It is one of the biggest infrastructural, technological and scientific projects ever undertaken; a project so big it almost defies belief. And while the challenges are huge, so too are the rewards. If the International Thermonuclear Experimental Reactor (Iter for short, which means ‘the way’ in Latin) works, it will prove that fusion is a viable means of clean energy, a game-changing proposition in the battle against climate change.

The scale of the project, located in Saint-Paul-lès-Durance, in the south of France, is astonishing: the reactor itself weighs 23,000 tonnes, while 3,000 tonnes of superconducting magnets (some bigger than a Boeing 747) will be connected to it by 200km of superconducting cables. One of the electromagnets currently being built in the US will have the magnetic power to lift an aircraft carrier. The road to the site from the nearest port (Berre L’Etang, just north of Marseilles), had to be modified so it could handle loads of up to 900 tonnes.

The goal is to resolve a number of scientific and technical issues, and lead the way towards a demonstration fusion power plant. Key will be producing 500MW of fusion power (only 16MW of fusion power has ever been generated) from 50MW of power injected – a “gain factor” of 10. “Another goal is to demonstrate the feasibility of the various technologies used to support the reactor, such as the cryogenics that keep the magnets cool,” Iter’s Sabina Griffiths says. The magnets keep the plasma ‘confined’ and hold it stable within the reactor.

“Fusion is the energy that powers the sun and the stars,” says Sabina. “The sun’s energy is a result of hydrogen atoms fusing, which happens due to the sun’s mass. It’s a lot more difficult to do that on Earth,” she says. “Hydrogen atoms are positively fused to overcome this repellent force, which is the strongest force we know on Earth, so you either have to use a lot of gravitation or work out another way to do it.”

Iter is just one of multiple projects around the world all aiming to achieve fusion power [a way of generating electricity by using heat from nuclear fusion reactions], albeit with different methods.

There are many ways to do that, but Iter has chosen “magnetic confinement.” “We have huge, very powerful magnets that force these atoms to fuse together, with a lot of heat, creating a sort of magnetic cage,” Sabina says.

The reactor, once finished, will house the hottest place in the universe (150 million °C, more than five times hotter than the centre of the sun), while the coolant system will be the coldest place in the universe (at minus 269 °C). The complexities of the project are only increased by the fact that 28 of the EU states are involved, along with Switzerland, the US, Russia, Japan, South Korea and India. Iter’s Director General, Bernard Bigot, has said: “constructing the machine piece by piece, will be like assembling a three-dimensional puzzle on an intricate timeline with the precision of a Swiss watch.”

The idea of fusion power is nothing new, of course. In the 1920s, the British physicist, Arthur Stanley Eddington first proposed the idea that the sun and stars were powered by the fusion of hydrogen into helium. In the 1950s, Russian physicists, Andrei Sakharov and Igor Tamm developed the tokamak, a magnetic confinement device that uses powerful magnets to ‘confine’ and shape the ‘burning plasma’. The 1970s and ‘80s saw a range of (often incredibly expensive) fusion experiments around the world, but it was not until 1991 that the first controlled release of fusion power was released. Progress since then has been slow (witness this old scientists’ joke: “fusion energy is 30 years away and always will be”), which is not a huge surprise given the complexity and cost of these projects.

Above: Inside the Tokamak pit (credit: Christian Luenig). Main image: the ITER Vacuum vessel being assembled (credit: ITER Organization).

The idea of a collaborative international project to develop fusion energy was proposed back in 1985 at the Geneva Superpower Summit, when Soviet leader Mikhail Gorbachev suggested it to US President Ronald Reagan. A year later, an agreement was reached: the US, Soviet Union, Japan and the EU would jointly work on designing a international fusion facility, and so Iter was born. Conceptual design work began in 1988, followed by increasingly detailed engineering design phases until the final design for ITER was approved by the Members in 2001.

“Everything at Iter is designed from scratch,” Sabina says. “It is at the same level as space exploration, and involves the most powerful magnets in the world and incredibly hot and incredibly cold temperatures.”

The cost, will be worth it, Sabina says. “It’s really about achieving an efficiency of reaction. We will never have more than 3-4 grams of fuel injected into the machine, and with that we can generate 500MW of power. A net gain of fusion power has never been generated for more than a few milliseconds. With 50MW of heating power we need to fire up the plasma and conduct the magnets, we can get 500MW and hold that for about an hour, which would be a giant step from what the world has seen so far.”

The €20 billion project will, researchers hope, prove that it is possible to generate fusion power on a commercial scale, and prove that a fusion power plant can be designed. While that would be a game changer, it won’t mean limitless clean energy. “We have to understand that energy is precious, but what it can do is take over from fossil fuels,” Sabina says. “And this is of course a long term thing: fusion definitely won’t be available in the next thirty years.”

The first plasma is due to be created in 2025, and as that date nears, excitement is building. “We are seeing huge interest in fusion from multiple groups, from the financial world, the utility companies, big industries, and from the likes of the International Energy Agency and the International Atomic Agency,” Sabina adds.

Does Sabina think this will work? “Everyone who works here thinks it will work,” she laughs. “We are all optimistic.”