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New Solar Cell Harvests Hydrogen From Water
Engadgets is reporting that researchers at Penn State have built a new kind of solar cell that can harvest hydrogen directly from water. "The folks at Penn State have now developed a process that more closely mimics the photosynthesis process in plants, and while we won't pretend to understand all the nitty gritty of dye usage and other such nonsense, we do know that such a system could eventually attain 15% or so efficiency, providing a nice and clean way to gather power for that fuel cell car of the future."
The summary = the article.
The original article was on Science Daily a few days back.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
I thought that current solar cells have efficiencies of up to 40%. So how is this better?
Step 4 is "put it outside in sunlight" I think the point is that they have bypassed using electrolysis, instead using the sunlight to stimlate a dye and catylist that splits the water directly. If so, it would be much more efficient than using a solar cell and electrolysis.
GE/CS/IT d- s: a- C++++$ UL+++ P-- L++++ E W+++$ N+ o? K- w---() !O M- V- PS+ PE(++) Y+ PGP+++(+) t+++ !5 X++> R- t
First they want to make energy from our food. Now they are making it out of our drink. What's next... Soylent Oil?
But it really bugs me when someplace says "Hey look at this cool thing we figured out how to do!" And then just doesn't tell you how it's done. And they post this info on places where there's a reasonable percent of people who would actually want to know these things. And try to treat them like the rest of the people that just want stuff to work.
Sigs are too short to say anything truly profound so read the above post instead.
Isn't "could eventually" one of those warning phrases that tells you something is dubious, like "up to twice as long" or "she has a great personality" or "you're violating our patents but we don't want to tell you which ones"?
I'm an American. I love this country and the freedoms that we used to have.
Worse than electrolysis of hydrogen by electricity from a nuclear power plant. (25-45%)
And then begins the energy intensive liquification stage. Having those carbon atoms attached to your hydrogen is just a huge advantage.
Who cares if the efficiency is 10% and you have to cover your whole house in the stuff?
Engineering is the art of compromise.
15% efficiency would actually be pretty good considering by some calculations photosynthesis efficiency is around 5 to 20%.
:( )
Here is one calculation showing ~6.6% photosynthesis efficiency
It takes into account things like canopy shading, which wouldn't necessarily apply to this, but here's the link:
http://www.upei.ca/~physics/p261/Content/Sources_Conversion/Photo-_synthesis/photo-_synthesis.htm
I tried to find a peer reviewed one, but can't find one right now(I'm at work, break almost over...
Accentuate the positive, don't waste your mod points on the negative.
Not necessarily. If this new technology could eventually reach 15% efficiency, then it's still nothing particularly wonderful when you take into account the fact that some firms like Boeing Spectrolabs boast solar cells with efficiencies as high as 40% (they do use "solar concentrators", so it's possible that their panels may take up several square meters of surface area for every square meter of panel surface. Not having seen their designs, I wouldn't know).
Take a 40%-efficient solar cell and use it to feed power to a 50%-efficient electrolyzer, and you get a net total efficiency of 20%, which is better than the maximum estimated efficiency of this dye-based approach.
If they dye approach proves to be cheaper or can also be enhanced by solar concentrators or what have you, then it may have some value from an economic perspective, but I don't see anything 15% efficient providing dense solar power solutions compared to other technologies already available.
The other thing to keep in mind is that the output from this dye is hydrogen, not electricity. If you need electricity from one of these dye-based hydrogen generators, you'll need to marry it with a fuel cell or something long those lines which will further degrade efficiency. In terms of raw electrical output-per-square meter of deployed solar collectors, you'd be better off with conventional solar cells in the 15-20% efficiency range.
Efficiency is not so important in this application because of the useage of your typical car. A car typically sits around for 75% of the day doing nothing. This whole time this process could be converting water into hydrogen.
The only time it would not work is during long highway trips. During these times some kind of accelerated process or hydrogen filling station would be needed.
Duct Tape* I used to think it was duck tape too. But then I got arrested by the RSPCB and put through their re-education program, kinda like in that Clockwork Orange thingy.
which is totally what she said
Of course we also need to get engines that run on hydrogen that are also safe and efficient, but this is a step at any rate.
If you own a four stroke, spark ignited, internal combustion engine, you have one now. The conversion to run on hydrogen gas instead of liquid gasoline is quite trivial.
What is this Engadgets? I've been to Engadget before, but I've never heard of Engadgets. (follows link)
Oh, looks like another round of we-don't-need-to-fact-check-much-less-spell-check-around-here.
"We shall grapple with the ineffable, and see if we may not eff it after all." - Douglas Adams
Depends on how efficient the solar cell is. Since 15% effciency is the maximum projected for this photolysis process and solar cells are already up to 40% efficient, I'd put my money of regular solar cells + electrolysis in the long run. That is, assuming you would ever bother with hydrogen production at all. Hydrogen just isn't valuable enough to waste any resource (sunlight or electricity) to make it. Electricity is far more valuable per joule. Generally you want to be making electricity from chemical fuels... not the other way around!
The only situations I can imagine where making hydrogen might make sense is where you can't otherwise make electricity. Say, for example, from the waste heat of a nuclear power plant.
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
So they don't even pretend to understand how it works, but they know it can eventually attain 15% or so efficiency.
That relies on the tech that the cells are driving playing nice. Look around at the tech we have - playing nice isn't something that many engineers do. Many go for the cheap option, or the convienient option, not the one that serves the greater good.
It's more likely that the exhaust from these systems would be released into the atmosphere and effectively lost from the system.
Even if you do filter most of it back in, you still have to increase the capacity of your sewage/treatment plants and your pipelines (may not be possible in many existing cities) to match. There are huge costs and service disruptions inherent in that that many countries will not be able to afford.
And you still have the problem that a failure of any kind in the water system (drought, a burst main or dam, geological activity) would have a nice new force multiplier to play with.
Key infastructure should be independant as far as possible. Slaving one to the other like this can't be a good idea...
