The Billion-Dollar Race: Top Fusion Startups Revolutionizing Clean Energy

The Rise of Fusion Power

Over the last several years, fusion power has transformed from a distant dream into a tangible technology attracting massive investments. Fusion startups have raised $7.1 billion to date, with a handful of companies leading the charge. This surge is driven by three key advances: more powerful computer chips, sophisticated AI, and high-temperature superconducting magnets, enabling better reactor designs and simulations.

In late 2022, a U.S. Department of Energy lab achieved a controlled fusion reaction producing more power than input, marking a scientific breakeven. This milestone validated the underlying science, fueling momentum in the private sector.

Leading Fusion Startups

Commonwealth Fusion Systems

Commonwealth Fusion Systems (CFS) has raised nearly $3 billion, accounting for about a third of all private fusion capital. Their latest $863 million round in August 2025 supports the construction of Sparc, a tokamak reactor using high-temperature superconducting magnets. CFS aims to have Sparc operational by late 2026 or early 2027, with a commercial plant, Arc, planned for Virginia to produce 400 megawatts. Google has agreed to buy half its output. Backed by investors like Bill Gates and Breakthrough Energy Ventures, CFS is a frontrunner in the fusion race.

TAE Technologies

Founded in 1998, TAE Technologies uses a field-reversed configuration with particle beams to stabilize plasma. With total funding of $1.79 billion, including a $150 million round in June 2025 from Google and Chevron, TAE focuses on long-term stability for efficient energy extraction.

Helion

Helion targets electricity production by 2028, with Microsoft as its first customer. Using a field-reversed configuration reactor, Helion induces fusion through plasma collisions, harvesting electricity directly. Raised $1.03 billion, including $425 million in January 2025, with backers like Sam Altman and Peter Thiel.

Pacific Fusion

Pacific Fusion burst onto the scene with a $900 million Series A, using inertial confinement with electromagnetic pulses. Led by Eric Lander, funding is milestone-based, common in biotech, ensuring disciplined progress.

Shine Technologies

Taking a pragmatic approach, Shine Technologies focuses on neutron testing and medical isotopes before pursuing fusion power. With $778 million raised, it's building skills for future reactor development.

General Fusion

In its third decade, General Fusion uses magnetized target fusion with a liquid metal wall. Despite raising $462.53 million, it faced cash shortages in 2025, leading to layoffs and a $22 million lifeline from investors.

Tokamak Energy

Tokamak Energy employs a compact spherical tokamak design with high-temperature superconducting magnets. Its ST40 prototype achieved 100 million degree C plasma in 2022. Raised $336 million, with Demo 4 under construction for testing.

Zap Energy

Zap Energy uses electric currents to generate magnetic fields for plasma confinement, avoiding expensive magnets. Based in Washington, it has raised $327 million from investors including Bill Gates.

Proxima Fusion

Proxima Fusion stands out with a stellarator design, attracting €185 million in funding. Stellarators twist to accommodate plasma quirks, promising longer stability for fusion reactions.

Marvel Fusion

Marvel Fusion follows inertial confinement with lasers and silicon nanostructures, leveraging semiconductor manufacturing. Raised $161 million, building a demonstration facility by 2027.

First Light

First Light pivoted in March 2025 from fusion power to technology supply, after raising $140 million. It previously focused on inertial confinement.

Xcimer

Xcimer builds on National Ignition Facility science, aiming for a more powerful laser system with molten salt walls. Founded in 2022, it has raised $109 million rapidly.

This dynamic field continues to evolve, with startups pushing the boundaries of clean energy innovation.