Ariz. Team Seeks Fossil-Fuel Cost Parity, Using Solar Energy Concentrators

autospa writes "A University of Arizona engineering team led by Roger Angel has designed a new type of solar concentrator that uses half the area of solar (PV) cells used by other optical devices and delivers a light output/concentration that is over 1000 times more concentrated before it even hits the cells. This comes as a result of a broader goal to make solar energy cost competitive with fossil fuels (target = 1$/W) without the 'need for government subsidization.'"

Comments

Which government subsidization?

[timeOday]

It's hard to count all the ways our oil economy is supported and subsidized by the government. And we haven't even started cleaning up the mess yet.

Re:Which government subsidization?

[ynp7]

Exactly, to get cost parity (and then some) just stop subsidizing oil.

Re:Which government subsidization?

[houstonbofh]

Which subsidy is that? The 50% tax on gasoline, or the oil windfall profits tax? http://en.wikipedia.org/wiki/Windfall_profits_tax Oil is the most taxed industry in the US. OK, Cigarettes may have it worse, but I doubt it...

Re:Which government subsidization?

[khallow]

As a fraction of revenue, these new renewable resources are subsidized far more than coal and oil (coal being the subsidized material you should consider). It is refreshing to see these renewable power sources nearing an unsubsidized parity with coal. That's far more important than complaining about which one is subsidized more.

Re:Which government subsidization?

[Anonymous Coward]

Since 1988, no windfall profit tax has been enacted in the U.S.

Also from wiki,

In January 2011, motor gasoline taxes averaged 48.1 cents per gallon and diesel fuel taxes averaged 53.1 cents per gallon.

So no, it's not anywhere near a 50% tax on gas.

Re:Which government subsidization?

[fermion]

There are a few ways in which gasoline in subsidized in the US. First oil firms tend to pay a lower tax. It is not amount, but enough to knock down even Exxon profits a tick. Some distort the truth by bringing up laws that have not existed in 20 years. Such subjects are useful to consider as the repeal of such tax was a increase in subsidy, and likely did contribute to the doubling of he public debt as a percentage of GDP during he Reagan administration, from around 30% to well over almos 70%.

The tax on gasoline must be a Fox favorite fabrication, as I hear this a lot. That there is a dollar tax. That the tax is half he price. I would like see citation. My understanding is that federal tax is around 20 cents and state tax is no more than 30 or 35 cents. That is 50 cents. At $2 gallon that is 33%. At current average $3.5 this is less than 17%. This tax is to cover road wear and tear, but there is indication it does no. Another dime would end this subsidy, bringing the tax to 20%. Nowhere near 50%. Maybe in 1960, but arguing the world from 1960 is not valid.

The real subsidy is that fuel, not a critical item like food, is not subject to sales tax. This means that while in most states people pay tax on food but not fuel. This makes no sense that we would make food more expensive but not fuel.

Cigarettes are taxed from $3-$6 or so. Given what cigarettes cost in my area, this is still not 50%.

I am not sure how Oil is overly taxed. Exxon paid no income taxes in 2009. Oil companies are hugely profitable so the taxes are not interfering with that.

Re:Which government subsidization?

[houstonbofh]

Wikipedia had some more data before, I would swear it... It may have been 5 years ago, however when the tax came up again... :) Anyway, another link. http://www.taxfoundation.org/publications/show/1168.html And yes, I confused 50 cents with 50 percent. But once you factor in all the other taxes, it works out to almost $2 a gallon in 2005, so not really that far off.

As for the sales tax, that varies by state. Buy in all they states I have shopped in recently, food components (beef, cheese, milk) have no sales tax, but prepared foods (McDonald's) does. This makes sense because if you can afford to eat out, you can more afford a tax. But in the case of fuel, you pay the same regardless of if it is for a joy ride, or to get to work.

And I am not saying oil is overly taxed. Just that it is not "subsidized." After all, they are public companies. If they are doing so well, why is the stock not much higher? Why is the ROI so low? And why are more people not worried that most of the new offshore drilling on the US coast is foreign companies in "Cuba?"

Re:Which government subsidization?

[houstonbofh]

Saving time...
http://slashdot.org/comments.pl?sid=2025080&cid=35400852

Re:Which government subsidization?

[HiThere]

This surely depends on exactly what you consider a subsidy. E.g., I count the presence of US troops in the Middle East as an oil subsidy, so I count oil as being heavily subsidized.

If you don't count that, then do you count all the money spent by the government to build and maintain the roads? If not, why not? (I can see an argument that some of that money isn't a subsidy, as it's only paying for things that would be needed even if gasoline engines didn't exist, but not most of it.)

If you don't count either of those, then I may agree with your figures, but I won't agree with your model.

N.B.: Arguing that the oil industry is heavily subsidized isn't an argument that the subsidy is too large. Our population couldn't be supported if we used horses and oxen for motive power. I do happen to feel that the subsidy is too large, but how large it should be is separate from (though dependent on) what counts as a subsidy.

Re:Which government subsidization?

[Anonymous Coward]

Again with the handwaving. The tax paid at the pump is the tax paid at the pump. One cannot add in other mythical taxes just to prove a faith based argument. If that were so I would add in the diplomacy and war costs to keep the flow of oil running. Everyone has to pay for roads, everyone has o pay for raw product. Paying for a lease is rent, not tax. In the free market we want firms to uitilize real estate, so we, the people, charge rent to insure the land is exploited. And, of course, Exxon pays no tax, and never paid for the damage done to Alaska, but I do no believe in made up evidence o prove a faith based argument, so I won't bring that up.

Gas taxes are set a a fixed amount to maximize oil profit. They should be a percentage, like 25%, so we the people can have money o fix roads as inflation occurs. In 2005 gas excise was around 40 cents. A 2.50 tha is 15%, at $4 tha is 10%..

Re:Which government subsidization?

[rtb61]

First get to the crux of the matter. Fossil fuels are not being subsidised, lets just through that lie away, corporate profits are being subsidised.

Those elected representative, elected upon the basis of unlimited advertising and PR=B$ funded by corporate dollars are simply and corruptly returning those campaign investments at something like a thousand to one return as corporate profits subsidies.

Corporations are generating returns of something like 10,000% profit on their campaign contributions. Corrupt politicians are literally burning up $10,000 for each dollar they can squirrel away in their own pockets. Things are more than just a little out of control in the US, where in reality by far the most profitable business is the corruption of the US democratic process. A multi-national mass media enterprise has even devoted an enormous part of it's resources to it, in the form of Fox not-News (not a disparaging title simply a valid observation of it's willingness to pretend advertising is news, of course it is not).

Re:Which government subsidization?

[stdarg]

There are a few ways in which gasoline in subsidized in the US. First oil firms tend to pay a lower tax.

A lower tax than...? According to Business Week in 2008:

According to Securities & Exchange Commission filings, Exxon paid an effective tax rate of 34% to the U.S. government in 2007, or $5.12 billion. While cheaper than rates from some foreign governments, it's still a higher rate than many U.S. companies pay. A BusinessWeek collaboration with Capital IQ in December, 2007, found that the average percentage of earnings spent on taxes by companies that make up the Standard & Poor's 500-stock index was 26%

What do you mean by them paying lower taxes?

Some distort the truth by bringing up laws that have not existed in 20 years. Such subjects are useful to consider as the repeal of such tax was a increase in subsidy

Really, you're counting the repeal of a tax as an increase in subsidy? So since the high water mark for income tax is right after WWII when the highest tax rate was over 90%, according to you the entire population, along with every single company, is being heavily subsidized? And since we no longer pay any taxes to Britain, but we used to, we're being subsidized by them too?

The real subsidy is that fuel, not a critical item like food, is not subject to sales tax.

I don't understand. You already mentioned that there are state and federal taxes on gasoline. Sales tax is just a state-level tax. Why do you care that it's called a gasoline tax and not a general sales tax?

This means that while in most states people pay tax on food but not fuel. This makes no sense that we would make food more expensive but not fuel.

My state has separate sales tax rates for different types of food. Basic food items have low taxes, or even no tax.

I am not sure how Oil is overly taxed. Exxon paid no income taxes in 2009.

I was curious about this bold claim so I looked it up. I'm assuming you read the ABC, Forbes, or Mother Jones article that whined about Exxon paying $0 income tax to the US in 2009. And then you failed to read the followup from the original journalist who started it all by misunderstanding a financial statement.

Re:Which government subsidization?

[khallow]

E.g., I count the presence of US troops in the Middle East as an oil subsidy, so I count oil as being heavily subsidized.

But how much of a subsidy? Remember US troops are also a massive defense contractor subsidy. If the US spent $500 billion a year providing $25 billion in value to oil companies, then that wouldn't be much of a subsidy for oil even though a lot of money were being spent.

Re:Which government subsidization?

[operagost]

Remove the subsidies, then approve all the permits. Because he's turned the BP spill into a tool for his mission to make energy prices skyrocket. Only ONE permit has been approved since the dubious moratorium was lifted last year.

Re:Which government subsidization?

[operagost]

There are states where the gasoline tax is over $1 a gallon. And fuel is not a critical item? We need it to perform labor. Oh, and heat homes.

Re:Which government subsidization?

[LoganDzwon]

your supporting document shows the tax rate to be 50 cents... not $2 per gallon.

Re:Which government subsidization?

[pixelpusher220]

Well actually yes they are being subsidized; though perhaps not in the manner you assume.

What is the cost associated with releasing all that CO2 into the atmosphere? Zero? Not hardly. The effects may not manifest themselves in cost specific ways for 100 years, but they will manifest. And when they do, it is going to be catastrophically expensive.

So yes they are being subsidized in that we aren't paying for the waste they produce yet.

Re:Which government subsidization?

[pixelpusher220]

You do realize that fossil fuel prices are going to skyrocket completely independent of any government policy right? They will run out, they cause environmental damage. These 2 factors will cause their price to skyrocket way more than anything proposed so far.

Renewable sources will likely never achieve current fossil fuel prices. However, their price also won't ever 'skyrocket' they way a finite polluting fuel will.

The current proposals are to artificially inflate fossil fuel prices now so that over time we push ourselves towards renewable sources. This allows us to gradually switch rather than have to do it wholesale at a later date when the fossil fuel prices/environment cause prices to 'skyrocket'.

You can pay a little over time or you can wait and pay through the nose later. Take your pick, but the latter is much much more expensive.

Re:Which government subsidization?

[h4rr4r]

I would rather have the fish and the beach than the oil.

Re:Which government subsidization?

[HiThere]

A good question but remember:
"A billion here, a billion there, after awhile it really adds up." -- Senator Dirksen (IIRC)

Re:Which government subsidization?

[operagost]

I'm talking about in the short term. We are still in an economic downturn, and looking at a "double-dip". We can NOT recover if some uninformed ideologue's idea is to artificially raise prices to levels that the middle class cannot afford so that we all essentially end up on the public dole when the system collapses. The only outcome is a state capitalist economy like China's.

Re:Which government subsidization?

[operagost]

False dilemma. Safe drilling doesn't kill fish, and drilling on land is safer than in the sea; BUT ideologues like our president, Al Gore, and a host of special interest socialist organizations claim otherwise because they WANT oil drilling to be risky so that the public opinion will sway against it. We need oil and natural gas NOW, while we keep working on other energy sources for later.

Re:Which government subsidization?

[pixelpusher220]

I'm talking about in the short term. We are still in an economic downturn, and looking at a "double-dip". We can NOT recover if some uninformed ideologue's idea is to artificially raise prices to levels that the middle class cannot afford

Short term I don't disagree.

The fun part is this exact same statement could be made about the national debt. We can massively cut our spending trying to go cold turkey and in turn create even more economic depression; or we can plan an orderly transition to more reasonable spending/taxation/benefits policy.

Re:Which government subsidization?

[pixelpusher220]

Uh, sorry, the OIL industry claimed it was perfectly safe and GWB/Cheney chastised anyone who questioned big oil on those claims. Until they proved that it wasn't.

'Safe Drilling' is a misnomer. There is no such thing. Some methods may be 'safer' and less likely to accident or error, but then we were told the Titanic was unsinkable weren't we?

If you claim it can't possibly fail, but if it does it can be contained and cleaned up (in a document that says part of your clean up efforts will protect the WALRUSES in the Gulf of Mexico) - and then can't contain it or clean it up - well sorry, no sympathy for putting onerous restrictions on your ability to do business. You failed, you don't get to keep on keeping on until we the people are satisfied you aren't just still blowing smoke about your abilities.

Re:Which government subsidization?

[StikyPad]

As for the sales tax, that varies by state. Buy in all they states I have shopped in recently, food components (beef, cheese, milk) have no sales tax, but prepared foods (McDonald's) does. This makes sense because if you can afford to eat out, you can more afford a tax. But in the case of fuel, you pay the same regardless of if it is for a joy ride, or to get to work.

Which is ridiculous, because it costs less to buy a quarter pounder from McDonalds than it does to buy all the ingredients and cook it oneself. This is partly because burgers are loss leaders on things like fries and soda, but also because restaurants buy and prepare on a much larger scale. Now I won't go so far as to argue that it's a healthy option to eat fast food, but the idea that one will necessarily get more value for their money when buying groceries is idealistic to say the least, particularly when one must maximize his calories per dollar spent.

Sweet!

[Aighearach]

I knew it was hot in AZ but this is ridiculous!

subsidization?

[polar red]

without the “need for government subsidization.”

ALL sources of energy receive subsidy. some examples : Oil (how much did all those wars cost?), coal(damage to public health=hidden subsidy), nuclear(research since the forties)

Re:subsidization?

[Anonymous Coward]

without the “need for government subsidization.”

ALL sources of energy receive subsidy. some examples : Oil (how much did all those wars cost?), coal(damage to public health=hidden subsidy), nuclear(research since the forties)

It doesn't matter.

A couple of months ago in Scientific American, they interviewed a venture capitalist - I can't remember his name. Anyway, he had this very interesting point: we can't have subsidies on alternative energy. Why? Because the countries where it's imperative that they adopt such clean tech do not have subsidies nor can they afford them. So, if the energy cannot be cost competitive without subsidies then it isn't worth it.

Subsidize in the beginning until it does become profitable? If that were the case, then MAYBE. But the thing is, many of these technologies cannot scale or if they can, they do not become more cost effective.

We in the West are pretty clean for the most part - it's getting India, China and other developing countries to clean up and they don't have the money to subsidize any technology.

Any green tech that can compete with fossil even with their tax subsidies will win hands down. I think it is possible - probable.

Re:subsidization?

