Still thinking

This 3rd year, our research teacher is preparing us to our research for the next year. But i cannot decide of my research. I am thinking of solving the problem in the society, global warming and oil price hike. I am thinking of biofuel as my research but others said that it is expensive. It is still needed to test the medium. I am trying to use dried leaves but it is difficult enough. I read one article stating that european researchers are trying to use the Landfill as the source of bio energy from the waste material. When i try to research about that kind of source. It says that a certain gas was available and existing to those waste materials. I think its a nice research but a little bit expensive