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When people talk about a nuclear debate they usually mean fission. However, there is another form of nuclear power, and while it is not yet practical, one day it could be far more important.
Most of the energy entering the Earth's biosphere comes from nuclear fusion processes in the Sun. As such, fusion is the ultimate energy source of all life on Earth.
Harnessing fusion power in the laboratory is the philosopher's stone of science. If harnessed, nuclear fusion offers abundant base-load energy with zero greenhouse gas emissions, very little radioactive waste, and no threat of nuclear weapons production.
Taken together, the Earth's reserves are sufficient to power civilisation for billions of years. The only exhaust gas will be helium, which is naturally lost to space and cannot represent a long-term atmospheric contaminant on Earth.
For fusion researchers, the promise of abundant, safe energy is one that 30 years of intensive research has yet to achieve. The problem is simple: how do you push miniscule nuclei close enough together so they fuse and release energy?
Gravity does this on the Sun, but gravity on Earth is too weak for this to happen under everyday conditions. Scientists cannot manipulate the force of gravity to mimic the Sun; therefore they must find another way to make nuclei merge.
One approach to fusing nuclei is to push them together with extreme pressure using many high-powered lasers. Another is to heat the nuclei up so that they move so fast that they sometimes merge when they collide. This means heating the nuclei to extremely high temperatures. For example, fusion occurs between deuterium and tritium (D-T) at temperatures around 100-150 million degrees Celsius (Fig. 1).
Deuterium and tritium are chemically similar to hydrogen. Each has a single proton, but while hydrogen has no neutron, deuterium has one and tritium two.
Deuterium is as safe as hydrogen and occurs naturally in seawater. Tritium is more dangerous than hydrogen as it radioactively decays into helium-3 via beta decay. The beta particle radiated by this reaction can, however, be stopped by a piece of paper.
A working reactor would make tritium onsite by combining the neutron from the D-T reaction with lithium. If the neutron is captured by other nuclei it...