[AvitarX]

China appears to have plenty of money to subsidize our subsidies (low interest credit), which leads me to believe they could subsidize their own energy too.

Re:subsidization?

[WaffleMonster]

Subsidize in the beginning until it does become profitable? If that were the case, then MAYBE. But the thing is, many of these technologies cannot scale or if they can, they do not become more cost effective. We in the West are pretty clean for the most part - it's getting India, China and other developing countries to clean up and they don't have the money to subsidize any technology.

??? Dude wake the fuck up... China is currently kicking ass and taking names in both wind and solar production. The US BY ITSELF is right now responsible for half of the worlds pollution...yet it accounts for only 1/22th of global population.

We're fucking up the world more than anyone else while making other countries pay the price for our actions. "Clean" ... no I don't fucking think so.

Re:subsidization?

[HornWumpus]

You would think so.

However currently in China they are having ongoing problems with traffic jams made up mostly of trucks hauling coal.

In the 'western world' we have mostly gone to the power plant right near the mine model. Transmission line losses are nothing next to freight train costs, much less trucks.

China's banks also have big problems. Apparently there are some people who's loan requests cannot be turned down. US bonds are the best part of many Chinese banks assets. Corruption is endemic.

China is a leader in building photovoltaic panels, mostly for Europe.

Re:subsidization?

[CyprusBlue113]

You know what? Visit Shanghai, then visit LA, and let me know which you think is cleaner air wise.

The US may have issues too, but that doesn't justify cherry picking data. Using per capita to compare US and China on something like pollution is almost to the level of Fox News statistics reporting. It's like trying to compare Arizona or Nevada to Japan, disingenuous at best.

Compare industry, fine, but not per capita.

Re:subsidization?

[myth24601]

For some reason people love to glorify China right now because of their economic growth. China is basically a third world country with a privileged class that gets to live in the large cities, it's economy is so large because of the sheer size of the population.

China has passed the US in electricity production but their pollution controls are near non-existent.

Re:subsidization?

[presidenteloco]

So you must think that an American has a (god given?) right to emit GHGs 6 times as much as a Chinese person and 13 times as much as an Indian citizen.

Who should have to "clean up" first, the person emitting 6 times (13 times) as much, or the other person.

Per person is the only fair way to count it. Otherwise you are not so subtly admitting that you value some people (by citizenship) more than you value other people, and that the privileged people (the special people) have an inherent right to contribute more to the problem before having to clean up their act. If you believe that, then say so openly.

The reason I pick greenhouse-gas emissions is that by far that is the most serious global issue being caused by fossil-fuel based electricity production. Particulate air pollution is a local problem. Serious yes. A lot easier to see and understand yes. But way way less important on the global scale of issues.

 

Re:subsidization?

[c6gunner]

The US BY ITSELF is right now responsible for half of the worlds pollution...yet it accounts for only 1/22th of global population.

This is, of course, complete bullshit. The number is nowhere near what you quote. Moreover, most of those figures include CO2 output as "pollution". If we just stick with actual pollution, the picture looks a lot different.

Re:subsidization?

[Lennie]

Actually the oil industry in the US gets money from the government. This is because getting oil out of the ground in the US isn't very economically viable anymore.

Maybe the last few months it wasn't necessary anymore because the oil price was high. But people really do (maybe did) get paid to do so.

Re:subsidization?

[HiThere]

CO2 output *IS* pollution. So counting it that way is fair.

Ask any veteran of WWII submarines, and they'll be surprised that you need to ask. CO2 is pollution.

We don't generally care much about it because it doesn't tend to concentrate, and because plants consume it as food. But they consume shit, too. We aren't plants.

Currently the world is producing more CO2 than is being consumed, and over time this means that the world is going to be like a WWII submarine that's hiding from a destroyer. Over time this becomes deadly.

P.S.: Plants don't like a really strong concentration of CO2 much more than you do. It does very bad things to them. Long before that, of course, the oceans will become more acidic than they've been in a very long time, and we can't predict all the consequences. But every single one that we can predict is bad.

Re:subsidization?

[Vancorps]

Actually, you are comparing 1 billion people to 300 million people and clearly lack an understanding the issues China is dealing with. China easily has a few hundred million people living in large urban areas with emissions worse than that allowed in the U.S.

Have you forgotten about the Olympics already? China had to shut down almost half of their urban factories to clean the air enough so athletes could compete. There is no where in the U.S. with air quality that poor and somehow you're trying to say they emit less?

Maybe instead you should be more sensible and realize that there are a lot of ways of comparing countries, you should not stick to one statistic as that will never paint an even remotely accurate picture. Carbon emissions in Nigeria per capita are way below China even and they spill as much oil as the Exxon Valdez disaster every year! They are hardly clean.

It is more productive to realize that we all have our problems, China has jumped ahead 60 years in the last 10, you can expect them to deal with many of the same problems that we in the U.S. dealt with and continue to struggle against.

Re:subsidization?

[c6gunner]

Ask any veteran of WWII submarines, and they'll be surprised that you need to ask. CO2 is pollution.

That's silly. By the same reasoning, nitrogen is pollution. Oxygen is pollution. Every element in existence is pollution.

Currently the world is producing more CO2 than is being consumed, and over time this means that the world is going to be like a WWII submarine that's hiding from a destroyer.

Eh, no. CO2 makes up less than one tenth of one percent of our atmosphere (0.03% by volume). In order for it to be toxic, it would have to hit 5% or more. In other words, we would have to increase the amount of CO2 in the atmosphere to a level that's more than 150 times higher than the current levels. Even if we burned every single bit of oil, coal, and natural gas we can get our hands on, we wouldn't get anywhere near that level. The issue with CO2 is that it contributes to the greenhouse effect - it's toxicity is irrelevant when discussing the Earth as a whole.

Re:subsidization?

[Khyber]

"This is because getting oil out of the ground in the US isn't very economically viable anymore."

Do you live in LA, by chance?

A large portion of the taller buildings are only there to hide operational oil derricks.

It has never ceased being viable. In fact, there's several out in the open oil derricks right behind my friend's apartment.

It all depends upon one thing, as most other businesses depend upon - location, location, location.

Re:subsidization?

[flyingkillerrobots]

So stop exhaling. And seal yourself in a plastic bag, so that when your suffocated corpse decomposes nothing goes back to the atmosphere.

Re:subsidization?

[presidenteloco]

You do realize don't you that it is American and British oil companies exploiting the resources of Nigeria and leaving them with a massive pollution mess to clean up, right? Sorry but in global evironmental exploitation and degradation, Western multi-national companies and the Western consumers (I'm guilty too) they sell to are by an order of magnitude the worst culprits on the planet, and have been for 60 years at least.

What are they teaching you American kids in school these days?

Re:subsidization?

[mosb1000]

Yes, but fossil fuels like petroleum and natural gas do not require a subsidy in order to be economical. We have wars in the middle east to increase the volume of oil available. It would still be cost effective to pump oil out of the ground here, but we would have to use less of it.

As for coal, it seems like that could still be cost effective as well, since you can use scrubbers to clean the exhaust and you can properly dispose of the ash and still be cheaper than oil. I'm not sure why they insist on doing it the dirty way on existing power plants, I guess they just like the $$$.

Nuclear power could have been developed without government funding. They built reactors before they ever build a bomb (no, they did not generate electricity), and the only difference between a nuke plant and any power plant is the heat source. The big expense with nukes is handling the fuel and dealing with the waste, that's what makes them uneconomical.

So yeah, they all receive a subsidy, but they don't all require it.

Re:subsidization?

[operagost]

Ask any veteran of WWII submarines, and they'll be surprised that you need to ask. CO2 is pollution.

Ask any veteran of WWII submarines, and they'll tell you that water is deadly.

Re:subsidization?

[HiThere]

Sorry, but Nitrogen is pollution only under extremely high pressures. CO2 is a poison (needed in small quantities to regulate breathing). Nitrogen is basically filler. Spacecraft with low pressure don't bother with Nitrogen, but they still need some CO2. Just not very much.

N.B.: Even plants can't absorb Nitrogen from the air. Only some bacteria have that capability.

Re:subsidization?

[HiThere]

I'm rather sure you don't know anything about the subject, but yes, breathing water is deadly. If you had to ask, I'd think you were rather silly.

For that matter, drinking too much water is also deadly. I think more than about a gallon a day is probably eventually fatal, but I don't know the exact amount. Every once in awhile you encounter news about some idiot who died from drinking too much water.

Even the things we need, we need in the correct amounts. Going outside those boundaries is, indeed, deadly. CO2 happens to be one where we are edging up toward the level where we don't know all the long-term effects, but the ones that we do know are quite unpleasant. (E.g., plants grown in an atmosphere that's high in CO2 appear to be low in protein.) Note that the amount of CO2 present is almost never the rate-limiting step in growth. So nothing gets any significant benefit out of increased CO2. (An exception occurs for the growers of ornamental plants. It's not beneficial to the plants, but it can be beneficial to the grower is there is SLIGHTLY more CO2 in the atmosphere where those plants are grown. You can get larger leaves and petals. They may not be as healthy or as strong, but they're larger, because the cost of extracting the CO2 from the air is lower.)

P.S.: This info about plants growing in atmospheres high in CO2 is based on general science articles. I am NOT an expert in the field.

Re:subsidization?

[Vancorps]

They are teaching me to look at the actual issues. Shell is not the only one responsible for the oil spills in Nigeria, the government there has failed to secure their country. Most spills are the results of vandals or other third parties.

I will however agree that oil companies need to take a much greater responsibility but these are multinational companies so you can't lump them all into one country. The U.S. has little to no control over what one of Shell's subsidiary companies does in Nigeria for instance and even less control over what BP does.

I would go so far as to blame the country of Nigeria for allowing these companies to continue operating while destroying their land. We have much tighter controls in the U.S. but of course even we're not immune from the problems faced with oil and gasoline production.

Re:subsidization?

[pixelpusher220]

Because the countries where it's imperative that they adopt such clean tech do not have subsidies nor can they afford them

Uh, they 'subsidize' by taxing the hell out of the fossil fuel prices. Leveling the playing field can either be reducing cost of A or increasing cost of B. *Both* are subsidies to A.

What does $1/W mean?

[OrangeTide]

I pay about $0.10/kWh. (1000 W per Hour)

Re:What does $1/W mean?

[tmosley]

A watt is a unit of power, a watt hour is a unit of work. The goal is $1/W which means that a 1000 W system, which produces ~8KWh per day (more further south), only costs $1000, and would pay for itself in about three years, making it economically viable for most people.

Re:What does $1/W mean?

[polar red]

they mean 1$ per maximum possible output wattage. (so a 1000000$ for a 1MW peak power plant)

Re:What does $1/W mean?

[Dr. Cody]

I pay about $0.10/kWh. (1000 W per Hour)

The figure in the OP is highly non-standard usage. In the US, only the kilowatt is a unit of energy.

Re:What does $1/W mean?

[wealthychef]

a 1000 W system, which produces ~8KWh per day

Pardon my ignorance, but shouldn't a 1000 W system produce 24 kWh per day, since there are 24 hours per day? Or is the 1000W input, and the 8kWh output?

Re:What does $1/W mean?

[Anonymous Coward]

The sun does not shine 24hours/day... at least not on our planet.

Re:What does $1/W mean?

[Anonymous Coward]

Think daylight.

Re:What does $1/W mean?

[vlm]

I pay about $0.10/kWh. (1000 W per Hour)

What it probably means is they're scammers. Capital costs for coal and nuke run from $1.50 to $3.00 per watt installed. They're claiming $1 per watt. The problem is no matter how unconventional the heat source, no matter how magically free, the employee lunchroom costs $ per plant, the parking lot paving costs $ per plant, the pipes from the magic heat source to the turbines costs $ per watt, the turbine itself costs $ per watt, the water pumps and filters cost $ per watt...

PERHAPS they mean the capital cost of their magic heat source alone costs about $1 per watt. The problem is some recent historical nukes (not in the backwards USA, but civilized countries like France, etc) have come in at $1.50 per watt total plant cost delivered. So, on one side, their costs probably will decline as they are new vs the very mature nuke industry. On the other hand, can you build an entire thermal electric plant for well under 50 cents per watt? Then again, can a new tech be nearly as reliable as ancient technology nuke plant?

Re:What does $1/W mean?

[ryansm1]

He is taking into account that the sun shines about eight hours on average (hence "more further south"), giving only 8kWh energy.

Re:What does $1/W mean?

[tzot]

> In the US, only the kilowatt is a unit of energy.

I thought that a watt was a unit of power, not energy, everywhere in the world. Power multiplied by time (e.g. the kilowatt-hour unit) is energy.

Re:What does $1/W mean?

[Anonymous Coward]

The new EPR nuke in Finland (built by the French) cost 6.4 billion euros. It's net power is 1600W so that's 4 euros / Watt!

Re:What does $1/W mean?

[wealthychef]

LOL, my bad.

Re:What does $1/W mean?

[ColdWetDog]

I pay about $0.10/kWh. (1000 W per Hour)

What it probably means is they're scammers. Capital costs for coal and nuke run from $1.50 to $3.00 per watt installed. They're claiming $1 per watt. The problem is no matter how unconventional the heat source, no matter how magically free, the employee lunchroom costs $ per plant, the parking lot paving costs $ per plant, the pipes from the magic heat source to the turbines costs $ per watt, the turbine itself costs $ per watt, the water pumps and filters cost $ per watt...

PERHAPS they mean the capital cost of their magic heat source alone costs about $1 per watt. The problem is some recent historical nukes (not in the backwards USA, but civilized countries like France, etc) have come in at $1.50 per watt total plant cost delivered. So, on one side, their costs probably will decline as they are new vs the very mature nuke industry. On the other hand, can you build an entire thermal electric plant for well under 50 cents per watt? Then again, can a new tech be nearly as reliable as ancient technology nuke plant?

My impression (and damn these mindless 'articles') is that this is an ultimate goal. That figure isn't unreasonable even if it's cheaper than a coal fired plant. Small scale repetitive parts may well bring down capital costs compared to large purpose build structures - the employee break room is not the big ticket item in a nuc plant. Even if they don't get to the $1/watt figure, you have to remember that typical costs for nuc plants especially have enormous subsidies from the government in terms of waste disposal and insurance costs. Likely the same if you figure out the true environmental costs from a coal plant.

So, I'm not sure that they're a scam but equally unsure that it will lead to any significant commercial application.

I like the glowing ball, though. A whole field of those would be neat.

Re:What does $1/W mean?

