Sugarcane and switchgrass might be able to close the loop, but these take a lot of mechanical processing and land to do so, which could introduce additional cos

Sugarcane and switchgrass might be able to close the loop, but these take a lot of mechanical processing and land to do so, which could introduce additional costs. The promise of syntetic fossil fuels from things like water and CO2 is that you don't need a lot of land, you just need energy, and that energy can be renewable.