Parent is first one to point out storage benefit... someone with points should mod up.
This is the biggest problem with solar/wind power, the power generated often needs to be supplemented with conventional generation technologies to ensure constant energy supply. Production of stored energy source like hydrogen solves this issue.
Well, personally I don't care how we get H2. It's all pointless anyways. H2 will never be a common fuel for motor vehicles.
Here's why:
In regards to using liquid H2 in vehicles:
- It's too dangerous. You're driving a bomb. Every car using liquid H2 is a has-mat vehicle by legal definition. Imagine the terrorists glee where they don't have to rent a car and then build a bomb because the rental car IS a bomb.
- it must be trucked in liquid form - can't be pipelined, and therefore we'll have to deal with massive supply issues, thouands more has-mat trucks on the roads, and reduculous logistics.
- fuleing requires extensive safety measures and extremely specialized and expensive equipment
- you either have MASSIVE pressurized tanks (taking a very large portion of your vehicle space and weight) or you have to have the H2 actively cooled to extremely cold termurateres, requiring the car to be powered 100% of the time.
For metal infused H2 gas vehicles:
- well, it's much safer... but:
- maximum range uning even theoretical technologies is about 220 miles per fill up, assuming you leave enough seating room in a large SUV for 5 people and no luggage.
- the tank is huge, and weighs hundreds of pounds, eating at vehicle efficiency and space (too big for those small commuter cars in Europe)
- IT TAKES UP TO 8 HOURS TO FILL UP, and requires active cooling to prevent explosions while doing it.
H2 in general:
- it's dangerous to use a vapor gas as a fuel. Imagine auto shops all over the country having to worry about gas being spilled during repairs? Spill hydrocarbon, just avoid dropping a spark in the liquid until you soak it up with sawdust. Cause an H2 leak and you have to evacuate the building, no different than a natural gas or propane leak. Also, if liquid H2 leaks, you not only have to worry about combustion, but vapor expansion and extreme freeze issues.
- It costs 3-5 times more energy to make it that it would to simply run the car on electricity
- It's expensive. best estimates, you go the same distance on H2 for 2-4 times the cost of gasoline, and that's with all the current government funding lowering the costs.
- Where do you plan to store all the H2? Large scale containers are very difficult to make assuming you're storing it in liuquid form. We simply don't have enough room to store it in gaseous form.
- Fuel cells don't get repaired, they get replaced. The repair costs will be immense, collision insurance even worse (not to mention the danger issues insuring rolling bombs).
- burning H2 directly in ICEs is barely more efficient than burning ethanol.
- minimum car price. You can forget about those $7,000 cars. Minimum price for a fuel cell vehicle will be in the 20K range once the government subsidies stop becoming affodable.
no, we can't power every vehicle on earth on ethanol
yes, we will run out of oil, sooner than you like to admit
yes, we havre to do something, but what?
What is the answer? Super conducting electrical grids (which we can make today with existing technology at reasonable costs), fed by renewable energy in target locations around the world (wind farms where it's windy, water where there's natural falls, solar in the deserts, etc). We use all that to recharge plug-in cars using batteries from Toshiba and others companies that have already been developed which have as quick as 90 second recharge times. For those of you who say we can't do it, that we can't run recharge units all around towns for people to plug into on the run, well look at how Alaska has done it, and many other countries in the fridgid north of Europe, where cars that don't have engines running need to be plugged so their heaters can prevent fuel lines from freezing. Every parking meeter in some coutries have power cables attached. We CAN do it. It's been done before. We'll still use ethanol as a backup to the battery using ethanol in ICEs until small turbines (like BMW uses in their motercycle) become more cost effective through mass production.
There is no contest in life for which the unprepared have the advantage.
Sadly, hydrogen cars are basically a scam brought about by oil companies to distract attention and funding away from gasoline alternatives that are actually realistic.
I don't believe oil companies would fund with that in mind because it seems terribly counter productive.
If an oil company were to fund an alternate non-fossil fuel, don't you think they would want to back the one that already matches their existing infrastructure? If hydrogen became the next big thing, they'd have an awful lot of new equipment to buy. And a lot of old stuff to tear up first.
Remember, oil companies aren't in the oil business - they're in the energy business. It's just that currently the easiest way to get energy to the customer is through oil. They'd happily switch to anything else just so long as it made them a buck.
Weaselmancer
rediculous.
http://www.physorg.com/news95605211.html dives into how plants achieve almost 100% efficiency.
The only situations I can imagine where making hydrogen might make sense is where you can't otherwise make electricity. Say, for example, from the waste heat of a nuclear power plant.
Yup, and even there, the best way to use it is in fuel cells on site, not transporting it for use in cars.
Not a typewriter
The US per capita continuous total energy consumption averages out to about 10.5kW thermal (100e18 J annual national total/300M people). With hydrogen combustion at 286kJ/mol, it would take 62 liters of water per day per person to provide hydrogen for *all* the energy currently used in the US. Residential water consumption is already around 400 liters per person per day, industrial usage is more than that, and agricultural usage is many thousands of liters per day per person. IOW, this won't be a significant increase in overall water use. If it really got to be a problem, just set it up by the ocean and use some extra solar energy to run desalinization plants.
Fuel cells is not what will drive demand for hydrogen. Instead CO2 neutral ways to produce ammonia, which is used to create fertilizer and a huge variety of compounds used to produce pharmaceuticals will be driving alternative means of generating hydrogen. As prices of natural gas rise producing fertilizer and drugs will get increasingly more expensive, and that will hit the poor of the world very hard unless alternative hydrogen sources are found. It is a particularly interesting application of wind power and solar since their intermittent nature is much less of a problem than it would be for electricity generation. The main question is if it can be economically competitive with thermochemical hydrogen production from nuclear reactors. Of course, there is no reason ( except cost ) why you can't use both, and chances are we will have to if we are to meet demand.
