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Politics : Politics of Energy -- Ignore unavailable to you. Want to Upgrade?

To: Road Walker who wrote (1146)	8/1/2008 4:11:40 PM
From: TimF	Respond to of 86355

You forgot to include the link. I think this is the right one. web.mit.edu As far as I can tell from the article, this isn't specific to sunlight, but is generally a cheaper and more efficent way to produce hydrogen and oxygen from water with electricity and a catalyst ("When electricity -- whether from a photovoltaic cell, a wind turbine or any other source -- runs through the electrode"). We already can slit water with electricity, but if this process means we can use noticeably less electricity than it could be quite useful. I'm skeptical about larger "hydrogen economy", and "hydrogen powered cars" idea, because of the difficulties in transporting and storing hydrogen, and its fairly low energy density (in terms of volume, in weight terms it has a very high energy density), but local storage at a powerplant wouldn't be as difficult as thousands of filling station tanks combined with hundreds of millions of car tanks. It doesn't really seem to be all that similar to photosynthesis to me, so I'm not sure why they mention that so much, but that's a quibble not a problem. ---- From another article about this news "John Turner, a research fellow in photoelectric chemistry at the National Renewable Energy Laboratories (NREL), called the work a "significant result." But he said that a number of improvements still need to be made before realizing the "hydrogen economy." Right now, systems to produce hydrogen and oxygen from water would require huge amounts of land and materials to make catalysts. "The initial results look promising but it doesn't answer all the things you need in a catalyst," he said. Turner's research focuses on improving ways of harvesting light energy to crack water molecules. " news.cnet.com Also, saving perhaps the most important point for last, I'm not so sure this really is more efficient than older methods (or how it would be if it is), rather than just fairly normal electrolysis using cheaper and more benign materials. Cheaper and more benign is good, but unless there is a real gain in efficiency as well its less of a breakthrough than it initially appears. ---- "The energy efficiency of water electrolysis varies widely with the numbers cited below on the optimistic side. Some report 50–80%[2].[3] These values refer only to the efficiency of converting electrical energy into hydrogen's chemical energy. The energy lost in generating the electricity is not included. For instance, when considering a power plant that converts the heat of nuclear reactions into hydrogen via electrolysis, the total efficiency may be closer to 30–45%.[4] en.wikipedia.org And that 30 to 45% is from heat to electricity to hydrogen, if you want to later convert the hydrogen back to electricity than there is another step and a bit more loss. ----------- Here is another idea for Hydrogen production that I didn't know about - using algae en.wikipedia.org However it produces CO2, and also (from the above link) "It would take an algae farm the size of the state of Texas to produce enough hydrogen to supply the energy needs of the whole world. It would take about 25,000 square kilometres to be sufficient to displace gasoline use in the US; this is less than a tenth of the area devoted to growing soya in the US but would equal the size of the state of Vermont, or three times the size of the everglades swamp in Florida, all dedicated to raising this form of algae."