Thanks to the sun, nuclear fusion powers our planet. Now scientists are ready to build a new fusion reactor that will prove whether human beings can mimic the interior life of the sun to deliver cheap, clean, abundant energy and transform the way we live.

I read this fascinating article about the possibility of producing nigh on limitless power from just sea water and a bit of lithium (like the batteries you find in your mobile phone!) It all sounds too good to be true, let’s hope not!…

It’s a beguilling prospect. Some sea water, the battery from a laptop computer and the ideas of a dissident Soviet scientist could be all we need to meet the world’s energy demands, solving most of our global warming problems at the same time.

That might sound far-fetched to you, but it doesn’t to the scientists who are bringing this mind-stretching concept into reality. Twenty years ago at a summit meeting in Reykjavik, Ronald Reagan and Mikhail Gorbachev gave the green light for the construction of a power station that would mimic the way energy is produced in the sun. Now a $5 billion project that will create the world’s first nuclear fusion power station is almost ready to leap off the drawing board.

Power from nuclear fusion has been a dream since 1929, when the scientists Atkinson and Houtermans applied Einstein’s discovery that E=mc2 to predict that large amounts of energy could be released by fusing atomic nuclei together. You only have to look up at the sun and the stars to see the power of that dream: their heat and light comes from nuclear fusion reactions that, once kicked into action, give out more energy than needs to be put in. Fusion works by heating 2 atoms or squeezing them together until their cores fuse, releasing vast amounts of energy, but without the harmful by-products of nuclear fission (breaking a nucleus appart). And all you need is some sea water and a bit of lithium.

The sea water is to provide hydrogen or, more specifically, deuterium: a heavier form of hydrogen that makes up 1 part in 5,000 of the hydrogen in the sea’s H2O. That might not sound like much, but fusion can turn the deuterium in one bathful of sea water and the lithium from one lap top battery into enough energy to supply the average person in the developed world for seven years. And the supplies are virtually limitless: the surface waters of the earth contain billions of tonnes of deuterium, and the land deposits of lithium will yield thousands of years of supply.

Take one tokamak…

So what will a fusion reactor look like? This is where the dissident Soviet scientist comes in. In the early 1950’s, Andrei Sakharov dreamed up the ‘tokamak’. Shaped like a ring doughnut, it uses magnetic fields to hold the nuclei together and gradually squeeze them as they are heated. Put the deutrium, tritium derived from lithium and enough electricity and heat into Sakharov’s tokamak, and out comes fusion energy and not a lot else.

A cutaway diagram illustrating the impressive scale of the International Thermal Experimental Reactor (ITER)

The main by-product of of fusion energy is helium, a harmless, non-radioactive gas that makes no contribution to global warming. So, if we can get enough fusion reactors going, we will slash the environmental impact of world energy production in a single stroke. There’s no air pollution, no high-level nuclear waste, no risk of a nuclear accident and no generation of weapons material. The one troublesome by-product is hot neutrons, which have the potential to damage the walls of the tokamak and render them radioactive. Ongoing materials research will have to deal with this. But in the scheme of things, it’s a minor consideration.

Limitless energy could also transform the way we live. Although energy from fusion would not be free, the worldwide availability of the raw materials would eliminate tensions over scarce fossil fuels, for example, and would promote a more level econimic playing field. Not only would we all breathe cleaner air, but millions, possibly billions, of people in the developing world could enjoy unprecidented economic opportunity.

It all sounds too good to be true. If we have known about the potential of fusion for decades, why haven’t we exploited it yet? The answer is that it is extremely hard to do. The running joke amongst critics is that a useful reactor is just 40 years away from commissioning date… and always will be.

But that joke is running out of steam. Although the 40 years is still about right, it no longer looks like we will need anymore time than that. During the past three years, fusion researchers have made significant advances that seem to smash down the previously insurmountable barrier to fusion power.

The trouble with plasma

The problem has always beenin achieving ignition: getting the fusion ingredients hot enough to make the reaction self-sustaining. Once the fusion ingredients get hot they become what all physicists call a plasma, and plasmas are very hard to handle. They write about, creating strange, turbulent currents, and they shed heat very, very easily. “It’s 10 times hotter than the core of the sun,” says Chris Llewellyn-Smith, director of Europe’s leadingfusion research station, in Cullham, England. “You’ve got to hold it away from the walls, otherwise it cools down.”

For decades, this has been a source of fustration. But researchers at Culham have managed to tweak and twist the shape of magnetic fields in the joint European Torus (JET) reactor such that the plasma keeps it heat and shape, ensuring that fusion keeps on pumping out energy. Finally scientists can start on the path to commercial power production.

It’s still not going to be quick enough. “Three generations of devices will be required,” says Antonio DeMeo of the Princeton University Plasma Physics Labratory. First will come an engineering test reactor, then a demonstration fusion reactor, and finally a full-scale prototype fusion power plant. “Commercial Fusion power plants could follow around the middle of the century,” DeMeo says.

But the first stage is now close to starting. It’s an impressive project: the International Thermal Experimental Reactor (ITER) - a collaboration between the European Union, the USA, Japan, Russia, China and South Korea - will be 30 metres high and 20 metres across. Using partice beams and massive electric currents, ITER will heat nuclei to somewhere above 100 million degrees centigrade. If all goes according to plan, the ensuing fusion will produce around 10 times as much power as it consumes.

ITER’s location should be decided by the end of the year - the possible sites are Rokkasho in Japan and Cadarache in France - and for the first time since the fusion dream was born, the signs are good. The problems look as though they are succumbing to science, and by 2050 power stations may well have made a giant leap, harnessing the power of the stars without costing us the Earth.