Let's take your average car. Not being picky, I'll surf over to Carmax and choose whatever pops-up first
- Engine: 2.4L 166-hp (~575kW) inline-4
- Outside dimensions: 172" x 72" (4.4m x 1.8m)
So you've got 7.92 sq.m. of available roof area. I'll assume you can cover that 100% with your solar converter, and I'll further assume you can keep it pointed normal to the incident light. Typical insolation is 1000W/m^2, so your roof-mounted collector can harvest 7.92kW. Period (i.e. you don't get more energy than what is incident on the vehicle's cross-section.) You're collecting solar energy, and storing it in the potential reactive energy between hydrogen and oxygen. With a 15% efficiency, your converter stores 1.188kW while it's illuminated.
Getting back to our example Honda Element - 575kW engine
And therein lies the fundamental limitation. There isn't enough energy intercepted in a vehicle's cross section to make this structure viable. At 100% conversion efficiency, you just start to be able to power the econobox-class vehicles for around-town drives. Anything with distance or power requirements will need to be fueled by something much larger than the vehicle itself.
Okay, then let's put sails on it - LOL
Seriously, what type of converter is needed for the hydrogen pullout in this theoretical vehicle?
Beer is proof that God loves us and wants us to be happy.
Oh no! When the "singularity" of computer intelligence is reached, the machines are going to take over the world and then they will process all the water on earth into energy using solar panels. What use do machines have with all the water? Then answer is none. Maybe THAT is what happened to mars?
-- Betting on the survival of the media industry is a serious risk. I advise investing elsewhere.
31.25 percent efficiency rate topples 1984 record ALBUQUERQUE, N.M. --On a perfect New Mexico winter day -- with the sky almost 10 percent brighter than usual -- Sandia National Laboratories and Stirling Energy Systems (SES) set a new solar-to-grid system conversion efficiency record by achieving a 31.25 percent net efficiency rate. The old 1984 record of 29.4 percent was toppled Jan. 31 on SES's "Serial #3" solar dish Stirling system at Sandia's National Solar Thermal Test Facility.
Each dish unit consists of 82 mirrors formed in a dish shape to focus the light to an intense beam.
The solar dish generates electricity by focusing the sun's rays onto a receiver, which transmits the heat energy to a Stirling engine. The engine is a sealed system filled with hydrogen. As the gas heats and cools, its pressure rises and falls. The change in pressure drives the pistons inside the engine, producing mechanical power, which in turn drives a generator and makes electricity.
I drank what? -- Socrates
Go ahead and try. Electricity is far more valuable than chemical fuels. You can do so much more with it with much more efficiency. Electric cars, for example, run at, what, 90% efficiency? Electric heat pumps can actually get more heat in your home than they use to do it. You can produce light very efficiently as well. Ever try to light your home with natural gas? Electricity is the universal form of energy with the highest value, joule for joule.
I'm repeating myself in this thread, I know, but this point is very important:
The ONLY reason that chemical fuels seem valuable now is because we essentially get them for free. Or rather, all the work has already been done to store the energy. We just need to dig it up, refine it a bit, and get it where it is needed. If there ever came a time when there was no natural hydrocabons available, we'd very quickly realize just what a waste chemical fuels are.
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
Yes, but your numbers are off. Typical insolation at the surface is a LOT less then 1000 Wm^-2, typically from 240-340 Wm-2, depending on time of year. So, our power would be less by over a factor of 4.
Taking into account latitudinal issues (the Sun's not that bright in the northern hemisphere during winter) and the fact that clouds can reflect 150-200 Wm-2, or aerosols that reflect 5-10 Wm-2, you're in a deep, deep hole. Perhaps in the desert during summer, we may approach 500 Wm-2 of direct insolation, but not any of that.
Now consider that your typical 1 car garage is 250 sq ft or ~24 sq m. That gives a ratio of 16:1. Given 12 hours or 720 minutes of insolation you get 45 minutes of drive time at 10% power. That's starting to sound pretty reasonable. Of course 100% efficiency is laughable as is 10% power use (cruising on the highway requires ~, but your at least close to the right order of magnitude. In fact according to these calculations maintaining a 55mph cruise takes about 15kW so you only need to be ~25% efficient, not too far off from what these panels are supposed to be capable of so you'd need to cover part of the house too =)
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
166Hp is about 123Kw isn't it?
http://www.statman.info/conversions/power.html
Hmmmm... Maybe I'm getting this all skewed, but I'm pretty sure that 1hp roughly equals .75kW
Therefore the Honda Element has a ~125kW engine.
10% of peak power = 12.5kW
12.5/1.188 = ~10.5 minutes of insolation for one minute of driving.
Is that any better? Probably not enough to make it workable.
So, this is also exactly why we also don't drive around in portable oil refineries. A slightly more clever arrangement of the involved technolgoies could prove surprisingly useful in real-world applications.
You see? You see? Your stupid minds! Stupid! Stupid!
They also have substantially higher energy density today than the theoretical limit of chemical batteries. That counts for an awful lot.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
That's actually a lot more optimistic then I would have thought. More realistically, if you cover half the surface with 30% efficiency you get 1.2 kw? My Fiat Punto has 44 kw max, and I almost never use more then half in the city. Umm... no, this is wrong. There should be a better way to compute energy (not power) consumption. Peak power is not an issue with electric motors enyways.
Most gasoline-fueled internal combustion engines, even when aided with turbochargers and stock efficiency aids, have a mechanical efficiency of about 20%, dicet wikipedia.
Also wikipedia says the energy content for Diesel is 38.6 MJ/l, which if I'm not wrong is about 11 kwh. Good. Now, I make around 8 km/l in the city, or about 1.4 kwh per km at 20% efficienty. At 85% efficienty for an electric motor that is 0.30 kw/h per kilometer, so in about 12 hours of light that's 48 kilometers. More than I make everyday, anyways. And the power is not limited. In fact if i'm not mistaking, electric motors have higher efficiencies at higher powers.
The problem here is of course the surface, which is never going to be even half covered. But it may be worth a shot in sunier latitudes.
