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Blood Protein Used to Split Water
brian0918 writes "The Imperial College in London is reporting that genetically-engineered blood protein can be used to split water into oxygen and hydrogen. The abstract can be viewed for free from the Journal of the American Chemical Society." From the article: "Scientists have combined two molecules that occur naturally in blood to engineer a molecular complex that uses solar energy to split water into hydrogen and oxygen. This molecular complex can use energy from the sun to create hydrogen gas, providing an alternative to electrolysis, the method typically used to split water into its constituent parts. The breakthrough may pave the way for the development of novel ways of creating hydrogen gas for use as fuel in the future."
The mention efficiency many times in the article, but do not mention the most important efficiency number - that is total energy in/out.
... at 4.7 MJ/L (Wikipedia) * 1/1000 (L/mL) * 1/3.6e6 (kWh/J) * 1e6 (J/MJ) =
So, a quick calculation of efficiency:
FTA
Light in:
6 hours, 450 W light = 2.7 kWh
H energy out:
0.044 mL H
= 5.7 e -5 kWh
Disclaimer:
This probably has an error, please help me correct it.
It has been a really long time since I did physics or dimensional analysis.
I could not find in the paper the pressure for the 0.044 ml of generated hydrogen, nor it's weight, so I made a gross assumption the energy density listed in Wikipedia (at 700 bar) was close enough.
Regardless, if you put in 2.7 units of energy and get out 0.000057 units... that seems really (s)low.
It has, it's called photosynthesis. Granted, here you're not liberating free hydrogen. But to counter the GP argument of using up all water on earth... can you imagine how incredibly unstable the local environment would become for one of these organisms in the wild? They'd be very liable to kill themselves off either through pH changes or simply setting their environment on fire if they reproduced unchecked. That combined with the fact you could never split all the water on earth faster than it will recombine if sunlight is your only energy input.