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Commonwealth Fusion Systems

High-field tokamak fusion, building SPARC and the world's first fusion power plant

NuclearEnergy
What they build

The product

High-temperature superconducting (HTS) magnet-based tokamaks. SPARC, under construction at the Devens, MA campus, is designed to be the first machine to demonstrate net-energy fusion (Q>1). ARC, sited in Chesterfield County, Virginia, is the planned 400 MW first-of-a-kind commercial fusion power plant.

Why it matters

The thesis

CFS has raised $4 billion, more than any other private fusion company, while advancing both SPARC and its first commercial plant in parallel. SPARC was reported nearly 80% complete in August 2026, and ARC has entered the PJM interconnection process with Google and Eni contracted for more than half of the first plant's planned output.

Operating model

How it runs

CFS follows a staged build-own-and-commercialize roadmap: manufacture high-temperature-superconducting magnets and operate SPARC as the net-energy demonstration, then develop ARC grid-scale plants and replicate them with an industrial supply chain.

Revenue model

How it earns

Commercial revenue is expected from long-term electricity offtake agreements from ARC plants. Google contracted for 200 MW from the first 400 MW ARC plant and holds options for future plants; Eni signed an offtake agreement valued at more than $1 billion. Detailed pricing terms remain undisclosed.

Strategic edge

Why it wins

CFS combines the well-studied tokamak approach with 20-tesla-class high-temperature-superconducting magnets developed with MIT, enabling smaller, higher-field machines that it says can be built at lower cost; its SPARC-to-ARC sequence is designed to retire technical risk before commercial replication.

Source material

Evidence ledger

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