Nuclear fusion is what powers our sun and all other stars. It is a process by which two atomic nuclei combine at a very high temperature to form one single heavier nucleus. This releases a massive amount of energy that is completely clean - no emissions and no pollution. It could be the ultimate energy source for humanity, but it has never been commercially harnessed. The international group called ITER is a coalition of 30 countries led by the European Union. They have been working on an experimental fusion reactor in France for some years, and hope to be operational in 2034.  

Commonwealth Fusion Systems in the US is going a step further by building the first nuclear fusion power plant that will actually be for commercial use. They use a system called “tokamak”, which is the same system that ITER uses. It is a doughnut-shaped chamber enclosed by superconducting magnets that will heat hydrogen isotopes to 100 million degrees Celsius. This causes them to fuse together and release energy. There is no significant fuel cost, because the hydrogen isotopes are easily obtained from seawater. The plant is expected to be operational by 2032, and will be capable of generating 400 megawatts of electricity. That is enough to power over 200,000 homes.