Above: The Sun (seen here in ultraviolet) is the ultimate nuclear fusion reactor, but can we harness this power on Earth?
Last week, we compared the human and environmental cost of nuclear power and fossil fuels and nuclear came out as the clear winner. But nuclear power’s current means of extracting the power of the atom – nuclear fission – is still far from perfect.
To truly harness the energy locked away within the atom we need to look to the Sun.
The Sun is essentially a massive nuclear furnace but, instead of tearing atoms apart – as nuclear fission reactors do – our local star uses its massive gravitational power and million-degree heat to fuse atoms together. Fusion reactions can unleash many times more energy than nuclear fission and, instead of a mess of radioactive particles, the only byproduct is a harmless helium atom. When it comes to liberating energy, nuclear fusion makes fission look down-right clumsy.
Unfortunately, the mechanisms that make fusion possible in the core of the Sun – tens of millions of degrees and a star’s worth of gravity – are very difficult to recreate on Earth.
Scientists have been trying to master nuclear fusion since the 1950s and it has become a bitter joke that nuclear fusion and ‘power too cheap to meter’ has been 25 years away ever since. Now it is 2012 and nuclear fusion as a reliable, practical power source is still at least 25 years away. That’s not to say that the industry hasn’t made huge advances, it’s just the problem was far greater than anyone could ever imagined back in the 1950s.
The two most promising methods have made huge advances in recent years. One method, inertial confinement fusion, will use lasers to bombard a pellet of fuel with more energy than is used by the entire United States in a fraction of a second.
But perhaps the most promising contender is a method called magnetic confinement fusion, which uses magnets to squeeze atoms together in a 150million-degree ring of plasma.
Several of these devices, also called tokomaks, are in operation around the world but, so far, only one has (albeit briefly) managed to create more power than was put in. Located near Oxford, the Joint European Torus (JET) is the current world leader in this area of fusion science.
The lessons learned at JET are being applied to a next-generation facility being built in Cadarache, France. Called the International Thermonuclear Experimental Reactor (ITER), it should be able to match the power output of an average-sized coal-fired power station.
That may not sound impressive but all that energy will come from fuel extracted, not from environment-destroying mines or polluting refinement facilities, but from good old-fashioned sea water.