Nuclear fusion: Design work starts on a European commercial power station

The EuroFusion consortium hopes its DEMOnstration Power Plant will take fusion power from the lab to commercial electricity supply by 2054

By Adam Vaughan

Nuclear fusion engineers are starting to design a European power station they hope will mimic how the sun works to provide a clean, almost unlimited source of energy on Earth.

Today marks the beginning of a five-year “conceptual design” phase to flesh out key technology decisions for the DEMOnstration power plant (DEMO), a project backed by a Europe-wide consortium, EuroFusion, to take fusion power from the concept stage to a commercial reality. The group plans for the 300 to 500 megawatt reactor to be generating low-carbon energy by 2054.

There has been plenty of experimental work on nuclear fusion, largely with machines known as tokamaks. These use powerful magnets to confine and control hot matter – or plasma – usually in the shape of a doughnut. The plasma is typically produced from two hydrogen isotopes: deuterium and tritium.

Much of the research has focused on tweaking the materials and magnets in the walls of tokamaks, and better modelling how experiments with plasmas will play out, with the ultimate aim of getting more energy out of a fusion reaction than goes in.

That major milestone of “net gain” has yet to be achieved, though there is progress: a new global energy record was set last year. More progress may occur when an €18 billion experimental research tokamak in southern France, known as ITER, is switched on. It is due for completion in 2025 and should achieve full power in 2035.

The DEMO power station will need to control and maintain the plasma for much longer than experiments to date. DEMO will also need to collect the heat from the reaction and turn it into electricity, all while working 24 hours a day. “It’s hard. But that’s why we need to start — that’s exactly the point,” says Ambrogio Fasoli, chair of the EuroFusion General Assembly, the decision-making body for the consortium, which is funded by EU member states and Switzerland.

There are problems to overcome, such as generating tritium. Supplies of the isotope are limited and expensive because it decays quickly. Research projects have so far used grams of the material, but a power station will need kilograms. This will require design choices about how to create more tritium by allowing neutrons to escape the plasma and interact with lithium in the tokamak’s walls.

Other design choices include what shape of tokamak to build – an elongated design that produces a doughnut-like plasma, or a spherical one that confines the plasma in a more compact shape. There are also decisions to be made about the materials to use in the tokamak walls, which will be exposed to a huge influx of neutrons from the fusion reaction. “The dose [of neutrons] that the structure absorbs is much, much bigger than we ever had to do. It’s really orders of magnitude larger,” says Fasoli.

He says work on DEMO can’t wait for the completion of ITER, but must happen in parallel. “[Otherwise] there will be a big gap of decades and then nobody will have an interest in fusion anymore,” says Fasoli. Nonetheless, he says DEMO must learn from ITER.

Where the power plant will be built remains to be seen. Juan Matthews at the University of Manchester, UK, is betting on Germany, given it has no fusion device and France and the UK have won competitions to host previous ones.

Whatever DEMO’s conceptual design looks like when it is finished in 2027, the plant is unlikely to be the world’s first fusion power station. Several private fusion start-ups have claimed they will have one operating by the early 2030s, while the UK government has said its “STEP” fusion power plant will be running by 2040. China has said it will have one complete in 2035.

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