The CO2 + 2H20 -> CH4 + 4O2 has seemingly been done (per the paper linked). I agree that the issue would likely be economic factors, but perhaps it's worth inve

The CO2 + 2H20 -> CH4 + 4O2 has seemingly been done (per the paper linked). I agree that the issue would likely be economic factors, but perhaps it's worth investigating those more fully. There are already tankers that transport liquified natural gas all over the world, so there's clearly enough economic incentive for that. The question, of course, is the solar bit.