The potential for fusion energy is enormous. The JET experiment used the elements deuterium and tritium -- which are isotopes of hydrogen -- to fuel the fusion. Those elements are likely to be used in commercial-scale fusion,and can be found in seawater.
"The energy you can get out of the fuel deuterium and tritium is massive. For example, powering the whole of current UK electrical demand for a day would require 0.5 tonnes of deuterium, which could be extracted from seawater -- where its concentration is low but plentiful," Tony Roulstone from the University of Cambridge's Department of Engineering told CNN.
He said the fusion generated by JET was around the same as a wind turbine, and could power one house's energy for a day.
"But if generated repeatedly, it could power thousands of houses."
Experts say the results prove that nuclear fusion is possible, and no longer a pipedream solution for the climate crisis.