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Scientists have been experimenting with ways to generate energy through nuclear fusion since the 1950s. Since then, the promise of boundless energy with low environmental impacts seems always to be just out of reach. But could a series of milestones in 2025 and a step up in research efforts globally mean that fusion energy will finally become reality?
Fusion energy is the opposite of nuclear fission: combining lighter atoms rather than splitting heavier ones. When two forms of hydrogen, deuterium and tritium, are heated to 150,000,000°C – 10 times hotter than the core of the sun – they form a plasma and can fuse together and release energy.
When this happens, helium and neutron are produced, releasing huge amounts of carbon-free energy, which can then be used to create steam and turn a turbine to generate electricity, just like in any conventional power plant.
Fusion energy is carbon-free at the point of generation, continuously deployable with a fuel that is potentially abundant in the sea and the Earth’s crust. It is safer than fission, since chain reactions cannot occur, and the waste produced is both shorter-lived and lower level. In addition, one gram of fuel is sufficient to generate 340 billion joules of energy, more than any other process.
Commercial viability of fusion is currently blocked by a series of engineering and technological challenges. These include developing materials that can tolerate extremely high temperatures and radiation, both for structures, and diagnostics and sensors.
The UK is part of a global race to solve the fusion puzzle. Since 1983, it has hosted the Joint European Torus (JET) in Oxford, where its team of nuclear researchers – in collaboration with a network of more than 31 European laboratories – have demonstrated the ability to reliably generate fusion energy. The project set a world record for energy output, producing 69 megajoules of high-fusion power consistently for five seconds, using 0.2 milligrams of fuel. JET concluded its scientific operations in December 2023 and is now being decommissioned.
A new project is being established by the UK Atomic Energy Authority (UKAEA) – a prototype fusion plant known as Spherical Tokamak for Energy Production (STEP), to be built at the site of the former West Burton A coal-fired power station in Nottinghamshire.
“Fusion is the process that powers the stars. We understand the process and the conditions very well – the challenge is how to recreate those conditions on Earth. This is what STEP plans to do,” explains Professor Howard Wilson, director of science and technology at STEP Fusion.
The team behind STEP are targeting first operations in 2040. “That might seem a long time away, but with the scale of this infrastructure and brand new technology, this is pretty aggressive and rightly so – there is a global race here and the economic value is in getting this done early,” says Paul Methven, CEO of the STEP programme.
The first phase of consultation with local communities in Lincolnshire, North Nottinghamshire and South Yorkshire was in January and February, with an application for a Development Consent Order expected to be made in 2029.
The 330 hectare site will accommodate the STEP facility, along with the UKAEA Skills Centre and a business campus, which together are expected to provide 6,500 full-time equivalent jobs once fully operational, with an estimated 1,500 at STEP and 5,000 on the business park, according to an assessment by consultancy Amion. Bassetlaw District Council bid to host STEP in order to catalyse opportunities on the three former power station sites, and regeneration for the wider area.
“We were looking at what the replacement for the coal-fired power stations could be, and STEP was an obvious opportunity to start the process of regeneration,” says cabinet member for business and skills Charles Adams.“One of the reasons why the STEP site was awarded here was because there was a very positive response from the community about the proposal, and in fact, campaigning for it,” he adds.
The council believes that the plant will be positive for jobs, not just in the district, but also in the East Midlands, Lincolnshire and South Yorkshire, and potentially the West Midlands. It also hopes to secure infrastructure upgrades, with the former rail line used by the coal-fired power stations brought back into use for transporting construction materials, equipment and workers. The river Trent could also be used for transport, reducing the impact of the development on the local road network.
STEP’s researchers will aim to solve some of the materials science questions at the heart of unlocking fusion energy. These include structural materials for making tritium, which does not exist in sufficient quantities on Earth, so will need to be ‘bred’ in a specially designed ‘blanket’ surrounding the core of the fusion machine, according to Amy Gandy, head of the materials science and engineering programme at UKAEA.
Research on materials science is also focusing on reducing the amount of radioactive waste produced by STEP. Although the amount of waste generated through nuclear fusion is relatively small compared with fission, and categorised as intermediate-level waste rather than fission’s high-level waste, some of it will still need to be managed.
According to Wilson, STEP is working on developing low-activation steel, which produces less active waste than regular steel when neutrons interact with it.
“The waste you get depends on the materials you use to build your power plant. Steel is essentially iron with trace elements. It’s the interaction of neutrons with those trace elements that gives you the waste, so by engineering your steels with the appropriate trace elements you can minimise the waste,” he says.
A spokesperson for STEP added that a temporary storage facility will hold waste that needs treatment on site, and remaining intermediate-level waste will be transported to the UK’s Geological Disposal Facility for permanent storage. However, the government’s search for a location for such a facility has already been under way for decades.
For the programme to succeed, there will be a huge need for new skills. Multiple academic institutions are already working on the engineering and science skills, with students being trained at both undergraduate and postgraduate levels, according to Dr Aneeqa Khan, lecturer in nuclear materials at the University of Manchester’s School of Engineering.
For example, the Engineering and Physical Sciences Research Council’s Centre for Doctoral Training (EPSRC CDT) in Fusion Power is a collaboration between Durham, Liverpool, Manchester, Oxford, Sheffield and York universities to train students in materials science and plasma physics.
Students of the subject in other universities, such as Bangor and Edinburgh, are being funded through the EPSRC, industry and other institutions, while international collaboration, such as with the Korea Institute of Fusion Energy, has given students and academics opportunities to learn from and collaborate with colleagues in Korea.
“STEP is encouraging a real investment in fusion training within the UK, which is fantastic,” Khan says.
Start-ups around the world are involved in PhD projects through project funding and/or supervision, as well as providing internships, she adds. “It’s a wide and diverse ecosystem. Hopefully, STEP will encourage more and more development of industrial collaborations and supply chains.”
There will also be a huge need for construction skills locally. The council has a skills development plan with local education providers and industry providers.
Despite the enthusiasm and optimism of its proponents, fusion research has a long way to go. In its 2025 annual report, the International Atomic Energy Agency said fusion output could only rise meaningfully in the latter half of the century, assuming that the technology becomes commercially available around 2035.
In the agency’s base-case scenario, fusion would account for about 15% of global electricity generation by 2075 and roughly 27% by 2100.
Methven acknowledges that STEP will not be operational in time to help the UK meet its 2050 net-zero target, even if all goes to plan. “That’s not our aim. We’ll hopefully get some on the grid around that time, but it’s not part of the net-zero roadmap. We don’t think it’s credible in terms of commercial solutions.
“We think fusion will be really critical to decarbonisation globally, particularly for difficult-to-decarbonise technologies, in the second half of the century,” he says.
Catherine Early is a freelance journalist