[timeOday]

the pipes from the magic heat source to the turbines costs $ per watt, the turbine itself costs $ per watt, the water pumps and filters cost $ per watt...

RTA, there are no pipes, turbine, pumps, nor filter. It's photovoltaic. I don't know whether they can beat a nuke plant in the real world, but the relative simplicity of this system compared to a nuclear power plant is certainly striking.

Re:What does $1/W mean?

[Dunbal]

$1/W means you pay $1 to be able to produce 1 W over the lifetime of the solar cell (usually 20 or so years). Not to be confused with your kWh, we're not measuring the same thing. Just like if you use 2000kWh per month on your electric bill and try to set up a solar system, don't expect to be able to get away with only installing 2000W worth of solar panels...

Re:What does $1/W mean?

[Dunbal]

No because the sun doesn't shine 24 hours per day. Also solar panels do not product 100% of their rated output if partially covered by shadows, debris, etc. Also you normally don't see solar panels that move to maintain the optimal angle with the sun except in very expensive set ups. Therefore you often need many more Watts' worth of solar panels than what you calculate your electrical usage as.

Re:What does $1/W mean?

[Anonymous Coward]

The sun shines on the planet on average 12 hours per day regardless of where you are. The period over which you average changes with latitude, in the far north and far south you have to average over a year instead of a day.

Re:What does $1/W mean?

[Xacid]

Technically it does. You might just have to chase it around a little. ;)

Re:What does $1/W mean?

[BisexualPuppy]

The sun does not shine 24hours/day... at least not on our planet.

Actually yes, it is, at the poles. Both of them beeing part of the same planet.

Re:What does $1/W mean?

[wealthychef]

Does the angle of the sun come into play here? Is it really the same at 4PM as at noon? Or is 1000 W an average?

Re:What does $1/W mean?

[Anonymous Coward]

The installed cost of a power plant is about $500-$1000 per kilowatt for a natural gas combined cycle plant, and over $1000 per kilowatt for a coal fired plant. This includes equipment, design, construction, and owners costs like land, financing, permits, easements, etc. A solar plant at $1000 per kilowatt (or $1 per watt) would indeed give fossil fuels a run for the money, since of course there's no cost of fuel.

Re:What does $1/W mean?

[Dunbal]

Capital costs for coal and nuke run from $1.50 to $3.00 per watt installed.

Absolutely meaningless because I am damned sure a coal burning station or a nuclear power plant do not have exactly the same lifetime. When dealing with capital costs you are interested in a return on your investment. The only way to calculate this is by knowing not only how much it costs up front, but how much it will cost per unit of time and how long it's expected to work. If it stops working before you get your money and opportunity cost back, you don't invest.

Your argument about lunchroom costs is true regardless of the type of facility since all facilities need employees. Every business has its problems whether it's replacing damaged PV cells or spent fuel rods or a mandatory upgrade of the scrubbers for the smokestack. While it's very likely that the theoretical solar boys have forgotten to include a few real world practical costs, it's really an apple vs oranges comparison and you need ALL the numbers to make a decision. Your statement is just as general as the generic "cost per W".

Re:What does $1/W mean?

[burni2]

In the wind industry that way we calculate the costs per installed Watt of rated power, I think it's the same here

3,6MW would equal to 3,6 Million $

Re:What does $1/W mean?

[vlm]

the pipes from the magic heat source to the turbines costs $ per watt, the turbine itself costs $ per watt, the water pumps and filters cost $ per watt...

RTA, there are no pipes, turbine, pumps, nor filter. It's photovoltaic. I don't know whether they can beat a nuke plant in the real world, but the relative simplicity of this system compared to a nuclear power plant is certainly striking.

I did read the article, I did not believe at concentration factors over 1000 the cells would survive very long without active cooling.

Although its handling about the same heat flux as any other thermal plant, you can run colder, so the pipes and pumps can be cheapo low pressure low temp units... but that implies higher flow rates, and pumps unfortunately scale much worse than linear WRT flow rates. So the total plumbing cost is probably going to be "about the same".

If they're doing this with passive cooling, all I can say is "wow". They are concentrating sunlight at a ratio that liquefies asphalt.

Re:What does $1/W mean?

[Anonymous Coward]

It most certainly does shine 24 hours/day on this planet -- if you're further north than the Arctic Circle in the summer, for example. I've seen it there in July, and it is distinctly weird. The Sun just circles around close to the horizon.

However, if you built the station there I suspect the cost of the wire to connect to the grid in Arizona would probably be prohibitive, not to mention low solar insolation and the problem of any power production in the winter :-)

Re:What does $1/W mean?

[vlm]

Ahh but to calculate your NPV or whatever you have to know how much it costs up front. I think their estimate is ridiculously low compared to some proven technologies that handle/dissipate similar quantities of heat.

So long before you make the interest rate, maintenance cost, and operations cost calcs you mention, my point is their capital estimate is way low, even if their magic electricity and heat generating box were completely free (unlikely) the rest of the plant that keeps the magic box cool is going to cost alot.

Re:What does $1/W mean?

[Dunbal]

my point is their capital estimate is way low, even if their magic electricity and heat generating box were completely free

On this we agree - but this is typical for anything offered by a university. Scientific knowledge != business acumen. There are bound to be oodles of hidden costs in a brand new industry which are well known in an older, established one. That's why you never want to be the first one in the pool...

Re:What does $1/W mean?

[HornWumpus]

Of course you do.

Is that how you bill your customers too?

I bet somewhere, someplace there is an evil old troll who calculates it as $/kWh

Re:What does $1/W mean?

[Anonymous Coward]

Well, it shines 24 hrs/day for 6 months, then 0 hours a day for 6 mths. I wonder what that averages out to?

Re:What does $1/W mean?

[ShooterNeo]

Slow your roll, man! "Scammers??!!!"

RIGHT NOW you can purchase thin film solar panels for $1/watt. Now, this doesn't include the inverters, which add more cost, nor labor or mounting hardware...but we are actually a lot closer to the threshold than you think.

The theory is that if $1/watt is the installed cost of solar panels, including labor and inverters, and you don't have to pay for fuel, and the maintenance costs are very small, it would be cost competitive with conventional power sources. The cost stability - fuel prices can't go up, and once you install the panels you do not have to worry about prices changing for the next 25+ years, means that solar would become the preferred source of new power plants.

Re:What does $1/W mean?

[zippthorne]

Divide that by pi to account for the varying angle of the sun through the typical day and you'll see it's quite close to the 8kWh they're claiming as an average.

What you're doing this: \int{sin(x)dx_{0}^{pi}} \over \int{1_{0}^{2pi}}

The assumption here being that you can approximate the output as P*{sin(x) : 0<=x<=pi ; 0 : elsewhere}

Re:What does $1/W mean?

[Anonymous Coward]

Actually, the sun does shine for 24 hours a day. We just don't always see it.

Re:What does $1/W mean?

[Mike_EE_U_of_I]

What it probably means is they're scammers. Capital costs for coal and nuke run from $1.50 to $3.00 per watt installed. They're claiming $1 per watt. The problem is no matter how unconventional the heat source, no matter how magically free, the employee lunchroom costs $ per plant, the parking lot paving costs $ per plant, the pipes from the magic heat source to the turbines costs $ per watt, the turbine itself costs $ per watt, the water pumps and filters cost $ per watt...

PERHAPS they mean the capital cost of their magic heat source alone costs about $1 per watt. The problem is some recent historical nukes (not in the backwards USA, but civilized countries like France, etc) have come in at $1.50 per watt total plant cost delivered. So, on one side, their costs probably will decline as they are new vs the very mature nuke industry. On the other hand, can you build an entire thermal electric plant for well under 50 cents per watt? Then again, can a new tech be nearly as reliable as ancient technology nuke plant?

The proposed system is not a thermal system. It would use concentrated light shining on solar cells to produce electricity directly. So, to answer your points:

1) the employee lunchroom costs $ per plant

    Since employees only have to guard the plant and fix things that break, the number of employees can potentially be lower, much lower. That depends on how reliable their devices are.

2) the parking lot paving costs $ per plant,

    If there are fewer employees, there is a smaller parking lot.

3) the pipes from the magic heat source to the turbines costs $ per watt,

    There are no pipes because it is not a thermal plant, cost zero.

4) the turbine itself costs $ per watt,

      There are no turbines, cost zero.

5) the water pumps and filters cost $ per watt

    There are no water pumps or filters. Indeed, the original article even includes the sentance "It uses no water"

    Can they make it work? Sure. Will the costs be as low as they think? I doubt it very much, but not for your reasons. I think they will fail on cost because they have to build a giant structure with lots of moving parts. I wish them good luck with that. That is a very tough nut to crack.

Re:What does $1/W mean?

[hairyfeet]

Question: Why does everyone seem so focused on Solar cells, which as everyone points out wear out, will need cooling at these temps, etc, instead of molten salt solar power where the more heat you create the better it runs and the heat stored in the salt itself can be used as a battery? Was there a hidden gotcha I haven't heard about, or is there some sort of kickback or subsidy for cell production?

Because it seems to me that cells are just the wrong direction to go. With Molten Salt it is basically a big tank and focusing mirrors which will make for lower costs, the life of the unit as a whole should beat cells, and the salt as a battery helps deal with the storage problems. So why so much focus on cells?

Re:What does $1/W mean?

[Jamu]

It certainly does. It's always illuminating half of our planet at any one time.

Re:What does $1/W mean?

[tqk]

I haven't read the article. Hearing they're doing this with photovoltaics is a surprise to me.

They are concentrating sunlight at a ratio that liquefies asphalt.

However, the latest science show related to this I watched on TV was about shaped mirrors heating oil in pipes which ultimately powered a steam generator. With a huge insulatated underground tank holding superheated oil, it could go 24/7. The most complicated part was actuators that made the mirrors follow the sun for maximum efficiency.

Photovoltaics may work, but there's other (simpler?) ways to harness solar.

Re:What does $1/W mean?

[tqk]

I think their estimate is ridiculously low compared to some proven technologies that handle/dissipate similar quantities of heat.

Uh, what am I missing here? The whole point of solar is to absorb solar energy, yes? This is an argument against phovoltaics.

Mirrors focussed on pipes superheating oil, which eventually drive steam generators, should be more efficient, simpler, and easier to maintain, possibly cheaper to build.

Re:What does $1/W mean?

[vlm]

So why so much focus on cells?

I agree with you completely in that thermal is a better solution in almost all cases at "power plant size" levels.

Problems:

1) Scalability. You can demo and test and experiment with "one" off the shelf cell if you really want. Even if the plan is to later deploy one million cells at the site all wired in parallel. If you try to run a GW class steam turbine on 100 watts, you're not even going to make it physically warm, much less run. Proof of concept is a bit tough. Also its easy to install 50% more PV units, assuming physical space. But its really hard to "upgrade" a turbine by 50%.

2) Moving parts. Nothing ever really breaks on a PV system. Maybe the filters and cooling fans on the inverters need the occasional dusting / replacement. Cells have to be washed / dusted about as often as my home's windows (somewhere between every couple years and once per generation).

3) Shutdowns. You never really shut down a PV unit for maintenance. Ever. There are no tasks I'm even remotely aware of that must take more overnight, worst case overnight during winter. On the other hand, as per #2 above, you're going to have to shut down for a week to replace the turbine, someday, if absolutely nothing else. And valves leak, and pumps wear out., either while under power, or scheduled maintenance.

Basically a thermal salt system is very much like running a factory, while a PV system is very much like running a telco central office or a big repeater site or maybe a small data center. With all that implies in number of employees, skill level of employees, maintenance required, etc.

Re:What does $1/W mean?

[vlm]

But I can buy a whole French Nuke plant, delivered, the whole thing, not just a reactor, for $1.50/watt. Or maybe that was the Russian plant. And it runs 24/7 for years at a time... You're just talking about panels. Not mounting systems. Not active trackers, nor wiring, nor a control building.

I bet I could build a PV ish plant using these $1/watt modules for maybe $1.50/watt. But that only outputs "nameplate power" half the time over the course of a year... Hmmm. Just nuke it.

Scammers is a bit harsh.. .If they were asking for "investment funds" then I'd get worried. But... Theres something a little off about claiming they made it to $1/watt so its all good. It isn't.

Re:What does $1/W mean?

[Anonymous Coward]

You forgot, if you do have a shutdown, the salt solidifies. How do you get it liquid in all the pipes again?

That's a problem. No problem for PV.

Re:What does $1/W mean?

[Anonymous Coward]

Solar is so low maintainence to where the costs are virtually meaningless. Unless they gay up the technology with something retardedly high maintainence like hydraulics then I imagine you could make a facility with zero maitainence. The very places where solar is most effective the land is also insanely cheap, so I don't understand why all of these companies want to tie up capital in high output photovoltaics when the output/square foot is so unimportant. Make it up in quantity using solar thermal or thin film technology. There's profit potential now. These hippies are too focused on getting the square footage down so they can "save the world" tomorrow instead of making money today.

I hate solar by the way. The profit margins are too narrow. If you ask me, we should nuke a small country and use the mass grave as storage for spent fuel rods. Liquified souls make a surprisingly good working fluid, and to this day I find it difficult to believe that "too much heat" can be considered a problem with a straight face. Canada would probably work pretty well. They aren't really using it anyway, and the low air temperature will increase the efficiency of the process. We'll just build them a reservation in Antarctica with a few Casinos. It's all snow anyway so they probably won't notice the difference. They're pretty far North already so it shouldn't be too long of a walk.

It's actually painful to me watching all the overpaid idiots in the world bumbling around constantly. The quality of engineer our universities seem to be turning out is frighteningly low. Just goes to show you can't teach talent and killer instinct. If there were 1000 clones of me, nobody would have to work anymore because I would have the time to make all of your jobs redundant. Unfortantely, it takes X hours of time investment to make a specific color of featherbedding technologically obselete and I only have enough time in the day to take down 5 or 6 in my lifetime(I'm being modest as a matter of courtesty).

When I found out that aircraft carriers were still steam powered I almost died laughing. Personally I think it's intellectual laziness that makes people stick to the safe, tried, and true. You see these obsolete methodologies with 100 year life spans because of a long heredity of ass covering among the limited number of decision makers along the way.

So hit me with your best shot. I'm pretty much perfect.

Re:What does $1/W mean?

[fast turtle]

The short Answer is "NO". The reason for this is you never figure on more then 5 hours of Peak Sun unless you're at the equator, where you can figure 8 hours. The reason for this is pretty simple. It's called Axial Tilt, resulting in our seasons.

