Every merger startup that has raised more than $300 million

In the past few years, fusion energy has gone from being a joke—always a decade away!—to an increasingly tangible and enticing technology that has attracted investors.

The technology may be difficult to master and expensive to build, but fusion promises to harness the nuclear reaction that powers the sun to generate nearly limitless energy here on Earth. If startups can complete commercially viable fusion power plants, they have the potential to upend trillion-dollar markets.

The surge in fusion power has been fueled by three advances: more powerful computer chips, more advanced artificial intelligence, and powerful, high-temperature superconducting magnets. Together, they have helped deliver more sophisticated reactor designs, better simulations, and more complex control schemes.

It doesn’t hurt that in late 2022, a U.S. Department of Energy lab announced that it had produced a controlled fusion reaction that produced more power than the lasers were imparting to the fuel pellet. The experiment passed the so-called scientific break-even point, and while it’s still a long way from the commercial break-even point, where the reaction produces more than the entire facility consumes, it was a long-awaited step that proved the basic science was right.

Founders have seized that momentum in recent years, pushing the private fusion industry forward at a rapid pace. Fusion startups have raised $7.1 billion to date, according to the Fusion Industry Association, with most of that going to a handful of companies.

Commonwealth Fusion Systems

With a $1.8 billion Series B round, Commonwealth Fusion Systems catapulted itself into a leader position in 2021. The company hasn’t done any fundraising since (unsurprisingly), but it’s been hard at work in Massachusetts building Sparc, its first-of-its-kind power plant that’s expected to produce what it describes as “commercially significant” levels of energy.

The Sparc reactor uses a doughnut-shaped tokamak design. The D-shaped cross-section is wrapped in high-temperature superconducting tape, which, when excited, generates a powerful magnetic field that will contain and compress the superheated plasma. The heat generated by the reaction is converted into steam, which drives a turbine. CFS designed its magnets in collaboration with MIT, where co-founder and CEO Bob Mumgaard worked as a researcher on fusion reactor designs and high-temperature superconductors.

Cambridge, Mass.-based CFS, which is backed by Breakthrough Energy Ventures, The Engine, Bill Gates and others, expects the Sparc plant to be operational in the early 2030s.

General merger

Now in its third decade, General Fusion has raised $440.53 million, according to PitchBook. The Richmond, British Columbia-based company was founded in 2002 by physicist Michel Laberge, who wanted to prove a different approach to fusion known as magnetized target fusion (MTF).

In a General Fusion reactor, a wall of liquid metal surrounds a chamber into which plasma is injected. Pistons surrounding the wall push it inward, compressing the plasma inside and triggering a fusion reaction. The resulting neutrons heat the liquid metal, which can then circulate through a heat exchanger to produce steam to spin a turbine.

The company is currently building its first LM26 demonstration plant, which is expected to reach scientific break-even by 2026. Investors include Jeff Bezos, Temasek, BDC Capital and Chrysalix Venture Capital.

Helion

Of all the fusion startups, Helion has the most aggressive timeline. The company plans to produce electricity from its reactor in 2028. Its first customer? Microsoft.

Helion uses a type of reactor called a reverse-field configuration, in which magnets surround a reaction chamber that looks like an hourglass with a bulge where the two sides meet. At each end of the hourglass, they spin the plasma into doughnut shapes that are shot toward each other at more than 1 million miles per hour. When they collide in the middle, additional magnets help trigger fusion. When fusion occurs, it amplifies the plasma’s own magnetic field, which induces an electric current inside the reactor’s magnetic coils. That electricity is then collected directly from the machine.

Based in Everett, Washington, Helion has raised $607.64 million, according to PitchBook. Investors include Sam Altman, Reid Hoffman, KKR, BlackRock, Peter Thiel’s Mithril Capital Management and Capricorn Investment Group.

TAE

Founded in 1998, TAE (formerly known as Tri Alpha Energy) was spun out of the University of California at Irvine by Norman Rostoker. It uses a reverse-field setup, but with a twist: After the two plasma beams collide in the center of the reactor, the company bombards the plasma with particle beams to keep it spinning in a cigar shape. This improves the stability of the plasma, giving it more time to fuse and extract more heat to spin the turbine.

TAE has raised $1.32 billion, according to PitchBook. Investors include Alphabet, Chevron Technology Ventures and Venrock.

Zap Energy

Zap Energy doesn’t use superconducting high-temperature magnets or super-powerful lasers to keep the plasma in check. Instead, it uses an electric current (get it?) to condense the plasma, which then generates its own magnetic field. The magnetic field squeezes the plasma by about 1 millimeter, at which point it ignites. Neutrons released by the fusion reaction bombard a liquid metal blanket that surrounds the reactor, heating it up. The liquid metal is then passed through a heat exchanger, where it generates steam to power a turbine.

Like Helion, Zap Energy is based in Everett, Washington, and the company has raised $327 million, according to PitchBook. Investors include Bill Gates’ Breakthrough Energy Ventures, DCVC, Lowercarbon, Energy Impact Partners, Chevron Technology Ventures and Bill Gates as an angel investor.