Tokamak Energy, one of the leading private energy companies, recently announced a milestone in their UK reactor as it successfully generated plasma in its core. The fusion reactor, named ST40, can produce temperatures of up to 100 million degrees Celsius (180 million degrees Fahrenheit) or seven times hotter than the center of the Sun.

At this temperature, hydrogen atoms can fuse into helium, releasing heat that could be used to make steam turning a turbine, generating nearly limitless energy with scant carbon emissions.

Today’s nuclear reactors rely on nuclear fission where atoms are split apart, and not fused together as in ST40. Fission relies upon heavy elements, uranium or plutonium and produces nuclear waste that must be permanently and deeply buried. Fusion relies on highly powered magnets to control a plasma (ionized gas) at extreme temperatures and requires only salt water to function.

Fusion reactors do not run the risk of meltdown, as was seen in the fission reactors at Fukushima, Chernobyl, and Three Mile Island so there is an environmental benefit to changing the face of nuclear energy. The major setback with this kind of energy source, however, is the cost. The largest functioning fusion reactor in Germany costs upwards of 14 billion dollars and, thus far, fusion reactors use more energy than they emit.

The record for the longest lasting plasma is only 6 minutes and 30 seconds. Still, reaction outputs have increased significantly from only milliwatts in the 1970s to 16 megawatts today. One megawatt may power 400 to 900 homes. The current record of fusion energy output is 65% and was made only recently in 1997. Tokamak Energy plans on providing its first electricity by 2020 and is slated to provide energy to the electrical grid in 2030. Other nations are working on tokamak reactors so it remains to be seen whose reactor will come online first.