[orcafood]

CO2 removed from the emission source would be way more efficient over removing it from thin air. I bet they are using soda lime, CaOH2 with catalytic NaOH. Since energy is lowered when CO2 forms carbonate ie spontaneous, wouldn't energy need to be added to release the CO2?

Usually to make hydrocarbons they would do it step by step, first CO2 would go to CO via some catalyst then it would be separated out. A variety of well known reactions can be used to try and generate hydrocarbons under intense pressure over catalyst beds from the carbon monoxide. Beating out syngas with a photocatalyst to cleave the CO2 to CO is unlikely for the near future. Plants are very very good at fixing carbon and look at how slow they grow. Eventually supply will go down though, demand up, and the prices will come closer. My good friend did this as his final project at NCSU, they took raw syngas and synthesized methanol at a theoretical plant they designed, of course at the lowest possible cost.