If using electricity, it's "easy", first you split water into hydrogen and then use the Sabatier reaction. Of course, any electricity is fine. One could get (m

If using electricity, it's "easy", first you split water into hydrogen and then use the Sabatier reaction. Of course, any electricity is fine. One could get (much) higher efficiency by using the heat from a nuclear power plant directly (never producing electricity) but I guess that would have to be a completely custom design. https://en.wikipedia.org/wiki/Sabatier_reaction https://en.wikipedia.org/wiki/Sabatier_reaction