UK takes step towards world's first nuclear fusion power station

A model of the proposed STEP fusion power plant


The UK today embarked on a step toward building the world’s first nuclear fusion power station, by launching a search for a 100-plus hectare site where it can be plugged into the electricity grid. However, there are still major hurdles to overcome before it could start generating power.

Prime minister Boris Johnson last year an extra £200 million to flesh out the possibility of building the project, known as the Spherical Tokamak for Energy Production (STEP). The UK Atomic Energy Authority (UKAEA), the government body overseeing STEP, hopes construction could begin around 2030, with the plant operating as soon as 2040.

Ian Chapman at the UKAEA says STEP may cost around £2 billion, the equivalent cost in today’s money of building , an existing fusion reactor in the UK that was constructed in the 1980s. Francis Livens at the University of Manchester, UK, says the cost and timeline are “ambitious but not implausible”.


However, as the name suggests, JET was an internationally funded endeavour, while the UK government hopes to pursue STEP alone. Moreover, it has a different, pioneering design, with accompanying engineering challenges. “STEP is a hugely ambitious programme: to be at the forefront, to be the first in the world to produce a prototype fusion power plant, and then export that round the world,” says Chapman.

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The plant is pitched as an important plank in efforts to hit the UK’s target of . But fusion faces big challenges to play that role. Reproducing the way the sun makes energy, by fusing hydrogen together to make helium, requires significant energy on Earth to heat and control the hydrogen with huge magnets.

No fusion reactor has yet produced more power than it consumed. That might change in 2025, when the world’s biggest fusion project, ITER in France, is due to switch on. The hope is it will turn 50 megawatts of power into 500MW, proving a net gain is possible.

STEP’s power output goal is more modest – a net gain of 100MW – but unlike ITER, it will be connected to the ordinary electricity grid to understand how a fusion plant operates day in, day out.

This week, UKAEA is calling on communities in the UK, be they councils or landowners, to host STEP, as the authority’s current home at Culham in Oxfordshire is full. Nominations can be made until March 2021, with a plan to pick a site by the end of 2022.

Later down the line, cost could be a a major hurdle. While running costs should be relatively cheap, £2 billion for a 100MW plant is not. “Those are some expensive electrons,” says Richard Howard at analysts Aurora Energy Research. He estimates that to be competitive with today’s new large nuclear fission plants, such as , STEP would have to cut its capital costs by about 80 per cent to even be on a par.

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The UKAEA says funding could come from a mix of public and private money. Catherine Mitchell at the University of Exeter says, given the lack of public benefit from fusion so far, further fusion development is better left to the private sector. If I was a minister and I had so many other calls on my money I would cease all public funding for fusion,” she says.

Scale is also an issue – 100MW is tiny given that England, Scotland and Wales have. And Howard expects electricity consumption will be about 50 per cent higher by 2040 due to the electrification of cars and heating, making 100MW even more insignificant.

Building the case for a bigger plant later would require years of data from STEP, meaning fusion makes no practical contribution to tackling climate change until after 2050. “None of this means we shouldn’t do it. If it can be proven, it would be enormously helpful,” says Howard.

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