Vast New Energy Source Almost Here: Solar Hydrogen Fuel Dream

[Trillo]

Will Soon Be A Reality, Australian Scientists Predict

Australian scientists predict that a revolutionary new way to harness the power of the sun to extract clean and almost unlimited energy supplies from water will be a reality within seven years.

Using special titanium oxide ceramics that harvest sunlight and split water to produce hydrogen fuel, the researchers say it will then be a simple engineering exercise to make an energy-harvesting device with no moving parts and emitting no greenhouse gases or pollutants.

It would be the cheapest, cleanest and most abundant energy source ever developed: the main by-products would be oxygen and water.

"This is potentially huge, with a market the size of all the existing markets for coal, oil and gas combined," says Professor Janusz Nowotny, who with Professor Chris Sorrell is leading a solar hydrogen research project at the University of New South Wales (UNSW) Centre for Materials and Energy Conversion. The team is thought to be the most advanced in developing the cheap, light-sensitive materials that will be the basis of the technology.
more...
http://www.sciencedaily.com/releases/2004/08/040825094820.htm


~~~~~~~~~
I've been seeing a LOT of hydrogen news lately, here's another one
~~~~~~~~~~

Title: Molecular assemblies created to convert water to hydrogen gas


Wonder where the fuel will come from for tomorrow's hydrogen-powered vehicles? Virginia Tech researchers are developing catalysts that will convert water to hydrogen gas.
The research will be presented at the 228th American Chemical Society National Meeting in Philadelphia August 22-26, 2004

Supramolecular complexes created by Karen Brewer's group at Virginia Tech convert light energy (solar energy) into a fuel that can be transported, stored, and dispensed, such as hydrogen gas.
The process has been called artificial photosynthesis, says Brewer, associate professor of chemistry. "Light energy is converted to chemical energy. Solar light is of sufficient energy to split water into hydrogen and oxygen gas, but this does not happen on its own; we need a catalysts to make this reaction occur."

One major challenge is to use light to bring together the multiple electrons needed for fuel production reactions. Electrons are the negatively charged particles that surround an atom's nucleus, allowing atoms to react and form bonds.

Previous research has focused on collecting electrons using light energy. The Brewer group has gone the next step and created molecular machines that use light to bring electrons together (photoinitiated electron collection) then deliver the electrons to the fuel precursor, in this case, water, to produce hydrogen.
more...
http://www.physorg.com/news934.html


~~~~~~~~~~~~
I wonder if anyone is going to make a kit so we can convert our existing gasoline-powered cars to run on hydrogen?

[phantom power]

1. There's a lot of "potential" and "almost" in their claims. But it

sounds like it would be quite useful, if they can get it to work.

I'm pretty skeptical about using hydrogen directly as a fuel, but it can also be used as a reagent in producing manufactured hydrocarbons.

[Q3JR4]

2. Hopefully they're not talking about "pure" water.

We seem to be running out of that as well.

[kestrel91316]

19. No fresh water needed...................

just use solar power to distill pure H2O from polluted or nasty or salt water. A simple, tidy solution.

[HysteryDiagnosis]

3. Will Soon Be A Reality, Australian Scientists Predict

Uh oh... gonna have to go to war with Australia....



www.ch2bc.org

[movonne]

4. Oil companies will have something to say about this. NO, NO, NO.

[Maple]

5. Fuel cells have been around for a century

But oil was cheap, and there were fortunes to be made.

Capitalism holds back progress, for all that Rand says about it.

[LiberalEsto]

6. Good idea! But hydrogen has some pitfalls that need to be resolved

Hydrogen, by its nature, is extremely difficult to store and transport. It can "age" the materials it is stored in, making them brittle and useless. Hydrogen is also explosive. The Hindenberg zeppelin disaster involved hydrogen, which is why later blimps used helium, a stable gas.

