Nuclear fusion could rescue the planet from climate catastrophe

Nuclear fusion could be the clean energy the world needs—and private companies are now working on machines to harness it.

By Jon Asmundsson and Will Wade, 28 Sep 2019, Bloomberg Markets

About two dozen private companies around the world are working to harness a transformative energy technology that could rescue the planet from climate catastrophe. One is using space in an old factory that’s home to a mothballed U.S. Department of Energy-funded research machine in Cambridge, Mass. Another is housed in an industrial building behind a Costco outside Vancouver. A third is down the street from a self-storage facility in the foothills of Orange County, Calif.

The companies are working on commercializing fusion.

Fusion’s promise is huge. It would be the most energy-dense form of power: A liter of fusion fuel is equivalent to 55,000 barrels of oil. In its most common form, that fuel would come from a practically inexhaustible source: water. In fact, 2 cubic kilometers of seawater could in theory provide energy equivalent to all the oil reserves on Earth. “It’s ubiquitous, inherently safe, zero-carbon energy—at a scale that can fuel the planet,” says Matt Miller, president of Stellar Energy Foundation Inc., a nonprofit that promotes the development of fusion power. “Now that’s worth working on.”

It was only about 100 years ago that people came to understand that fusion was the process powering the sun. Shortly thereafter, scientists began trying to re-create it. From tabletop experiments, fusion quickly developed into Big Science. Since 1953 the U.S. government has devoted more than $30 billion to fusion research, including basic science and weapons-related work, according to data from Fusion Power Associates, another nonprofit. European countries, Russia, China, and Japan have also made huge investments in pursuit of the holy grail of energy.

Since the 1950s, however, expectations that researchers were on the verge of breakthroughs have repeatedly come up short. What’s different now is that advances in technology are bringing fusion within reach.

Turning theory into practical devices is being enabled by advances in supercomputing and complex modeling, says Steven Cowley, director of the Princeton Plasma Physics Laboratory and former head of the U.K. Atomic Energy Authority. Fusion used to be defined as “the perfect way to make energy except for one thing: We don’t know how to do it,” Cowley says. “But we do.”

So what is fusion again? The idea is deceptively simple: Smash two atoms together so they fuse into a single heavier element and release energy. It’s the opposite of fission, the process used in today’s nuclear power plants and the bombs dropped on Hiroshima and Nagasaki.

In fission, a large, unstable nucleus is split into smaller elements, releasing energy. Fusion, by contrast, starts with light atoms. Take two hydrogen nuclei, for example. Ordinarily, their positive charges repel each other. But apply enough heat and pressure, and they might get close enough for the attraction of the extremely short-range but powerful strong nuclear force to kick in, joining them into a single helium nucleus. When that happens, the mass of the newly formed nucleus ends up slightly less than the sum of the two hydrogen nuclei. And that difference in mass gets released as energy, in accordance with Albert Einstein’s famous equation E=mc2. Simple. Stars do it. The sun does it. It’s the basic energy process of the universe.

Early efforts to harness it, though, gave fusion a reputation for hype and disappointment. After World War II, an Austrian scientist who’d worked in Germany ended up in Argentina, where he persuaded dictator Juan Perón to fund his fusion experiments. On an island in a remote Andean lake, the scientist, Ronald Richter, set up an elaborate facility. In February 1951, he detected what appeared to be heat from a thermonuclear reaction in his reactor. The next month, Perón announced at a press conference that Argentina had harnessed the atom to create unlimited energy. A subsequent investigation found that a glitch in Richter’s instruments led to his mistaken heat reading. Richter was discredited.

Long Road
Fusion’s history is studded with disappointments as well as advances

1920
British astronomer Arthur Eddington’s “The Internal Constitution of the Stars” posits that stars including the sun are powered by the fusion of hydrogen.

1938
Nuclear physicist Hans Bethe describes the fusion reactions that create the energy emitted by stars, for which he later wins the Nobel Prize.

1951
Juan Perón and scientist Ronald Richter announce that Argentina has developed fusion energy.

1952
The first test of a hydrogen bomb, code-named Ivy Mike, uses a fission explosion to ignite a fusion reaction in deuterium fuel. The 10-megaton blast leaves a big crater on Enewetak atoll.

1958
ZETA excitement and disappointment as U.K. researchers announce they’ve likely created a controlled fusion reaction, but later retract.

1964
A fusion demonstration at Progressland at the World’s Fair in New York.

1969
In an example of cooperation, the U.K. brings laser equipment to the Soviet Union to measure the temperature of the T-3 tokamak, confirming 10 million C plasma.

1982
Tokamak Fusion Test Reactor, or TFTR, starts at the Princeton Plasma Physics Laboratory. It sets a record plasma temperature of 510 million C.

1985
The Soviet Union proposes international collaboration on fusion at the Geneva summit of Mikhail Gorbachev and Ronald Reagan, which leads to the start of ITER.

1989
Chemists Martin Fleischmann and Stanley Pons’s cold fusion experiment can’t be replicated.

1997
The Joint European Torus, or JET, sets a record with a fusion output of 16.1 megawatts, equivalent to about 67% of the input energy, a Q of 0.67.

2019
Construction of ITER, an international fusion demonstration project, in the south of France is 60% complete. When turned on, ITER is expected to produce 10 times the energy it consumes, a Q of 10.

