I watched a very interesting presentation by Bill Gates on one of my favourite websites that bring innovative ideas from many people together. He mentioned some of the initiatives going on around the world to reduce the impact of producing energy, and went into some detail of what he was involved in personally.
One of the things that he's working on is creating nuclear power plants that would burn depleted uranium (which is the waste from nuclear power plants today). This will eliminated more than 90% of the waste form nuclear power today, since they will use the waste of the process used today to power newer processes in the future.
I believe that this is one of the more realistic ways of creating long lasting power for the world over the next 200 years.
If anyone is interested in seeing the wh*** presentation this is the link: http://www.ted.com/talks/bill_gates.html