Research is being done into the use of carbon nanotubes to store and transport hydrogen, but there have been some worrisome findings lately that nanomaterials can cause cancers.

And there are still a lot of details to be worked out in creating a hydrogen fuel infrastructure.

This info from Australia is the most promising thing I've seen yet for creating a source of hydrogen.

I wouldn't hold my breath about converting existing cars to hydrogen power. Once again, a lot has to do with the special materials that will be needed to store the hydrogen, and I don't know if that is possible with a conventional car. It might need major modifications.

[Bruce McAuley]

7. Just needs a special tank

Hydrogen will combust in a standard internal combustion engine, gotta jiggle the carburetion/injection a little, but not much different than burning propane, I wouldn't think. Adding one carbon atom to the hydrogen will create methane, which stores well at standard pressure and temperature.
VERY interesting!

Bruce

[Trillo]

9. I imagine a stainless steel exhaust system would be nice.

Anything past the combustion chamber would have a tendency to rust.

I do know that "I" would convert my existing cars to hydrogen fuel, if that fuel was widely available (I like to tinker with my cars), and it was legal for me to do so. There are kits available for converting to both propane and CNG, with the latter favored because of its higher octane rating. I agree with you that it likely wouldn't be any more work than either of those.

http://www.hydrogennow.org/Facts/Theautomobile.htm

Kerry's planning on putting 5 Billion into hydrogen research. It sounds like we (mostly) need to figure out how to get industry to support this and build the infrastructure.

[Dogmudgeon]

11. Hydrogen safety

Actually, I'm a big proponent of using airships to replace both commercial air travel and cargo hauling, even cargo that is usually moved by truck.

While most modern airships use helium as their lifting gas, hydrogen is still viable. Modern fire-suppression technologies and design principles allow airships to be built with an extremely low probability of explosion; materials have been developed that resist decomposition in the presence of free hydrogen gas.

Gas mixes can also reduce hydrogen flammability dramatically and still provide superior lift.

But I agree with you 100% on this point -- there are still a lot of details to be worked out in creating a hydrogen fuel infrastructure.

--bkl

[NNadir]

12. I don't think that hydrogen is particularly safe in most applications.

It has especially poor properties as a fuel owing to its extremely low viscosity and extremely low critical temperature (the second lowest of all elemental substances). In fact the only property recommending hydrogen as a fuel is the combustion product, which is of course water.

I think though that hydrogen is a viable option for lift to replace Helium, as such applications may exist, especially when cut with a light inert gas like Neon. (Neon actually has lifting capacity, being lighter than air.) It is worth noting that Helium, the preferred gas now used for lift is NOT a renewable resource. All of the Helium now found on earth (largely obtained from natural gas wells in Kansas) is derived from the decay of radioactive materials in the earth's crust and core. (An alpha particle in alpha decay is actually a helium nucleus.)

The mean molecular speed of a gaseous atom or molecule is proportional to the square root of RT/m where R is the gas constant, T is the temperature (in Kelvin) and m is the molecular mass. For Helium and hydrogen, it can be shown through an equation known as the Maxwell-Boltzman distribution that a significant number of molecules at terrestrial temperatures exceed the escape velocity. This means they boil off into space eventually. (This property explains why there is no water on Venus; the radiation flux there was high enough to create a temperature high enough to boil off the water, allowing for a runaway greenhouse effect when CO2 was not sequestered in water solutions. That can happen here folks.)

Helium does not boil off immediately; if my memory serves me well the average lifetime for Helium atoms in the atmosphere is about 100 years. Still, Helium is not forever. In the future all of the element will need to be obtained from the radioactive decay of Tritium into Helium-3 or from the radioactive decay of short lived actinides like Curium-242.

[Trillo]

13. Hydrogen not good as a ICE fuel? Is Gasoline particularly "safe?"

Remember the Pinto?
