Nuclear fusion no longer a pipe dream – but it could be too late for climate crisis

Jennifer Johnson

Tokamak reactors are a promising technology in the development of viable nuclear fusion (Credit: Shutterstock)
Tokamak reactors are a promising technology in the development of viable nuclear fusion (Credit: Shutterstock)

Nuclear fusion, so an industry saying goes, is a technology that will forever exist 30 years in the future.

Researchers have been trying to work out how to produce controlled fusion inside reactors since the 1940s – but commercial-scale success has remained elusive. However, the reasons for persevering are persuasive.

Fusion promises an almost unlimited supply of zero-emission power with none of the dangerous by-products created by fission reactors. Yet much work still needs to be done before fusion can make any contribution to global decarbonisation. The world must reach net-zero greenhouse gas emissions by 2050 in order to limit global warming to 1.5°C. It remains to be seen whether fusion reactors will be operational by this point, although governments are increasingly throwing their weight behind the technology.

STEP forward

In October, the UK government announced that it will invest £220m to enable the creation of a nuclear fusion power station at Oxfordshire’s Culham Centre for Fusion Energy. The funding is meant to facilitate the design of a reactor known as the Spherical Tokamak for Energy Production (STEP) by 2024. This is seen as a move towards the eventual construction of a nuclear fusion plant by 2040. 

Meanwhile, the European Investment Bank has agreed to loan €250m to Italy’s Divertor Tokamak Test Facility near Rome. The scheme is aiming to produce fusion power by mid-century at a cost of €500m.

“To achieve a climate-neutral Europe by 2050, we need to keep investing in new solutions,” said European Commissioner Miguel Arias Cañete. “Fusion is a potential source of safe, non-carbon emitting and virtually limitless energy. If we succeed in making a breakthrough, it could significantly contribute to our efforts to make Europe the first climate-neutral major economy.”

Despite momentum in the sector, there is no existing fusion facility that has been able to generate more energy than it takes to operate. Creating the conditions for a fusion reaction – in which energy is released from the fusing of two light atomic nuclei into one heavier atom – is an immense engineering challenge. First, two types of hydrogen, tritium and deuterium, have to be heated to more than 100 million degrees Celsius until they form a plasma. They must then be held together long enough for fusion to take place.

Fusion is the process that powers stars, including our own sun. But stars are able to contain the plasma through the force of gravity. Proposed reactor designs use magnetic confinement, in which magnetic fields hold the ionised atoms together while they’re heated up. Scientists have also trialled a technique called inertial confinement fusion, which uses powerful laser beams to compress and heat the hydrogen isotopes to the point of reaction.  

Tokamak timeline

The UK’s STEP project is based around a magnetic confinement concept, as is the world’s most advanced fusion programme, ITER. Headquartered in France, ITER is a collaboration between China, the EU, India, Japan, Korea, Russia and the US. Scientists from these member countries have been working for decades to build the world’s largest tokamak, a magnetic fusion device, with the stated aim of being the first such project to produce net energy.  

The reactor is not expected to produce “first plasma” until 2025. This is just the first step in generating fusion power, a hurdle that ITER is expected to clear in the middle of the following decade. 

China is travelling along a similar timeline with its own domestic fusion reactor. 

Environmentalists and policymakers have noted that the decades-long R&D process will almost certainly prevent fusion from contributing to near-term decarbonisation. Writing in The Conversation, scientist Thomas Nicholas of the Culham centre claimed that fusion will likely be an energy source in a post-carbon society. 

Sceptics have claimed that creating fusion power is akin to “putting the sun in a box”. And, while the technology is not the climate panacea some optimists have wished for, there is reason to believe that progress is on the horizon.

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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.

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