Many physicists were skeptical of the initial report, but news of the apparent breakthrough spurred research in the U.S., the U.K., and the Soviet Union. At Princeton, a top-secret U.S. government project aimed at working on the H-bomb started researching fusion technology. In 1951 scientists there began developing a device called a stellarator that would use magnetic fields to confine superheated plasma. The effort, code-named Project Matterhorn, was eventually declassified and became the Princeton Plasma Physics Laboratory.

In the U.K., work on a machine called Zeta, which “pinched” fusion fuel by running a huge current through it, led to another premature announcement of the dawn of the fusion age, in 1958. It turned out that strange instabilities in the fuel were what led researchers to mistakenly think they were seeing evidence of fusion.

The Argentine news also fast-tracked work on an idea developed by Soviet physicist Andrei Sakharov, a dissident and Nobel Peace Prize winner: confining fusion fuel in a doughnut-shaped configuration with a machine called a tokamak.

Since the 1960s, when government labs and universities around the world began constructing tokamaks in earnest, more than 200 working machines have been built. A key sign of progress in the fusion field is the chart of the so-called triple product, a measure of reactor performance. Plot this number—how hot, how dense, and how well-insulated the systems are—against a timeline, and it looks a lot like Moore’s law, the famous doubling of computing power every two years. But fusion’s improvement is even faster. “Tokamaks have beat Moore’s law,” says Bob Mumgaard, chief executive officer of Commonwealth Fusion Systems, which was spun out of MIT.

So why does it matter how hot a fusion system gets? Consider the sun. Our local star has a lot of plus-size gravity to apply to the fusion process. Its interior brings the pressure of a mass equivalent to about 333,000 Earths and a temperature of about 15 million C (27 million F). That’s the kind of forge in which fusion happens.

On Earth, with so much less gravity, you need higher temperatures: 100 million C, for example. So the first step to get there is to heat a gas and turn it into a plasma, says Michl Binderbauer, CEO of TAE Technologies Inc., based in Foothill Ranch, Calif. “That happens through adding more energy, so at some point the ions and electrons that make up the atoms fall apart into a soup of charges,” he says. “That’s the state that actually most of the universe is in—what we call a plasma.”

Almost all of the visible stuff in the universe is plasma. “We’re living probably in one of the few specks of the universe where there’s no plasma in our immediate surroundings other than lightning or something,” Binderbauer explains. What’s more, in the 1950s, when instabilities and other “funky behavior” in plasma turned out to make fusion much harder than expected, Mumgaard says, it led to the development of an entire discipline, plasma physics. The field has in turn contributed advances in medicine and in manufacturing semiconductors.

Now, heating plasma to 100 million C sounds daunting and terrifying. Wouldn’t it vaporize whatever it touches? Short answer: no. The plasma is a handful of particles in a vacuum chamber, Binderbauer says. It’s millions of times less dense than air, its state is extremely fragile, and if it touches anything it instantly cools down. TAE’s Norman machine heats plasma to 35 million degrees, says Binderbauer. If, hypothetically, he could stick his hand into the vacuum shell, he says the plasma wouldn’t burn him. “My arm will absorb all of the energy,” he says. “I won’t even turn very warm.” Fusion, unlike fission, has no risk of meltdown. “You have to protect the plasma from the surrounding environment, not the other way around,” he says.

Fusion would have one other important benefit over solar, wind, and other intermittent sources of renewable energy, says Christofer Mowry, CEO of General Fusion Inc., based in Burnaby, B.C., near Vancouver: It’s “dispatchable” power. In most of the applications anticipated for fusion, the energy created in a reaction would heat water and run a conventional steam turbine generator. Plants could be safely and conveniently situated in cities and other places power is needed, Mowry says.

One obvious downside to fusion, reflected in the field’s 70 years of history and dashed hopes for imminent breakthroughs: It’s extraordinarily difficult to bring off.

In 1983 the late Lawrence Lidsky, an associate director of what was then called MIT’s Plasma Fusion Center, wrote an article titled “The Trouble With Fusion.” Fusion, he wrote, “is a textbook example of a good problem for both scientists and engineers. Many regard it as the hardest scientific and technical problem ever tackled, yet it is nonetheless yielding to our efforts.” Still, Lidsky laid out a laundry list of problems that, he contended, made it unlikely that fusion would ever be an economically viable source of power.

More than three decades later, the problems Lidsky identified remain. Chief among them is radioactivity. To be sure, the fuel used in fusion doesn’t pose quite the same dangers as fission’s uranium and nuclear waste. To understand fusion’s radioactivity challenge requires a slightly deeper dive into the science.

To begin, a variety of different light elements can be combined in a fusion reaction. However, the fuel that’s easiest to fuse is a 50-50 combination of two isotopes of hydrogen: deuterium and tritium. D-T, as it’s called, has thus been the main focus of the field. Deuterium is heavy hydrogen, the stuff found in seawater. Its nucleus consists of a proton plus a neutron (in contrast to plain old hydrogen’s lonely proton). Tritium is heavy, heavy hydrogen: a proton with two neutrons. It’s radioactive, with a half-life of about 12 years. It’s also extremely rare and expensive, but it would be bred in fusion reactors.

When deuterium and tritium nuclei fuse, energy gets released as an alpha particle (a helium nucleus, which is two protons and two neutrons) and a very energetic neutron. Those neutrons are neutral, unconfined by the magnetic field holding the plasma. They crash into whatever material is facing them, which in tokamaks, for example, is called the first wall. The crash transfers heat and also knocks the atoms in the wall’s material out of place, damaging it and making it radioactive.