European scientists say they have made a breakthrough in their quest to develop nuclear fusion – the same energy process that powers stars.
The UK-based JET laboratory has broken its own world record for the amount of energy it can extract by squeezing two forms of hydrogen together.
If nuclear fusion can be successfully recreated on Earth, it has the potential to generate virtually unlimited amounts of low-carbon, low-radiation energy.
The experiments produced 59 megajoules of energy in five seconds (11 megawatts of power).
This is more than double what was achieved in similar tests in 1997.
It’s not a huge amount of energy — just enough to boil about 60 kettles of water. But the experiment is the basis for an even larger fusion reactor being built in France.
“The JET experiments brought us one step closer to fusion energy,” said Joe Milnes, chief of operations for the reactor’s lab. “We’ve demonstrated that we can create a mini star inside our machine and keep it there for five seconds and get high performance, which really takes us to the next level.”
The ITER (International Thermonuclear Experimental Reactor) project in southern France is supported by a consortium of governments including the United States, China, Russia and members of the European Union. This is expected to be the last step in proving that nuclear fusion can provide reliable energy in the second half of this century.
Fusion-based power plants of the future would generate no greenhouse gases and only very small amounts of short-lived radioactive waste.
“These experiments we just completed needed to work,” said JET CEO Ian Chapman. “If they hadn’t worked out, we would have had real concerns about whether ITER could achieve its goals.”
“This was a high-stakes thing and the fact that we got it was because of people’s brilliance and their confidence in the scientific pursuit,” he told BBC News.
Fusion works on the principle that energy can be released by forcing atomic nuclei against each other rather than splitting them, as is the case with the fission reactions that generate energy in today’s nuclear power plants.
At the core of the Sun, enormous gravitational pressures allow this to happen at temperatures of around 10 million degrees Celsius. At pressures much lower than on Earth, temperatures to produce fusion need to be much higher — above 100 million degrees Celsius.
There are no materials that can withstand direct contact with this heat. To achieve fusion in a lab, scientists created a solution in which a superheated gas, or plasma, is held within a donut-shaped magnetic field.
The Joint European Torus (JET), located in Culham, Oxfordshire, has pioneered this merger approach for nearly 40 years. And, over the last ten years, the equipment has been configured to replicate the ITER configuration.
Roger Harrabin’s Analysis
BBC environment reporter
The merger announcement is great news, but unfortunately it won’t help in our fight to lessen the effects of climate change.
There is huge uncertainty about when fusion energy will be commercially viable. One estimate suggests that it could still take 20 years for that. And after that, it would still need to be perfected, which means a delay of a few more decades.
And here’s the problem: the need for carbon-free energy is urgent – ​​and the government has promised that all electricity in the UK will be zero emissions by 2035. That means more nuclear and renewable energy, and more energy storage.
In the words of my colleague, journalist Jon Amos: “Merger is not a solution to getting us to zero emissions by 2050. This is a solution for society in the second half of this century.”
The French lab’s preferred “fuel” for making plasma is a mixture of two forms, or isotopes, of hydrogen called deuterium and tritium.
JET needed to find a coating for the 80 cubic meter toroidal vessel that houses the magnetic field that would work efficiently with these isotopes.
For the 1997 experiments, JET used carbon, but the substance absorbs tritium, which is radioactive. So, for the most recent tests, new coatings were built with the metals beryllium and tungsten, which are ten times less absorbent.
The JET science team needed to tune their plasma to work in this new environment.
“This is an impressive result because they were able to demonstrate the highest amount of energy production from fusion reactions of any device in history,” commented Arthur Turrell, author of The Star Builders: Nuclear Fusion And The Race To Power The Planet.
“It’s a milestone because they demonstrated the stability of plasma in five seconds. That doesn’t seem like a long time, but on a nuclear time scale, it’s a very, very long time. And it’s very easy to go from five seconds to five minutes to five. hours or even more.”
The JET can no longer work because its copper electromagnets get too hot. For ITER, internally cooled superconducting magnets will be used.
Fusion reactions in the lab are famous for taking more energy to start than they can produce. On JET, two 500 megawatt wheels are used to run the experiments.
But there is solid evidence that this deficit can be overcome in the future as plasmas are scaled up. The volume of the ITER toroidal vessel will be ten times that of the JET.
This is a long marathon and it is important that of the approximately 300 scientists working as JET, a quarter are at the beginning of their careers. They will have to carry the research baton forward.
“Merging takes a long time, it’s complex, it’s difficult,” said Athina Kappatou, in her 30s. “That’s why we have to make sure that, from one generation to the next, there are scientists, engineers and technical staff who can take things forward.”
Many technical challenges still exist. In Europe, these challenges are being addressed by the Eurofusion consortium, which comprises around 5,000 science and engineering experts from across the European Union, Switzerland and Ukraine.
The UK also participates. Its full involvement in ITER, however, will first require the country to “associate” with certain EU science programmes, something that has so far been impeded by disagreements over post-Brexit trade deals (the UK’s exit from the European Union), particularly in relation to Northern Ireland.
JET is likely to be decommissioned after 2023, with ITER starting plasma experiments in 2025, or soon after.
