Over the past several years, fusion power has evolved from a perennial punchline—always a decade away!—into an increasingly tangible and enticing technology that has drawn investors off the sidelines.
The technology remains challenging to master and expensive to build today, but fusion promises to harness the nuclear reaction that powers the sun, generating nearly limitless energy on Earth. If startups can complete commercially viable fusion power plants, they have the potential to disrupt trillion-dollar energy markets.
The bullish wave buoying the fusion industry has been driven by three key advances: more powerful computer chips, more sophisticated AI, and powerful high-temperature superconducting magnets. Together, these technologies have enabled more advanced reactor designs, better simulations, and more complex control systems.
It also helps that, at the end of 2022, a U.S. Department of Energy lab announced a controlled fusion reaction that produced more power than the lasers had imparted to the fuel pellet. This experiment crossed what is known as scientific breakeven. While still far from commercial breakeven—where the reaction generates more power than the entire facility consumes—it was a long-awaited step that validated the underlying science.
Founders have built on that momentum in recent years, pushing the private fusion industry forward at a rapid pace. As of 2026, several private fusion companies have raised over $100 million, reflecting growing investor confidence in the sector's potential to deliver commercial reactors within the next decade.
Commonwealth Fusion Systems
Commonwealth Fusion Systems (CFS) has raised approximately one-third of all private capital invested in fusion companies to date. Its latest round, which closed in August 2025, added $863 million, bringing total funding to nearly $3 billion.
CFS’s Series B2 came four years after its $1.8 billion Series B, which helped propel the company to the forefront of the industry. Since then, the startup has been hard at work in Massachusetts building Sparc, its first-of-a-kind power plant designed to produce power at what it calls “commercially relevant” levels.
Sparc’s reactor uses a tokamak design, resembling a doughnut. Its D-shaped cross section is wound with high-temperature superconducting tape. When energized, the tape generates a powerful magnetic field that contains and compresses superheated plasma. Heat from the reaction converts water to steam, driving a turbine to produce electricity. CFS designed its magnets in collaboration with MIT, where co-founder and CEO Bob Mumgaard worked on fusion reactor designs and high-temperature superconductors.
Based in Massachusetts, CFS expects Sparc to become operational in late 2026 or early 2027. Later this decade, the company plans to begin construction on Arc, its commercial power plant targeting 400 megawatts of electricity. The facility will be built near Richmond, Virginia, and Google has agreed to buy half its output.
CFS is backed by a diverse group of investors, including Breakthrough Energy Ventures, The Engine, Bill Gates, and others.
via TechCrunch