Comment by adrian_b

Technologies of making synthetic fuel using energy, water and carbon dioxide are a century old and they have been used for producing great quantities is special circumstances when the price did not matter, e.g. by Germany during WWII (though at that time they produced cabon monoxide by burning coal, instead of reducing carbon dioxide from air, because this was cheaper).

The only reason why they are not used now is that the current price of fossil oil is significantly lower.

There is research to develop more efficient methods for the synthesis of hydrocarbons, based on the electrolytic reduction of carbon dioxide, but their progress is slow, in good part because such critical research is funded much less than frivolous research, such as that for AGI.