This approach seems interesting: > "Heirloom, a company working on capturing CO2 directly from the air, recently made headlines after raising $53 million in venture capital. For the XPRIZE, Heirloom teamed up with a company called Carbfix, which specializes in turning CO2 into stone. Carbfix is already demonstrating its technology at a working carbon removal facility in Iceland."
Note also that there's a real tie-in with SpaceX here, which runs rockets on a variety of fuels, i.e. RP1 which is essentially highly refined jet fuel, and methane, CH4. Mastering carbon capture and conversion technology, i.e. running processes like CO2(atm) + H20 -> C + H -> CH4, long chain hydrocarbons (RP1), would be critical to synthesizing fuel on Mars for example, which has an atmosphere of CO2 and apparently, water ice in the subsurface. This could also make SpaceX independent of fossil fuels: imagine a giga-scale carbon capture and methane synthesis factory in Texas providing all the fuel Starship needs.
Also, in a fossil-fuel free world, international air travel would require jet fuel, and that's possible with DAC and water-hydrogen, via a modified Fischer-Tropsch process, first used with coal gas / steam as inputs.