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by woofuls 3928 days ago
Have they made a cheap device entirely out of sustainable materials? No. The photoactive GaAs/InGaP would be extremely expensive to fabricate. Have they tested it for commercially relevant timescales? 40 hours is hardly close, realistically they need to do stability testing for thousands of hours. They did use non-precious materials to protect the semiconductors from the corrosive solution and inexpensive catalysts, but this is a very long ways from practical. Further, they didn't even hit the 10% efficiency mark which has long been heralded as starting point for these devices.

It is not clear to me that this approach could ever be economically viable even with the right semiconductors. H2 just doesn't provide enough bang for your buck.
1 comments
avmich 3928 days ago
> H2 just doesn't provide enough bang for your buck.

This seems to be a stretched generalization. You do need energy accumulator to use it in transport systems, and H2 is pretty efficient by mass. It's not without problems of course, but dismissing it as a whole...

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woofuls 3928 days ago
Absolutely not. H2 gives 5.6 MJ/L @ 700 psi, which is too weak compared to diesel which gives 35.8 MJ/L @ 1 atm. Also, compressed H2 is considerably more difficult to work with than diesel.

The Department of Energy mandated that these same researchers pursue liquid fuels in the future (note, they do not mean H2) from the reduction of carbon dioxide, because they do not think H2 stands a chance.

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zw123456 3927 days ago
Right but the advantage of H2 using a system like this could make solar a viable round the clock energy source. If one could run on conventional solar cells during daylight hours whilst also using another array of these to stockpile H2 for use in a fuel cell at night, then it could provide 24hr power vs. Lion batteries with .6MJ/kg. Clearly they have a lot more work to do before it would be viable, but I think it has interesting possibilities.
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woofuls 3927 days ago
Right now every solar hydrogen production technology is an order of magnitude more expensive than steam reforming with little opportunity of ever becoming competitive.
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