Egregoros

What I'd like to do is create a sink for consuming solar energy in the summer. Take charcoal made from hay -> generate methanol and store it.

One interesting reaction you can do with methanol is this thing: https://en.wikipedia.org/wiki/Gas_to_liquids#Methanol_to_gasoline_(MTG)_and_methanol_to_olefins

It generates a bunch of heat, so you can run that reaction in the winter and heat the house with it, and the output is *surprisingly* similar to 87 octane gas, given it doesn't involve any kind of fractional distillation.

The problem for making methanol from hay or woodchips is not intractable, it's just that the way that is known to work is annoying.

A round bail might have 200kg of carbon, if you could turn that ALL into methanol (CH3OH) that would make you about 533kg (178 gallons) of methanol - by adding 66.7kg of hydrogen and rest of oxygen since methanol has an O.

Hydrogen has 33.3 kwh/kg of chemical energy, and electrolysis cells are about 70% efficiency, so you would use about 3173 kwh of electrical energy in order to make that hydrogen.

The resulting 533kg of methanol has 2945kwh of chemical energy. 200kg of carbon has 1820kwh, so 1820 + 3173 - 2945 -> 2048kwh of loss in the methanol process because it generates heat.

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Now the problem is that a bail of hay is not pure carbon, it's a whole bunch of tars and contaminants, and any contamination of the methanol catalyst is going to put a fast end to that process.

You can make it into pure carbon by heating it and driving off the tars, i.e. charcoal kilning, but you lose carbon in the process. But even once you have pure(ish) carbon, you still have a problem because carbon is a solid - you need carbon dioxide and/or carbon monoxide to make methanol.

Again, you could burn the carbon, but that is a massively lossy proposition. All of your 1820kwh that was to be contributed by the carbon goes away because you've just burned the carbon and made heat - which you can't really re-use in the process.

If you burn the carbon in a steam environment, it will rob oxygen from the water and output CO2 and hydrogen, thus re-capturing some of the energy that was lost from burning it, but you're still making an insane amount of heat.

To add insult to injury, the methanol process needs to run at 100bar (1500psi) so you need to compress that CO2 and H2, so you're gonna need to cool it down a lot. The methanol process also makes more heat, and that needs to be kept at 300C or else you melt your catalyst. The methanol process also makes heat, and you can use that heat to make something like steam - since it's 300C, but the carbon + water -> hydrogen + CO2 reaction needs 900C, so basically you're forced to send in oxygen and burn the carbon - and make more heat.

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So the big question is: Is there any way to do carbon + water -> hydrogen + CO2 in a cold (<300C) environment, by using electricity and/or catalysts to drive the process?

If the answer is yes, then we can go from 3 big lossy heat-generating events, down to only 2 (charcoal kilning and methanol reaction)...