besides biofuel I got an Idea. Ever used a toy car with a spring that stores energy ? U just key in the wounds on the spring and the energy is released as it unwounds. I am saying this because its a battery, yes it is. SO why not take it to a whole new level using this http://www.terradaily.com/news/materials-05zv.html If we create an array of this material then we may be able to store enough energy to run a real car for long time. Offcourse this has to be researched, I did google but no such attempt I could find. But then to charge the battery we must use a green source.