Writing for the Institution of Mechanical Engineers (IMechE) (
www.imeche.org), Jennifer Johnson said that, while researchers have been trying to work out how to produce controlled fusion inside reactors since the 1940s, 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.”
In October, the UK Government announced that it will invest £220 million 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 lend 250 million euros to Italy’s Divertor Tokamak Test Facility near Rome.
The scheme is aiming to produce fusion power by mid-century at a cost of 500 million euros.
Ms Johnson added: “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 deg 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, but they can 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 are 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.
“However, environmentalists and policy makers have noted that the decades-long R&D process will almost certainly prevent fusion from contributing to near-term decarbonisation.”