I'm told you'd get methanol from fermentation of cellulosic corn waste -- the stalks and shucks. Makes sense to me -- there's a reason they called it wood alcohol once upon a time.
Popular Mechanics once mentioned something called "dissociated alcohol" -- using the waste heat going out the exhaust manifold (c. 20% of the energy evolved from burning the fuel, used to expel the burnt charge from every combustion and not available at the crankshaft) to crack alcohol into two gases, CO and H2, and burning these in the cylinders without even needing the engine up to temp. It was supposed to up the mileage by quite a bit. Anything to this?
FWIW, somebody patented the process.
Solar: high installment cost, low running costs. Helpful to have a nice big desert handy... make photovoltaic units as immortal as you can and you'll see a steady long-term increase.
The ultimate in photovoltaic by any process is a Dyson sphere, however. Sci-fi types have wondered just how much such artifacts would resemble red-giant phase stars from a long way off.