if you can build it for a reasonable cost vs a traditional system. I think it helps a lot if you're building a home from scratch rather than retro-fitting an existing home.

Re:A/C on solar cell?

[Anonymous Coward]

Can somebody explain why this was modded as "troll" ?

Re:slaughter birds,

[RockModeNick]

I was just thinking that a birds getting whacked and laying dead here and there on your property was kind of gross, not that we'll kill off all the birds with them.

The innumerate are outnumbered

[museumpeace]

by those who couldn't explain or even recognize principles of thermodynamics...this crock will probably sell well, especially in countries where credulous consumers no longer doubt you can get something for nothing.

Maxwell's Daemon?

[jpg5]

This "thermal-collection technology" sounds to me like the Maxwell's daemon or something.

Re:Not that it matters.... but it does...

[CodeShark]

Oops, you are correct. Which means that the system has to operate at high pressure to raise the boiling point. Which means thick, custom metals usually. Thing is, there are already quite a few things out there that boil low, such as ammonia, freon, R-XXX whatever version is used in the AC of the house already. There are even binary (two gas) systems that operate at a fairly low temp.

Well, I will track, read and report back to /. if this proves to be more interesting than I am seeing at the moment.

Don't burst the hippies bubble.

[HornWumpus]

Economic Fascist. ;-)

We'd be getting all our power in sustainable and natual ways if it was'nt for people like you.

Free Energy - Air conditioning

[esobofh]

it's not coincidental that when any power generation or power savings breakthrough is announced it comes with the promise of allowing us to cool our homes cheaper or provide some sort of advanced way to cool our homes. Air conditioning is expensive, and a huge drain on our resources. Not suprisingly, the most simple and elegant solution - utilizing the heat of the day to cool a home - was developed centuries ago by the romans (or at the very least, they stole the idea from someone).

The solution involves the use of two towers - one at the "hot side" of a home and the other at the "cool side" of the home. The hot tower (and this can be made hot in any number of ways.. normal sunlight, green house-style warming, fire.. whatever you like. The air in the heated tower moves upwards drawing air through the sealed home who's only intake is the cool tower. This in itself would be enough to cool the house significantly, but the technology is improved by a sort of bell tower at the top of the cool tower; The tower has a water resevoir and the air openings have draped in front of them a cloth or reed mesh. Water is then cascaded over the cloth/mesh/reeds (or whatever) at a controlled rate, and the subsequent evaporation cools the material. The air then being pulled through the mesh intake is even further reduced in temperature.

The only work required here is to fill the cool tower with water (easily accomplished if one lives below a water source) - or you can rig up a pump system that's electrically powered (just think of all that money you save on air conditioning, might as well use some electricity to fill the water tank :).

Of course.. one could manually fill the tank and kill both the electricity/resource *and* obesity problems at the same time ;).

I've actually made a dog house version of this - it works great.

Re:Free Energy - Air conditioning

[cr0sh]

Here in Arizona there is a publicly "accessible" form of this at the Boyce Thompson Arboretum - albeit just with the "cool" tower. They typically operate it in the dry summer months (not during monsoons) - basically the same system as you describe, except with a fan at the bottom of the cool tower to draw the air down, which is then pumped into their outside "lobby" area. It makes the lobby area a very nice place to be after walking through the park...

Re:Deep in the earth...doesn't help much.

[IBitOBear]

Actually the ground is a very good conductor of heat, especially if there is ground water. It's not steel sticking out of an iceberg, but it's damn good. The thing you don't account for in your analogy is the fact that "the earth" is "massive". It's huge. Much bigger than you imagine. And every day the surface absorbs a huge amount of heat, and then at night radiates it right back out. The energy transfer rates are stong enough to create daily winds.

Lose, airy soil is a pretty good insulator, which is why there is usually grout added around the ground loops etc.

Don't beleive it? Do an experiment. Try to heat a section of packed earth. The energy has to be going somewhere; "you can't have it both ways."... 8-)

No, I am not saying your 52F ground isn't going to go up to 53F (or whatever). If, however, you imagine that you dig a 4 by 60 foot trench 12 feet deep, put a slinky-shaped 2-foot-diameter loop of piping in that trecnch, and pack good soil into it and then run something through that pipe that is going to heat that mass of ground to a significant temprature, you're nuts.

How do I know? The pipes to my master-bath run through my driveway slab. It takes _forever_ to get the water hot and if I turn off the water for a short time, it takes forever again. I loose a good 10F making the run, it doesn't get to full temprature in the time it takes to drain a whole taknk from the water heater. And we are talking about 130F water here, not sinking an 80F source.

