You don't, a little 250cc motorcycle will do the job in a very green manner.I think that the problem with cars is not so much what they're powered with, (fossil fuels, which are just stored solar energy, or something else that ultimately derives its energy form the sun), but why I need something that weighs over a ton to carry my 170 pound body around.
But I've been riding all my life and the general population constantly asks why, because they are so dangerous.
So when I "and they" want to feel safe, I get in my big Ram 1500 pickup truck and others get out of my way.