Making Renewable Hydrogen

I think these guys on this “renewable energy” group on Facebook like to screw with readers, getting them to buy into the most ludicrous concepts imaginable.  Maybe they have an internal contest going, to see who can get the most “likes” for the most preposterous ideas. Most of these are not theoretically impossible, but they, like this one, come under the heading: not impossible, but fabulously impractical.

It’s essentially:  Use solar to electrolyze water, then combine the hydrogen with atmospheric CO2 using Fischer-Tropsch to make methane (CH4).

Issues:

Electrolyzing water is inefficient and expensive, but it’s done in cases where the hydrogen is getting put to good use (which is not the case here).

The concentration of CO2 in the atmosphere is 400 PPM, meaning that 99.96% of our air is not CO2.  Without point sources of CO2 with the concentrations at 20% or so, this is impractical in the extreme.

If you’re going through all the expense, you’re not going to make methane; you’re going to make something that has far greater value: gasoline, diesel, or jet fuel.