Over at Peak Oil Optimist
, Rob waxes optimistic
about a catalyst for the electrolytic reduction of CO2
. He specifically claims "Using a platinum-based catalyst, the team was able to convert raw CO2 to various hydrocarbon chains (benzenes and simple sugars)."
Maybe there's a flaw in the PowerPoint translation system of OOImpress and it leaves something out, but I have been over both slideshows
and I don't see it. The presentation mentions sugars, but I could not find anything to indicate that such complex molecules had been produced. As far as I can tell, the accomplishment of the researchers is to have reduced CO2 to oxylate ion (C2
); the significance of oxylate is that it has covalently bonded carbons. I am not a chemist and I'm in no position to say if this is a major step toward synthesis of less-oxidized molecules. The cell-voltage requirements of ~1.7 V is more significant, as 1.7 electron-volts is in the energy range of visible photons; the relevance for artificial photosynthesis is obvious.
As far as I'm concerned it would be just as good to produce carbon monoxide (CO) and carbonate ion (CO32-
); carbon monoxide is both a fuel and a base for synthesis, and carbonate ion can be immobilized relatively easily. (Perhaps too easily, if it can't be kept from clogging equipment like it clogs my tea kettle.)
But that's just one way to convert CO2 into fuel. Other pathways are better-understood, and if you have a source of pure CO2 and a source of hydrogen it appears that the doorways are already open. Consider the synthesis of methanol. Methanol synthesis plants are well-understood and inexpensive, to the point that methanol synthesis is being combined with IGCC electric plants
. (I thought I had several links regarding this subject, but I seem to have mislaid them.) Once you have methanol, you can synthesize gasoline
with what appears to be relative ease. Other possibilities include synthesis of methane via the Sabatier reaction (proposed for Mars in-situ propellant production
) and heavier hydrocarbons and olefins
None of this gets you anywhere unless you have a method of capturing and purifying carbon dioxide, and a source of energy (either in the form of electricity or hydrogen) to power the process. The source of the energy is all-important. The prime mover in all cases comes back to one of the usual suspects, and adds further difficulties into the bargain. It appears to this observer that chemosynthesis is one of the smaller difficulties here.