> Cost effective fusion reactors
We *might* build a working fusion reactor someday.
However, we already know it will not be cost effective. Everyone knows this. The head of the French nuclear research group and the director of the Max Planck Institute co-wrote a paper explaining why. So did the former director of the US fusion program. So have lots of other people.
The problem is very simple. A wind turbine consists of a generator, a turbine, and a metal pole. A coal plant consists of a generator, steam turbine, cooling, piping, coal boiler, scrubbers and a very large building. Thus, after initial development during the 1990s and 2000s, wind turbines have become much cheaper than coal plants. As a result, coal plant construction has fallen. You may point to China, but China is installing more wind than coal, as is everyone else on the planet.
And this will be true forever. The inherent comparative complexity of the two systems means that wind will always be cheaper. In fact, even if you skip the boiler, the rest of the plant is still more expensive. Make sure you understand that; a complete wind turbine is less expensive than half of a coal plant.
A fusion plant consists of all of the same parts as a coal plant, except we replace the boiler with a FANTASTICALLY EXPENSIVE fusion reactor, lithium cooling system, tritium extractor, superconducting magnets, etc etc. This part will always, always, be fantastically more expensive than a coal fired boiler. So it will never, ever, be cheaper than wind turbines. Ever. Not even remotely close.
At this point you'll want to say something like "you can't predict the future" or similar twaddle, in spite of science having been invented to do just that. But there's a more powerful counterargument: as it stands, wind is cheaper than a coal plant without a burner. So even if you can build the fusion reactor for zero dollars, no one will build one. So now you start thinking of ways to lower the cost of the rest of the system, inserting unobtanium or some science fiction energy extraction system. The problem is you've just made coal and fission cheaper too.