Why the 5 hour figure is simple and it's called Winter. That's when you have less sunlight that provides energy due to angles of incidence. Sure a PV panel can provide some output if faced directly at the sunrise but until 9am it's going to continue increasing as the amount of energy reaches saturation levels of the array. This will remain until 3pm (1500) during the winter as the sun passes it's peak and begins declining until the energy provided is less then what's being demanded.

In order to retain reliability, a PV array is generally in a fixed possition that's solidly mounted. This ensures the maximum amount of energy will be generated during the Peak Sun period and may include a seasonal adjustment for Summer/Winter tilt. Any method used to shift a PV array has to remain as mechanically simple as possible and the only ones that work reliably with minimal maintenance are fixed angle.
Yes you can use a more sophisticated tracking system but then you're reducing the actual output by the amount needed to power the tracking system.

Re:What does $1/W mean?

[gd2shoe]

Uh, the article is sparse and images aren't detailed. I see the "giant structure", but it looks like a simple tracking parabolic dish. I don't see "lots of moving parts". What else needs to move? Just curious.

Re:What does $1/W mean?

[Anonymous Coward]

No, the angle of the sun has no effect. The second some sun appears on the horizon, it irradiates the ground at 100% solar efficiency until the second is sets. It's like an on-off switch. Latitude does not matter either, nor the time of year. This is because the sun is closer to the earth during the early morning hours than it is during the late afternoon hours, and moves farther away during noon, as it moves around the earth in a giant ellipse.

Re:What does $1/W mean?

[rcw-home]

Does the angle of the sun come into play here? Is it really the same at 4PM as at noon? Or is 1000 W an average?

A number like 1000W would refer to the peak power output that you'll get from it with the solar cells perpendicular to the sunlight with optimally clear skies. Since the earth receives a maximum of about 1100W/m^2 of solar energy, and ordinary silicon cells are about 12% efficient, you can expect such a system to be a little less than 10 m^2 in size.

4pm is not noon, no. First off, the lower the angle of the sun in the sky, the more atmosphere it goes through, which filters things out somewhat. Second, while you can steer the solar panels so that they are always perpendicular to the sky, most are just fixed to a south-sloped roof and more of their surface area will be going to waste.

If you google for insolation map you can get nifty maps of what areas get how much sunlight. Note that most of these maps are for plain photovoltaic installations, where diffuse light (cloudy skies) is still better than nothing. When you're using solar concentrators (mirrors), those mirrors can't focus anything but specular light (sunny skies). I don't know if any maps have been drawn taking that into account.

Re:What does $1/W mean?

[Mike_EE_U_of_I]

To do concentrated solar PV, you have to have a two axcis tracker. Compared to what non-concentrating panels require (no tracking, or single axcis tracking), that is lots of moving parts. The tracking has to be very precise or power output drops to almost nothing.

    While this doesn't sound that hard to do, the reality of it has been that the concentrated solar folks have never been able to be cost competitive with the non-concentrated solar folks. These days there are something like 100 watts of non-concentrated solar built for every watt of concentrated solar. Even solar thermal plants (where the tracking does not have to be as precise, so it can be cheaper) are being canceled all over the place because simple non-concentrating PV panels are cheaper.

    So these guys come along and say they can do tracking cheaply. Well, I've heard that people saying that for about 20 years now, and no one has been able to do it. It's not hard to make it work. It's hard to make it work cheaply.

Re:What does $1/W mean?

[Khyber]

"The sun does not shine 24hours/day... at least not on our planet."

This is wrong. It may not shine BRIGHTLY 24/7, but near the solar system oriented 'top' and 'bottom' of our planet get 24 hours of light for multiple periods during the year, for months and months on end.

Re:What does $1/W mean?

[Khyber]

"No, the angle of the sun has no effect"

This is incorrect. The angle of photon flux hitting our atmosphere will ultimately determine how much photon flux is/is not scattered from the target location.

We do not consistently hit 2,200+ umol/m^2/s-1 on every square inch of the planet on a cloudless day, and that photon flux ultimately determines how much power we can harness.

Re:What does $1/W mean?

[Khyber]

There are maps for solar insolation via direct irradiation, but not for PV systems, but biological systems (plant zones.)

Re:What does $1/W mean?

[Anonymous Coward]

No matter where you are in the world, the kilowatt (kW) is a unit of _power_ (energy per unit time) and the kilowatt-hour (kWh) is a unit of energy.

Re:What does $1/W mean?

[riverat1]

You forgot the /sarcasm tag.

Re:What does $1/W mean?

[ShooterNeo]

Regarding the french nuke : you have to pay for operating costs (expensive), maintenance (VERY EXPENSIVE), fuel (cheap today), waste disposal (ungodly expensive), and liability insurance (ungodly expensive).

A large solar PV plant can be run entirely by computers. It only needs human intervention once in a blue moon. A couple guys with a pickup will have to be there to do repairs, and they can improvise repairs using whatever cheap method they want. (rather than using ungodly expensive spare parts, wearing radiation suits, and filling out reams of paperwork)

A PV plant needs no fuel, the waste of the dead panels goes in landfills, and there's close to zero liability risks, especially if the plant is on cheap lands in rural arizona.

On the other hand, once we have a lot of solar plants, we will have to start paying for energy storage which will raise the cost significantly. The compressed air in a salt cavern method is one energy storage technique, however, that stores a huge amount of energy and is relatively cheap.

Re:What does $1/W mean?

[Anonymous Coward]

Regarding the french nuke : you have to pay for operating costs (expensive), maintenance (VERY EXPENSIVE), fuel (cheap today), waste disposal (ungodly expensive), and liability insurance (ungodly expensive).

Not to mention the cost of decommissioning. Decommissioning France's Brennilis plant cost about 480 million euros, which is about 20x the initial cost estimate, and it was only a 70 MW plant.

Re:What does $1/W mean?

[Anonymous Coward]

Solar concentrators unlike traditional Solar Cells require some form of tracking system. Which unfortunately increases costs, but at the same time and limits them to sunny day's, however they are at peak power for longer.

Crystal Ball

[Aighearach]

I always suspected that PV technology was just missing a glowing crystal ball.

To the stars, Merlin!

Solar cells is a bad idea for concentrators

[BlueParrot]

If you are using concentrators for solar power you really ought to consider a thermal cycle like a brayton turbine or a sterling engine, rather than solar cells. Thermal cycles tend to have higher conversion efficiencies, the equipment is more reliable, and their power output is more easily converted to grid voltage ( AC as opposed to DC ). Solar cells also tend to see reduced lifetimes when used with very concentrated light. The advantage with cells is pretty much that they don't need concentrators to work, since they don't rely on a high temperature. They can also be used in places where space/weight is an issue, such as on sailboats, rooftops or sattelites. Thus if you are already using a bulky concentrator to get the light intensity up, you may as well use a sterling engine.

 

Re:Solar cells is a bad idea for concentrators

[Anonymous Coward]

Wrong! Sterling engines have moving parts which cause them to need replacing sooner than solar cells.

Re:Solar cells is a bad idea for concentrators

[Waffle Iron]

If you are doing a thermal cycle with concentrators, you need a *big* system. Small thermal engines aren't much more efficient than garden variety solar cells. (And presumably, concentrated solar would use high-tech cells that rival the efficiency of big heat engines anyway.) That means that you have to use a complex "power tower" arrangement with a field of precision synchronized mirrors pointed at one huge collector. You also need a big cold sink for thermal cycles; most power plants use a bunch of water for that, which is hard to come by in the desert.

The solar cell approach would also have the advantage of mechanical simplicity, and the ability to add capacity in small self-contained increments.

Re:Solar cells is a bad idea for concentrators

[jmorris42]

If you are using concentrators you either take a huge loss because solar cell output drops off at high temp (and suffer shortened service life) or you end up with a cooling system for the cells. Once you have the cooling system you should just yield to the physics and accept that the best use of concentrated sunlight is in heat, not direct conversion to electricity. Solar cells only convert a few frequencies (three in the article for this story) while dumping the light over to heat uses much more of the spectrum..

Re:Solar cells is a bad idea for concentrators

[Waffle Iron]

So? At the end of the day, overall net system efficiency is what matters. Heat engines will always be saddled with the laws of thermodynamics, which force them to waste much of your enhanced spectrum. Solar cells, without the limitations of the Carnot cycle, can convert more of the available energy in the part of the spectrum that they *do* use.

Solar cells also don't need to be cooled to the same low temperatures that the outlet of a heat engine requires to run efficiently. In the desert, that's much easier to achieve.

Re:Solar cells is a bad idea for concentrators

[Dunbal]

But the moving parts are far cheaper to replace... a burned out PV cell can throw your whole panel off.

Re:Solar cells is a bad idea for concentrators

[vlm]

The problem is the Carnot eff at a relatively cool nuke plant is still around/over 33%. Good luck finding a production off the shelf solar cell with decades of operating experience that can dream of reaching 33% efficiency.

If you're willing to try "exotic" PV units, I want to try "exotic" carnot units, like maybe a century old binary fluid system like the old fashioned two stage mercury and water system. Maybe something a little less toxic that vaporized mercury. A century or so ago those ran around 50% carnot eff. They were also horrific toxic beasts, but maybe with some more advanced materials... Maybe a modified cycle with yellow hot helium thru an exotic turbine, then its waste heat thru a sodium vapor turbine, then an "old fashioned" water cycle...

There is also the engineering problem.... Thermal means a very traditional water boiler design, no question marks at all except for the weird source of heat. PV means multiple areas of engineering experiment, the concentrators, the PV units, the cooling system for the PVs, etc.

Re:Solar cells is a bad idea for concentrators

[Anonymous Coward]

Yeah, but those nuke figures are for large reactors. You can't really scale them down well, nor can you own your own, nor can you get the cost to build one down to $1/watt. The rig pictured in the article isn't as simple as a flat roof panel, but it's a hell of a lot more simple than anything with combustion or pumps, and it scales up and down by surface area of the reflectors and chips.

Re:Solar cells is a bad idea for concentrators

[ShooterNeo]

Just one panel, and every panel is identical to every other panel. And every subunit on every panel is identical to every subunit on the same panel and every other panel. This repetitiveness means that once you develop an extremely cheap and fast method for making one solar cell, you can make trillions of them the same way and replace most other forms of power generation.

Stirling cycles and thermal plants have more "fiddly bits" that have to be designed, manufactured, quality controlled, and maintained. In the long run I think the PV panels will win because of their simplicity - probably the straight PV panels without light concentrators, for that matter.

Re:Solar cells is a bad idea for concentrators

[Anonymous Coward]

Let's say: I can put a concentrated PV system on the roof of my office building. I can't put a gigantic solar thermal system up there.

Re:Solar cells is a bad idea for concentrators

[Software Geek]

Presumably, most of the cost in this system is the concentrators, not the PV cells. So, perhaps the PV cells can be replaced when they deteriorate without driving the overall system cost up too much.

Re:Solar cells is a bad idea for concentrators

[Anonymous Coward]

You left out the Goswami cycle -http://www.eng.usf.edu/~hchen4/Goswami%20Cycle.htm.

Re:Solar cells is a bad idea for concentrators

[Anonymous Coward]

How about a 25 kW Stirling engine with 31.25% sun-to-grid efficiency? http://share.sandia.gov/news/resources/releases/2008/solargrid.html

Power towers are less efficient, but they typically have lots of heat transfer fluid that can be used to store heat. This allows continued generation during clouds or for a few hours after sunset.

Re:Solar cells is a bad idea for concentrators

[Anonymous Coward]

Although solar cell (photovoltaic or PV) efficiencies up to around 40% have been achieved, the typical commercial-scale power plant uses PV panels with efficiencies closer to 10 or 15%. Combine that with single-axis or no tracking and inverter losses and you're probably well below 10% efficiency for all but the peak hours of the day.

Re:Solar cells is a bad idea for concentrators

[Anonymous Coward]

Not entirely true, sunlight is (somewhat) thermalised. Solar cells are going to have thermal limits just like anything else, otherwise we could extract useful energy from something at low temperatures using a big antenna.

Re:Solar cells is a bad idea for concentrators

[TheTurtlesMoves]

Direct conversion is saddled with quantum physics. Only one colour of light can be converted with ~100% efficiency. Even in theory it is much less. Trippe junctions can do better etc, but is not in fact better than the theoretical performance of a heat engine. Don't forget to first or even second order you have a black body spectrum. In practice both work well in different situations and both get no where near there theoretical efficiency.

Re:Solar cells is a bad idea for concentrators

[radl33t]

So. you're right. At the end of the day total system efficiency is what matters and there is no PV technology that can compete with a heat engine. There will NOT be any commercially viable PV solution for decades based on the development time of _all previous energy conversion technology_. Also what's this funniness about not needing cooling? Nothing will survive at 1000 suns without a massive cooling system.

Re:Solar cells is a bad idea for concentrators

[Waffle Iron]

Please reread both of my posts more carefully. This time, try to understand the qualifiers.

Re:Solar cells is a bad idea for concentrators

[Anonymous Coward]

Solar cells are also limited by the Carnot cycle. However the hot side in their equation is the surface of the sun not the heat collecting plate on a thermal engine.

Bullshit.

[Anonymous Coward]

I keep hearing this repeated as though it were a fact.

And yet, gas taxes keep coming out the wazoo.

For the end user, those subsidies don't exist.

Re:Bullshit.

[Desler]

Yeah, those subsidies clearly don't exist. That's why at one point Obama claimed he was going to cut $36.5 billion in them.

Re:Bullshit.

[sumdumass]

That's somewhat of a misnomer. The subsidies are mostly tricks to get the oil industry to invest in areas that are not profitable for them and they wouldn't otherwise be at.

In more plain terms, if the subsidies didn't exist, oil companies would not miss them, they simply would not be doing some of the things they are now at the request of the government. Eliminating those subsidies would have no real noticeable effect on price or profit.

Re:Bullshit.

[damn_registrars]

That's why at one point Obama claimed he was going to cut $36.5 billion in them.

You must have missed the memo. Let me remind you, you are writing on slashdot and are under no circumstances allowed to suggest that President Obama is a reasonable and/or intelligent human being. Furthermore in some crowds here you might not be allowed to even suggest that he is indeed a he or a human being.

Re:Bullshit.

[Desler]

And yet despite claims that they wouldn't miss them, they continue to lobby and fight against their removal.

Re:Bullshit.

[sumdumass]

They do? Your right, because they can explore other areas of business and develop techniques to deal with it in the future without a large loss. However, that doesn't mean they would continue to do so if they were removed.

