Novel Alloy Could Produce Hydrogen Fuel from Sunlight

[HysteryDiagnosis]

Possibly the most important scientific article ever.

http://www.sciencedaily.com/releases/2011/08/110830151229.htm



Scientists from the University of Kentucky and the University of Louisville have determined that an inexpensive semiconductor material can be "tweaked" to generate hydrogen from water using sunlight.

<snip>
Using state-of-the-art theoretical computations, the University of Kentucky-University of Louisville team demonstrated that an alloy formed by a 2 percent substitution of antimony (Sb) in gallium nitride (GaN) has the right electrical properties to enable solar light energy to split water molecules into hydrogen and oxygen, a process known as photoelectrochemical (PEC) water splitting. When the alloy is immersed in water and exposed to sunlight, the chemical bond between the hydrogen and oxygen molecules in water is broken. The hydrogen can then be collected.

[ChairmanAgnostic]

1. the oxygen can be collected too

which suggests use for space use, so long as they are close enough to the sun.

[TheWraith]

2. Most important scientific article ever?

I take it you've never heard of either electrolysis or photovoltaic reactions? If it's highly efficient, then it'll be useful, but "most important scientific article ever" is stretching it.

[HysteryDiagnosis]

3. Let me say it again, this is the most important scientific article ever produced anywhere

in the universe.

[drm604]

5. In the universe?

I agree that this may be a very important breakthrough, but we have no idea if there's an alien race somewhere that's made an even bigger breakthrough of some kind.

[HysteryDiagnosis]

7. They don't have this technology, least not yet. n/t

[drm604]

8. How could we possibly know that?

:shrug:

[HysteryDiagnosis]

9. I just have a strong feeling about it.... and I am being facetious. n/t

[drm604]

4. I don't know that it's the most important article ever but...

Because pure hydrogen gas is not found in free abundance on Earth, it must be manufactured by unlocking it from other compounds. Thus, hydrogen is not considered an energy source, but rather an "energy carrier." Currently, it takes a large amount of electricity to generate hydrogen by water splitting. As a consequence, most of the hydrogen manufactured today is derived from non-renewable sources such as coal and natural gas.

Sunkara says the GaN-Sb alloy has the potential to convert solar energy into an economical, carbon-free source for hydrogen.

There are no figures in the article but it seems to imply that electrolysis is currently not efficient enough to be economical and that this new method is. So this could be a pretty big deal.

Of course, it's only being predicted in computer models. It remains to be seen what happens when it's actually tried.

[Ready4Change]

10. That's the real question.

Is this method cheaper than producing hydrogen by splitting fossil fuels?

Beyond that is another possibility: Would using the sun to split hydrogen from water using this method, and then feeding that hydrogen into a fuel cell, result in a higher energy collection rate than current PV cells?

I dunno.

[kristopher]

11. There are a wide array of methods to produce hydrogen

This is just one more. Even if it is a huge improvement in this particular part of the process, in the entire system that produces, distributes and uses hydrogen it would only amount to a minor overall change in the efficiency of the technology.

[Ready4Change]

12. I'm thinking of it in terms of powering a house.

I've a friend with a 2 kw PV system with battery backup good for about a days worth of conservative electric use. It's PV panels are able to maybe convert 18% of the sunlight that reaches them into electrical power. Then you have some power line and conversion losses. Let's say when he flips a light switch, in total, the sun to switch conversion rate is about 15%,

I'm wondering what the conversion rate would be if you replaced the PV panels with this technique, using sunlight and this catalyst to split hydrogen from water. Then take that hydrogen and feed it through a fuel cell to generate electricity. The power comes from the sun, but how much of the suns energy is converted, after losses to heat, and leaked hydrogen, and conversion inefficiencies in the fuel cell, etc? When that light switch is turned on, would this system have converted 10% of the available sunlight to electricity? 15%? 20%?

[kristopher]

13. Yes, there is a definite lack of detail in most early announcements of "breakthroughs"

For a home system like that I'm not sure the "sun to switch" metric is the best way to look at the challenge unless there is a significant constraint on the area available for harvesting light. While system efficiency is extremely important, in this case the inclusion of fuel cells as part of the system is prohibitively expensive. I don't expect to see fuel cell costs start to decline until they find a major niche to exploit. Personally I think that will be the electrification of the trucking fleet. Long haul trucks are expensive capital investments that have high operational costs for maint and fuel. Electrifying them with fuel cells running on (best to worst) reformed ethanol, natural gas or petroleum would probably produce significant savings over the life of the truck - IF the cost of the fuel cells can be reduced just a bit more than what I believe them to be now.

However, IMO that will still probably not get a home cost down to where it is an attractive choice relative to the alternatives. That's because right now 1) the price of solar PV is dropping dramatically and 2) the electrification of the vehicle fleet is bringing down the up front costs of heavy duty battery packs that are ideal for home storage. Additionally, the battery packs in the EVs are only suitable while they are able to store and deliver more than 80% of their new capacity. Once they drop to 80% it's recommended they be replaced. Eventually this is going to create a booming business for home storage based on these used batteries.

[WingDinger]

6. If it's that important, it will be monopolized for killing.