It's a matter of the economies of scale.

Re:Just use solar already..I do and it works great

[Doug Coulter]

You're just dead wrong on this. See www.coultersmithing.com (my site) for some pics of a system that has been running for two decades already (it was mounted on posts before the building in the picture was built), has paid for itself over and over by any measure, and has never had a failed panel. Even the one stripped off the roof by the wind still works. I have another system on another house that's even older. It had 4 panels fail, 20 years out, and the company, Solarex, paid for shipping them back and replaced them for free. They knew they had made a bad batch, and observed the 25 year warranty at any rate. Yes, the systems are expensive. So is grid power, even paying only their bill, not the hidden costs. Wind doesn't work here, as it's not very windy, and there is an important threshold at about 7mph below which no turbine works (wind power is proportional to the 3rd power of wind speed). And they attract lighting really well... Polycrystaline panels do pretty well in diffuse light, as we often have in winter. No AC loads then, and the freezer is in an unheated space, so the demand actually goes down just fine, thanks. Best time of year is spring, when the hours get long before things heat up and drive freezer and AC drains, worst is in fall as it's still warm, but the hours are getting shorter. The above commenter obviously hasn't actually tried this. Or is like the power company employees who used to take down my adverts for solar systems.

DTEC/LTEC?

[cr0sh]

I have wondered if such a device is possible - I am sure you have heard of an OTEC - Ocean Thermal Energy Conversion - where you basically hook a Stirling engine driving a generator up to a system where your temp differential is obtained from two different ocean thermal layers. So, why not something Land/Desert-based? Your thermal gradient would be the difference between the outside air and/or a black heated metal plate (or buried copper tubing lines in asphalt - a use for all of that road surface, maybe?), and another set buried 20 feet or so underground (where the temperature is pretty stable and very cool). Possibly at night you could even reverse the process (use the metal plate as a night sky radiator and heat from the soil just below the surface), though it would probably be less efficient. I really think something like this could work if you could find the appropriate working fluid for the Stirling engine (not sure, is helium the best?)...

Re:DTEC/LTEC?

[gweihir]

...and another set buried 20 feet or so underground (where the temperature is pretty stable and very cool)

Problem with that is that it dies not stay stable and cool when heat flows into it.

Re:DTEC/LTEC?

[cr0sh]

Yeah, that would be a problem - I wonder how long it stays "hot" that way? Maybe put some temperature probes in the surrounding area, have multiple buried sinks in spaced apart locations, and round-robin the system? Probably all of that complexity would outweigh any gains (all the energy gain total would go into keeping that system working).

TNSTAAFL and all - that I know, but there should be a way to use Stirling engines to generate power on land without requiring massive dishes, mirror arrays, or solar panels to drive one small engine (personally, I would love to see a system that could give you enough output to run a house and cost way less than what is needed for a solar panel setup - even if it takes up more room).

Not really...

[Ogemaniac]

I already have the headquarters of the world's largest chemical company in my backyard (I am not joking - I can see it from my window). It's plants are less than a mile away.

Of course, it is in my backyard because I am employed at its subsidiary and prefer to live close to work.

"EROIE "

[kfg]

Damned dyslexia.

KFG

Not true... electricity demand follows sun

[taharvey]

Cells will fail and will need replacing from time to time, and will be expensive to do.

Most manufacturers Guarantee their panels for 20-30 years, so that is minimum life. Of course on average they will last longer. Longer than most power plants, and yes, virtually maintenance free.

home energy usage is pretty much the exact inverse of when the most solar radiation is available

In fact, the average electricity demand on the grid typically follows the sun cycles, especially in summer when electricity use peaks. The peak grid loads are typically ~40% higher at midday than the nighttime minimum. Even in the winter, when the day peaking is less pronounced (and shifted towards morning/evening), solar could address as much as 35-40% the national electricity demand even without storage. See http://currentenergy.lbl.gov/pjm/index.php for an example of demand curves.

Of course storage on the grid is important, and needs work, but we could address a HUGE amount of US electrical need without it.