Below the tags, there is a genuine, old fashioned, read link in the summary of TFA, which points to the actual article: http://www.physorg.com/news122534699.html
Aphorisms don't fix code. (Bart Smaalders)
True, but if the energy didn't come free with the fuel, the cost of making it would make the energy density moot.
Here's a little hypothetical. Which option would you choose:
1) Fill your gas tank with 10 gallons of gasoline at, say, $30/gallon (because it has to be synthesized rather than just dug up from the ground) and get 300 miles. Hydrogen would surely be more expensive because it is much more difficult to store and transport. That is $1 for every mile. A simple commute to work could cost you $20.
2) Charge your batteries with $4 of electricity and go 100 miles.
(http://www.ecoworld.com/home/articles2.cfm?tid=373)
I don't know about you, but couldn't afford chemical fuels if they didn't happen to be sitting in the ground ready to burn. I'm not saying that gasoline cars are a bad idea now. I'm simply making a point about chemical fuels in general. If they happen to be just laying there ready to use, that is one thing. If you have to synthesize them (as you would with hydrogen), forget about it. Time to bite the bullet and focus on batteries.
-matthew
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
Electric heat pumps can actually get more heat in your home than they use to do it.
Heat pumps as the name implies aren't generating heat, they're moving it from one place to another and heat pumps using chemical fuels (like natural gas) also get more heat into your home than they use to do it. I doubt converting electrical energy to heat via resistive heating is any more efficient than converting a chemical to heat via combustion. (Certainly not when you consider that most of that electricity is generated using the exact same chemical combustion to produce the same heat, to produce pressure, to spin a turbine, to generate electricity, carried with transmission losses to your electric heater.)
The ONLY reason that chemical fuels seem valuable now is because we essentially get them for free. Or rather, all the work has already been done to store the energy. We just need to dig it up, refine it a bit, and get it where it is needed.
Certainly that's PART of the appeal but I think it's also significant that you can easily store chemicals but it's hard to store electricity. This is particularly relevant when what you want to do with the energy is transportation where you have to store the energy in the vehicle itself. (There are of course modes of transportation like trains which have set routes and it can be arranged that they can be plugged into the grid on those routes, but there are obvious limitations to such vehicles which vehicles that store their own energy don't face)
- Outside dimensions: 172" x 72" (4.4m x 1.8m) So that's 122 kW (not half a megawatt) and 7.92 m^2 roof area. (It's probably more like 6 m^2 unless you can put panels on the windows)
According to http://firstlook.3tiergroup.com/solar, Los Angeles averages 5.11 kWh/m^2/day in horizontal insolation.
So, at a within-reach 20% efficiency, you get 6 * 5.11 * 20% = 6.1 kWh/day.
The GM EV1 had either 18.7 or 26.4 kWh of storage, depending on configuration (http://en.wikipedia.org/wiki/General_Motors_EV1), with a range of about 150 km for the low-capacity batteries. Which makes for at least 8 km/kWh, in a car that could go 0-60 in 6.2s.
So our all-solar commuter car could go 48.8 km/day. Enough for short commutes in sunny climates?
Oh, I'm sorry sir, I thought you were referring to me, Mr. Wensleydale.
Duck Tape: When you don't have time to do the job right, do the job.
Never answer an anonymous letter. - Yogi Berra
You have presented a false dilemma. In fact there are many more choices. Also, the total energy consumption of the vehicle must be considered. It's possible to make engines which take far less energy to produce than current models (because they lack the huge castings.) But the energy cost of making batteries is quite high and can only be reduced so much (although it CAN be reduced significantly.) The only reason Hybrids are affordable at all is because their high production cost is subsidized by raising the prices of other vehicles. That's right, if you buy a new non-hybrid Camry, you're helping to subsidize someone else's Prius.
Now, I know that full-electrics eliminate the majority of the objections; parallel hybrids are just a bad boondoggle, but electrics have some promise. But currently only the most expensive models have acceptable range. It seems like THIS will continue to be true.
Anyway, any organic matter can be recycled into Butanol, which is a direct substitute for gasoline. Hopefully that will start happening on some kind of useful scale soon.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
I've never heard of a natural gas heat pump. But I'll take your word for it that they exist. How efficient are they?
Well of course converting electrical energy to heat via resistance isn't more efficient than other methods. Most people would consider that a waste of electricity. I know I do. My apartment is heated that way and it is expensive.
But that's OK because electricity is in constant demand so it is usually enough to have it flowing through the grid rather than store it.
I'm going to make this point more time and then I won't mention it again, I swear.
The only significant reason chemical fuels seem valuable now is because we're only paying for the transportation, and perhaps some refining, of them. If we actually had to *synthesize* our chemical fuels and put the energy into them (as very uninformed hydrogen advocates suggest we do), we would quickly find that they are very inconvenient and uneconomical. Electricity is the ideal form of energy for most any application. The only reason we don't use it for everything is because fossil fuels are still such a readily available source of "free" energy.
Batteries are getting better. And as the price of fossil fuels rises, we'll see more and more things converted to electric... because it is better all around. You might not like only getting 150 miles on a charge at first, but I'll bet that you'd dislike paying $30/gallon for synthentic chemical fuel even more. In a world without fossil fuels, batteries start looking pretty damn good.
-matthew
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
So you're saying that you could make an internal combustion based automobile so cheap that you could justify paying for sythentic chemical fuels to run it? Yeah right.
Hybrids still derive their power from chemical fuels. They're just a little (and I do mean a little) more efficient than traditional automobiles.
You're ignoring my hypothetical situation. Consider a world where we have to sythesize our chemical fuels rather than dig them out of the ground. This puts electricity and chemical energy on a level playing field.
As a stopgap measure, at best. There's no way it could possibly feed the appetite of modern combustion engines. The future is electric. You may want to push it off because batteries are not as convenient at the moment, but you can't deny that electric is teh future.
-matthew
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
They also have substantially higher energy density today than the theoretical limit of chemical batteries. That counts for an awful lot.