You wrote:

"It has especially poor properties as a fuel owing to its extremely low viscosity and extremely low critical temperature (the second lowest of all elemental substances). In fact the only property recommending hydrogen as a fuel is the combustion product, which is of course water."

Got any links backing up your statement that it's a poor ICE fuel?

"When used as a fuel in ICEs, either as 100% hydrogen or as a blended fuel with CNG, hydrogen appears to offer reduced air emissions and maintenance benefits, and it may provide power benefits as will. However, the economics of 100% hydrogen-powered or H/CNG-powered vehicles are not well defined. Concurrently, hydrogen infrastructure requirements, including hydrogen production and storage, are another are that requires greater understanding and development."
http://avt.inel.gov/whathydrogen.html

PDF chart of alternative fuels for automobiles:

"Hydrogen has an excellent industrial safety record; codes and standards for consumer vehicle use are under development."
http://www.eere.energy.gov/cleancities/afdc/pdfs/fueltable.pdf

[phantom power]

14. gasoline is a larger molecule, and you don't have to pressurize it

By most criteria, gasoline really is safer than H2. Also cheaper/easier to store and transport.

pressurized H2 needs to be sealed at all points, or it escapes. And it requires special sealing, since it's so darn small.

[Trillo]

15. Thank you.

The size of the molecule reminds me of the difference between R-12 and R-134, which requires less porous hoses.

I do note that hydrogen has the highest octane rating of all the fuels listed on the PDF link referenced.
Hydrogen: 130.
CNG: 120.
Propane: 104.
Gasoline: 86-94 (The highest I'm able to buy right now is 91)

Also, hydrogen is right up there with Gasoline and Diesel for BTUs per gallon, all the other alternatives are lower.

Gasoline, given that wars are now apparently fought over it, doesn't appear particularly "safe".

[phantom power]

16. I advocate manufacturing hydrocarbon fuels

There are many options on the table. Propane, diesel oil, di-methyl ether, I'm sure there are dozens of options. Pick your carbon-based fuel.

At least some of these actually use hydrogen as an input to the process, so there's a place for H2 production. The other big input is CO2, so you get a carbon neutral cycle.

The big catch with this is, we need energy sources to do the manufacturing with. But this can be supplied with nuclear, or renewables.

Another big catch is, we have to build a bunch of fuel-manufacturing plants.

But if we got it all into place, we'd have a sustainable, carbon-neutral fuel cycle. And we wouldn't have to fool around with pressurized hydrogen.

[NNadir]

17. I don't have any links.

I simply know that the critical temperature for hydrogen is extremely low and that the viscosity is the second lowest in the periodic table. I would love to provide you with links about whether or not hydrogen is or is not an "ICE" fuel but I don't know what an "ICE" fuel is. Internal combustion engine perhaps?

It is currently illegal to drive, say, in the Lincoln Tunnel with compressed flammable gases, and for good reason. I don't think it would be particularly wise to revise this rule just because water is non-polluting.

I suspect that the reason that hydrogen has an excellent safety record in industrial settings is that the containers in which the hydrogen is contained are generally not in motion. Also the hydrogen is handled by professionals who have a healthy respect for its properties. The systems in which it is used are well maintained and flawlessly maintained. Then too, hydrogen is not used on anything like a grand scale; the more systems you build, the greater the potential for failure. Almost all of the hydrogen now manufactured is for captive use, mostly in the hydrogenation of fuels. Hydrogen is not transported great distances because it is not economic to do so.

I have worked with hydrogen in the lab, and don't regard it as incredibly dangerous, even though the only laboratory fire in which I have been involved resulted from allowing a filter paper with a hydrogenation catalyst (Platinum) to go dry. (I have also observed another chemist who ignited Palladium on Carbon after a hydrogenation reaction.) Still, I shutter at the thought of ordinary Joe's and Jane's running around on freeways at 150 kph with the stuff.

