It is my opinion that efficient Nuclear Fusion for use as a power source is only a matter of time. A look into the history of fusion power shows that there has been a substantial increase in efficiency, temperature, and confinement time from the 50's up to now.
Fusion can already be shown to be safer in the long run than Fission, with its major waste products from the dirtiest fuels lasting on about 100 years instead of thousands. This greatly reduces the expense, danger, and construction requirements of waste storage sites.
In addition, there is literally zero chance of any dangerous "meltdown" or similar incident at a fusion plant. The physics behind fusion require that we heat the fuel to millions of degrees AND keep it confined to a space sufficiently small enough for it to fuse efficiently. Any loss of containment instantly causes the fusion reactions to cease, as the confinement of the fuel has been lost.
Now, I want to make sure that you understand that there ARE dangers with Fusion just like there are with any power source. The easiest fuel to use produces large amounts of radiation that, while being able to be shielded and harnessed, can still be dangerous if people do not follow safety procedures adequately. A breach in the reactor itself would release radioactive tritium and similar substances, however the amounts and makeup of these are drastically less harmful than any Fission reactor. That of course is assuming a complete breach from the reactor all the way through any protective containment buildings and similar objects.