What "theoretical limit" do you speak of? I've never heard of any sort of "battery limit". So far, it's all seemed to be due to engineering and materials challenges -- for example, like the recent silicon nanowire anode to replace graphite anodes in li-ion batteries, which allows 8x (10x on the first charge) higher lithium density. Get a corresponding cathode improvement, and you've increased the energy density of li-ion batteries 8-fold. Which would easily make EVs have longer range than gasoline cars, let alone hydrogen cars (which are only minimally longer range than EVs currently, at the cost of having half the energy efficiency, a lot more containment problems, and no real cost savings (thanks to how expensive fuel cells are))
Sometimes I doubt your commitment to Sparkle Motion.
You don't need synthetic chemical fuels. That's why you're engaging in logical fallacy. There's also biodiesel and butanol; biodiesel is made from algae (at least, most economically) and butanol is made by allowing bacteria to consume organic matter.
You can also use hydrogen, I guess, if you can solve problems with storage and embrittlement. Efficiency for electrolysis of water is over 50% already and climbing. This is less inefficient than other current options for turning electricity into a storable fuel.
But my point is that we can do a number of things to dramatically enhance the efficiency of vehicles which use fuels. For one, we could replace the alloy engine block with steel-sleeved ceramic or carbon fiber, technologies which have been successfully tested in racing. And we could also use turbines, a technology Chrysler pioneered for automotive use back in the 1960s. New transmission designs, or the use of a series electric hybrid, would make their use in modern, lightweight vehicles (unlike the land yachts in which they originally installed their turbine engines) quite effective. Using a series hybrid provides the regenerative braking functionality that helps make electrics so desirable.
You're ignoring my hypothetical situation. Consider a world where we have to sythesize our chemical fuels rather than dig them out of the ground. This puts electricity and chemical energy on a level playing field.I elect instead to consider worlds we might actually live in one day. You can convert solar energy to something useful without turning it into electricity.
As a stopgap measure, at best. There's no way it could possibly feed the appetite of modern combustion engines.It's a good thing we're always moving into the future then, isn't it?
The future is electric. You may want to push it off because batteries are not as convenient at the moment, but you can't deny that electric is teh future.You have no idea what the future is any more than I do (at least since my crystal ball broke.) For all we know we'll discover a new form of energy and we'll all be flying through space with reactionless drives within a decade... though I doubt it. Still, the fact remains that the theoretical limit of battery energy density means that even if the future is electrical, it's not going to be battery-based. And I've been hearing about cheap supercapacitors "in five years" for about fifteen fucking years now.
Bring on the shipstones! Until we do, we will have many vehicular applications for liquid fuels.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
The DoD has Solar Cells that have upwards of 60% efficency.
There are theoretical limits based on the energy which can be stored in the bonds. The only good-looking reference I could find on short notice was http://www.hq.nasa.gov/pao/History/conghand/inpower.htm (I'm on a modem... forgive me)
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Just plant moss or ferns on your car. Drive to work on gas, burn the plants on the way home, buy more at Home Depot. My car is greener than yours! ;)
160hp is ~= 119kw Not 575kw. Ive been in a 500+kw car, and its alot more lively than your typical honda.
In Soviet Russia the insensitive clod is YOU!
Any limit on bond energy would also apply to chemical fuels. You may limit a particular battery chemistry (although the limits they show aren't particularly constraining at all, and they didn't touch li-ion, which clearly isn't anywhere close to it's limits), but not all battery chemistries. Their info is also sorely dated (which would probably be why li-ion wasn't even mentioned); it's a bunch of references from the 1950s. 40Wh/lb for silver zinc? Try 80.
Care to try again?
Sometimes I doubt your commitment to Sparkle Motion.
Unfortunately it doesn't scale very well. And you're throwing a away a lot of energy by burning it.
And then burn it at 30% efficiency and end up with a HUGE waste of electricity. Awesome. I'm not sure you undersatnd this, so let me reinforce this fact: Any process that converts electricity to chemical fuel is a gigantic waste. Even if you could do it at 100% efficiency, chemical fuels just don't have as much value per joule as electricity.
Oh please. The auto industry has had over 100 years to improve upon the internal combustion engine. And in that time there's only been marginal improvements. They're thermodynamically limited in how efficient they can be. They'll never match pure electric. Never.
You could. But doing so would be stupid.
An electric future. Hybrids being the bridge to that future. Use the chemical fuels that we do have to power the electric drive trains of cars until they are perfected by economies of scale and then swap out the motors for high capacity batteries or super-caps and you're there.
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
Which one doesn't scale? So far Butanol doesn't, but it doesn't have to. We could stop pumping our shit to a plant to be processed, for example, until after we run it through the ABE process. Biodiesel will, because it parallelizes nicely, and we have a lot of desert we're not using.
Awesome. I'm not sure you undersatnd this, so let me reinforce this fact: Any process that converts electricity to chemical fuel is a gigantic waste.I do understand this, and I've gone out of my way to make that fact apparent. Are you going out of your way to be obtuse? However, a lot of energy goes to waste, and if we captured more of it, and did less senseless wasting, we would have more capacity for wasting that at least makes sense.
Oh please. The auto industry has had over 100 years to improve upon the internal combustion engine. And in that time there's only been marginal improvements. They're thermodynamically limited in how efficient they can be. They'll never match pure electric. Never.That's true. But they can be improved dramatically, not least in the area of simply making them lighter in weight. The mass of the average vehicle could be reduced to half of what it is now without compromising safety (so long as we did it to ALL vehicles over time.)
Meanwhile, we do again have other options for burning fuel, including fuel cells (a long way off from economic practicality - but so are full electrics from fully replacing current automotive use) and turbines. We don't have to use an ICE.
