Our fusion future

People walking on a yellow path toward a city with fusing of nuclei above.

Focus on Astrophysical Sciences

Our fusion future

Princeton Plasma Physics Laboratory aims to harness the sun’s power to achieve climate goals

By Allison Gasparini

Illustration by Manuel Šumberac

Brutal heat waves marked the summer of 2022, which brought us the hottest July ever recorded in the United States. Scientists and experts regard global warming as the crisis of our time, and with fossil fuel consumption at the center of climate change, deploying clean energy is one of the most important pursuits of the modern era.

Fusion, a process in which two lighter atoms collide to form one heavier atom, unleashes huge amounts of energy. As the world looks for sustainable alternatives to fossil fuels, fusion could be the ultimate clean energy answer. “If the Earth becomes an inhospitable place for humans, that’s a disaster,” said Steve Cowley, director of the Princeton Plasma Physics Laboratory (PPPL) and a professor of astrophysical sciences. “Fusion can help change that.”

Although fusion occurs naturally at the core of our sun, creating a similar process on Earth requires building complex machines that can contain the fuel and heat it to temperatures millions of degrees hotter than the sun.

At PPPL, researchers are leading the scientific charge to turn fusion into reality. If harnessed, the energy released in fusion reactions could provide electricity to power our homes and cities for thousands of years.

While excitement for wind and solar has inspired fields of turbines and panels, those energy sources depend on good weather. “The wind doesn’t always blow and the sun doesn’t always shine,” Cowley said. “The combination of fusion plus renewables is probably the perfect energy system.”

The fact that fusion energy can power homes around the clock isn’t the only benefit. Fusion is also green. It requires just two ingredients or feedstocks, deuterium and tritium, both forms of hydrogen. Deuterium can be harvested from seawater while tritium can be produced through neutrons interacting with lithium inside a fusion reactor. Although lithium demand is high due to its use in batteries, new extraction technologies promise to make the element more available.

“Fusion is, in principle, a potentially very democratic source of power for the world,” said Emily Carter, senior strategic advisor for sustainability science at PPPL and Princeton’s Gerhard R. Andlinger Professor in Energy and the Environment. “The feedstocks are found in places that most countries have access to, which is not true for nuclear power.”

Today’s nuclear power reactors split atoms in a process called fission, whereas fusion reactors smash atomic nuclei together. Unlike fission, fusion doesn’t create long-term hazardous waste or the potential for meltdowns like the Chernobyl disaster. “With fusion, because of the very nature and the way in which the physical process takes place, there cannot be meltdowns,” Carter said. When deuterium and tritium collide, they produce helium, an inert gas, and neutrons, which can fuel more fusion reactions by creating tritium from lithium, or be used to make steam for power plants to create electricity. “Moreover, tritium as fusion waste is much more short-lived than nuclear waste, and thus can be handled in a way that makes it much more attractive than nuclear power in the long run,” Carter said.

The benefits of fusion energy have increasingly captured the interest of those looking for future sources of clean energy. In April, the Biden administration put forward a statement on their strategy to accelerate fusion energy research. The U.S. Department of Energy (DOE), which funds PPPL, also announced $50 million to support partnerships between for-profit companies, national laboratories, universities and others for the design of a fusion pilot plant.

In recent years, private sector interest in fusion energy has soared. “One of the really exciting things that has happened is the amount of private money that’s coming into fusion,” said Elizabeth Paul, a Princeton presidential postdoctoral research fellow in astrophysical sciences. “For the first time, the private funding has surpassed public funding.”

The White House estimates that $4 billion in fusion investment is coming from the private sector. “Continuing to push engagement from private companies would accelerate fusion research and fusion energy on the grid at a reasonable cost,” said Ahmed Diallo, a principal research physicist at PPPL and a program director for the DOE Advanced Research Projects Agency-Energy (ARPA-E).

Last year, 2021, was a pivotal year in fusion energy research. In the United Kingdom, researchers at the Joint European Torus broke the record for the most energy produced during a fusion experiment. Then, at the National Ignition Facility in California, researchers reported creating a self-sustaining fusion burn using an array of high-powered lasers. The multinational fusion demonstration project ITER, located in France and funded by countries including the United States, will begin operating in the next decade.

Between the increase in private efforts, and innovations led by PPPL and collaborators across the globe, it appears the future of fusion-based clean energy is brighter than ever.