As it nears completion of an estimated $500-million nuclear fusion demonstration complex near Boston, developer Commonwealth Fusion Systems has gained $863 million from global tech investors in its latest funding round to also advance work on a planned 400-MW power plant in Virginia to produce fusion energy at commercial scale. 

The firm uses high-temperature superconducting magnets developed in partnership with MIT to build what it says are smaller, lower-cost tokamak fusion systems and is on track to produce more output power than input power as early as 2027 at its SPARC pilot site in Devens, Mass. The pilot facility, set to produce from 50- to 100 MW of power, is about 65% complete with ongoing testing and assembly of components, said Bob Mumgaard, Commonwealth Fusion developer CEO and co-founder in a statement. 

“This round of capital
isn’t just about fusion generally as a concept, it’s about how
do we make fusion into a commercial industrial endeavor,” he told media.

Since installing the 24-ft dia, 75-ton disc-shaped stainless steel cryostat base in March at the SPARC site, the company team is beginning to build “the heart of our fusion energy system,” said Samer Hamade, vice president of projects.

Commonwealth Fusion announced last month that the $863 million raised in a just completed Series B2 fundraising round now has boosted its private investment total to nearly $3 billion since its founding in 2018, which it claims is one-third of all total capital investment in private fusion development projects. The round was “oversubscribed,” the company said.

New investors include tech giant Nvidia, Morgan Stanley and a consortium of 12 Japanese energy and financial firms led by Mitsui & Co. Ltd. and Mitsubishi Corp. Existing investors such as Google and Bill Gates-founded Breakthrough Energy Ventures increased their stakes.

Work on ARC, Commonwealth Fusion’s larger successor to SPARC and the first commercial grid-scale power plant planned for a site near Richmond, is “in the early stages of approvals and site design,” with plans to be online in the early 2030s, according to a company spokesperson. The new financing will allow Commonwealth Fusion to start plant construction in the 2027-2028 time frame, she estimated. 

For the ARC plant, the team is focusing on two materials that can handle the tokamak’s heat, radiation and mechanical stress, according to the Commonwealth Fusion website. These include “a vanadium alloy for the vacuum vessel structure that must withstand the powerful forces within the machine while operating at high temperatures for many years.”

So far, project development has been led by engineering consultant HDR, construction manager Bond Civil and structural engineers Thornton Tomasetti and VHB. 

Google also signed on June 30 its first commercial commitment to fusion power, in an agreement with Commonwealth Fusion to purchase 200 MW of power from the ARC plant, comprising half of its planned output, and to have an option for power buys from future plants. 

Fusion Power Expands

Other U.S. fusion energy firms also are moving forward to scale up development. Startup Helion Energy, which has $1 billion in private funding, announced in July the start of construction of its first planned power production reactor in Washington state—the 50-MW Orion reactor along the Columbia River set to deliver power into the Pacific Northwest grid.

The company also said it is on track to generate electricity later this year from its Polaris test reactor that was completed in 2024. “Early testing has been encouraging, and they expect to demonstrate electricity this year,” a spokesperson told S&P Global. Helion aims to use superheated fuel to produce fast-pulsed reactions that rhythmically change the surrounding magnetic field, directly generating electricity. 

Helion has not disclosed the full cost of the project and said it still needs to obtain state permits. The firm touts a signed power supply contract with Microsoft and a $375-million investment from OpenAI CEO Sam Altman.

According to sector trade group Fusion Industry Association, global private investment in fusion energy development around the world now totals more than $9.7 billion in about 50 projects, with $2.6 billion raised just last year.

The U.S. Energy Dept. Energy under former President Joe Biden chose eight fusion developers to receive multiyear grants based on successful completion of a series of technology milestones in commercialization. On Sept. 10, the agency awarded $134 million in new grants under two programs to bolster U.S. leadership in fusion technologies. Commonwealth Fusion will collaborate with Oak Ridge National Laboratory through one DOE program, said the company spokeswoman. 

While Energy Secretary Chris Wright has voiced support for fusion, sector proponents seek more funding commitment from the Trump administration and Congressional Republicans. The fusion trade group has asked for $10 billion over five years for milestone-based programs and test facilities.  

The House Science, Space and Technology Subcommittee on Energy will hold a hearing on Thursday, Sept. 18, 10:00AM, to discuss the future of nuclear fusion power and the federal government’s role, with Commonwealth Fusion CEO Mumgaard and other sector leaders set to testify.