I didn't say there wasn't a benefit for them. I said the benefit wouldn't effect their profit or prices if it was removed. Instead, they would just go back to what's normally profitable until such time prices are high enough for them to get into those areas on their own.

Re:Bullshit.

[Anonymous Coward]

"Furthermore in some crowds here you might not be allowed to even suggest that he is indeed a he or a human being."

Correct. It's nutty to say he's human. He is not. He is a Republican.

Re:Bullshit.

[DJRumpy]

It's difficult to argue though, that the tax payer should subsidize exploratory ventures for companies which make some of the largest profits on the planet. In short, they could afford these ventures on their own with no help from the taxpayer. It is to their benefit to keep the taxpayer addicted to oil as long as possible. About the only karmic result of all this is that the oil industry will eventually have to expand into other energy sources or face extinction.

As a taxpayer, I say the sooner the better. Total dependency on an energy source that we do not and cannot control is borderline insanity.

That said, I happen to agree that some government incentives for alternate fuels is absolutely necessary. Sometimes they do 'hit the jackpot' so to speak, and if such ventures into solar prove to be a feasible alternative fuel, then I would consider that money well spent.

Re:Bullshit.

[sumdumass]

It's difficult to argue though, that the tax payer should subsidize exploratory ventures for companies which make some of the largest profits on the planet. In short, they could afford these ventures on their own with no help from the taxpayer. It is to their benefit to keep the taxpayer addicted to oil as long as possible. About the only karmic result of all this is that the oil industry will eventually have to expand into other energy sources or face extinction.

There's really two parts to answer this.
First, it's not really all that difficult when you understand the pork barrel spending. 70% or more of the subsidies is designed to keep the oil companies in an area in which a congress person would benefit from. Some of it happens to do with keeping jobs, others is keeping revenue from well leases and so on. I completely understand what you are saying though, but if you approach it already knowing that the oil companies don't need it, you can start to see who does.

The second part, It is not only a karmic results, it's what some of the subsidies are designed to do. The oil industry already has the distribution network there, the processing capabilities and expertise, it's just a matter of jobs being kept to get them to transition close to how it is now, verses off shoring everything. There is a large push (concealed within some of the subsidies) to get oil companies into alternative energy sources sooner then later. Perhaps much sooner then karma alone could accomplish.

As a taxpayer, I say the sooner the better. Total dependency on an energy source that we do not and cannot control is borderline insanity.

Yes, I agree. The problem is, currently, we don't have a comparable replacement. What this and other stories seem to glance past, (maybe it's just the commentators), is that when we inflate energy costs and alternatives not otherwise become viable, it crashes our economy. Sure, there was a lost more to it, but we can't discount the impact that high prices for energy played into it. It sucked the free money away from everyone.

That said, I happen to agree that some government incentives for alternate fuels is absolutely necessary. Sometimes they do 'hit the jackpot' so to speak, and if such ventures into solar prove to be a feasible alternative fuel, then I would consider that money well spent.

I agree too. Except I think we need more of an investment into the raw sciences to make it happen then into an industry. Either way, something happening overnight will not come out well. It will take 20 or more years to replace the majority of oil dependent embedded infrastructure as soon as something is figured out.Cars, machinery, HVAC systems, all need to see the end of a useful life instead of expecting people to just throw them out for the next big thing.

Real article

[Anonymous Coward]

The linked article is just copy taken from REhnu's site (see http://www.rehnu.com/news ). Their news page links to an article with a bit more content:
http://www.solarnovus.com/index.php?option=com_content&view=article&id=2008:energy-telescope-aims-for-1watt-&catid=52:applications-tech-research&Itemid=247

Still the same problem as with all solar

[RightwingNutjob]

It doesn't work at night when you need electricity to power your lights. Which is especially a problem in the long winter nights when you need to heat your home. Can we please finally put this solar-for-everyone nonsense to bed?

Re:Still the same problem as with all solar

[Anonymous Coward]

Would you look at this... someone who never heard of batteries. ;)

Re:Still the same problem as with all solar

[Aighearach]

If only somebody would invent some sort of device that could store electricity for later use.

Then I could finally ditch the diesel generator I have to drag around to keep my mp3 player running!

Re:Still the same problem as with all solar

[BlueParrot]

Energy consumption is largest during the day, and thus solar can actually help do some load leveling. Yea, you can't get all the energy from solar, but having the plant peak in power output around noon is actually a good thing.

Re:Still the same problem as with all solar

[Desler]

Who ever claims that solar is for everyone despite a minority of kooks? Anyone sensible knows that you need to store excess generated energy in batteries for later or to have a backup generator for when night comes. What you are doing is the classic strawman.

Re:Still the same problem as with all solar

[RightwingNutjob]

And then you'd have the fun and moral satisfaction of purchasing a new set of heavy duty batteries every year or two. Mind you that would be a very large set, to account for the possibility of many short cloudy winter days in a row.

Re:Still the same problem as with all solar

[Desler]

No, that's why you have backup generators, usually natural gas, as do most generators of solar power.

Re:Still the same problem as with all solar

[jmorris42]

Look into the efficiency of a battery sometime. Unless you buy really expensive ones you lose about half of the energy putting it into and getting it back out. More losses if you are putting in AC and needing AC back out. And the really good (from an efficiency pov) lithium-ion batteries don't suffer many charge discharge cycles before hitting the 50% capacity point generally considered as replacement time. We currently have zero methods to store electricity that are cheap enough and effective enough for use on the grid. All electricity is generated as needed, with vast arrays of 'peaking power' generation capacity that largely sits idle. Believe me, if there were a good way to store electricity the industry would be using it already.

Worse, while electricity can be sent large distances, it is best to generate close to the point of use because of the line losses. So even if we were willing (and shot enough enviromentalists) to cover our deserts with solar arrays we would lose most of the power heating the lines getting it to where the customers are. Same for wind, it mostly occurs in areas where there aren't many people... or more accurately windmills near populated areas attracts more environmentalists.

Re:Still the same problem as with all solar

[cduffy]

If electricity is cheap in the daytime and scarce/expensive at night, the market will figure it out.

Maybe that means people have incentive to charge their cars at work. Maybe it means entrepreneurs buy excess electricity on the spot market during the daytime, use it to pump water uphill, and use the potential energy of that water to generate more expensive electricity at night. (Is that process lossy? Sure! But the market will only reward it if it provides a net benefit, so it's all good. Same for battery / ultracapacitor / other technologies -- if they're a good fit for the problem, someone will make money using them; if not, they won't).

Re:Still the same problem as with all solar

[Anonymous Coward]

The deep cycle lead acid batteries used for solar systems (L-16 type) generally last 5-10 years if properly matched to a load.

Re:Still the same problem as with all solar

[RightwingNutjob]

Which sort of makes my point for me. If the power source needs a diesel backup that's going to be used often enough (ie some/most of the winter?), then it's not it's not as viable a source of renewable energy as that same diesel running on synthetic fuel would be. Unfortunately, there is not (yet) a viable large scale production capacity for synthetic fuel. Equally unfortunate is that people and research funding bodies have this solar pathology tattooed on their brains.

Re:Still the same problem as with all solar

[Anonymous Coward]

It doesn't work at night when you need electricity to power your lights. Which is especially a problem in the long winter nights when you need to heat your home. Can we please finally put this solar-for-everyone nonsense to bed?

Solar concentrators heat a pile of molten sodium, sodium powers a generator, peaking in the day, but working 24/7. If the sun goes away for a week, the sodium might cool down too much to generate power, but then we have bigger problems to worry about. Are you serious that you've never heard of these type of solar installations despite numerous Slashdot articles about them? Now 'm not saying we should specialize on ANY one power source, but your arguments against solar are very uninformed.

Re:Still the same problem as with all solar

[Anonymous Coward]

There is. Flywheels seem to be going up in demand.

Re:Still the same problem as with all solar

[Dunbal]

Peak electricity demand is lunch-time and supper-time. Lunch-time is pretty much covered with solar, and depending where you live, a good chunk of supper-time is too. "Powering lights" is by no means the biggest use of energy, even if lights is all you see when you look outside at night-time. The biggest energy consumption comes from things used to make heat (cooking, hot water) and everything with a motor (cooking again, air conditioning, laundry). Your light bulbs (especially nowadays with LED's and compact fluorescents) don't actually use all that much electricity.

Re:Still the same problem as with all solar

[Anonymous Coward]

$1k of T-105 batteries (1.6kwhr) will easily satisfy all of my night time lighting, refrigerator and electronic needs. The problem comes with storing enough energy for the washing machine and dishwasher. This is easily alleviated with simple lifestyle changes. I'm already on a utility plan where I don't use certain high powered equipment at certain hours. The only real problem that I see is storing enough energy for night time AC use.

Batteries will have a 10+ year lifespan with care and proper maintenance.

Re:Still the same problem as with all solar

[cgenman]

We have an energy surplus at night, due to things like nuclear facilities that run at the same output no matter the demand. Really, we need to expand our power system to handle larger peak energy during the day, when everyone is running their air conditioners. Expanding into more nuclear is politically difficult. Gas and Coal are polluting. Solar would help us during the day, when power usage is highest.

So no, no one energy source can be our only generation point. But solar could definitely help when it is needed most.

Re:Still the same problem as with all solar

[physicsphairy]

The sound you are hearing is not a diesel generator, it is the background "melody" of your songs. You need to stop letting your grandchildren (whose existence I infer from your five-digit UID) upload the music which is on your mp3 player.

Re:Still the same problem as with all solar

[ShooterNeo]

Uhh, ever heard of compressed air and salt caverns? That method is cheap and allows storage of large amounts of energy.

Re:Still the same problem as with all solar

[Anonymous Coward]

Well, we can't base our assumptions on laptop batteries; house batteries would have much more forgiving constraints on energy density and weight. That means we can make different tradeoffs - accept more weight/volume in order to use materials that don't pack the power in as densely, but have better lifespans. And the systems you'd build for residential use wouldn't have to be the same as the ones that a large power plant would use, either. Batteries can work at a home level, pumping water uphill (reclaim the power with hydro generators) has been used before at a power plant level, and, in between, there's some kind of neat fluid battery that is used for some factories. One of the other posts under me suggests flywheels, too.

Solar lets you generate fairly arbitrary amounts of power fairly close to its destination, since the size of solar panels (or panels with collectors, like in the article) is also easy to scale. There's lots of unused roof space. And, even with minimal batteries, there are things you can still do with the peak sunlight hours, like doing most of your home heating/cooling work (heat or cool a lot of water, for example). Basically you can store that power thermally instead of electrically. And you don't use solar as one giant array in a desert for the entire nation; you use it decentralized, lowering the demand on the grid throughout.

Wind is available all along the coasts, which, for the US, happens to also be close to the majority of the population. Building a nation's supply of wind turbines in the heartland would be stupid, and has only really seriously been proposed by the guy who wanted to own it all. And, again, wind wouldn't be the sole power source. Though the sun doesn't always shine and the wind doesn't always bow, the combination is better than either one alone. And there's always something you can be doing with excess wind-generated (which will happen, sometimes) - desalinate some seawater. That's energy intensive, yet it's "free" whenever you have more windpower than you have demand, because you already built the turbines anyway...

Re:Still the same problem as with all solar

[SeaFox]

I wonder if a flywheel storage on the generator might be applicable for this. Wind up the speed during the day, feed off the energy stored as inertia for hours afterward.

Re:Still the same problem as with all solar

[Anonymous Coward]

Exactly. The whole concept that non-constant power generation isn't worthwhile is armchair engineer nonsense. It's a shame that somebody has to raise it every time there's a solar/wind thread on any tech blog.

Consider:
    * Already today there are energy-intensive operations that track when excess power is available.. for instance some large aluminum smelting operations scale back depending how much slack capacity is on the grid at any time (and are rewarded with cheaper electricity, which makes it profitable to do so)

        If hydrogen ever takes off as a transportation fuel this would be another example: when the sun is shining and you're getting lots of solar power you could ramp up production. Not sure if that's likely to happen for other reasons though: mainly that hydrogen likes to leak out of everything so is such a pain to work with.

    * The "smart grid" you always hear about is basically trying to expand this downwards. The classic example is charging an electric car (wind dies down, everybody's car starts charging a little slower) However, there are more mundane examples: for instance think of all the electricity your refrigerator uses. All you care about is that it remains in a temperature range (say 35F-38F) During a production glut you could direct everybody's fridge to run and get to the colder side of the range, then you've banked that energy

        There are other potential places to use something like that. For instance, imagine a large data center getting cheaper power in return for using 20% of their UPS capacity for load-elasticity. i.e. the whole facility could be supplies slightly more or less power than it needs at any given instant based on the available load. Some people have even suggested (although I don't know if anybody has yet implemented) systems where the actual CPUs working on large batch-processing tasks would scale their power usage based on the needs of the grid. When there's excess capacity it could be soaked up within milliseconds by making those tasks run faster.

    The whole idea that our electricity load is inelastic is outdated. We have the technology to solve that problem.

* In many places there is already flexible power-production available: the classic example is hydroelectric. By controlling how much water you let through, you can dial in exactly how much electricity you want to produce.. so if your solar/wind production is temporarily high, just let less water drain. Even better while the hydro production is completely off, you can pump water back into the reservoir and use the system as a huge, very efficient battery (some wind farms already do this)

It's true that we do need something to provide a base load for when the wind is still and the sun isn't shining. This can be hydro where it's available, fission elsewhere (along with a mix of other players like geothermal, tidal energy, etc) Still, with the right engineering solar/wind can easily provide a large piece of our electricity needs, no matter what the random slashdot "experts" say.

Re:Still the same problem as with all solar

[jmorris42]

> That means we can make different tradeoffs...

Blah, blah. Neither of us know enough to say but I am smart enough to observe what the people who DO know are doing. They are building peaking power plants and not batteries. They aren't building flywheels either. And yes I too read that long ago that somebody had hit on the idea to run pumps at night to push water back uphill so they could run the hydro plant during the day when demand was high. But I never read just how efficient that process was, just that it allowed them to meet the peak power demands without building another plant.

As for home solar, pointless. The only reason anybody is doing it is because a) they live in an area where the government provides a massive subsidy or b) are doing to prove to everyone how green they are or c) are part of a research project aimed at eventually making it practica or finally d) have no choice because their location is off the grid. At current PV prices you have no hope of competing with the grid.

> Wind is available all along the coasts, which, for the US, happens to also be close to the majority of the population.

