I believe that small scale fusion will be the long term energy solution and it may not be too far away. Several of the "cold fusion" experiments have the basic setup. They just need to keep the physical structure of their equipment aligned with the universe.
Fission power is much to expensive when one includes risk and cleanup. Even newer plants designed to be safer will still have large scale and transmission power loss and there is still the possibility to modify for weapons development. The spent fuel from fission power plants is a long term expense and problem. This waste material is a hazard and a target for terrorist that does not just go away; someone will be paying for the care of this stuff for a very very very long time. We all live with the risk of having it around until someone comes up with a way to pay for the safe storage of radio-active waste for thousands and thousands and thousands of years.
More immediate is global warming. This is a problem that is growing every year and becoming more serious and more costly to address.