I do note, while on this point that a hydrogen leak in an area where catalytic converters (Platinum supported on Aluminum Oxide) from gasoline fueled engines are around (even if the engine is off) will result in a spontaneous explosion.

I simply think that hydrogen as a fuel is way, way overhyped, which is why the national moron, George W. Bush, is pushing it: It's a bad idea. It is much safer and much more economical (for reasons of transport and simplicity of handling systems) to make hydrogenated fuels to serve as hydrogen equivalents.

I will once again repeat my oft repeated preference for dimethyl ether, which I regard as a wonder fuel. I would have no objection to the use of this wonder fuel in reforming systems for the regeneration of hydrogen in situ through a reformer, perhaps coupled with a fuel cell; indeed I think such a system may prove to be close to ideal. It may not prove necessary to develop such exotic systems: DME runs diesel and turbine systems perfectly well, with close to zero pollution, and in fact DME can serve as a much more greenhouse neutral subsitute for compressed natural gas, propane or butane. It's worth noting that this fuel, although flammable, is an excellent refrigerant and solvent (liquified under moderate pressure). It is currently used as the CFC replacement in hairspray. (In this application it is quite nearly perfect. The lifetime of DME in the atmosphere is about 5 days.) DME can be synthesized by the direct hydrogenation of carbon dioxide.

[Trillo]

18. (I)nternal (C)ombustion (E)ngines (ICE)

We already have a number of ICEs running on propane and natural gas. Not a large percentage of the whole, but enough that there are CNG refueling stations. We have one 30 miles away (while gasoline is right around the corner).

BareKnuckeledLiberal gave the source press release for the Australian study. From that PR:

"1.6 million individual households equipped with 10m x 10m solar hydrogen panels would meet all of Australia's energy needs."

Whether or not hydrogen is used to power automobiles en-masse, it is not hard to imagine this products competitive effect on the price of (P)hoto(V)oltaic (PV) cells. Right now the cost of production of those cells is small; according to a Discovery TV show about them roughly 15 years ago, the (at the time) new laser process would reduce the cost of production of PV cells to pennies per square foot--but (now, 15 years later) retail prices are still high, about $300-500 for a 2 by 4 foot panel (about 8 square feet). With about 80 of those PV panels I can disconnect my home from the electricity company.

But I digress. You wrote:

I do note, while on this point that a hydrogen leak in an area where catalytic converters (Platinum supported on Aluminum Oxide) from gasoline fueled engines are around (even if the engine is off) will result in a spontaneous explosion.

Three-way catalytic converters reduce emissions of carbon monoxide, hydrocarbons, and nitrous oxides. Since using hydrogen as a primary fuel in an ICE doesn't produce these in its combustion, there'd be no real need for a catalytic converter. With existing automobiles, if there's a gasoline leak near a catalytic converter, there's also danger as it vaporizes. With a hydrogen powered ICE car, in the event of an accident, the H tank should be automatically shut off, as a safety precaution, and a crash proof tank would be necessary.

" Because it is so light, hydrogen disperses and floats skyward when leaked—it won't pool or soak into clothing like gasoline, just waiting to ignite. (Spilled hydrogen won't soak into the earth and pollute ground water either, or cause an environmental disaster like the Exxon Valdez.)
<snip>
Many real-life tests have demonstrated the safety of pressurized hydrogen storage. Simulated 55 mph crash tests left the car totaled, but the hydrogen tank intact. To prove the safety of its hydrogen vehicles, BMW tested its hydrogen tanks in a series of accident simulations that included collision, fire and tank ruptures. In all cases, the hydrogen cars fared as well as conventional gasoline vehicles. And hydrogen-fueled cars are designed to preclude the possibility of leaked hydrogen collecting within the vehicle."
http://www.rmi.org/sitepages/pid536.php

You wrote:

I simply think that hydrogen as a fuel is way, way overhyped, which is why the national moron, George W. Bush, is pushing it: It's a bad idea. It is much safer and much more economical (for reasons of transport and simplicity of handling systems) to make hydrogenated fuels to serve as hydrogen equivalents.

