Sounds like it would be more realistic to just have every vehicle tow a trailer planted with sod so the magic unicorns can graze. To fill up, you just pull over, collect some of the droppings, drop them into the tank, and off you go.
Obama, John P. Holdren [White House Science and Technology Czar] the EPA and the Dept of Energy are suing, regulating, blocking, shutting down and in every way possible, working to de-devolve [cripple] the U.S. economy. By hamstringing fossil fuel [cheap, available energy] they believe costs will rise and GREEN technology will become competitive — meanwhile free market capitalism goes down the tubes.
A more realistic source of renewable energy would be to simply attach generators to the grave of Nikola Tesla, who is no doubt, spinning at several thousand RPM by virtue of having his name attached to this racket.