Lightning in a Bottle: How Zap Energy’s Steady Grind Could Reshape Fusion
A twenty-fold jump in sustained power sounds impressive—but the real story is what the company isn’t saying.
EVERETT, Wash. — Inside a vacuum chamber not much bigger than a household water heater, Zap Energy has been quietly chasing a goal that rarely grabs headlines in the world of fusion: making the unglamorous parts work, and making them work every single time.
Today, the private fusion startup revealed that its Century test platform now runs at 0.2 Hz—one plasma shot every five seconds. Each pulse channels 500 kiloamperes of current into a chamber lined with circulating liquid bismuth. The machine sustains 39 kilowatts of direct chamber power, a twenty-fold leap from where it stood in 2024.
And yet, missing from the announcement is the word that fusion fans love to hear: breakthrough. Zap isn’t claiming net energy gain, world-record plasma conditions, or even fusion itself. Century runs on plain hydrogen or helium, not the deuterium-tritium mix that fuels real fusion reactions. No neutrons fly out. No energy gets multiplied.
That restraint may be the most telling part of the story.
A Machine That Strikes Like Lightning, Over and Over
Think of it this way: every plasma pulse carries about twenty times the current of a lightning bolt, squeezed into a space you could tuck inside a kitchen appliance. A liquid loop pushes 2,500 pounds of bismuth through the chamber, moving at speeds and temperatures that would shred ordinary materials. To keep everything balanced, a custom-built air-cooled heat exchanger whisks away 200 kilowatts of heat, while liquid-metal-tipped electrodes shrug off the pounding from those massive pulses.
Since rolling out in June 2024, Century has fired more than 10,000 times in various setups. In February, the Department of Energy signed off on a three-hour campaign where the machine produced 1,080 shots back-to-back—an early milestone under DOE’s $1.2 billion Milestone-Based Fusion Development Program.
The achievement feels deliberately modest. While other labs and companies trumpet record gains or aggressive timelines, Zap talks about electrode cooling systems and liquid-metal stability. It’s not the stuff of splashy headlines, but it’s exactly the kind of detail that makes or breaks a future power plant.
Building the Parts No One Sees
Zap’s vice president of systems engineering, Matthew Thompson, put it plainly: “Century’s real-world tests mean we’ve already started identifying and solving many of the toughest commercial technology problems.” Notice the choice of words—solving, not solved. This is a long game.
What Century truly showcases is integration. It brings together three vital technologies for pulsed fusion: power systems that can fire thousands of times without failing, liquid metal walls that soak up intense heat, and electrodes tough enough to survive conditions no solid material could endure.
None of this is glamorous. Engineers wrestle with how Lorentz forces ripple liquid metal, how to keep bismuth vapor from contaminating plasma, how pulsed-power capacitors survive relentless firing, and how electrode designs resist erosion over millions of shots. It’s the engineering equivalent of plumbing—messy, essential, invisible when it works.
A peer-reviewed paper published last month in Fusion Science and Technology details Century’s design and early runs, underscoring Zap’s preference for methodical engineering over hype.
Why Bismuth, and Why That Matters
Choosing bismuth for the chamber walls says a lot about Zap’s strategy. Bismuth conducts electricity, shields surfaces, and carries away heat without boiling off under vacuum. It lets researchers explore liquid-metal hydraulics, magnetohydrodynamics, and heat management in conditions close to what a real plant would see.
But bismuth has a big shortcoming: it can’t breed tritium, the radioactive isotope that partners with deuterium to fuel fusion. Actual plants will need lithium-based coolants for that. So Century sidesteps the thorny issues of tritium production, neutron damage, and strict regulation. In effect, it’s a sandbox where engineers stress-test the “balance of plant” systems while leaving fuel-cycle questions for later.
This means Century doesn’t directly prove Zap’s fusion concept—the sheared-flow-stabilized Z-pinch, which compresses plasma with magnetic fields generated by current flowing through it. For that, Zap uses a separate machine, FuZE, which does produce neutrons. Century is about the scaffolding, not the spark.
Competition Heats Up
Zap’s announcement comes at a time when the fusion conversation is shifting. Just last year, Helion Energy broke ground on the world’s first privately funded, grid-connected fusion plant in Washington state, backed by a Microsoft contract that bets on electricity by 2028. General Fusion, meanwhile, is building its LM26 demo plant, aiming to show fusion gain within the next couple of years.
Compared with those big promises, Zap’s focus on subsystems could seem underwhelming. But in liquid-metal engineering and repetitive pulsed-power, Zap is quietly proving it belongs among the top players. Industry watchers suggest its work on liquid-metal walls may already outpace what most public programs have achieved.
Still, in today’s market, technical merit isn’t enough. Investors and customers—especially data centers hungry for clean, steady power—care less about capacitor banks and more about contracts to deliver electricity. The fusion sector has pulled in $9.7 billion across 53 companies, with $2.64 billion raised in the past year alone. Capital is following the outfits that look closest to plugging into the grid.
The Gap Between Now and the Grid
Century’s 39 kilowatts of chamber power is a far cry from the megawatts—or gigawatts—that real plants will need. Bridging that gulf isn’t just a matter of scaling up; it means wrestling with fundamental challenges in plasma physics, materials, and systems design.
Commercial plants would need repetition rates of one to ten shots per second, sustained for months. That’s a brutal environment for capacitors, switches, and electrodes. The components that hold up at 0.2 Hz may wear out fast at ten shots per second. And when neutrons from real fusion enter the picture, electrodes and walls degrade in ways no one has fully solved.
What Investors Should Watch
For backers, Century’s progress lowers the technical risk for pulsed fusion in general. It shows liquid-metal walls and repetitive power systems can work at meaningful scale. That boosts confidence not just in Zap but in any company pursuing similar ideas.
Market forces also tilt in fusion’s favor. Data centers, factories, and utilities are desperate for round-the-clock clean power. Historically, it takes five to ten years after a new energy technology proves itself before buyers commit in a big way. If fusion timelines hold, the 2030s could be the decade it finally enters the market.
But investors should remember: Century doesn’t answer the toughest questions about neutron-proof materials, tritium breeding, or full fuel cycles. The companies that crack those puzzles first—and demonstrate them in integrated machines—will likely command the highest valuations.
Looking Ahead
Zap’s next steps are incremental but important. Engineers plan to push Century toward faster repetition rates—perhaps 1 Hz—and higher power levels, topping 100 kilowatts, still with non-fusion gases. That lets them refine the plumbing and cooling before stepping into fusion-grade territory.
Eventually, though, Zap will need to tackle lithium coolants, neutron environments, and tritium handling. Until then, Century remains a proving ground for the less glamorous but utterly essential technologies that underpin any future plant.
The fusion sector is shifting from science projects to industrial ventures. Success will depend less on physics breakthroughs and more on the grind of engineering—signing contracts, winning permits, building plants. When fusion finally lights up the grid, it won’t arrive in a single thunderclap of discovery. It’ll come from the steady drumbeat of thousands of tests, each one nudging the technology closer to the day when lightning doesn’t just strike—it powers your home.
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