Thursday, May 21, 2009

Abundant Energy from Water and CO2?

Northwestern University scientists aim to go where no scientist or engineer has gone before. They plan to use H20 and CO2 to create syngas and subsequent hydrocarbons, with the final end product being H20 and CO2!
Researchers at Northwestern University are proposing, and have begun experimental validation of, a renewable liquid-fuel energy storage cycle based on the co-electrolysis of H2O and CO2 using a solid oxide electrolysis cell (SOEC) powered by renewable electricity to produce syngas. The syngas is then in turn converted into liquid fuels (e.g., methanol or synthetic hydrocarbons) which could be used in a direct fuel cell.

The direct fuel cell produces electricity, with water and CO2 as byproducts of the oxidation of the liquid fuel in the fuel cell. These would be captured and recycled back into the co-electrolysis process. _GCC
As you can see from the diagram, O2 is removed from the CO2 and H20 mix in the electrolyser to yield CO + H2 -- syngas! Syngas can be converted to liquid fuels, which when reacted in a fuel cell will yield CO2 and H20. These products can then be used as reactants in the electrolyser once again.

There is a bit more involved, of course. There will be a great deal of fancy catalysis going on at all stages. More at link above and here.

Most approaches for using CO2 to create energy that do not involve a biological intermediate, are PR stunts and gimmicks. But biology achieves its magic via biochemical catalysis, which can be reproduced and mimicked by scientists in the lab and by chemical engineers in the processing plant. My main concern is that humans may use so much CO2 for energy that the biosphere of the world will go starving for its vital food gas. ;-)

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