Using only the sun to split water and make hydrogen
As cool as the promise of quick refueling and emitting only water is, fuel cells still have that sticky issue of needing hydrogen before they can really catch on. In spite of hydrogen being the most common element in the universe it almost never appears in isolation. Separating hydrogen from the compounds that it is usually a part of tends to take a lot of energy. The most common methods today are steam reformation of natural gas and electrolysis of water. The former unfortunately produces carbon dioxide as a byproduct and electrolysis uses electricity. Green hydrogen proponents can point to a lot research being done on various renewable means of hydrogen production - such as using tidal or geothermal energy to power electrolysis or by biological means - but we're not there yet.Profs. Thomas E. Mallouk and W. Justin Youngblood at Penn State University have been working on a solar cell that can directly crack water into hydrogen and oxygen. Electrodes from the cells inserted into water can split the molecules. Unfortunately at this point the system is only about 0.3 percent efficient. The researchers are investigating a number of different catalysts to help stimulate the reaction. They are also looking at different dyes for the cell itself to improve the sensitivity to a larger portion of the light spectrum. Another issue is making the reaction self-sustaining. Currently much of the oxygen and hydrogen quickly recombines after splitting, limiting the amount of hydrogen that can be recovered. It's an interesting concept but clearly still a long way from being viable.
[Source: Eurekalert.org]
Reader Comments (Page 1 of 1)
Mike Z 9:35PM (2/19/2008)
Like most here I have a hard time seeing the advantage of hydrogen power cars.
However, this idea requires some attentions with regard to power generation.
After all, IF the cost could be brought down to be compared with photovoltaic cells you can use this to store excess hydrogen (ie underground in deleted natural gas wells) to provide constant power day or night.
Additionally you might be able to use a combined cycle power plant instead of a fuel cell to create AC power directly instead of having to invert the DC from solar cells.
Of course it all depends on if the cost can come down, but worthy of research.
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Paul 9:12AM (7/14/2008)
Hi, you can power a car with hydrogen useing the battery, it takes 12V @2amps to part fuel a car, granted you still need petrol but if we use 3/4 of fuel 1/4 of hydrogen we will be moving forward. Plus if manufacturers would make the cars more eficient instead of less we would'nt need a new fuel source!
Karen Pease 1:16AM (2/20/2008)
This tech is less advanced than solar was in the '60s. It requires an expensive "special glass" (haven't seen anywhere that is more specific), only lasts for a matter of days due to corrosion (water is corrosive enough on its own, let alone with free hydrogen and oxygen in the mix), and is very inefficient. It's a very unimpressive tech in the forseeable future, even if hydrogen cars were desirable. They're not.
As for storage of energy, pumped storage (water or air) is generally much preferable. Hydrogen is bulky, inefficient, extremely leak prone, poses safety risks, corrosive, and is in general an expensive pain to deal with.
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TX CHL Instructor 8:58AM (2/20/2008)
"Unfortunately at this point the system is only about 0.3 percent efficient."
IOW, it's roughly 50-60 times better to just use sunlight to charge batteries...
Even if there was NO COST at all to produce hydrogen, it would still be a suboptimal fuel. And it's not 'green' in any meaningful sense of the word. For starters, it's the most powerful ozone-depletion agent ever produced by man, and it is not possible to contain it 100%.
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Mike Z 9:21AM (2/20/2008)
It requires an expensive "special glass"
Do you have a link to where this is referenced?
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Karen Pease 12:44PM (2/20/2008)
Well, if their tech is at all similar to this one:
http://www.hydrogensolar.com/basics.html
"The key to the Tandem Cell™ is the performance of the metal oxides in reacting to the photons of the incident light. We are developing processes to obtain high efficiency films in a usable form. The metal oxides are expected to be the limiting feature of Tandem Cell™ efficiency, but we also need to optimise all other aspects, including the counter-electrodes, the electrolytes and the mechanical design to maximise light gathering and hydrogen collection. The most expensive component of the Cells is currently the special glass, on which the nano-crystalline films are deposited. Cheaper alternatives will be found to reduce the cost of the Cell. We envisage arrays of Tandem Cells™ incorporating optical collection devices optimised for maximum efficiency."
Saying "cheaper alternatives will be found" is, of course, like saying "more efficient ways to make solar cells will be found". You can't schedule innovation, and they can't even make what they have really work right for a relevant length of time.
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Steve 3:02PM (2/20/2008)
I continue to be bewildered by the fact that people like this come up with a system that's only 1% as efficient as some current solar designs today (and less than 1% as efficient as others) and yet they STILL think hydrogen is a good idea. How stupid can you get?
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Jeff Gilleran 9:46PM (2/20/2008)
I think its because the " you might be onto something" factor that goes along with any new idea.
Might seem cheesy, but some of the best designs started off rather lame.
Im just chalking this up having potential.. maybe it can be used at the same time as another innovation making a great product?
Time will tell.
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Chris M 12:22AM (2/21/2008)
Plants have been using sunlight and cholorophyll to split water for millenia. But plants don't try to store the H2, instead, they do the sensible thing and use that hydrogen to synthesize carbohydrates, and other easy to handle "fuels".
Maybe we should learn from mother nature. Biofuels, anyone?
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GenWaylaid 11:13PM (2/21/2008)
But...the sun IS hydrogen! Let's just send Richard Branson up there to grab whatever we need.
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Craig 6:06AM (3/04/2008)
There are 330 MILLION cubic MILES of ocean on earth. Each Cubic mile contains approximately 44 million TONS of hydrogen. When you burn hydrogen you get energy and potable water. Using electricity generated with wave energy, solar or wind you electrolicize the water and recover the hydrogen. The oxygen can be recovered too or released into the atmosphere. If H is the most common element in the universe and we're not using it it's because big petrol doesn't want us too. Storage, recovery, infrastructure can be worked out. HOW ABOUT THAT MDI AIR CAR? I'm preaching to the choir here...
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Craig 6:47AM (3/06/2008)
I mispoke. I grossly understated the hydrogen content per square mile. A more accurate figure is 509 Million tons, not 44 million (! don't know where that figure came from)
Craig
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