Solar energy, carbon dioxide and water directly to butanol. In other words, store solar energy directly as fuel. There are other versions that generate hydrogen

Solar energy, carbon dioxide and water directly to butanol. In other words, store solar energy directly as fuel. There are other versions that generate hydrogen, but that has a much lower energy density than liquid fuel. Just modify your existing ICE to run on butanol and you're good to go. <a bit of hand waving there.> See https://www.intelligentliving.co/biofuel-solar-energy-co2-water-microorganisms/ https://www.intelligentliving.co/biofuel-solar-energy-co2-wa... for where we were a year ago.