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," van der Laan says.
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.
Six parties -- the European Union, the United States, China, Japan, Canada, and Russia -- have pooled their expertise to build the first fusion reactor.
But for more than a year now there has been a dispute about where the $13 billion facility should be built. The EU wants it at Cadarache in southern France, the Japanese at a fishing village called Rokkasho on the northern part of the main island.
The EU has threatened to withdraw from the group, and to go ahead and build the reactor at Cadarache if need be without the financial and technical support of the Japanese or the Americans, who have sided with Tokyo. Japan has also remained firm.
However, senior officials from Tokyo and Brussels met this week and decided to set a deadline of July for the dispute to be resolved.
Supporters of this complicated and costly way of generating electricity say the prize is worth the effort. They say one 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," van der Putte says.
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," van der Putte says.
The environmentalists, like van der Putte, instead prefer simpler energy-developing processes closer to nature, like solar power, windpower, and tide power. He says their technologies are proven, and are today practical. 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.