Nuclear fusion could be the clean energy the world needs—and private companies are now working on machines to harness it.
About two dozen private companies around the world are working to harness a transformative energy technology that could rescue the planet from climate catastrophe. One is using space in an old factory that’s home to a mothballed U.S. Department of Energy-funded research machine in Cambridge, Mass. Another is housed in an industrial building behind a Costco outside Vancouver. A third is down the street from a self-storage facility in the foothills of Orange County, Calif.
Commonwealth Fusion Systems, Cambridge, Mass.
TECHNOLOGY: Developing high-temperature superconducting magnets to confine plasma in a small tokamak called Sparc.
FUNDING: $115 million
INVESTORS: ENI, Breakthrough Energy Ventures*, Future Ventures, Khosla Ventures, and others
(* Michael Bloomberg, founder and majority owner of Bloomberg LP, which owns Bloomberg Markets, is a member of the Breakthrough Energy Coalition)
Commonwealth Fusion Systems, which was launched by professors from MIT’s Plasma Physics and Fusion Center in 2018, is looking for space. For the time being, CFS and MIT design and technical teams are working in what used to be the control room for Alcator C-Mod, an Energy Department-funded experimental tokamak on MIT’s campus. The machine, which sits in a large bay two doors away, ran a so-called high field using especially powerful magnets and set a record for plasma pressure.
CFS is seeking to make the next advance in magnetic confinement using new, commercially available high-temperature superconductors. The discovery of such materials was an advance that won the Nobel Prize in Physics in 1987.
Before high-temperature superconductors became available in the past decade, tokamak builders faced a trade-off: use a lot of power to run a high magnetic field or run a lower magnetic field in a much bigger device, like ITER, says Mumgaard of CFS. The new superconductors will enable the company to build a smaller, cheaper version of an ITER-like machine. “Two years from now, we will have that magnet done,” he says.
CFS’s subsequent step will be to build a demonstration machine called Sparc that will use the new magnet technology. Sparc will be about 12 feet tall and could fit into half a tennis court. Construction is supposed to start in 2021 and finish in 2025. A commercial version, called Arc, is expected to follow. It would be approximately twice as big, fitting into a basketball court.
CFS’s tokamak will burn D-T fuel, which means it will confront the first-wall problem. The solution, Mumgaard says, is “to build a machine so you can replace the wall very easily.” Replace it often enough, he says, and it wouldn’t get very radioactive and could be stored and then recycled. “You can choose what you put around the machine,” he says. “Right now we can go with the stuff that’s cheap and easy. And yeah, it’s activated. But in the future we can put in stuff that lasts longer.” One potential solution would be using specialized alloys that are more resistant to becoming radioactive, though the industry is still working to develop such materials.
The radioactive material from fusion reactors is drastically different from fission waste, Mumgaard adds. “It’s basically not stuff that’s biologically active,” he says, unlike the volatile gases that can escape in a fission accident. “So it’s like a completely different category. Whether or not we can explain that well to the public, you know, is one of the challenges that we have to figure out in fusion.”
Still, Mumgaard is upbeat. “Fusion is a big endeavor, and there’s a lot of excitement around it,” he says, adding that enthusiasm is coming from energy people, investors, and academics. “We’re trying to birth an industry here. And it’s a fun place to be.”