Nuclear fusion

Possible energy source - not viable yet.

Energy inputs

Major problem

Takes more energy than it produces. EROI is still below 1. ^{[ELABORATION needed]}

Scarcity of fuels

Problem in some cases

There are no viable reactors yet, but of the prototypes so far, some rely on tritium, an extremely rare form of hydrogen. Supply would be an issue.

Other possible fuels include deuterium, lithium or boron, which are comparatively less rare. In any case, only small amounts of the fuel are needed to produce large amounts of energy.^{[QUANTIFICATION needed]}

Ideally, fusion reactors could rely on ordinary hydrogen, which would be abundant enough to last hundreds of millions of years.^{[QUANTIFICATION needed]}

For now, all of this is hypothetical - regardless of fuel, no prototype so far has been able to produce more energy than it takes to run it.

See also

• Nuclear fission