Reposted from a reply I gave to that other thread of yours:
Firstly, fusion power research has been happening for decades with no real progress. Check out the Joint European Torus project. Fusion has occured, but only for virtually immeasurable instants of time. There has been very little progress in actually making nuclear fusion a viable energy source, despite much investment and effort.
The next 'best' option is nuclear power which is far from 'clean' and is very, very expensive to commission. Combined with the long-term problems associated with de-comissioning and the day-to-day process waste, it is far more economical to generate electricity using modern, efficient gas turbines (for example). This might change in the future, but for next few decades (in the UK at least) using natural gas is by far the best option, both economically and environmentally.