The experimental fusion reactor will be constructed at Cadarache in southern France. It will be used to demonstrate whether nuclear fusion presents a vast and safe source of energy that could reduce the world's reliance on pollution- producing fossil fuels.
Speaking in Brussels, Pia Ahrenkilde Hansen, a spokeswoman for the European Commission, said construction on the plant could begin by the end of 2005.
"Now we can complete the final technical agreement for the project and start construction as soon as possible," Hansen said. "We hope that it will be by the end of this year. And we are, of course, extremely pleased that we were able to find a solution that allows this project to move forward with the full cooperation from the international research community."
The threat of global warming is bringing nuclear power, long out of favor, back into focus as a way of generating energy. The present nuclear-power process is based on fission, but many scientists have lain hopes on the process of fusion.
Fission is a process that leaves tons of hazardous radioactive waste, which can remain dangerous for eons. That's its Achilles' heel, along with the potential danger of accident, as happened with the Chornobyl disaster in 1986.
Fusion, on the other hand, leaves only grams of residue, and then only if impurities have crept into the process. With optimal design, no radioactive detritus at all remains.
Scientist Jaap van der Laan of the Netherlands Energy Research Center says fusion is the "green" version of nuclear-power generation. "Essentially, although you can describe fusion as a nuclear technology, which of course it is, it's a 'greener' form of nuclear energy than fission, and remains emission-free," he said.
What exactly is fusion? It occurs when lightweight atoms are fused together to make heavier atoms. To use this reaction as an energy source, a gaseous fuel must be heated to a temperature of more than 100 million degrees. At these temperatures, the gas becomes a plasma, and the plasma particles, deuterium and tritium, fuse together to form helium and high-speed neutrons. That releases energy, which can be used to generate electricity.
As such temperatures are far too high to be held by any container, one operating scenario calls for the hot plasma to be contained within a magnetic field. That would keep it constantly in looping paths that would not touch the walls of the container.
That is the basic idea. It has yet to be seen whether it is a practical process, hence the need for an experimental reactor.
The six parties involved in the project -- the European Union, the United States, China, Japan, Canada, and Russia -- will pool their expertise to build the first fusion reactor. Today's decision to build the reactor in France follows more than a year of wrangling.
The project's supporters say the prize is worth the effort. They say 1 kilogram of fusion fuel would produce the same amount of energy as 10 million kilograms of fossil fuel.
But environmentalists are far from convinced. Greenpeace nuclear expert Jan van der Putte says the clean-burning fusion does in fact leave a pollution footprint. "As to radioactive waste, you have large volumes generated, because you have a very, very aggressive neutron flux in the reactor, and all the steel which surrounds the plasma is bombarded continuously with an extremely hard neutron flux and is deteriorating rather quickly, so many [radioactive] steel pieces need to be replaced very regularly," he said.
And van der Putte says there is another major drawback -- namely the way fusion reactors could add to the dangers of nuclear-arms proliferation. "A fusion reactor with its extreme neutron flux would be the ultimate tool to breed weapons-grade plutonium, or from thorium you could produce uranium, which could be used to produce nuclear weapons," he said.
Environmentalists, like van der Putte, instead prefer simpler energy-developing processes closer to nature, like solar power, wind power, and tide power. He says their technologies are proven, and are practical today. He says that in Europe, wind power already produces the same output as two to three fission reactors.
However, scientist van der Laan disputes the likelihood that these ecological technologies can serve the mainstream. He says China, India, and Brazil, which are presently poor developing countries but will be big energy consumers later this century, are particularly interested in fusion.