Which is also close to the majority of the environmentalists, making those locations out of bounds unless we start shooting greens. And no we can't just outvote them, as they have a tendency to go terrorist if they don't get their way so we would end up shooting them. And if we can work up the will to shoot the enviros we can just skip a step and just drill for dead dinosaurs off those same coasts and stick the windmills on top of the rigs when the wells run dry.

Re:Still the same problem as with all solar

[proverbialcow]

(Is that process lossy? Sure! But the market will only reward it if it provides a net benefit or focuses supply to a few producers, so it's all good.

Fixed that for you. No need to even yield net benefit if you can choke supply. Ask OPEC.

Re:Still the same problem as with all solar

[Anonymous Coward]

Pumped storage is a very efficient way of storing energy. From memory, round trip efficiency is above 90%.

Also, line losses only become significant when you step down voltage for local distribution. Transmission losses are around 3%.

Re:Still the same problem as with all solar

[BlueStrat]

Which sort of makes my point for me. If the power source needs a diesel backup that's going to be used often enough (ie some/most of the winter?), then it's not it's not as viable a source of renewable energy as that same diesel running on synthetic fuel would be. Unfortunately, there is not (yet) a viable large scale production capacity for synthetic fuel. Equally unfortunate is that people and research funding bodies have this solar pathology tattooed on their brains.

I'm mostly in agreement. Another point that few people think about concerning alternate energy plans that incorporate the idea of localized, i.e. per-residence or facility generation as in rooftop solar cells, is how does one provide for emergency situations such as storms & earthquakes where many thousands may be without power.

No big utility company vehicles and manpower out to restore power. This will put the poor, old, and lower-income people at higher risk.

The recurring cost and initial then ongoing infrastructure development cost that the government would have to provide would be absolutely huge, probably exceeding those of the health care plan, and thus require the government to take even more money from the people in taxes and fees.

I'm all for alternate energy. It's silly for an intelligent species to put all their civilization's energy production technology-base eggs in one basket.

However, it's equally insane to force a move to non-viable sources or those simply not advanced enough at this point in our technological development to do the job in a more economically viable manner than the existing sources. It must do the job *much cheaper and in a much more practical manner* in order to make the cost incurred in any massive changeover not cause economic and infastructure/logistic disaster.

I just haven't seen anything up to this point that wins on all those points you made as well as those I've stated. It will come in it's time when it's cheap and practical enough to be a better solution than what we have now to most people without needing any government subsidies and/or mandates. Doing otherwise is to do great harm to the entire population both in terms of economics and in the standard of living even to include food costs.

I, and likely most other people, don't think our standard of living is too high. I'm sure you don't either.

Strat

Re:Still the same problem as with all solar

[Lennie]

That is why people keep saying we'll be using a mix of all these forms because some are going to be more expensive and others are not reliable enough.

Re:Still the same problem as with all solar

[Anonymous Coward]

But other things do. Just for starters, assume you cease all Hydro production during the day, and use it at night.

There are some other "battery" approaches that work on a large scale. A Hydro company we work with explained that they see 90% efficiency in their system when pumping below dam water back up into the reservoir when rates are low, and then generating from it again when rates are high.

See: http://en.wikipedia.org/wiki/Hydroelectricity#Pumped-storage

Now put that in the context of using excess daytime solar to pump the water back up into the reservoir.

Easier said for us in Canada. 60% of total usage is from Hydro vs. 6% in the US. But it a good start.

Re:Still the same problem as with all solar

[Anonymous Coward]

Hope you are not native at speaking the english?

Re:Still the same problem as with all solar

[rcw-home]

Look into the efficiency of a battery sometime. Unless you buy really expensive ones you lose about half of the energy putting it into and getting it back out.

I have looked into it. There aren't many numbers on the Internet - most of the stats on Wikipedia are single-sourced from sites such as powerstream.com, but coulometric efficiency generally varies by cell chemistry type. Lead acid is about 70%, NiCd is about 83%, NiMH is about 66%, Lithium-Ion is 80-90% (and there are some sources that say it's higher than that). For large-scale grid energy storage you might look into Sodium Sulfur, which is reported to have efficiencies of 89-92% and is inexpensive but requires operating temperatures of 300-350C to work. In any case, 50% is very very pessimistic.

I still think that the solar power tower molten salt vat approach to energy storage is the most practical storage option (where hydroelectric pumping isn't available, anyway) in the short term.

Re:Still the same problem as with all solar

[linuxpyro]

We currently have zero methods to store electricity that are cheap enough and effective enough for use on the grid. All electricity is generated as needed, with vast arrays of 'peaking power' generation capacity that largely sits idle. Believe me, if there were a good way to store electricity the industry would be using it already.

Pumped storage is already used quite a bit. It would be nice if it were more efficient, but utilities do make use of it for storing power at off-peak times where geography allows. Flywheels and other methods have come up; check out grid energy storage on Wikipedia. There are even some battery technologies that have been used.

Worse, while electricity can be sent large distances, it is best to generate close to the point of use because of the line losses. So even if we were willing (and shot enough enviromentalists) to cover our deserts with solar arrays we would lose most of the power heating the lines getting it to where the customers are. Same for wind, it mostly occurs in areas where there aren't many people... or more accurately windmills near populated areas attracts more environmentalists.

Generating electricity close to its point of use is a big strength for solar, at least for PV as you can put panels on roof space that would otherwise go unused. (It's difficult to do this with wind, of course, when it comes to cities or suburbs.) Regarding transmission, you're right that generating close to the load is best. However, the problem still exists everywhere in our power grid, and that's why high voltages are used (less current means less energy lost as heat).

Re:Still the same problem as with all solar

[lenski]

I work in an industry that works with power companies, allowing them to "shed" load essentially on command, and those commands tend to be issued during peak air-conditioning periods.

Sheds are usually scheduled to begin shortly after lunch and last until just before dinnertime, usually around 500PM. That's when businesses ordinarily reduce air-conditioning costs by allowing indoor temperatures to fluctuate naturally until morning.

I've been in this industry for several years and have never heard of lunch/dinner peaks.

Back to the topic of PV, though: Glossing over many important details, many of us in the emerging load-leveling industry believe PV might work pretty well where peak loads are caused by air-conditioning. FWIW, peak load is extremely expensive, so any technology that reduces the effects of peak load has a higher $/kW value than in typical usage.

Re:Still the same problem as with all solar

[Anonymous Coward]

Would flywheels be a better battery at the scale needed for the grid?

Re:Still the same problem as with all solar

[riverat1]

There is lots of available wind energy in the Upper Midwest, particularly the Dakota's. That's not along the coasts.

Re:Still the same problem as with all solar

[Anonymous Coward]

We currently have zero methods to store electricity that are cheap enough and effective enough for use on the grid. (...) Believe me, if there were a good way to store electricity the industry would be using it already.

There is currently no economical need to store electricity. It's much cheaper to keep some gas turbine plants and some fig-leaf pump-storage plants around to provide peak power when needed.
If there were one, there are many (expensive) means of energy storage. Magnetically levitating flywheels, superconductors, uprating dams, etc.

Re:Still the same problem as with all solar

[Anonymous Coward]

use the electricity to pump water up hills, then get it back with hydroelectric. OK, you'll loose via efficiency, but someone do the maths and work out if it's worth it.

Re:Still the same problem as with all solar

[TheTurtlesMoves]

And is very inefficient (25%). Compressed air is even worse. Figures as low as 10%. So you need 10x more solar or wind. Also you need a salt cavern somewhere around. It is not cheap by any stretch of the imagination.

Re:Still the same problem as with all solar

[TheTurtlesMoves]

Unfortunately none of these are cheap. They often have location requirements which means they can be a long way from where the power is produced. Finally, only a very small percentage of the total daily energy is stored. If you want to use solar/wind for everything, its a totally different scale of problem, and far from proven. How many reversible Hoover Dams can you build and where....etc

Re:Still the same problem as with all solar

[Anonymous Coward]

Maybe it means entrepreneurs buy excess electricity on the spot market during the daytime, use it to pump water uphill, and use the potential energy of that water to generate more expensive electricity at night.

They're already doing this here. Near my city, there is a hydro-electric / flood control dam on the Allegheny River. They are always generating power, but since they can't alter the output of the dam too much (need to keep it high enough for shipping, low enough not to flood cities) they can't change how much electricity they produce by very much. So they built a massive reservoir on top of the hill by the dam. When electricity demand is low, they pump water to this reservoir, and when the demand is higher, they open the gates and generate a massive amount of power. The storage reservoir is probably 1000 feet higher than the generating station, and the underground pipes running to it are big enough to drive a dump truck through. It's quite interesting. It's a viable solution, and they've been doing it since the 60's. I'm talking about the Kinzua Dam and the associated Seneca Pumped Storage Project. Google it, it's quite interesting. Also interesting is that now, almost 50 years later, the Native American tribe that was forcefully moved when the dam was constructed, want to take ownership of the hydro generating station. They want to sell all the power locally, at a much reduced rate. It will be interesting to see how this pans out.

Re:Still the same problem as with all solar

[Anonymous Coward]

More nuclear is not only "politically difficult" but also pollutes - radioactive waste that no one has a good solution for.

Re:Still the same problem as with all solar

[Anonymous Coward]

I don't remember where its being used but I've seen at least one example of the load balancing you're getting at. I saw a program a while ago where some facility (I think it was a school) was using off peak electricity & cooler temperatures at night to give a two fold increase in their Air conditioner power usage/cost. Basically at night the the AC would run, but instead of cooling the building it would cool several large, insulated sealed tubs of water into a slushy ice, then during the day it would pipe the refrigerant through the tubs of water as part of the heat exchange cycle. At the time of the program I think they were still figuring out how much the system was improving efficiency but it was looking very promising. While its a bit off track it reminds me of something I heard the Japanese were messing around with a few years ago. A home/business has a sizable buried concrete tank (for a small business it would be about the size of a truck) on site, during the winter snow would be shoveled into it until full, it would then be closed up. Then during the spring/summer the AC heat exchange line would be piped through it. Not sure how cost effective it turned out to be but an interesting idea to say the least, not only would it improve the AC efficiency but it if implemented on a larger scale it would decrease snow removal costs & decrease spring strain on drainage systems.

Re:Still the same problem as with all solar

[Anonymous Coward]

You forgot pumped storage, and Flywheel's. Both of which avoid the pitfalls of chemical storage.

http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

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

PS: There are a few company's making money from storing energy generated at night for daytime use. Until solar is a significant portion of the grid producing energy in the day time is worth more than the 24/7 average.

Re:Still the same problem as with all solar

[Anonymous Coward]

We currently have zero methods to store electricity that are cheap enough and effective enough for use on the grid.

WRONG
We have one, Hydro, reverse the flow during off peak and pump the water back up hill
Works extremely well and is used all over the world.

Re:Still the same problem as with all solar

[ShooterNeo]

Where are you getting your numbers. According to "Wind and solar power systems: design, analysis, and operation", reasonable efficiencies are about 50% for compressed air storage. It depends upon compressor efficiency, leakage, motor generator efficiency, and several other variables.

It costs about $1-$1.50 per wat-hourt your store this way today. Bigger systems built per often should lower that cost. A big solar system that produces 5 or 6 watt hours per day per watt of capacity would need to store a couple watts of that for the night. At $1/watt for the solar system itself, that would be $2 worth of storage.

These numbers don't seem completely unfeasible : they are within a factor of 2 or 3 of what you need to compete with coal generation today. Just put a tax on the coal power producers proportional to the ecological damage they are doing, and this solar method would probably prove workable quite soon.

Re:Still the same problem as with all solar

[linuxpyro]

The flywheel technology looks interesting, and in theory doesn't depend much on location. (Although safety is a concern.) The flow batteries are interesting too. Renewable energy or not grid energy storage is something that we do need to develop, if only to even out demand and provide some redundancy. Research on these will continue, and they will become more affordable.

Re:Still the same problem as with all solar

[TheTurtlesMoves]

Where the hell are you getting your numbers? Compressed air can't get close to that unless you can keep the heat of compression, which you can't if its bigger than a plastic toy. 50% *one* way may be feasible if you try hard. That is 25% both ways. Again you need to keep the heat of compression (ie a reversible thermodynamic process).

Oh and a factor of 2 or 3 is nothing...Look at your power bill and x3 and see how "good" that is. You also ignored the fact that you still need to find this cavern.

Re:Still the same problem as with all solar

[TheTurtlesMoves]

I have run some numbers on this. Yes it can work. But again it adds a factor of 2-3 to any wind/solar/wave etc energy system. Which is already still 3x more expensive that anything else (at least).

Re:Still the same problem as with all solar

[Anonymous Coward]

Wind power can work at night time, for instance.

Re:Still the same problem as with all solar

[ShooterNeo]

You make the caverns by drilling a hole into an underground salt pocket and sending down water to gradually mine out a huge cave by disolving the salt. Since you leave a many feet thick lining of salt all around the caverns are inherently hermetically sealed. Ironically, you use very similar equipment to that used in the petroleum industry.

Except that once you make one of these caverns, it lasts just about forever. Probably centuries for most of them. And so the only thing you have to fix in your system is damage from mechanical wear to the machinery, which can last for decades with occasional maintainence. There are enormous salt layers running for miles across entire states they can tap for this, and once the electric grid is finally nation wide it won't matter where we put the caverns. (a tie system is being built right now to make the electric grids interlinked)

As for the "heat of compression" nonsense : that heat is still in the compressed gas down in the huge cavern. Since the surface ara of the cavern is very small compared to the volume of gas inside, and you are only storing the gas a few hours, the gas will be hot when you let it out and use it. Current systems use the gas to increase the efficiency of a natural gas turbine generator.

Re:Still the same problem as with all solar

[TheTurtlesMoves]

You do realize that in most places there are *not* salt deposits lying around that are suitable and that transmission costs *do* matter. Current compressed air systems are loosing 50% or more of there heat of compression. However adiabatic compression efficiency is higher than i recall. Its more like 70%-80% one way at a fixed pressure ratio while expander tend to be a little less, more like 60-70%. So both ways in a ideal system, *if* you have a salt deposit lying around and you have a use for the millions of tons of salt water or don't mind it in your water table, is still about 50%. Heat losses come out of that and they are substantial, you can't arm wave it away. Current "adiabatic" systems that are planed (none have been built yet) store the heat is a separate heat sink. Isothermal compresses are small and have very bad efficiency.

Either way, its still expensive (100MW compressors+motor are not cheap) and adds significantly to the cost of a wind/solar instillation and there is little hope of scaling this up to city power storage levels (current systems are for peak load only and are no good for cloudy days or night capacity).

