Zap Energy has begun operations of Century, its new high-rep-rate, liquid-metal-cooled fusion test platform, and closed $130 million of fresh capital, marking significant steps toward a commercial fusion power plant.

Century is the first fully-integrated demonstration of several fusion power plant-relevant technologies, including one of the largest tests of a plasma-facing liquid metal blanket to date. Century has already demonstrated a test run of more than 1,000 consecutive plasmas in less than three hours into a chamber lined with flowing liquid metal.

Zap’s $130 million Series D was led by Soros Fund Management LLC, with participation by new investors that include BAM Elevate, Emerson Collective, Leitmotif, Mizuho Financial Group, Plynth Energy and Xplor Ventures. Current investors participating in the new round include Addition, Breakthrough Energy Ventures, Chevron Technology Ventures, DCVC, Energy Impact Partners, Lowercarbon Capital and Shell Ventures.

The new funding will be used to continue parallel development of both plasma R&D and systems-level plant engineering and integration, including the next generation in the company’s FuZE device series and a cutting-edge pulsed power capacitor bank.

The team is now attempting to reach a milestone outlined as part of the U.S. Department of Energy’s (DOE) Milestone-Based Fusion Development Program, and hopes to do so by the end of the year.

“The race for fusion commercialization has historically been thought of as a triathlon: science, then engineering, then commercialization,” says Zap CEO Benj Conway. “But at Zap, we’re attempting to swim, cycle and run at the same time – such a parallel approach is key to delivering commercial fusion on a timescale that matters. Century is a vital part of the engineering leg and we’re quickly coming up to speed.”

Zap VP of Systems Engineering Matthew C. Thompson explains the motivations for building Century.

Z-pinch fusion from lab to grid

Zap Energy’s fusion approach, known as a sheared-flow-stabilized Z pinch, avoids large superconducting magnets and powerful lasers, and is far smaller than conventional systems.

To generate net energy from fusion, regardless of the type of device, the plasmas inside must satisfy fusion’s triple product: they must be hot enough, and dense enough, for long enough. With a track record of rapid progress in plasma physics using two workhorse fusion devices, and recent results reinforcing the viability of the path ahead, Zap has begun work engineering new devices to face greater extremes and harness fusion’s energy output.

“From its inception, Zap Energy’s founders had an idea of how a power plant based on our Z-pinch configuration would work,” says Zap Vice President of Systems Engineering Matthew C. Thompson. “Our job is to develop and validate those plans by actually building, testing and maturing key technologies. Century is our next major step in that effort."

About Century

Century is the world’s first 100-kilowatt-scale repetitive Z-pinch system. Its goal is to integrate and test three major aspects of Zap’s power design: repetitive pulsed power supplies, plasma-facing circulating liquid metal walls, and technology for mitigating electrode damage.

Century is designed to simulate plant-like operation by:

• Firing high-voltage pulses of power every ten seconds in a steady sequence for more than two hours (>1,000 pulses at 0.1 Hz).
• Circulating 70 kilograms of hot liquid bismuth in its initial configuration and well over a ton in its final configuration. Air-cooled heat exchangers will remove the intense plasma heat absorbed by the liquid metal.
• Testing critical strategies for mitigating electrode damage due to extreme heat and neutron flux. Century's Z-pinch plasmas are fueled with hydrogen and will simulate plasma dynamics but will not produce fusion reactions or neutrons.

“Zap’s fusion approach is pulsed, so ultimately it will run like an internal combustion engine with cylinders firing all day long to produce steady energy output,” explains Thompson. “As you do that you also generate large neutron flux and heat loads in the system over time, which is exactly the energy output that you want, but requires unique engineering solutions. Century will test a lot of our assumptions and define the best path toward our first plant.”

Century’s structure is the first to take Zap’s sheared-flow-stabilized Z-pinch chamber design and orient it vertically. Pulsed power is injected through the top of the device while liquid metals circulate in a receptacle at the base. Independent test stands built over the past two years at Zap validated previous generations of each of Century’s subsystems.

The first test of plasmas and flowing liquid metal occurred on June 13 and a few weeks later completed a run of 1,080 consecutive shots. Century’s next aim is a milestone run for the DOE, which will be subject to confirmation by the program.

Zap’s power module designs have a circulating liquid metal wall to absorb heat and neutrons from the fusion plasmas. This video shows the small-scale version that was first tested in 2023 (left) and has been integrated with Z-pinch plasmas in Century. On the right is the conceptual model of a Zap power module based on flowing liquid metal walls.

Next year the platform will gradually ramp to 100 kilowatts of average input power. For comparison, the 100 kilowatts that drives Century is roughly equal to taking the average power draw of 75 U.S. homes and concentrating it into a chamber the size of a hot water heater.

Century, with a central stack about the size of a double-decker bus, is close to the eventual size of a single Zap Energy module that will produce 50 megawatts of electricity. Future power plants will have multiple modules.