Fusion energy: A different kind of nuclear power

Martin Daks//March 21, 2022

Fusion energy: A different kind of nuclear power

Martin Daks//March 21, 2022

The National Spherical Torus Experiment is a magnetic fusion device. – PRINCETON PLASMA PHYSICS LABORATORY



A lab in Great Britain recently reported a breakthrough advance in developing fusion energy, which powers the sun and could help make fossil fuels obsolete. And a group of physicists in the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) contributed to the development.

“Fusion energy is non-polluting, and leaves no radioactive waste,” said Steven Cowley, director of PPPL. “Unlike wind and solar-generated energy, whose reliability may vary depending on weather conditions, fusion energy will be available at the flick of a switch as needed.”

Shattering an energy record

In February, thanks in part to research developed at PPPL, the Joint European Torus (JET) announced it set a historic record in the production of experimental fusion energy. The experiments produced 11 megawatts of power for about five seconds—more than double what was achieved in similar tests back in 1997, according to published reports.

It didn’t represent a massive energy output — only enough to boil about 60 kettles’ worth of water, according to the BBC. But the advance did validate design choices that are being incorporated in a larger fusion reactor that’s under construction in France.

A movable (fission) feast

A small company in Plainsboro is making big advances in scalable nuclear fusion reactors. Michael Paluszek is the president of Princeton Fusion Systems — a spinoff of Princeton Satellite Systems — and has received more than $2 million in funding from the federal Department of energy’s Advanced Research Projects Agency-Energy (DOE ARPA-E). The company works closely with the DOE’s Princeton Plasma Physics Laboratory and is working to scale down fusion reactors so they’ll be usable outside of a research facility.

If the five-employee, two-consultant company is successful, plug-and-play fusion engines the size of a minivan, with a 30-year life, could power devices from satellites to ocean-going vessels. Potentially, they could fit on the back of a utility truck and could be driven to disaster sites, providing power until permanent repairs can be completed.

“The concept of the Princeton field-reversed configuration (PFRC) reactor was developed through collaborative research and experience at the Princeton Plasma Physics Laboratory, and funded primarily by the U.S. DOE and NASA,” said Paluszek, a former engineer at GE Astro Space in East Windsor. “It is our mission to develop the Princeton FRC compact fusion reactor into a portable power plant that can provide power in off-grid locations and in modular power plants. From remote industrial applications to emergency power after natural disasters, to offworld bases on the moon or Mars, the PFRC is the ultimate microreactor solution.”

Right now, Paluszek and his colleagues are working on a second-generation system aimed at demonstrating proof of concept. If that’s successful, they hope to deploy a third-generation device capable of generating fusion-level reactions. A working reactor could, in theory, be developed in the next 10 to 15 years.

“At this point, we still need to demonstrate that the high temperatures and pressures necessary for a fusion reaction can be generated in our compact design,” he said. “From there, we need to build a prototype. Once that’s accomplished, there’s no limit to the possibilities. Someday, our design may be powering human colonies on other planets.”

“There’s been a friendly rivalry between JET and Princeton since the 1970s, when PPPL developed its Tokamak Fusion Test Reactor (TFTR),” said Cowley, referring to a machine that used donut-shaped magnetic fields to help achieve temperatures far hotter than the 27 million degrees Fahrenheit core of the sun.

Fusion reactions work on the principle that energy can be released by forcing together atomic nuclei — which the sun and other stars do with huge gravitational pressures — instead of splitting them, the way that fission reactions do in existing nuclear power stations. Fusion represents a long-term power source — the sun has been burning for more than 4 billion years and will likely blaze for another 5 billion. But unlike fission, which generates radioactive waste and can be difficult to control — think Three Mile Island and Chernobyl — fusion’s only byproduct is helium, an inert gas.

“PPPL developed the TFTR in the 1970s and, in 1994, set a world record for fusion power production,” said Cowley, who has headed the Princeton laboratory since 2018. “Theoretically, fusion is a perfect fuel source.”

Some lingering questions

But Cowley tempered his enthusiasm with a few caveats. One is the time it’ll take to make fusion power commercially available. “The challenge is that we can reach temperatures of 250 million degrees that’s necessary to obtain a fusion reaction and must maintain it to produce continuous power; so there’s still a lot more research needed.”

Another issue is that while fission reactions generate a lot of heat, no one’s figured out just how to efficiently convert that to electricity. “We have ideas,
we’re still investigating that,” he said. “One issue is that we have to deliver [star-like] heat for a sustained period of time, a lot longer than the five seconds that’s been attained by JET. But PPPL and other research centers are continuing to work on this. At PPPL, for example, we recently received a federal grant to make a three-dimensional design for a better magnetic ‘bottle,” referring to the magnetic field that holds the atomic nuclei in the plasma that fuels fusion reactions in place long enough to extend the fusion reaction.

One good thing — if the research at PPPL and other labs does work out and fission-generated power can be achieved, it could be delivered without tearing down and rebuilding existing power lines and other infrastructure.

“The power plants themselves would be replaced by relatively compact fusion reactors,” he noted, adding that, unlike nuclear reactors, nearby homes
and businesses wouldn’t be at risk. “So fission-generated electricity could be delivered over existing power lines.”

Assuming that controlled fusion reactions achieved, yielding a clean and sustainable source of energy, will it necessarily mean lower prices for businesses and other energy consumers? “We know we can do fusion and it’ll be cleaner than fossil fuels,” said Cowley. “But will it be less expensive? That’s still an open question. We’ll need to be able to scale it before the pricing becomes manageable. Still, there is some precedent: look at the Wright brothers. It took a long time until air travel was affordable for the masses, but we did get there eventually.”