There is an old joke among scientists: fusion power is 30 years away, and always will be.
Yet as we enter the decade in which the big questions on the future of energy must be answered, is it time to revisit fusion and its unrivalled potential to change the way the world generates power?
The past few years have seen a dramatic shift in the conversation around climate change, with a significant rise in environmental activism and increasing pressure on political leaders and big businesses to fix the problem.
Just this week, the government announced plans to ban the sale of new petrol and diesel cars by 2035. Such a move is part of the UK’s mission to meet its target of net-zero emissions by 2050, but the impact will be limited without the development of new, clean energy sources.
With no CO2 emissions, no risk of meltdown, and no long-lived radioactive waste, fusion is a promising solution and has been for decades, but it is hard to achieve. So why has it proven so difficult in the past, and what is changing now?
Fusion occurs in stars, including our sun, where the huge gravitational force creates pressures and temperatures so intense that charged particles which normally repel each other collide and fuse.
On Earth we need to create similar conditions, and hold a hot plasma with fusion fuel at high enough pressure for long enough for energy-generating reactions to occur.
This is a difficult problem that has occupied some of the world’s brightest minds for over 60 years. Different approaches to fusion energy are being pursued: from cold fusion (which still lacks evidence and may never work), to inertial fusion (which could work), to magnetic fusion — which really does work.
The magnetic fusion approach uses strong magnetic fields to contain the hot plasma. There are many different configurations of magnetic fusion devices, but the best performance, by far, has been achieved in ring-doughnut-shaped devices known as “tokamaks”.
The world record is held by the JET tokamak at Culham near Oxford, which achieved 16MW of fusion power in 1997.
However, progress since then has slowed. The successor device, ITER, is an impressive but colossal project which has succumbed to numerous delays and cost increases. In recent years, some have been investigating the possibility of a smaller, faster and cheaper way to fusion with all sorts of novel concepts proposed.
But what of the tokamak? Is there a way of reducing the scale of this most highly developed and top-performing device?
Within the class of tokamaks there are two choices: the conventional doughnut shape such as JET, or the apple-shaped spherical tokamak. Pioneered in the UK, the latter caught the eye of Boris Johnson over the summer, when he visited the research centre in Culham
The spherical tokamak has two big advantages. First, as a squashed-up version of the tokamak, it is inherently compact. Second, it uses the magnetic field more efficiently.
Its limitation has always been the tricky engineering due to lack of space for magnets. But recently a solution has been found.
The latest generation of high temperature superconductor (HTS) is able to conduct high currents with zero resistance at temperatures well above absolute zero and in a strong magnetic field. Exceptionally high-field compact magnets can now be made, allowing much simpler solutions to the engineering problems of magnet cooling and protection.
So instead of building ever-larger tokamak devices, with huge costs and long timescales, we can see a way forward by increasing the magnetic field in more compact devices.
This turns the pursuit of fusion energy from a single big moonshot to a series of engineering challenges: can we build a tokamak with all its magnets made from HTS? Can we get to fusion temperatures in a compact device? Can we get to fusion breakeven in a compact device? Can we get sufficiently beyond breakeven to produce electricity for the first time? And can we go on from that to build reliable, economic, fusion power plants?
We are confident that we can — and have a plan to build a grid connected power plant by 2030.
As the evidence for fusion mounts, the next challenge is finding the right model for supporting innovation using all of our strengths. The Prime Minister has committed £200m over five years for a design study of “STEP” — Spherical Tokamak for Energy Production. Looking to the US, we see examples of public-private collaborations in the pursuit of green energy, which retain constructive competition.
Fusion is undoubtedly hard to achieve, but the difficulty of the challenge is more than matched by the value of the solution. A mere 1kg of readily available fusion fuel can produce the same energy as 10m kg of coal or oil in a process that is safe, scalable, and cost-effective.
The recent advancements in fusion energy come at a perfect time. The much-needed answer to the world’s most pressing issue isn’t anything radical, absurd or out of reach, but is instead a process that is well underway. Watch this space.
Main image credit: Getty