Nuclear fusion

Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifested as either the release or absorption of energy. This difference in mass arises due to the difference in atomic "binding energy" between the atomic nuclei before and after the reaction. Fusion is the natural engine that powers stars.

There is plenty of hydrogen in the oceans to sustain hydrogen fusion for millions of years at the consumption of 2kg/s. About one hydrogen in every 6000 in ordinary seawater is deuterium (a hydrogen isotope). It is estimated that if all the deuterium in Earth's seas were collected and burned in fusion power stations, it would supply all our energy needs at the present rate of consumption for the next 5-10 billion years, roughly the expected lifetime of the Sun.

A nova reactor can be used to generate elements heavier than iron using conditions similar to those found in a supernova, although in a smaller-scale, much more controlled way. Nova reactors do not produce net energy and so must be fed energy to achieve the insane temperatures and pressures needed for these fusion events to occur.

Muons can be used to catalyse the initiation of a fusion reaction without the need of immense pressures and temperatures. The heat generated by the reaction will then act to provide the conditions needed for further reactions. This is called cold fusion.

Spaceships, large oceanic vehicles and large energy-hungry cities use various types of fusion reactors. Plasma is preferred over antimatter as it is safer, and is confined by a magnetic field. Fusion is widely used as a power source in Type I and beyond.

In comparison, nuclear fission releases far less energy.