Several fusion researchers who don't work for private firms told Nature that commercial fusion in a decade is overly optimistic. Tony Donné, programme manager of the Eurofusion consortium which conducts experiments at the Joint European Torus, says private companies say they will have it working in ten years, but that is just to attract funders. They all say that they are ten years away from a fusion reactor.
Melanie Windridge, the UK director of communications for the Federation of American Scientists and a communications consultant for the fusion firm Tokamak Energy, says that timelines should be seen as motivational. She thinks bold targets are necessary. Ian Chapman, chief executive of the UK Atomic Energy Authority, said that state support is likely to be needed to build a fusion power plant that feeds electricity into the grid.
Practical nuclear fusion seems to be on the horizon, whether it comes from small-scale private enterprise, huge national or international fusion projects, or a bit of both. Chapman is convinced that it will happen. Chris Kelsall is the chief executive of Tokamak Energy. He says that soon or later this will be cracked. It will be very significant.
A seventy-year dream.
Nuclear fusion is the only primary energy source that we have yet to exploit. The process that powers the stars was harnessed for hydrogen bombs in the 1950s, and technologists have dreamed of a more controlled way to use it.
Nuclear power plants release energy when heavy atoms decay. It is possible to produce energy by merging very light nuclei at high temperatures and pressures. Most attempts to harness it in a reactor involve heating the deuterium and tritium until they form a plasma, which is a fluid state of matter containing ionized atoms and other charged particles. fusion starts at lower temperatures and densities for these isotopes.
D–T fusion produces some radiation in the form of short-lived neutrons, but no long-lived radioactive waste. It is safer than fission because it can be switched off easily, and it can be brought below critical thresholds of temperature or density.
The deuterium and tritium are used to release energy. A fusion reaction can be created by this mix at around 100 million kelvin. The chamber can be made radioactive by the production of neutrons.
The fusion of protons with boron-11 (11B) doesn't produce neutrons, but it requires higher temperatures.
It's difficult to conduct in a controlled manner because of the challenge of containing the hot charged particles that are undergoing fusion at temperatures of around 100 million kelvin. Magnetic fields can be used to levitate the reactor. The instabilities in this infernal fluid make containment very difficult, and have so far prevented fusion from being sustained for long enough to extract more energy than is put in totrigger it.
Until this century, only state-run projects could muster the resources. The world's biggest fusion effort is being built in southern France and supported by 35 nations, including China, European Union member states, the United States, Russia, South Korea and Japan, with a price tag of over a billion dollars.
