Fusion energy possible within this decade — scientists

Source: By John Fialka, E&E News reporter • Posted: Wednesday, September 30, 2020

ITER fusion project. Photo credit: ITER/Facebook

The dream of making a power plant that doesn’t require fossil fuels or pose the potential for dangerous nuclear meltdowns has stumbled along since the late 1950s, when Russian scientists began experimenting with a fusion-powered reactor they called a tokamak.

But fusion brought its own set of hard problems that kept pushing it into the distant future — until yesterday. An international team of 47 researchers published seven papers asserting that the physics for creating peaceful, economical power from fusion may be demonstrated this decade.

“We believe it’s going to work,” said Martin Greenwald, deputy director of the Plasma Science and Fusion Center at the Massachusetts Institute of Technology. His statement is in line with a consensus of researchers who say fusion power plants could arrive in time to lessen some of the dangers of climate change.

Robert Mumgaard, CEO of Commonwealth Fusion Systems, a private company that is partnering with MIT on a fusion project, predicted in an interview that the end result will be a prototype for a medium-size electric power plant that can safely and cost-effectively make “a lot of power on a small plot of land.”

The company’s first step toward that objective will begin next year with the construction of SPARC, a plant that will demonstrate that it can produce from two to 10 times the amount of electric power required to run it.

Reaching that goal has eluded scientists since the 1970s, when nations were experimenting with dozens of tokamaks around the world. They’ve never achieved “breakeven,” the state of generating more power than it took to run them, which posed a major obstacle to their research.

A collaboration of 35 nations building an experimental fusion device in southern France called ITER plans to demonstrate “breakeven” by 2035, but Mumgaard’s company is among 22 private companies that are now betting they can move faster. Seventeen of them are American, and another is Chinese (Climatewire, Aug. 24).

Commonwealth is among the U.S. leaders and has raised over $200 million from investors, according to Mumgaard. It hopes to demonstrate proof of concept with SPARC by 2025 and then develop a prototype for a commercial fusion power plant in the “early” 2030s.

“The climate is really important, and we need more solutions on the table to deal with that,” Mumgaard explained. “That’s the thing that really motivates our team.”

Another motivator is what appears to be a solution for the most obvious obstacle that confronts fusion power: controlling hot plasma. It’s a gaseous soup of subatomic particles made from isotopes of hydrogen called deuterium and tritium.

The difficulty is that plasma must be heated to millions of degrees Celsius, sunlike temperatures that would easily melt a normal reactor and destroy the plasma reaction.

In fusion that occurs in the sun and other stars and in hydrogen warheads, the heat causes subatomic particles to collide and fuse with one another. As they do, they release much more energy than they consume.

The key to the tokamak reactor, as seen by the Russians and others, is that more powerful magnets would eventually emerge to confine the fusion reaction.

So far they haven’t, but Mumgaard says his company has spent most of the last two years developing magnets that can contain the fusion and do it more cheaply and efficiently than those being considered for the larger international ITER project.

The magnets will be built from a metal tape coated with a superconducting compound that makes its grip more powerful. “We can take hundreds of kilometers of that tape and integrate it into a magnet system that will be big enough,” he said, to make a “high-performance fusion machine.”

Like the tokamak, superconducting materials are another technology that existed as a concept but found little in the way of applications for decades. They are materials that conduct electricity without resistance. The phenomenon was discovered in 1911, when scientists found that liquid helium cooled some metals to the point where they became powerful conductors.

But to get to a liquid, helium must be cooled to near absolute zero, or minus 460 degrees Fahrenheit. Most laboratories found that hard to do, but in 1986 two scientists from IBM won a Nobel Prize by making a compound comprising four elements — yttrium, barium, copper and oxygen (YBCO). They cooled it to minus 320 F with liquid nitrogen. The material became a superconductor, and scientists began finding uses for it.

Another IBM scientist used it to teach a high school class in Gilroy, Calif., how to perform magic tricks. He obtained the liquid nitrogen from a dermatologist who used it to remove warts.

The students baked YBCO in a pottery kiln, and the result was a superconductor that became powerful enough as it cooled to levitate another magnet into the air.

Next year, Mumgaard will use YBCO to make magnets designed with a grip that is believed to be strong enough to confine fusion plasma. The more powerful the magnets, the smaller the fusion reactor can be. He predicts the process will soon lead to a medium-size commercial fusion power plant.

“We think that by doing that, we can improve the economics significantly because then it takes less stuff to build the machine,” he said.