The way I conceptualize about it: It's much more efficient to produce hydrogen directly, then use it as is. You're saying it's more economical to transform the solar-produced H into something else, perhaps several times, before allowing "people" to use it! This doesn't seem particularly efficient use of hydrogen produced by solar cells, perhaps located on your own roof.

By the way, Bush is being eclipsed in proposed dollars for hydrogen research funding by Kerry. In other words, Kerry is proposing to spend more to get us off hydrocarbons.

[phantom power]

20. efficiency of using hydrogen directly

I'm not sure it's necessarily more efficient.

As I recall, once you've produced pure hydrogen, the chemical reactions for creating hydrogenated fuels are exothermic. So, it takes no further (net) energy expenditure to produce intermediary fuels. In fact, it will release energy, which might be used to generate supplementary electricity, or heat for the chemical plant, etc.

Another factor is the special infrastructure to transport and store pure H2 safely. That represents additional cost, at least economically, if not thermodynamically.

[Trillo]

21. Grant me a little sarcastic leeway?

Each time the energy is converted into something else, someone is going to charge some amount for the "value" added by the process: that's just capitalist reality. If there is no further energy expenditure in this process, then the additional charge to the consumer will be for "nothing."

[NNadir]

22. I'm fifty two years old and having been hearing about the hydrogen

economy since I was a teenager.

I used to think it was a good idea, but I still consider the fuel too dangerous for the reasons already stated. I've also been hearing how many (solar cells, windmills, corn fields...) can provide the total energy needs of (The United States, Australia, Canada, New Zealand, the United Kingdom, Belize...]

If it were simple it would have been done.

I think I understand that the extremely dangerous hydrogen fueled automobiles wouldn't need catalytic converters. However I don't expect that even if these hydrogen producing solar converters (1) are scalable, (2) reasonably priced (3) robust (4) efficient (5) environmentally acceptable to manufacture (6) non toxic in their disposal, the start of their manufacture by say, next Tuesday, will not eliminate the existence for "ICE" (and how I hate unnecessary abbreviations that minimize rather than increase understanding and communication) by the following Friday. In fact, in a dangerous hydrogen fueled universe it is very easy to imagine a family with a hydrogen powered giant SUV parked in their 3000 square foot four car garage right next to their giant gasoline Hummer which DOES require a catalytic converter. Should the hydrogen bubble off (and if you've ever stood next to a cryogenic tank, they are always vented), and as a result, the concentration of hydrogen rise high enough in the garage (or for that matter in the Lincoln tunnel), well then...boom. That was my concern.

As for matters of efficiency and thermodynamics, this depends on the nature of the molecules and the particular reactions. I note that industry for the last century or so has in fact been routinely converting one molecule to another for reasons having to do with convenience, cost, and, oh yes, safety. A considerable amount of energy is lost in the process of thermally cracking petroleum to give gasoline for instance. The reason for proceeding with the process, called refining, nonetheless is that gasoline can be stored and used in automobiles, whereas asphalt cannot be so used. The hydrogenation of carbon dioxide to give dimethyl ether is exothermic, meaning that there is some energy loss in the energy value of the hydrogen, albeit a potentially recoverable energy loss. However, I would expect that the liquefaction of hydrogen is EXTREMELY exothermic when compared with the hydrogenation of carbon dioxide. When one adds the cost of maintaining liquid hydrogen below its critical temperature, (-240C or 33 Kelvin)

http://www.webelements.com/webelements/elements/text/H/heat.html

it's pretty clear to me that the direct use of hydrogen is much more wasteful of the total energy value than the hydrogenation of a suitable carbon compound.