Lets assume some magical 100% efficient full cycle compressor/expander using air. Lets assume a smaller city that uses 100MW average per day. So that is 8.6 x 10^12 J. If we compress to a pressure of 10 atm (very high compared to current and planed systems), then we get about 5.6kJ per mol of gas of energy storage and the temperature will be about 300 C (293 more accurately). So 1.55x10^9 moles of gas (more 44 000 metric tons of air) is required and a chamber volume of 7.2x10^6 cubic meters (the volume of over 15 million tons of dry salt) . If the chamber is a average of 5 meters high (unlikely due to geological reasons) then you need a chamber area of over 1.4 million square meters .

This will store just *one* days worth of a smaller city and assumes perfect performance. In practice getting compresses and expander to have high efficiency across the full 10:1 pressure ratio is hard at this power level, and in fact has not been done, real efficiencies across the chamber pressure range is poor . Also keeping that air at 600C is not easy either, the rock will absorb heat and if wet can absorb a *lot* (1kg water evaporating is 2.2MJ of energy). Last but not least, there is a very real issue of repeated loading and unloading the chamber and the chambers geological stability--it is not a given, and can be a real concern to the locals who generally don't like earthquakes, or collapsing ground.

Can it be done? Yes. Its it cheap. No. Is it efficient, current systems, no. Future systems planed are better but still worse than fuel cells. This storage is a tax on unreliable energy source and all current methods are both not high in efficiency requiring 2x or more the generating capacity (expensive), and are expensive no matter how you slice it.

Re:Still the same problem as with all solar

[ShooterNeo]

Again, I'm not an expert on this. You should read a textbook on the subject before making ignorant objections. I mean, your objections "sound" good...you sound like you've taken at least sophmore or junior level physics courses...but you are missing the forest for the trees.

In the case of a salt cavern, heat conduction through rocks is extremely slow. Where do you think the heat in the gas goes? It's irrelevant how much heat the cavern walls can absorb : the only factor that matters over multiple cycles is how fast the heat can conduct away which is pretty slow (rock is a good insulator)

Much higher pressures are obviously possible - gas bags under the great lakes is another proposed method. I don't know what the peak pressures for salt caverns are.

When you do the mining, you make a mountain of salt somewhere by evaporating it and then moving the crystals with heavy equipment. You don't dump the water into the water table, duh.

There ARE listed costs, I just named them. $1000-$1500 per kilowatt hour stored. Yes that sounds expensive, but assuming you only need a buffer against wind fluctuations at night (the solar would be for peak load in the day), you might need only a kilowatt hour per a few thousand watts of system capacity.

And actually the real plants they use right now are hybrid : they store energy using compressed air but they use the compressed air in gas turbine generators. Those gas turbine generators can work even when you're out of compressed air, providing a valuable amount of peaking capacity.

So again, a hybrid system that is mostly or totally renewable is entirely doable. A bunch of wind farms all over the country for base load, with compressed air to smooth out fluctuations. Solar arrays for heavy power usage in the day (when electricty would be cheap). Natural gas generators that use the compressed air for assistance for peaking and times when both the wind and the sun aren't ideal across the entire country.

Why would we do this? Cost. Have you seen how expensive a nuclear plant is? Coal is a finite fuel and it causes significant pollution that has a negative cost on the population. And of course burning oil is out of the question.

okay, makes sense now, thanks

[OrangeTide]

I see. so 1MW system can deliver 1000 kWh every hour. At $0.11 running 24/7 it could theoretically bring in $964,000/year and basically pay for itself. Assuming everyone had to pay 11 cents (industry probably pays a lot less, these are just so numbers I made up).

Re:okay, makes sense now, thanks

[Anonymous Coward]

I see. so 1MW system can deliver 1000 kWh every hour. At $0.11 running 24/7 it could theoretically bring in $964,000/year and basically pay for itself. Assuming everyone had to pay 11 cents (industry probably pays a lot less, these are just so numbers I made up).

Stop being continuously wrong.

Industry doesn't pay "a lot less" - they pay comparable. Paying effectively 7-8c/kWh is not "a lot less", it is comparable considering they need their own power distribution and regulation (they get electricity at much higher voltage). They pay less because utility doesn't need to incur capital costs at point of delivery.

1MW system doesn't deliver 1000kWh every hour, it brings in 1000kWh when it is active, like you know, the sun shines? So even if you have 200 days / year at 8h/day, that gets you $176k/year revenue. Since these systems tend to last 30+ years, effective cost of generating this electricity is 2c/kWh produced, comparable to coal..

Electrical power plants tend to be priced at $/MW, not $/kWh. This is why target is $1/W, because that makes sense when you capitalize the expense as power plants tend to be capital projects.

Re:okay, makes sense now, thanks

[Dunbal]

You are forgetting:

1) Solar panels produce direct current, not alternating current. Direct current is almost impossible to transmit across any meaningful length of electric cable.

2) Converting DC to AC is possible, however there are efficiency losses and thermal losses - these come out of your "profit"

3) At some point you are going to need to replace your solar panels - they only last 15-25 years. You need to set money aside for this, unless you plan on shutting down your plant at the end of 15 years.

4) Energy companies do not buy electricity at the same price at which they sell it to you. Often there is a HUGE discrepancy. Ahh, monopolies.

5) The obvious one - the sun doesn't shine 8 hours a day so your 1MW system will probably deliver 300kW every hour on average.

6) To provide power at night you will need some means of storing energy. Batteries work, but they need maintenance and they do wear out over time. Less profit.

Oh - suddenly it's not so profitable anymore.

Re:okay, makes sense now, thanks

[Dunbal]

my bad - there is no edit button - point 5 should read: the sun doesn't shine 24 hours a day...

Re:okay, makes sense now, thanks

[vlm]

Direct current is almost impossible to transmit across any meaningful length of electric cable.

Humorously, you have it exactly wrong. The longer the cable, the (relatively) cheaper the cost of HVDC conversion gear vs the rest of the project.

The power delivered by a AC line is based on the RMS voltage. However you have to insulate to peak, which is somewhat more. Insulation is a pretty major design constraint, as arcs to the ground or towers is kind of a waste of power...

As a very rough guess on a medium length line you can push about 1/4 to 1/3 more power for the same cost if you switch to DC.

The power levels I'm talking about are a couple GWs, distances of dozens of miles, costs vaguely around gigadollars. Capital costs of about a buck a watt per 50 miles, lets say. You can see the motivation of placing plants nearby cities, rather than in the middle of nowhere.

You can do long distance AC, and they used to, it just costs a heck of a lot more.

Re:okay, makes sense now, thanks

[heathen_01]

I just assumed you were posting from the UK.

Re:okay, makes sense now, thanks

[Dunbal]

Hmm? I thought the whole reason we use AC (thanks to Edison winning the argument with Tesla) was because there is less loss over long distances when compared to DC. Edison wanted One Big Plant generating power, and Tesla wanted many small, local plants. I guess I will have to re-read this - I apologize, I'm a biologist not a physicist.

Re:okay, makes sense now, thanks

[Mike_EE_U_of_I]

You wrote "1) Solar panels produce direct current, not alternating current. Direct current is almost impossible to transmit across any meaningful length of electric cable."

    Solar panels typically will feed into an inverter which converts the power in AC. It is only at that point that power is transmitted any significant distance.

You wrote "3) At some point you are going to need to replace your solar panels - they only last 15-25 years."

    It's more like 25-100 years, but yeah, they don't last forever.

You wrote "4) Energy companies do not buy electricity at the same price at which they sell it to you. Often there is a HUGE discrepancy. Ahh, monopolies. "

    Yes, the $1/watt goal makes solar competitive at wholesale rates. Solar is already cheaper than retail rates in some places (sunny places with expensive power)

    You wrote "5) The obvious one - the sun doesn't shine 8 hours a day so your 1MW system will probably deliver 300kW every hour on average. "

    Yes, that's called capacity factor. Solar is generally worse than that (.15 to .25 depending on how much sun a place gets).

    You wrote "6) To provide power at night you will need some means of storing energy. Batteries work, but they need maintenance and they do wear out over time. Less profit."

    If you are getting a _huge_ chunk of your power from solar, that's true. In most places today, power demand is much higher when it is sunny that when it is not. We could probably produce 10-25% of our power from solar with not much storage. That's around 100 times as much solar as we have now. But, yes, you are right, this is a huge problem if we ever want to get a large percentage of our power from solar. It's already a huge problem for wind farms. The reason is that wind farms can produce at low demand periods, when no one needs the extra power.

    Bottom line is if solar can get to $1 for every installed watt, you will be seeing solar installed everywhere, as it will simply blow everything else away, even with these problems.

Re:okay, makes sense now, thanks

[francium de neobie]

That was the a century ago when people hadn't discovered how to step up and step down DC voltages. There're still problems with transmitting high voltage AC across long distances - many long distance runs are actually HVDC now.

Re:okay, makes sense now, thanks

[Dunbal]

100 years? May I see a source please? Everything I have read states 25 years TOPS. And that is for regular use. When you bombard them with 1000x more light I'm sure you don't improve their useful life, either. You can't cheat entropy that way. Not in this universe, anyway.

Bottom line is if solar can get to $1 for every installed watt, you will be seeing solar installed everywhere

I agree with that, and believe me, I WANT solar to reach that price. It seems like a great energy source (after all, the sun powers all life on this planet) and a great use of wasted real-estate on our roofs. However I still think the OP's calculations were way off. You can't just take the cost/Watt x 24h x current kWh energy price and call it "profit" or "savings". It's a lot more complicated than that.

Re:okay, makes sense now, thanks

[EvanED]

Everything I have read states 25 years TOPS

Depends on what you mean by "lasts"; they degrade gracefully, not fail suddenly. Wikipedia and other sources say that several manufacturers warranty their panels at 80% output at 25 years. I'd consider that lasting well past 25 years.

Re:okay, makes sense now, thanks

[HornWumpus]

Back in the original AC vs DC battle it was damn near impossible to raise DC voltages and damn difficult to lower them without wasting a large part.

With AC a simple power transformer could raise the voltage on the lines. In the old days AC had a massive transmission line voltage advantage. These days it has the RMS disadvantage.

Re:okay, makes sense now, thanks

[Lloyd_Bryant]

Hmm? I thought the whole reason we use AC (thanks to Edison winning the argument with Tesla) was because there is less loss over long distances when compared to DC. Edison wanted One Big Plant generating power, and Tesla wanted many small, local plants. I guess I will have to re-read this - I apologize, I'm a biologist not a physicist.

You mean the argument that Edison *lost* - he was the big proponent of DC, while Tesla and Westinghouse were behind AC.

Re:okay, makes sense now, thanks

[Mike_EE_U_of_I]

100 years? May I see a source please? Everything I have read states 25 years TOPS. And that is for regular use. When you bombard them with 1000x more light I'm sure you don't improve their useful life, either. You can't cheat entropy that way. Not in this universe, anyway.

    You've got that flipped, most panels have a warranty of 25-30 years. That's the minimum life, not maximum. Just look at this wikipedia page and search for the section "lifespan". http://en.wikipedia.org/wiki/Solar_cell#cite_note-34

    As far as maximum, since panels haven't been around for 100 years, it's really anybody's guess as to how long they will last. This page mentions some of the prevailing views. Again, search for longevity http://www.solar-facts-and-advice.com/monocrystalline.html.

    The few data points I've seen on very old panels are extremely interesting. I personally know of some Solarworld panels that are over 35 years old that still are producing at over 100% of original rated spec. I've also read about a non-trivial size array that only had 10% decay on monocrystalline panels after 25 years. (can't find the link on that one, sorry) At that rate, you would still be getting 65% of original production at the 100 year mark.

    Yes, you are right, we can't cheap entropy. But entropy can be very slow.

Re:okay, makes sense now, thanks

[DarkOx]

Wow, umm no.\\

Go back and check your history. Edison LOST that argument with Tesla. Tesla wanted AC because it was better for running motors and was more efficient for long distance transmission. Edision wanted DC because its arguably safer.

Re:okay, makes sense now, thanks

[tylernt]

Tesla wanted AC because it ... was more efficient for long distance transmission.

With the technology of the time, sure. Modern semiconductors have made high voltage DC-DC conversion pretty darn efficient though:

"For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses" -- http://en.wikipedia.org/wiki/Hvdc

better for running motors

Also, brushless DC motors have also made AC pointless (to an extent).

Re:okay, makes sense now, thanks

[linuxpyro]

Edision wanted DC because its arguably safer.

Edison wanted DC because it was what he had started working with, and he wanted to keep using it.

The ironic thing though is that high voltage DC is actually kind of dangerous to work with, more so than similar AC voltages. This is because of the way inductance and capacitances behave as the frequency increases. As the frequency increases a capacitance starts to look more like a short, while an inductance starts to look more like an open. At DC (IE, at 0 Hz), it is the opposite. In DC, an inductance will resist changes in current. This makes it harder to build DC overcurrent protection devices, as in the event of a short the inductance inherent in the wiring can cause a voltage spike which can maintain an arc. In alternating current the zero crossing (every 8.3 ms at 60 Hz) inhibits this. Lack of a zero crossing can also make it harder to "let go" if you come in contact with a live wire.

  At transmission-type voltages, though, like what you'd use to get power across the country it's kind of a moot point as you don't really want to get between either of them and ground.

Re:okay, makes sense now, thanks

[Anonymous Coward]

The power delivered by a AC line is based on the RMS voltage.

What has Stallman to do with this???

Re:okay, makes sense now, thanks

[Blue_Wombat]

Your point (1) is plain wrong. DC can be transmitted over very long lengths of cable. High voltage DC links are often preferred for very long transmision distances. In many countries (thr Benmore -->Haywards link in New Zealand springs to mind) there are HDVC link many hundreds of miles long. They are actually more efficiant than AC for that type of transmission.

Your point (4) is a bit whacky as well. Not many business sell their product at exactly the same price that they buy it - they need a margin to pay for silly little incidentals like their infrastructure and staff wages, as well as making a profit.

Your point (6) is *almost* accurate. They need diverse supplies, not just one type. If they have, say, hydro, then they can use solar and wind when the sun shines and wind blows, and hold back the water to deal with peaks and periods when it's dark and the wind isn't blowing. It lets them eke out scarce hydro very economically - or they could use a thermal plant for the same thing. I recall that in Norway they were actually using a lake as a "battery" - using surplus power to pump water back up a hill into hydro storage, which could then be run back through the turbines when they needed extra.

