Nuclear fusion offers the tempting prospect of a sustainable source of energy that can never be depleted, and scientists at the Massachusetts Institute of Technology (MIT) have announced what they describe as a “basin moment” to make the technology.
Fusion occurs when two or more atomic nuclei fuse to create larger elements, releasing large amounts of energy along the way: it is what powers stars like our own Sun. However, so far it has not been possible to get it to work on Earth, in a system that does not consume more energy than it produces.
Superconducting magnets have previously been identified as a way to generate the ultra-high temperatures needed for nuclear fusion, and researchers have now produced the most powerful to date: this is actually the first time a magnet like this has been able to generate magnetic field strong enough for fusion to occur.
Magnet test. (Gretchen Ertl, CFS / MIF-PSFC, 2021)
“Fusion in many ways is the source of clean energy,” says geophysicist Maria Zuber of MIT. “The amount of power available really changes the game.”
With 16 plates stacked and a height of about 3 meters, the new magnet makes use of a superconducting material called ReBCO. With a run time of about two weeks, it was able to reach a record magnetic field strength of 20 tesla, which the team says is enough to make nuclear fusion possible.
Now that its capabilities have been demonstrated, MIT scientists and their collaborators from the Commonwealth Fusion Systems (CFS) startup can begin to figure out how the device fits into a nuclear fusion reactor. A circular tokamak design will be used, where trapped plasma can be heated to temperatures of 100 million degrees Celsius or more, triggering fusion reactions.
With the modular and compact magnet they have developed, the research team claims that it is possible to achieve similar performance in reactors that have a volume 40 times less than would have been needed before, if conventional magnets are used.
The scale of the technology is crucial to make the generation of fusion energy practical and cost-effective, so that it can be integrated into the electricity grid.
How the magnet would be placed inside a reactor. (Gretchen Ertl, CFS / MIF-PSFC, 2021)
The fuel used to power the reactor would be the hydrogen isotopes of the water and since we have an almost unlimited water supply, these reactors could run indefinitely. In addition, they produce very little in terms of waste.
All parties involved agree that there is still much more work to be done and many obstacles to overcome, but getting a magnet with these capabilities was one of the biggest challenges the team faced, and now that challenge has been met. Now, progress can be accelerated in the other parts of the project.
And we all know we don’t have time to waste. The Earth’s atmosphere is heating up at a catastrophic rate, and a substantial reduction in carbon emissions is very late. Coupled with two things we should already be doing right now: completely eliminating fossil fuels and implementing widely available and highly cost-effective renewable energy options, a breakthrough in fusion power production would be what our planet needs.
The MIT and CFS team expects to have an operational testing plant by 2025.
“It’s a great time,” says Bob Mumgaard, CFS CEO. “We now have a very well-advanced scientific platform, due to decades of research on these machines, and also commercially very interesting.
“What it does is allow us to build devices faster, smaller, and less costly.”