The transport and storage of hydrogen has been studied extensively over the last several decades and the conclusion has been uniformly the same: It is even more difficult, expensive, and dangerous to transport and store than is natural gas. (This doesn't mean it's impossible, only that it's expensive and dangerous.) I note that even in a world with a profound energy requirement, where natural gas is most often (dubiously) considered a "clean fuel" huge amounts of natural gas are flared (burned for no useful purpose) simply because it is too expensive to transport it to places that it might be used. As natural gas prices rise though, it becomes increasing possible to liquefy it and ship it by sea, a practice that has involved huge explosions and in some cases, loss of life, as occurred in Algeria recently. Hydrogen's physical properties make it much, much worse than natural gas, both in the areas of safety and economics.

I believe that hydrogen production will be a key industrial energy related process in the coming centuries, assuming that the human race prevents its own elimination via the mechanism of atmospheric collapse. However, I still shudder at the thought of hydrogen fueled automobiles.

As for the matter of John Kerry and George Bush, I am enthusiastically voting for John Kerry on the grounds that John Kerry can think and George Bush, who is detestable on other grounds as well, cannot think. I'm really not interested in the particular i's he dots and t's Kerry crosses in the mouthing of campaign rhetoric, since to be elected Kerry will necessarily, if sadly, be required to pander to the vast energetically naive or ignorant segment of the population. His energy programs when he is seated in the Oval Office thus restoring the office of the Presidency to the United States, will certainly evolve as he does. That's all I ask, is that the President of the United States think, since certain conclusions are on reflection obvious. I fully expect that John Kerry's energy program, which will certainly include expanded development of "renewables" including solar energy, will be enlightened, although I might quibble with the particulars. I also expect that John Kerry, who unlike the current occupant of the Oval Office, does not despise science, will have no trouble dispensing with the idea of the "hydrogen car."


I hardly expect any President to have the same energy policy I would have were I President. I have quibbled with the particulars of the energy policies of every President in my lifetime, both those I admired and those I despised. Even despicable Presidents - and note I am excluding Bush since he was never elected to the Presidency and thus is not a President - have had wise energy policies, and very good Presidents have made very poor energy decisions. For instance Richard Nixon advised Americans to drive 55 mph in order to conserve fuel, which was a a very good policy. Jimmy Carter on the other hand, sought to ban nuclear fuel recycling, which was a very poor energy and environmental policy. Of course I would have no trouble today choosing which of these two Presidents I prefer: I still often weep when I see Jimmy Carter speak and think of his accomplishments, his decency, and his high intelligence, whereas I consider Nixon to have vastly improved himself by the act of dying.

[Trillo]

23. Low-Pressure Storage Is Not The Only Option

The use of crude oil, and the attempts to make it safe, has involved all of mankind to some rather unsafe long-term consequences. Some have said this is because the capitalist financial system doesn't take all costs into consideration, especially environmental ones. The largest one I can think of is the total increase of C02, or essentially, the moving of a subterranean liquid into a gas all of us then breath, but which animals cannot utilize (plants can); in other words: climate change. These are not the only poisonous effects: smog, breathable impurities, etc., are all "unsafe" effects of the "more safe" cracked crude, and are costs not properly accounted for. Environmental dangers, while likely the most serious for all humans, are not the only deleterious effects: the greed of the international corporation and entrenched self-interest, the national disappearance of our middle class, preyed on by elite CEO types, all are related costs that are not directly reflected on corporate balance sheets.

Some of your concerns are certainly valid with respect towards the low-pressure storage of liquid hydrogen. Instead of thinking of this as dangerous, others think: "It is relatively easy and safe to store and transport in compact, lightweight, low-pressure containers."
http://www.llnl.gov/str/June03/Aceves.html
Low-pressure storage is not the only option: Three ways of storing hydrogen, but only one tank.

