For fusion power enthusiasts, reaching the “break-even point” is something of a holy grail. That is, the point at which the fusion reaction produces more power than is needed for ignition. Only one scientific experiment at the National Ignition Facility accomplished this feat, and it took more than a decade to tune the system to achieve this monumental result.
“The day the NIF results were announced was clearly this incredibly celebrated scientific result. They all deserve a Nobel Prize,” said Zap Energy Co-Founder and Chief Executive Officer ( CEO) Benj Conway told TechCrunch. “But the next day, the question is, what's going to happen with that? What's next?”
Although NIF succeeded in improving initial results, the device is something of a dead end. It was about exploring the limits of physics, not selling power to the grid.
For a startup like Zap, the “so what” requires a better answer.
Zap's answer for now is a new device it calls Century, for which it recently raised $130 million in Series D funding. After keeping Century a secret for several months, the startup gave TechCrunch a peek inside it, sharing exclusive details about its operations and what it hopes to learn from using it.
The Century prototype takes up about the same space as a double-decker bus. Image credit: Zap Energy
Zap employs a unique approach to fusion power generation known as shear flow-stabilized Z-pinch. Instead of using magnets or lasers to squeeze the plasma, it sends electricity through the plasma stream. That current creates a magnetic field, or pinch, that compresses the plasma, ultimately causing nuclear fusion. The company was studying the phenomenon using a series of instruments at its facility in Washington state.
But Century is more than just a physics guinea pig, Conway said.
“We focus not only on physics, but also on systems engineering. We are more than just a plasma physics company. We focus on the key enabling technologies needed to achieve commercial convergence. “We believe that doing all of this in parallel, all at once, is actually the fastest way to deliver a commercial product.” said. “Century is the embodiment of that.”
A worker inspects a capacitor at Century. Image credit: Zap Energy
The demonstration device is about a story and a half tall, and the liquid bismuth-lined reaction chamber inside is about the size of a domestic water heater. Together, the main components take up about as much space as a double-decker bus, and Zap believes a commercial-scale module that generates 50 megawatts of power would occupy a similar footprint.
To stay on track to becoming a commercial power plant, Zap must accomplish three milestones. First, it must be able to generate high voltage pulses frequently and continuously. A few weeks after powering up this summer, Century fired 1,080 consecutive pulses. So far, so good.
The next step is to demonstrate the technology for the Department of Energy. The technology produces at least 1,000 plasma pulses that are fired at 10-second intervals, allowing the device to run for more than two hours. Ultimately, to operate as a commercial power plant, Zapp's reactor would need to fire at 10 pulses per second for several months.
Work continues on Zap Energy's Century prototype. Image credit: Zap Energy
After Century completes its demonstration for the Department of Energy, the team plans to add more liquid bismuth to the reaction chamber. The molten metal absorbs heat while protecting other parts of the device, and in commercial implementations this heat can be used to generate electricity. Century is expected to be able to hold more than a ton of liquid metal, but currently starts at 70 kg.
Finally, the company must ensure that the electrodes, the parts that generate the electrical pulses, can withstand the heat and particles released by each fusion reaction. Those parts won't last forever. All commercial power plants must undergo maintenance at some point. Frequency and duration are usually the issues. Zaps need to be able to withstand long enough for the weakest parts to make economic sense for power producers.
The company plans to increase the amount of electricity supplied to the reaction chamber to reach 100 kilowatts by next year. Along the way, Conway expects the company to make incremental improvements to Century. “Century is one platform, one name, but there are multiple generations within it,” he said. “Iteration within iteration.”
If Century works as planned, “my hope is that we'll be able to successfully build a demo in this decade,” Conway said. And if that goes well, commercial power plants should follow by the early 2030s.
Exterior view of Century (right) and its power cabinet (left). Image credit: Zap Energy
Conway admits it's a lot of “what ifs”. “As we finish cutting the ribbon on our first power plant and think about the most difficult problems we've had to solve in the past five years, my guess is that plasma physics and gain are on the list. I'm sure. But I'm sure there are many more on the list.”
That “other thing” may determine the success or failure of commercial fusion power generation.
“Fusion has to compete with other methods of producing electricity and heat. If the cost of fusion power plants is much higher than other methods of generating electricity, there won't be many of them.” We might take the kids on field trips and have things to show them, but that’s it,” Conway said. “The economics of these things are going to be very important.”