However, for serious microgeneration, at the current time the only halfway practical and affordable renewable energy source is wind, which is vastly cheaper

Wind is very cheap, not halfway practical cheap, but cheap as coal cheap. Hydro is very cheap as in cheaper than coal cheap, and photovoltaics are the cheapest thing going when you don't have a 100 year old subsidized grid infrastructure. Because of that, photovoltaics is the only option in many places in the developing world, because the cost of the lines is 10 times more expensive than the coal plant that make the power. But more importantly, PV is getting exponentially cheaper to manufacture by the decade, and new low cost technologies are just starting to leak out of the lab into a marketplace near you. (However, note that demand has outstripped supply by 30% with 40%/year growth in the market for several years, even if the manufacturing is getting cheaper, it is not currently seen in the market because of high demand).

Bottom line, renewables are the cheapest things going, even without addressing the huge subsidy imbalance going to traditional fuel sources (oil, coal, nuclear, etc)

The energy to make a typical wind turbine is generated by the turbine over a period of six months - it's more like 6 years for solar.

Photovoltaics cells have an energy pay-back period ranging from 3 months for newer technologies (e.g. CIS, CdTe) to 3 years for traditional crystalline silicon. Even mainstream multi-crystal silicon has a payback period of 0.8 years. And these numbers don't even address the newer, and lower embodied energy low cost multi-junction concentrators or low temp printable cells.

So when you look at a 30 year life span, that gives PV an Energy return on investment of 10:1 for Crystal Si, 37:1 for multi-Crystal Si, and 100:1 with CIS. Compare that to typical fuels: Coal (9:1), nuclear (4:1), US oil (3:1), Mid-east oil (10:1-30:1).

Unless photo voltaic solar becomes vastly cheaper, it's simply a non-contender except for novelty value, even if you live in the desert.

A desert is not needed as solar insolation is relatively uniform throughout the US (and world). The best location in Arizona is only twice as good as the worst place in the Washington rainforest, with the majority of the US within 80% insolation of the best location in Arizona!

Even with today's "high" PV prices, PV is unique in that it is deployable on any rooftop, parking lot, or yard at the point of use. With net-metering or battery storage that means PV competes with retail energy not w

Bonus!

[douglips]

When someone burns it down, you get even more energy out of it!

so you heat the HE and then heat the boiler downst

[_Shorty-dammit]

If that's the case, you simply heat the HE first, and then further downstream you heat the boiler. The HE's small volume of liquid takes some of the energy from the heat source, leaving enough to still boil the liquid in the boiler. HE should then be hotter than the boiler.

and gravity?

[_Shorty-dammit]

hmm, well, even if it's only heating it to the same temp/pressure as the boiler, wouldn't the extra potential energy from gravity help it feed into the boiler? Ah well. Seems to me it's still quite a simple matter to heat it slightly more than the boiler's temp.

Energy payback is down to 2 years for modern cells

[egghat]

In a study by CERN (you know them as the inventor of the WWW) in 1996 they calculated an energy payback in around 6 years for Switzerland (which perhaps is the most beautiful place on earth but definitly not the most sunniest). In 2000 they updated their calculations and ended up with a number of appr. 4 years.
Solar cell technology has made a lot of significant advances in the last 10 year. Bank Sarasin, one of the biggest European advisor for ecological safe investments, concludes on page 30 that with modern solar cells energy payback comes after 1.5 to 2.5 years, depending on technology and country (1.5 years for the most modern, in production technology in Southern Europe, comparable to Florida; 2.5 years for middle Europe, comparable to New York).

One manufacturer of solar cells even claims 0.85 years with their "Dünnfilmtechnologie" (is flat film a suitable translation?), see on page 3 here (Enegierückzahldauer = amount of time for energy payback) .

So your 6 year number is definitly old.

Bye egghat.

Ok, look, here's something to think about:

[kfg]

When you hear people in the solar industry talk about reducing costs and thus prices, do you really hear them going on and on about economies of scale, or, perhaps, do you hear them talk about technological breakthroughs?

Maybe that's because they've run out of economic silver bullets and are looking for a technological silver bullet.

Come to think of it, the same thing goes for batteries too.

KFG

Errata:

[kfg]

By the time I processes it and ship it to you you're paying fifteen hundred dollars for ten cent a pound iron.

By the time I processes it and ship it to you you're paying fifteen hundred dollars for five pounds of ten cent a pound iron.

KFG

Re:no, it solves 100%, it clearly states ambient a

[Anonymous Coward]

"Anyway, so, you use that heat source to boil the liquid in the closed circuit. Don't forget, it ain't water. It's some liquid that boils at a pretty low temp."

With a few solar thermal panels of modern design connected in series boiling water is relatively easy. In fact one of the challenges with the level of thermal efficiency possible in modern solar thermal collectors is in NOT boiling water.