[NNadir]

24. You will find no argument with me on the toxicity of gasoline and its

combustion products. I have a long history of evoking these same arguments while arguing for the expansion of nuclear energy. In fact, I've spoken quite a bit here on the sulfur iodine cycle which is a thermochemical method of decomposing water into hydrogen and oxygen at comparitively low temperatures. One can imagine this cycle being driven by either nuclear or solar (parabolic mirror) means which would represent a real alternative to fossil fuel burning, which you've correctly identified as an extremely dangerous threat to humanity, if not life itself.

The Lawrence Livamore hydrogen tanks are cute, impressive even, but they don't actually address the other big issue in hydrogen fueled automobiles, the transport (and macroscale storage) of hydrogen. Even if one can safely store hydrogen in an automotive fuel tank (and I'm not sure these tanks can be built economically and reliably) it is still not possible to transport gases long distances at economically acceptable cost. (Neither is it possible to transport electricity long distances though people often wax romantic about superconducting power lines that might be built in some imaginable future.) Moverover, even if the tank is secure, you still have fuel lines, which the high molecular speeds of hydrogen, low viscosity, etc, still place limits on the safety of hydrogen fueled automobiles. In any case, hydrogen isn't a form of energy. It is simply a means of storing energy, and a dubious one at that, if not on safety grounds, then on economic grounds. I think we would spend our resources wisely in building a sane energy infrastructure (as in primary sources) than a possibly pleasant and appealing way of storing that energy once we've gotten it.

I'll leave aside the Naderist anti-corporate arguments which I find specious and hardly germane to the conversation. I don't think that a change in the energy infrastructure will in any way involve a change in our economic system.

[Trillo]

25. Dubious Paradigm: Why Transport Mega-quantities of Hydrogen?

The fuel lines in the many working-prototype hydrogen-vehicles don't seem to be an insurmountable problem.

I'll leave aside the ... anti-corporate arguments which I find specious and hardly germane to the conversation.

Perhaps we all have to live in a world with other entities who do find deep meaning in hidden and unaccounted for costs.

I don't know if long-distance transportation of hydrogen from production facilities to dispensing stations is the best conception of how this hydrogen economy could shake out, but given the corporate need for hierarchy and the permeation of corporate influence throughout our society, it's perfectly understandable that people may be trained to think that way. Transporting mega-quantities seems to be the old (and current) paradigm with crude: finding its geographic location, drilling, then transporting it from that well to the purchaser's location, to be transported again, eventually to end up at the end-users location.

Since this ceramic hydrogen production process is based upon water and sunlight (and the titanium oxide ceramic, which can presumably be safely transported anywhere) the question transforms from the old crude-in-the-ground geographic location to: where is water and sunlight?

There are details that haven't been released regarding how much hydrogen is produced by a 10M x 10M set of cells. Is it possible to envisage hydrogen-fueling stations that are also hydrogen-production facilities, located on, say, 1 acre of land?

This might be safer than transporting large trucks of low-pressure low-temperature liquid hydrogen (or truck-sized room-temperature 70-megapascal tanks) and if so, likely safer than the current transportation of semi-truckload quantities of refined gasoline to dispensing stations.

[NNadir]

8. There already is a cool "catalyst" for splitting water.

It's called chlorophyll. The existence of chlorophyll proves that the photochemical decomposition of water is possible at relatively low energies, that of visible light.

Technically neither this material nor chlorophyll are "catalysts" at all, since they do not effect the activation energy alone but do in fact change the energy of the (chemical) system as a whole. Such systems are energy conversion devices, in this case converting electromagnetic kinetic energy into chemical potential energy.

I think that photochemical systems like this have a huge potential, although I would imagine that the realization of commercially viable system is a long way off. I don't necessarily believe that we have enough time left to place our eggs in a "long way off" basket.

[Dogmudgeon]

10. Direct Link

Straight from the horses' -- I mean, investigators' -- mouths. Or pens. Or whatever -- here's the link:

http://www.unsw.edu.au/news/adv/articles/2004/aug/Solar_hydrogen.html

This looks good. Keep your fingers crossed.

--bkl