Fusion energy startup Commonwealth Fusion Systems (CFS) has raised $863 million in new funding, attracting high-profile backers including Nvidia, Google, and Breakthrough Energy Ventures, among others.
“We’re continuing our trend here of looking into the world and saying, ‘How do we advance fusion as fast as possible?’” co-founder and CEO Bob Mumgaard told reporters this week. “This round of capital isn’t just about fusion as a concept, but about making it a true commercial and industrial endeavor.”
Based in Massachusetts, CFS has now secured nearly $3 billion in total funding—more than any other fusion startup. Its largest raise came in 2021, when it closed a $1.8 billion round.
Fusion has long been touted as a nearly limitless energy source, but only recently have investors begun to see it as a viable bet. Advances in computing and AI have accelerated the field, fueling a surge of startup activity and investor interest.
In a fusion reaction, atoms are compressed and heated until they become plasma—a fourth state of matter. Under the right conditions of temperature and pressure, those atoms fuse and release massive amounts of energy.
CFS is currently building its prototype reactor, Sparc, in a suburb of Boston. The company expects to power it on next year and reach scientific breakeven—when the reactor produces more energy than it consumes—by 2027.
Although Sparc is not designed to sell electricity to the grid, it remains a crucial stepping stone for the company’s long-term plans.
“There are parts of the modeling and the physics that we don’t yet understand,” Saskia Mordijck, associate professor of physics at the College of William and Mary, told TechCrunch. “It’s always an open question when you turn on a completely new device—plasma may behave in ways we’ve never seen before, and we may uncover things we didn’t expect.”
If Sparc proves successful, CFS plans to begin construction of Arc, its first commercial-scale fusion power plant, in Virginia by 2027 or 2028.
Both Sparc and Arc are based on tokamak designs, which use powerful superconducting magnets to contain and compress plasma. Tokamaks are a well-established approach within the research community.
“We know that this kind of idea should work,” Mordijck said. “The question is, how will it perform in practice?”
Investor interest suggests optimism. The Series B2 round had no single lead investor, with many existing backers expanding their commitments, according to Ally Yost, CFS’s senior vice president of corporate development.
Returning investors that increased their stakes include Breakthrough Energy Ventures, Emerson Collective, Eni, Future Ventures, Gates Frontier, Google, Hostplus, Khosla Ventures, Lowercarbon Capital, Safar Partners, Eric Schmidt, Starlight Ventures, and Tiger Global.
New investors include Brevan Howard, Morgan Stanley’s Counterpoint Global, Stanley Druckenmiller, FFA Private Bank (Dubai), Galaxy Interactive, Gigascale Capital, HOF Capital, Neva SGR, Nvidia’s NVentures, Planet First Partners, Woori Venture Partners US, and a consortium of 12 Japanese firms led by Mitsui & Co., Ltd. and Mitsubishi Corporation.
This wide base of backers could help CFS as it develops supply chains, builds partnerships, and secures buyers for its electricity. Already, the company has struck a deal with Google to purchase 200 megawatts from its planned Arc reactor.
As the first of its kind, Arc will be far costlier than future plants, Mordijck noted.
Mumgaard added that Sparc’s role goes beyond proving fusion is possible. “That’s very important. But it’s also about knowing the capabilities you need, having the receipts, and understanding what these things actually cost.”
The newly raised capital will advance Sparc, but it won’t cover the multibillion-dollar cost of building Arc.
“The fact that it’s a first-of-its-kind technology adds complexity to where the capital will come from,” Mumgaard said. “We’re not entirely sure what shape that funding will take, but we are committed—and our investors are committed—to making this happen.”