Re:okay, makes sense now, thanks

[necro81]

Another key thing that was in AC's favor was that every piece of electrical generating equipment of the day produced AC, and rectifiers of the time were not very good.

Re:okay, makes sense now, thanks

[Muad'Dave]

For an example of efficient long-distance DC transmission, read about the Pacific DC Intertie. I was lucky enough to tour the Oregon end of this thing before 9/11, and it was truly amazing. The HVDC equipment looked like stuff straight out of sci-fi - inexplicable nodules and bumps, strange angles, etc.

Re:okay, makes sense now, thanks

[Anonymous Coward]

You can do long distance AC, and they used to, it just costs a heck of a lot more.

... Um, no. The cost of transporting AC over long distances is less because you can transform AC to High Voltage (which for a given amount of power means low current). Since resistive heating is proportional to current, high voltage lines are much better for long distance transportation.

Until recently there was no way to really transform DC, so you couldn't use high voltage transport lines. now however, there is talk about using, (in some cases) superconductive wires where resistance is non-existent and thus DC would be fine. However sine most superconductors only work at ultra low temperature (think less than 100K) maintaining a wire at that temp is expensive. As such the only place I have heard of using these kind of wires for massive power transport is to link the three main AC lines in the US. Sadly I can't find a link for that.

If a room temperature superconductor ever presents itself in a form that is maliable enough for wires (hundreds of miles long). Then we may see a push to use DC over 3-phase AC, until then, probably not.

But what do I know, I am only an electrical engineer.

Re:okay, makes sense now, thanks

[Anonymous Coward]

Good thing you are a Biologist not a historian
Edison wanted DC, Tesla wanted AC
Tesla won (despite enormous political presure from the mighty Edison corp) because AC makes it easy to change voltages.
DC is better for extremely long runs (500+ miles)
Anything less, AC is vastly better

The main use for DC feeds is moving power from remote hydro plants to cities

Re:okay, makes sense now, thanks

[Anonymous Coward]

Welcome to the age of the transistor. AC was easier to up-convert to high voltages before the transistor, and the up-conversion is essential to efficient transmission, to limit I-squared losses. (OK, there were utility-scale choppers on the scene at one point, and I don't know the economics of those. They appear to have been an interim solution.)

Nowadays, transformers are much less efficient than semiconductor-based DC-DC converters, and radiative losses in AC transmission over long distances dominate conversion losses. (According to http://en.wikipedia.org/wiki/High-voltage_direct_current, transformers/AC are typically still cheaper for short runs, though.) Plus there's the issue another poster raised with power-efficiency of insulation.

So, there's a sense in which you're right: AC made for cheaper distribution at the time. But it wasn't because it was AC.

The AC/DC battle in the early days, in the US, was pretty complicated. Politics, marketing, and pure ego played a huge role as well as technical issues.

Re:okay, makes sense now, thanks

[TheTurtlesMoves]

A 1 GW transformer is still much cheaper than 1 GW of DCtoDC conversion. AC still has an advantage.

Decepticons....

[kikito]

... ATTACK!

... And when we get the energy ...

... GET DRUNK!

CPV Isn't New

[Anonymous Coward]

"Instead of using expensive PV cells, the solar telescope uses commercially available triple-junction solar cells, which have three junctions that each capture energy from different wavelengths of light."
Tripple-junction cells are the expensive type, which is one of the reasons they're pretty much always used with concentrators (except on satellites). These guys, for example, have been doing this commercially for years.

Our response is obvious

[Anonymous Coward]

We must subsidize fossil fuels even more

This guy is an astronomer

[Animats]

Roger Angel is an astronomer. He's done good work on telescope design. Hence the fascination with mirrors.

There have been many elaborate schemes for solar power using collecting optics. The mirrors and supporting machinery usually end up costing more than you save by having less silicon area. Flat solar panels are simple to install, can be made resistant to high winds, and require minimal maintenance.

Re:This guy is an astronomer

[the_povinator]

Yes, when I saw the picture of their device I was concerned about winds. They make a big deal about the fact that it's made of out lightweight alloys. But the forces due to wind would be much greater than the gravitational forces, and the structure doens't look as if it is built in a way that you could collapse it somehow if a storm is expected.

Clouds

[Arlet]

Solar concentrators have a disadvantage that they only work on clear days. On cloudy days, the light won't concentrate, and they're useless. Still useful in some areas with lots of direct sunshine, but not where I live, for instance.

strange brew that's also good for you

[Anonymous Coward]

that would be home made kombucha(org). it's alive.

Maintenance is Good?

[simonbp]

The article seems imply that the fact that it requires so much maintenance is good because it's all local. But no matter where the maintenance jobs are, they cost money, and thus make it uncompetitive...

This group will get broken up soon...

[Anonymous Coward]

Otherwise that would throw a monkey wrench into the globalist plans of artificially raising the price of oil to $200/bbl, opening up the Baken, Stansberry, and Gull Island reserves (where we have a few centuries worth of oil at the current consumption rate), and yet still maintaining the high price.

Re: the clean West

[presidenteloco]

"We in the West are pretty clean for the most part - it's getting India, China and other developing countries to clean up..."

What the hell are you smoking? Or more aptly, what planet are you living on?

A person living in China is responsible for 17% as much greenhouse-gas emissions as is a person living in the United States.
A person living in India is responsible for 8% as much greenhouse-gas emissions as a person living in the United States.

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

and that's not even accounting for the fact that much of the most polluting parts of the Chinese and Indian economies are devoted to supplying the West with goods.

Thanks Big brother

[Anonymous Coward]

I like how my comments about the Baken, Stansberry, and Gull Island oil reserves were deleted. There was no vulgarity, slander, racism or anything else legitimately worthy of modding my post, but you did anyway. Congrats Big Brother.

Re:Thanks Big brother

[n6kuy]

You mean, this comment?

Take off your tin-foil hat. Slashdot NEVER deletes anything.

Pumped hydro is common.

[HornWumpus]

You pump water up hill at night, then use it for power during the day.

Yes fish blend.

Re:Pumped hydro is common.

[TheTurtlesMoves]

It is very inefficient (25%) so you now need 4x the capacity. Also you need somewhere to put the 5000+ hectare lake. Its not as easy as it sounds when you really run the numbers. Think Hoover dam running backwards, plus the issue that its not where you are generating the power...

Re:Pumped hydro is common.

[FirstOne]

";It is very inefficient (25%) so you now need 4x the capacity";

Obviously you're not an engineer,

"By 1933 reversible pump-turbines with motor-generators were available. Adjustable speed machines are now being used to improve efficiency. Pumped hydro is available at almost any scale with discharge times ranging from several hours to a few days. Their efficiency is in the 70% to 85% range. "

Now, one must ask... why would a person make such a wild claim??

table of large pumped hydro facilities around the world..

Re:Pumped hydro is common.

[TheTurtlesMoves]

Didn't notice the reply. It was a IIRC figure. And are a little check of my fluid dynamics reference, it was totally wrong. So the reason i made the claim was a honestly bad mistake.

However there is still the issue of where to put the lake and its environmental consequences. Even the 3Billion dollar facility are not that large (8 hours max output 1.6GW). They are not an economic solution to power when the wind does not blow or sun does not shine. Not unless you want to pay many times more that what you pay now. And it still push the price of wind and solar up several fold at least.

Projection effect

[tepples]

The sun shines on the planet on average 12 hours per day regardless of where you are.

But in the early morning and evening, the sun is shining at an angle that isn't directly on your panel. Take the angle between the vector to the sun and the panel's surface normal, integrate its cosine over a day, and see the effective insolation time drop from 12 hours to roughly 8.

you have to average over a year

Good luck with that until the next breakthrough in battery technology.

Re:Projection effect

[dwywit]

And in practical terms, you only base calculations for input on 4-5 hours/day - roughly 9:30am to 2:30pm, because power levels from the panels are relatively low outside those hours. Unless of course, you're using a fancy motorised rig to make the panels follow the sun across the sky during the day, and they consume almost as much energy as they produce - every solar installer I've spoken to said the same thing - take the money you want to spend on the motorised rig, and spend it on a couple of extra PV panels.

Come to think of it, why not use a bimetallic strip to move the panels? Have it set up to face east when the strip is cold, and as it heats up and starts to bend, use it to push the face of the panels to follow the sun.

Provisioned power capacity

[tepples]

Is that how you bill your customers too?

Electric power bills tend to have at least two line items. One is for actual used energy in $/kWh. The other is a monthly service fee, which for larger customers may include provisioned power capacity in $/W/mo.

Re: the clean West

[c6gunner]

What the hell are you smoking? Or more aptly, what planet are you living on?

I think it's more a question of what he's NOT smoking. Only hippies and potheads would look at GHG output as a measurement of how "clean" a country is. Not to mention the foolishness of comparing per-capita emissions between two nations of such wildly different industrial capability. It's like claiming that the homeless guy who keeps shitting in the middle of the street is more "clean" than me because he doesn't have a car.

AC, DC, transmission efficiency

[Beryllium Sphere(tm)]

It is high voltage that is more efficient for long distance transmission. The difference between AC and DC for that is that AC is relatively simple to step up in voltage with a relatively simple machine, a transformer.

Not so simple

[Iamthecheese]

It would have to cost 1 dollar per watt over the entire life of the device including manufacture, installation, and disposal.

TFA gets it wrong, twice

[GPS Pilot]

Instead of using expensive PV cells, the solar telescope uses commercially available triple-junction solar cells

In fact, triple-junction cells are far more expensive than garden-variety PV cells. The cost savings come from the fact that sunlight is concentrated onto a much smaller area of cells. And this is hardly the first company that has applied that idea; for example, see Energy Innovations, Inc.

Roger Angel has designed a new type of solar concentrator that uses half the area of solar (PV) cells used by other optical devices and delivers a light output/concentration that is over 1000 times more concentrated before it even hits the cells.

If the light is concentrated over 1000 times, wouldn't the the device require less than 1/1000 the area of solar cells, relative to a solar panel that lacked a concentrator?

Per capita is so bull shit

[Shivetya]

Sorry, but of course their numbers look good. Take away all their outer areas and the populations who basically are barely powered by anything and you get more reasonable. Look at their air quality in their major cities. Check their rivers and the like.

Per capita and they are broke too, but I don't think its a fair number to evaluate the earning power of those with modern jobs.

ever hear of siesmic events?

[Anonymous Coward]

I'm sure compressed air and salt caverens have been studied as least as much as fracking...
Aren't they both perfectly safe? ;^(

^^ To every comment above ^^

[Anonymous Coward]

^^ To every comment above ^^ . Is it me or has stupidity reached the next level. FFS its like people graduated retard school and have stopped thinking altogether....

solex agitator

[Anonymous Coward]

Wait, doesn't this technology create the potential for a world wide monopoly on solar power? Middle east countries would pay millions to keep this off the market. Maybe we should send in somone to protect the inventors. Look boss, da Sun!, da Sun!

Re: the clean West

[DNS-and-BIND]

Way to totally miss the point. In the West people raise holy hell for a new power plant of ANY kind. In China, they're building new coal plants as fast as they can make them.

First question on parity should always be...

[Eclipse-now]

Does that include $20 thousand dollars per household for batteries to charge up for this mysterious no-sun event we call the 'night'? Sorry folks, nothing to see here, move along, move along. Gen3 and Gen4 nukes are the only way to go until TRUE 'super-batteries' that are 'super-cheap' can actually deal with renewable's main problem, intermittency.

Re:First question on parity should always be...

[Anonymous Coward]

If your objective is to completely power something (House, Work, Factory, etc) with PV your right. However if your objective is to supplement current power generation this tech could be pretty useful. If my understanding of the power grid is correct you have a few very large "base load" plants which provide power 24/7, these plants cost the least to run but are the most expensive and difficult to build, these plants are ALWAYS on. Then you have a bunch of "peak load" plants that cost quite a bit more to run, but are cheap & easy to build, they are turned on as necessary when power usage exceeds the "base load" plants capacity. If this solar concentrator tech lives up to its hype this tech could decrease the need for the "peak load" plants, as current power consumption I believe shows, Peak Load plants are started up at right about the same time as PV would be producing.

Re: the clean West

[presidenteloco]

Only an ignoramus would think that "clean" is the most important environmental indicator.

I think you would get pretty good agreement among scientists that In rough order of long-term importance,
some environmental problems we are causing now are:
1. Removal of natural eco-systems and biodiversity.
2. Global warming (and its secondary effects like ocean acidification)
3. Overuse of fresh-water resources
4. Pollution of water resources and ocean life with toxins
5. Toxic waste deposits on land
6. Heavy metal and P.O.P. air pollution
7. Fossil-fuel particulate air pollution
 

Not a Scam

[DanielRavenNest]

The developer of this system, Roger Angel, is also in charge of the "Mirror Lab" at the University of Arizona, where they have produced many of the world's largest telescope mirrors. In other words, a respectable technologist, and not a scammer. Here is the company he set up to commercialize the research:

http://www.rehnu.com/

Umm

[ThatsNotPudding]

Edision wanted DC because its arguably safer.

Pretty sure Edison wanted DC because he had arguably more patents.

Re: the clean West

[c6gunner]

Only an ignoramus would think that "clean" is the most important environmental indicator.

Only a twit would ignore the context of the discussion.

Re: the clean West

[werepants]

It's like claiming that the homeless guy who keeps shitting in the middle of the street is more "clean" than me because he doesn't have a car.

By just about any metric besides "which one looks grosser" that homeless guy is almost certainly cleaner than you. You drive a car that introduces pollutants of various kinds into the environment, and which involves all sorts of dirty processes to extract fuel for, not to mention the initial construction. Your home is mostly likely powered in part by coal, which introduces plenty of nasty stuff including radioactive ash into our atmosphere. Each year, you probably produce a mountain of trash that would dwarf that homeless guy's little steaming pile, and when you take a dump, your convenient indoor plumbing dirties up a gallon+ of water that is more drinkable than that in much of the world.

Just because you don't see it festering in the middle of the street doesn't mean you aren't shitting all over the place yourself.

Re: the clean West

[c6gunner]

Now, the only question is, did you completely miss the point due to a legitimate problem, or are you just intentionally ignoring it?

Re: the clean West

[Lunzo]

China isn't clean; pick your pollutant there's plenty of it being dumped into the environment. And Greenhouse gas is one type of pollution (not the only one but its all the media goes on about these days).

http://www.chinahush.com/2009/10/21/amazing-pictures-pollution-in-china/