US start-up Commonwealth Fusion Systems (CFS) has submitted an application to connect its first ARC fusion power plant to PJM Interconnection, the largest US competitive wholesale electricity market, serving about 182,000 MW of capacity across 13 states and the District of Columbia to more than 65m customers. The application is the first-ever request from a grid-scale fusion power plant developer to a major regional transmission organisation.
In 2025, CFS raised $863m in a Series B2 funding round. The oversubscribed round of capital was the largest amount raised among deep tech and energy companies since its 2021 funding round raised $1.8bn. To date, CFS has raised close to $3bn.
CFS, spun-out from the Massachusetts Institute of Technology (MIT) in 2018, will use the funds to complete its SPARC tokamak under construction in Devens, Massachusetts. It will also progress development work on its planned ARC power plant in Chesterfield County, Virginia, which CFS expects will begin operation in the early 2030s. In July 2025, Google signed a power purchase agreement (PPA) for 200 MWe from the ARC power plant.
Submitting the interconnection request helps to derisk delivering power from the ARC plant since it is one of the long-lead actions necessary to connect a grid-scale power plant in the early 2030s. As part of the submission procedure, CFS will work through PJM’s diligent stress-test process to demonstrate that it can reliably help to meet the region’s surging energy demands.
Regional transmission organisations (RTOs) such as PJM synchronise the complex web of generators and transmission lines, helping to match power supply and demand on a second-by-second basis. This helps to avoid power outages. An interconnection application is the formal process of requesting to “plug in” a new power plant, It initiates a series of deep engineering studies to ensure the grid can safely and reliably handle the influx of the new generating capacity and energy being provided and assess whether any network upgrades are required.
Navigating grid interconnection is a complex process, and it involves more than a conceptual design. Submitting the interconnection request is one of the long-lead actions necessary for providing power in the early 2030s because the start of the study process to the generation of electricity can take four to six years. In the case of PJM, the operator will use sophisticated grid simulation models to diligently stress-test the generation systems of CFS’ fusion power plant to ensure it can connect reliably to help meet the region’s surging energy demands.
In order to submit this application, CFS needed a clear understanding of the fusion part of the ARC power plant and also the power delivery portion of that plant, including the steam, turbine, and generating systems. Dominion Energy advised CFS on best practices for navigating PJM’s interconnection process as part of its Joint Development Agreement with CFS. The application follows the successful navigation of several pre-construction milestones in 2025, which includes securing the world’s first Conditional Use Permit for a commercial fusion power plant.
“Our commitment to delivering the benefits of fusion, and enabling a future with abundant, secure energy, means that we’re not just proving fusion physics works, we’re showing exactly how fusion power plant watts get from our machine to the customer, working with the grid and a utility,” said Bob Mumgaard, Co-Founder and CEO of CFS. “By becoming the first fusion energy developer to enter a major grid operator’s interconnection queue, we’re demonstrating that when you’re serious about building a power plant in the early 2030s, you act now. This is execution.”
Ed Baine, Dominion Energy’s Executive Vice President of Utility Operations and President of Dominion Energy Virginia, noted: “This marks another significant milestone for Commonwealth Fusion Systems and the development of fusion power in Virginia. We are grateful for the opportunity to support CFS in their efforts to make this exciting project a reality for Virginia.” CFS also announced that the site in Chesterfield County, Virginia, on which its first 400-megawatt ARC power plant will be built, has been named the Fall Line Fusion Power Station. The name references the geological boundary where Virginia’s elevated Piedmont region drops down to the Tidewater coastal plain, creating the rapids on the James River.
