Commonwealth Fusion Systems Lands $863 Million to Bring Fusion Power Closer to Reality

Commonwealth Fusion Systems (CFS), an American fusion power company spun out from the Massachusetts Institute of Technology (MIT), has secured $863 million in Series B2 funding. The new round comes four years after the energy firm raised $1.8 billion, bringing its total to around $3 billion—an amount that’s “one-third of the total capital” invested in private fusion companies worldwide.”

With this fresh capital, Commonwealth Fusion states that it will use it to complete the construction of its SPARC fusion demonstration machine, as well as help build its ARC power plant in Virginia, which local regulators recently approved permits for.

The company did not reveal its current valuation, but Ally Yost, Commonwealth Fusion’s senior vice president for corporate development, confirms that it’s an “up round” from 2021. She also boasted that the Series B2 round was oversubscribed, with the firm’s original target set at $800 million.

A G20 List of Investors

Founded in 2018 by Bob Mumgaard, Brandon Sorbom, Zach Hartwig, and Dan Brunner, Commonwealth Fusion has emerged as one of the leading providers of fusion energy. It aims to build a small fusion power plant based on the ARC tokamak design, a conceptual design using specialized magnets to make a fusion reactor that is smaller, cheaper, and faster than previous designs. The Virginia plant is described as the world’s first grid-scale commercial fusion power plant.

“This funding recognizes CFS’ leadership role in developing a new technology that promises to be a reliable source of clean, almost limitless energy—and will enable investors to have the opportunity to capitalize on the birth of a new global industry,” Mumgaard says.

A roster of high-profile investors and industry luminaries backs the firm. In addition to the likes of Bill Gates, Emerson Collective, Coatue, DFJ Growth, Google, Footprint Coalition, John Doerr, Marc Benioff’s TIME Ventures, Khosla Ventures, and Breakthrough Energy Ventures, Commonwealth Fusion is bringing on board Brevan Howard, Counterpoint Global, former Duquesne Capital Chairman and President Stanley Druckenmiller, FFA Private Bank Ltd., Galaxy Interactive, Gigascale Capital, HOF Capital, Neva SGR, Nvidia’s venture arm NVentures, Planet First Partners, and Woori Venture Partners US. A group of a dozen Japanese companies led by Mitsui & Co., Ltd. and Mitsubishi Corporation also participated in the round.

“We’re continuing our trend here of looking into the world and saying, ‘How do we advance fusion as fast as possible? How do we align stakeholders? How do we do that in a transparent way? And how do you do that in a way that capitalizes on our execution and delivery of our objectives on a roadmap that’s been really consistent in the company about building the technology, but also about the opportunity to build an entire global industry?’ This is a representation of continuing on that roadmap towards an industry,” Mumgaard remarks at a press conference.

The Fusion Vision Becoming Reality

He asserts that Commonwealth Fusion has made considerable progress in demonstrating that commercialized fusion energy is feasible. The company’s SPARC device—now more than 65 percent complete—is expected to achieve a net-positive output soon, marking a significant milestone. It also landed Google as a customer, agreeing to provide 200 megawatts of offtake power—enough to power a small to medium-sized city—from the ARC plant.

“You’re starting to see now not just proof of concept and demonstration and execution at that level, but also the parts of the commercial ecosystem—who’s buying the power, how are we delivering it, [and] where is that going to be—is all coming together,” Mumgaard says.

Although it boasts that it’s well-funded, Commonwealth Fusion isn’t alone in this race to commercialize fusion energy. Other companies include Helion Energy, the 12-year-old startup backed by OpenAI’s Sam Altman, Peter Thiel, and Reid Hoffman, which has signed Microsoft as a customer and is planning to build a power plant in Washington state; TAE Technologies, a California-based startup backed by Google and Chevron that has raised $1.3 billion in funding to date; Zap Energy, another Washington-based startup that has raised $327 million and is backed by Bill Gates, DCVC, Lowercarbon, and Chevron Technology Ventures; and more.

When asked how investors should evaluate claims made by these 50+ fusion energy providers, Mumgaard urges transparency, noting that the underlying assumptions should be published and peer-reviewed, similar to those in biotech and other scientific fields with major societal implications. He notes that many of Commonwealth Fusion’s rivals are already sharing detailed models of their proposed power plants, including the milestones to be met and the assumptions underpinning their designs.

How AI Benefits From Fusion Power

Demand for data centers is surging with the rise of AI, pushing companies to seek new energy sources, from fossil fuels and renewables to nuclear power, and now, fusion. If Commonwealth Fusion and its peers succeed in bringing fusion to market, it could deliver virtually limitless clean energy, drive down costs, and shield communities from the harmful impacts of pollution.

Fusion energy can also be used to support the immense computational resources needed to train AI models. With technology embedded in every sector, including healthcare, finance, the home, and transportation, the demand for reliable, large-scale power will continue to grow. Unless there’s a breakthrough, the environmental cost of AI could ultimately outweigh its benefits.

As Mumgaard explains, fusion energy produces no carbon emissions and is not dependent on the weather or geography. There’s no risk of meltdowns or any long-lived radioactive waste. By providing abundant, clean energy, fusion could be the key to solving one of AI’s most pressing challenges: its massive and growing appetite for power.