[glang]

Its also limited by the production capacity of ethanol. You need the raw vegetable material and of course the industrial complexes to make it. Theres serious doubt that at the moment CO2 emissions are being saved because of the fuel used to produce and transport the stuff. I suppose there is a tipping point where finally this is achieved but modifications will be needed in internal combustion engines to optimise their running on that level of ethanol so we may never reach it before electric takes over...