An electric future. Hybrids being the bridge to that future. Use the chemical fuels that we do have to power the electric drive trains of cars until they are perfected by economies of scale and then swap out the motors for high capacity batteries or super-caps and you're there.Again, I've been hearing that supercaps will come in five years for about fifteen years now.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
You are basically correct, but your math is wrong too. If we were talking about real horsepower, then there is 0.749 kw per Hp, so the 166 Hp car is about 124 kw. However, cars are rated by some bogus BHP scam. Otherwise you would be able to use that Honda motor to pull a 6 bottom plow through clay soil. For comparison, Dad has a John Deere 4020. (http://www.tractordata.com/td/td64.html) It's rated (gas version) for 83.8 HP, or 62.5 kw at the drawbar, or 95.8 hp or 71.4 kw at the PTO.
Although I don't have figures to hand, the same engine in a boat has a much lower horsepower rating than it has in a car.
The point is that automobile horsepower ratings are totally bogus. You can't base anything on the advertising copy. At best they are consistent (between automobile lines) lies.
The other point is better, "assume you can keep it pointed normal to the incident light", In December around here, the mid day sun is about 25 degrees above the horizon. That makes for an interesting suspension if you are going to keep the car's solar array normal to the sun. The sine of 25 degrees is about 0.42, so actual collected power would be 2/5 of that 3.3 kw. Oh, and that 1000 w/meter^2 drops to about 700 watts per meter^2 in the winter, so now you are down to 2.3 kw.
If the sun is out.
Solar power has lots of potential in other places, but not on cars.
Assuming a drive train loss of 25% (not uncommon for a awd drivetrain), the stock version of my car does indeed make the advertised crank horsepower. How do i know? Physics. F=ma. Simply measure rpm vs time using a obd logger and do the math.
I wasn't aware of a efficient, comercial biodiesel algee in use. I've heard LOTS of theoretical or lab products. I don't believe we have sufficient spare organic matter currently to get withing an order of magnitude of what's necessary for butanol at the moment. This is all subject to change of course.
Your suggested improvements to the ICE aren't going to put it on par with an efficient commercial AC motor. In addition, the regenerative ability provided automagically by an EV has to be built into a combustion vehicle at the cost of mass and complexity (i.e. expense).
ICE and electric engine have been around vaugely the same amount of time. Compare the complexity, mass, efficiency and cost to manufacture.
Oh, and one other point. Electrolysis may be at >50% but you still need the electrical energy to begin with. You multiply your losses this way.
You can get rich if you own a politician, but you have to be rich to buy one in the first place.
You'd be better off stripping the H2 from the resulting hydrocarbons and run it through a fuel cell to create electricity. Or hell, burn it in a power plant to generate electricity at much higher efficiencies than individual automobiles can muster. That way it can be used wherever and however it is needed rather than trying to adapt every car on the road to use the chemical fuel du jour. If cars are all electric, it doesn't matter where teh energy comes from. Everyone can automatically take advantage of it.
Right, and what I'm saying is that distributing energy as chemical fuel is a senseless waste.
Maybe, but if you're still burning chemical fuel, what's the point?
I think batteries are a lot closer to being practical than fuel cells. And with fuel cells you still have the problem of dealing with the chemical fuel du jour. WIll fuel cells require pure hydrogen (bad idea)? Will they reform biodiesel internally? Will they take butenol? Natural gas? Again, if electricity were the common denomonator, you could use whatever fuel you wanted in centralized (or even decentralized) power plants which are usually more efficient at extracting power than you car is.
And I've been hearing that chemical fueled automobiles will get significantly more efficient for even longer. But there are cars from the early 90's that got as good gas mileage as many hybrids do now.
-matthew
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
No, the problem is the notion of high speed private transportation. It's intoxicating and amazing and utterly at odds with anything resembling a sustainable future. We shouldn't be looking for more ways to continue automobile culture. We should be looking into ways to quickly (and as painlessly as possible) re-organise society in such a way where the CAR is not only not necessary, but simply doesn't exist.
Things like TFA only prolong our foolish hope that some miracle will occur and allow us to continue driving. Sorry, but no: the party's over. The sooner you adapt your life to one without an automobile and you begin to focus on local food acquisition, the better.
RS
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That's interesting. Are they claiming 40% efficiency based on <energy output per unit area of cell>/<insolation per unit area of cell>, which isn't very interesting, and kind of misleading, or 40% based on the energy per unit area of the entire device?
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Boat engines are designed and rated for continuous operation at full power. Some car engines will overheat if run like that. The "same" engine isn't the same; it's got a different cooling system and a different exhaust system, and it's probably tuned differently to reflect its different operating profile.
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"I assumed blithely that there were no elves out there in the darkness"
Dammit, I was betrayed by the calculator. 166hp is 123.8kW. I haven't figured out how I screwed the pooch on that one. I tried backing our the math, and it doesn't make *any* sense. Ugh.
Ultimately, the insolation is the issue. Even under the most generous situations, there just isn't enough solar energy incident on a car to supply the power that's typically demanded.
> Although I don't have figures to hand, the same engine in a boat has a much lower horsepower rating than it has in a car.
:)
That's because horses can run much faster than they can swim, isn't it?
Perhaps not 1200lbs, but I see variations of http://en.wikipedia.org/wiki/Smart_Fortwo (1600ish Lbs) (including a 1700lb roadster) on the autobahn everyday. There are even lighter out there, and are reasonably save at autobahn speeds - even moreso for normal commuter driving.
Sorry to reply to myself, but speaking of affordable electric vehicles ... once it's made available:
http://en.wikipedia.org/wiki/Smart_EV will find it's way into my driveway. I've considered the ForTwo Hybrid - but full electric is just so hawt.
Damnit so I didn't have to change my terminology after all >_> people used to make fun of me and everything *Cries*
which is totally what she said
As far as I know, your HP-kW conversion is a bit off.
If my memory serves well, 1 kW = 0.736 HP. So the 166 HP is not 575 kW, but just 122 kW.
I do not check your 1.188 kW, so let's assume the ratio is 12.2/1.188 = 10.27, which gives about one hour of driving per day.
