New York Times: Most research on renewable energy has focused on replacing the electricity that now comes from burning coal and natural gas. But the spill in the Gulf of Mexico, the reliance on Middle East imports and the threat of global warming are reminders that oil is also a pressing worry. A lot of problems could be solved with a renewable replacement for oil-based gasoline and diesel in the fuel tank – either a new liquid fuel or a much better battery. Yet, success in this field is so hard to …