|Europe Aims for Endless Energy
27 November 2003
Europe's scientists hope to mimic the power of the sun and create limitless
energy on Earth with the help of a £6bn experiment in the south of France.
Ministers in Brussels gave the go-ahead yesterday for Iter, the world's
biggest and most ambitious fusion reactor, at Cadarache near
Aix-en-Provence. It will be 10 years in the making and, in its 20-year
operating life, researchers will experiment with a kind of slow hydrogen
bomb in the hope of extracting vast amounts of clean energy from tiny
amounts of heavy water.
Iter will replace Jet, the current joint European fusion research project,
based at Culham, Oxfordshire.
Sir Chris Llewellyn-Smith, head of the UK fusion programme, said yesterday:
"The Iter project will allow a major step towards an inexhaustible source of
environmentally friendly power."
Petroleum and coal deliver chemical energy liberated by the breaking of
chemical bonds in the form of fire. Nuclear fission of enriched uranium
exploits the energy released by the breakdown of a unstable heavy atom to a
lighter one. But the "ash" from a fission reaction is radioactive and it
stays too hot to handle for thousands of years.
The great prize has always been fusion power: the fusion of two hydrogen
atoms to make one of helium, releasing huge quantities of heat. Every
second, the sun converts 600m tonnes of hydrogen into helium and illuminates
and warms this planet from 90m miles away.
To do the same on Earth, engineers and physicists have to collect deuterium
and tritium -- isotopes of hydrogen -- and heat them to more than 100m C, many
times hotter than the heart of the sun. At these temperatures the heavy
hydrogen would become a plasma, a ball of subatomic particles which would
fuse to become helium and a shower of neutrons and a supply of heat. One
kilogram of heavy hydrogen would supply the heat now generated by 10m kg of
fossil fuel. There would be no greenhouse gases, no soot, and no long-lived
radioactive waste. The oceans contain all the heavy hydrogen such reactors
Fusion power would, in theory, be safe, because the challenge is not to stop
a fusion reaction, but to keep it going. But that is the catch. If plasma at
100m C so much as touched anything, it would go out like a light. The trick
is to keep tiny pellets of fuel suspended in a kind of magnetic "bottle" in
a sealed chamber. Then engineers would have to pump blasts of laser fire at
the pellets, compressing them to 20 times the density of lead, at which
point they would start to behave like tiny stars, releasing a thermonuclear
blast of neutrons to heat up a containment wall many metres away.
Fusion's most ardent enthusiasts believe that a viable power plant is 30
years away. Iter is just another stage in the research.
Although the Cadarache site has Brussels' backing, the decision has yet to
be confirmed by the other partners in the project. These include Canada, the
US, Russia, Japan, South Korea and China. There is one other candidate
site -- at Rokkashomura in Japan -- and the final decision could be made in
Washington next month.