That's the purpose of an SUV! The companies making them were betting on some sort of Mad Max-like post-apocalyptic future! Then the vehicle could be fitted with 3" steel armor without more than a ~30% increase in weight, and a portable oil refinery could fit inside the vehicle, so raw crude could be distilled while you drive, rather than having to deal with the vulnerable targets that are fixed refineries. Plus with little vegetation and wildlife to speak of, a nomadic lifestyle, and a certainly grim future for mankind, greenhouse gas emissions wouldn't be a big issue. No problem with gas prices either - demand plummets, prices go down. Add some extra fuel tanks to the vehicle and you're good to go.
"When information is power, privacy is freedom" - Jah-Wren Ryel
Similar to the 18650 cell (although larger, of course), there's no reason not to settle on a standard cell for vehicles. It might involve a little scuffling like for HD DVDs, but so what?That'd be awesome.
Today's sports cars use much the same petrol pumps as econoboxes, no? So why are the rules different for batteries?As opposed to the need to invest in large amounts of gas (and sealed underground storage tanks) today. Again, not so different.
(You may argue that battery packs are more expensive than gasoline, but I can argue that storage tanks can't be continuously refilled from the electricity grid, so it's not at all clear which is easier.)Like, for example, just about every laptop battery known to man?Why?
Own the car and lease the battery. Since the battery belongs to the manufacturer, not you or the fuel station, neither of you care how old it is or how old the replacement is; under the terms of the lease, it's an even trade.
(The only problem would be if people started taking the batteries out, abusing them, and then trying to swap them. That's not so different from doing the same thing with a Prius's battery and then trying to get it replaced under the 8-year warranty, and I suspect it'd be as uncommon and as unrewarding.)
None of your complaints hold up under scrutiny. His idea might not be a good one, but we still don't have a reason why it wouldn't be.
I have been working for my diploma thesis at the Swiss Institute of Technology (Lausanne) on such a device. This was a tandem cell coupling a dye solar cell with an photocatalyst (iron oxyde for instance)to produce directly hydrogen. The goal was to use the potential created and the light not used by the solar cell and produce hydrogen in the second cell. The yield was not very good (~3%) but it was feasible. I suppose that the work is still going on.
I wasn't aware of a efficient, comercial biodiesel algee in use. I've heard LOTS of theoretical or lab products.
Even the US DOE says that it should be commercially feasible using whatever algae colonizes the water by the time diesel fuel reaches $3/gallon. (see A Look Back at the U.S. Department of Energy's Aquatic Species Program .) It's well over that now and likely to stay that way barring some other development.
The beauty of algae is that it can be grown in salt water, which is only going to get more plentiful if certain ice melts :P
I don't believe we have sufficient spare organic matter currently to get withing an order of magnitude of what's necessary for butanol at the moment. This is all subject to change of course.
There is no one answer. Biodiesel, butanol, full-electrics, and maybe even hydrogen all have their place.
Your suggested improvements to the ICE aren't going to put it on par with an efficient commercial AC motor.
That is true. But they can make substantial improvements. Also, we have a number of technologies today that make cars more efficient which are seldom used - at least, in the USA. For example, vehicles with tiny turbocharged engines are much more efficient, and since they are smaller they can have less parts (generally having less cylinders) and thus are cheaper; so you can spend money on advanced materials, they come out around the same price, and you can still have high performance. When the pedal isn't slammed, however, they are much more efficient.
I understand that electric motors are far more efficient, around 85-90% in models currently in use in electric cars, whereas the most efficient ICE on the planet is a container ship motor the size of a house - and it's only at 50%. But then, we DO have alternatives like turbines, which while still not as efficient as electrics, are still significantly more efficient than ICEs.
Even with the horrible inefficiency of the typical gasoline motor, you still get far more range out of it than the best electrics today by just adding a larger tank, which becomes lighter as you drive.
Oh, and one other point. Electrolysis may be at >50% but you still need the electrical energy to begin with. You multiply your losses this way.
This is true, of course. I would imagine burning the hydrogen in micro-turbines or using it in a fuel cell (down the road) and it's only interesting because it has more energy density than a battery - hydrogen has relatively poor energy density compared to other fuels. I would prefer a turbine which runs on a variety of fuels including alcohol and diesel-like fuels, closely coupled to (or integrated with) a generator, and used as a series hybrid. As I blather on about often, this permits the use of minimal battery, maximum range, easiest refueling, support for the broadest range of biofuels, and high efficiency in the same package.
I do think that phasing out the ICE is the best thing to do. But in the mean time, what will we run them on? Do we continue to run our gasoline engines on dino juice? Or do we shift over to butanol? Actually, all the products of the ABE reaction (acetone, butanol, and ethanol) can be burned in a gasoline engine; ethanol burns clean, butanol burns pretty clean, but I'm not entirely sure about acetone. I do know that some people use it as a gasoline additive and claim it gives significant mileage improvements and reduction in emissions, but I don't know anything about the veracity of such claims.
In "modern" vehicles, with continuously variable lift, duration, and timing (as well as distributorless ignition and constant knowledge of the position of crank and cam(s)) it should be fairly simple to make any of the higher-compression engines run on a broader variety of fuels; it may be necess
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Hydrogen fuel cells are not. ready. for. prime. time.
And I've been hearing that chemical fueled automobiles will get significantly more efficient for even longer. But there are cars from the early 90's that got as good gas mileage as many hybrids do now.Parallel hybrids, and in fact all cars based on a reciprocating ICE, are stupid. Period, end of story, thank you very much. As noted elsewhere, the most efficient reciprocating ICE gets 50% efficiency, and it's the size of a house. Now, cars from the early nineties that got mileage better than hybrids actually existed, even on the American road. Unfortunately, both that I can think of are deathtraps, poorly designed to handle crashes: The Honda CRX HF (55 mpg fwy) and the Volkswagen Rabbit Diesel (~40-50 mpg fwy.) I wouldn't give a wooden nickel for your chances in a collision with practically anything in either of those cars. It's not because of their light weight, it's because of their light weight coupled with their unimaginative engineering. Granted, they were both trying to make cheap cars - and they succeeded.
