Since the 70's we have been looking for green power, and I think I can safely say the "future is now". In the last few years I have seen some amazing innovation in this field, more then I have ever seen in the last few decades For example there have been huge leaps in bio-fuels, and power generation (i.e.: solar, wind, nuclear, etc.).
I have to admit one of the area I find most interesting is waste products to fuel/energy conversion. There is some very interesting innovation in this field, from methane capture to converting solid waste material into fuel. So personally I believe if these technologies play out, waste will be the future of energy.