I wonder if corn could be grown hydroponically?


Oh yeah, and as for fuel for cars... A solar panel of just a few square meters should generate enough power that it could fully charge an electric vehicle's batteries for the day... perhaps several days. As battery energy density increases, as does solar panel efficiency, there probably won't be any need for hydrogen at all. Hydrogen is an expensive step that could be skipped completely, at least in commuter cars. Trucks may still run on hydrogen though.