Today's mileage champ, for production USDM vehicles, is the TDI Volkswagen. I don't know that I'd trust it to stay together, but I do know that the early golfs were getting 50 mpg on the freeway. I don't know what the new ones are like. But this is real-world mileage.
I very much want to see a series plug-in hybrid with about half the battery of the typical parallel hybrid. I just want it to be based around a fuel cell or a turbine. I don't see the fuel cell becoming practical any time soon - the only kind we have that is really super-useful right now is the natural gas kind, and that has problems of its own. The H2 fuel cells are fun toys right now, that's about it. H2 makes much more sense, in fact, in turbines or microturbines. Ford has also gotten some little zetec motor to run on H2 by using high-compression pistons and an electric supercharger (not like an E-Ram, I think it was made by Eaton.) H2 has a ton of problems, of course.
In fact, I have high hopes for MDI and Tata's air car for the short-range drivers. In the long term, once we have adjusted our societal expectations, I would hope that we would learn to buy air cars or full-EVs for our short range driving, and take public transportation or rent a long-range vehicle for long trips. But at least in this country, it's not going to happen any way but by necessity, except perhaps on a very long time scale.
Our very government is set up to pander to the interests of the people who are advertising to us and convincing us that we need a bunch of crap we don't need, the people who leased electric vehicles to determine if there was demand, discovered that the demand was overwhelming, and then crushed the vehicles after promising they would at least be recycled. Let's face it, you can't make any money servicing electric cars unless you build unsafe pieces of shit. You have to make the money selling them in the first place. This doesn't fit in with their business model; they depend on the service and parts revenue. GM in particular kicked their own ass with their generous pension plans; the union agreed to a pension cut because otherwise GM would just go under. They can't afford to lose that revenue stream right now.
All I can say is, go Tesla Motors! Go MDI! Go Tata! And piss on Toyota, GM, and all the rest.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Perhaps "average" is the wrong word... "typical"? I wasn't talking about semis. Which, by the way, are stupid anyway. More rail, less big trucks. The big trucks do the most road damage.
Remember we're talking about not just next week (although that's an interesting subject too) but forever. Or at least, until we transcend our physical forms, or at least our need to drive ourselves around instead of taking public transportation.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
No, but storage is becoming less and less important. And where it is important, batteries are getting much better. Only a relatively few applications will require stored energy in the foreseable future. Aviation for one. I can't imagine passenger jets running on electricity any time soon. But automobiles are getting pretty close.
You won't be saying that when the price of fossil fuels doubles.. and then triples... Like I said, chemical fuels seem nice now only because you're not paying to have them made. You're just paying to have them refined a bit and then shipped.
Oh please. You complain that batteries are 'under development' and you dare even mention fuel cells. At least batteries are practical now. Maybe not as convenient as your cheap fossil fuels, but they work now.
Give it up. Of all the possible chemical fuels, hydrogen is about as bad as you can get for consumer applications. It is difficult to store, difficult to transport, and has a poor energy density compared to other chemical fuels. And then on top of that you suggest burning it with 40% efficiency, at best. What a joke.
Try running your (currently ICE powered) car on electric power - you won't go very fast or get very far with just the started motor turning. Even if you did a conversion to an electric vehicle drive, ultimately the electrical power used to charge up its batteries has been generated (mostly) by the use of chemical fuels
Not where I live. Most of our power here is hydro. But even if it wasn't, once you get people using electric drive trains, it is much easier to upgrade the power source. You can use whatever is appropriate for a particular geographic area and people dont' have to change their cars to adapt. Electricity the same no matter how you generate. Chemical fuels, on the other hand, are all different and each requires a different motor configuration.
Ease of use, maybe, in some specific situations, but not flexibility. There is no form of energy more flexible than electricity. Just about anything you can do with a chemical fuel, you can probably do with electricity better and with much higher efficiency. I wonder if you've ever tried to run your computer on natural gas....
Electrical power is not a fuel. Electricity is what you want to be converting most of your fuel into... because electricity is more valuable in modern society.
Frankly, if Hydrogen can be generated (and stored - in a tank or whatever) with a 'cell' or even with a suitable a wind turbine then its use as a FUEL should not be discounted. Ever given any thought as to what you will power aircraft with in future? Something tells me that a
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
For algae, diesel is 4 bucks a gallon off by me. I still don't see any algae diesel pumps (nor have i heard of any algee farms contributing a noticable amount of oil). It'll happen eventually but I'd guesstimate we're looking at minimum 5, likely 10 years before algae oil accounts for 1% of the oil used. How fast it ramps up depends on competing technology.
re: hydrogen energy density - You're right and wrong at the same time. By weight, hydrogen has over 3 times the energy density of hydrogen. By volume liquid hydrogen has a bit less than 1/3 the energy. It's the catch that's been hampering H2. Still, generating H2 indirectly is another lossy conversion and not as efficient as direct electric power.
Solar is great for peak demand but outside of that it is inadequate. You either need a base load generator or some storage system. Your storage system efficiency then has a very large impact on the additional solar you need during the day. Wind, tidal, etc. are good niche power but have additional drawbacks.
I do agree that nuclear power is a Good Thing. Personally I think it's by far the best, cheapeast, SAFEST, and least polluting method available that can scale to handle 75-100% of our power needs until the more esoteric generation methods become available (fusion, space-based solar/microwave, etc.)
You can get rich if you own a politician, but you have to be rich to buy one in the first place.
Yeah, what can I say... I'm a sucker for a troll (good or bad) every now and then. I am particularly drawn in by trolls who really put in the effort as you seem to with your especially long winded (and often not even relevant) reply.
I should.
I actually don't regret my personal experience with 'chemicals.' But thanks for the concern. Oh wait, was that some kind of veiled jab at my sanity or something? Hmm, I'll have to remember to be offended next time.
Admitting you have a problem is half the battle.
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death