Technology · June 23, 2022

Fusion Energy Advance is celebrated by a Seattle startup

Zap Energy, a fusion energy start-up working on a low-cost path to commercial power generation, said last week that it had taken an important step toward testing a system that its researchers believe will eventually produce more power as it consumes.

This point is seen as a milestone in solving the world’s energy challenge as it moves away from fossil fuels. A burgeoning global industry made up of nearly three dozen startups and heavily funded government development projects embraces a variety of concepts. Seattle-based Zap Energy is notable for the fact that its approach — if it works — would be simpler and cheaper than what other companies are doing.

Today’s nuclear power plants are based on fission, which captures the energy released by the fission of atoms. In addition to the intense heat, the by-products of the process include waste that remains radioactive for centuries. Nuclear fusion, on the other hand, replicates the process that takes place inside the Sun, where gravitational forces fuse hydrogen atoms into helium.

For more than half a century, physicists have envisioned commercial power plants based on a controlled fusion reaction, essentially bottling the power of the sun. Such a power plant would produce many times more electricity than it consumes and without long-lived radioactive by-products. But none of the research projects came even close to reaching their goal. However, as fears of climate change mount, interest in the technology is growing.

“We think it’s important that fusion becomes part of our energy mix,” said Benj Conway, president of Zap Energy.

While many competing efforts use powerful magnets or bursts of laser light to compress a plasma to trigger a fusion reaction, Zap follows an approach pioneered by physicists at the University of Washington and the Lawrence Livermore National Laboratory.

It relies on a shaped plasma gas — an energized cloud of particles often referred to as the fourth state of matter — that is compressed by a magnetic field generated by an electric current as it flows through a two-metre-long vacuum tube. The technique is known as “shear flow z-pinch”.

Zap Energy’s “pinch” approach isn’t new. It may have been observed in the effects of lightning strikes as early as the 18th century and has been proposed as a route to fusion energy since the 1930s. While natural constrictions occur during lightning strikes and solar flares, the challenge for engineers is to stabilize the electric and magnetic forces in pulses long enough – measured in a millionth of a second – to produce radiation to heat a surrounding curtain of molten metal.

Brian Nelson, a retired University of Washington nuclear engineer and Zap Energy’s chief technology officer, said the company has successfully injected plasma into a new and more powerful experimental reactor core. A power supply is now being completed that will provide enough energy to enable the company to demonstrate that it is possible to produce more energy than it consumes.

If their system proves workable, the Zap researchers say it will be orders of magnitude cheaper than competing systems based on magnetic and laser confinement. It is expected to cost about the same as traditional nuclear power.

Researchers who tried the Z-pinch design found it impossible to stabilize the plasma and scrapped the idea in favor of the magnet approach known as the tokamak reactor.

Advances in stabilizing the magnetic field generated by flowing plasma by University of Washington physicists led the group to found Zap Energy in 2017. The company has raised more than $200 million, including a number of investments from Chevron.

Recent technical advances in fusion fuels and advanced magnets have prompted a surge in private investment, according to the Fusion Industry Association. There are 35 merger companies worldwide and private funding has grown to more than $4 billion, including from well-known technology investors such as Sam Altman, Jeff Bezos, John Doerr, Bill Gates and Chris Sacca. Mr. Gates and Mr. Sacca invested in Zap’s recent funding round.

But there are still vocal skeptics who argue that progress in fusion energy research is largely a mirage and that recent investments are unlikely to translate into commercial fusion systems any time soon.

Last fall, Daniel Jassby, a retired plasma physicist at Princeton University, wrote in an American Physical Society newsletter that the United States was in the midst of another round of the “fusion energy fever,” which has come and gone every decade since the 1950s be. He argued that claims by start-up companies that they are on the way to successfully building systems that produce more energy than they use are unfounded in reality.

“The fact that these claims are widely believed is due solely to the effective propaganda of promoters and laboratory spokesmen,” he wrote.

Zap Energy’s physicists and executives said in interviews last week that they believed within a year they would show proof that their approach was capable of reaching the long-awaited energy break-even point.

In doing so, they succeed where a number of research efforts – dating back to the middle of the last century – have failed.

Zap Energy physicists said they had argued for the “scaling power” of their approach to produce a steep surge in neutrons in a series of peer-reviewed technical papers documenting computer-generated simulations they would soon begin testing.

A power plant version of the system would encase the reactor core in moving molten metal to trap bursts of neutrons, resulting in intense heat that would be converted to steam, which in turn produces electricity.

Each reactor core will generate about 50 megawatts of electricity, about enough to power at least 8,000 homes, said Uri Shumlak, a physicist and professor at the University of Washington who is a co-founder of Zap Energy.

Their technical challenge now is to confirm what they simulated by computer, he said. This includes ensuring that the z-pinch fusion portion of the plasma remains stable and that they are able to design an electrode that can survive in the reactor’s intense fusion environment.

Mr. Conway said he hopes Zap can prove its concept quickly, in contrast to the large, costly development efforts of the past, which “build a multi-billion dollar iPhone prototype every 10 years.”