A clean energy source that scientists have chased for decades may finally be within reach. Fusion power, often described as the “holy grail” of energy, has long promised near-limitless electricity with little environmental impact. Now, new breakthroughs suggest that reality could be just a few years away.
One of the most promising efforts is underway just outside Boston. Commonwealth Fusion Systems, a startup spun off from the Massachusetts Institute of Technology (MIT), is building a new experimental reactor there. The device, known as SPARC, is expected to produce its first plasma by 2026. If successful, it could soon generate more energy than it consumes.
If SPARC performs as planned, it will lead to a larger facility named ARC. This follow-up plant would deliver up to 400 megawatts of power and could connect to the electric grid by the early 2030s. For comparison, most U.S. power plants generate between 100 and 500 megawatts. A typical nuclear plant produces about 1,000 megawatts, more than double ARC’s output. Still, researchers believe SPARC’s fusion technology could eventually power plants that reach the gigawatt scale.
Commonwealth Fusion Systems has already raised over $2 billion in private investment. If successful, the company could build the world’s first working fusion power plant, planned for Virginia.
How Fusion Works: The Power of the Sun on Earth
Fusion energy is created by combining two atomic nuclei into one. This process releases huge amounts of energy. In contrast, today’s nuclear plants rely on fission, which splits atoms apart.
There are two main approaches to making fusion power: inertial confinement and magnetic confinement.
Inertial confinement uses lasers to compress fuel and create fusion. This method is being tested at the National Ignition Facility in California. The lab uses 192 lasers to strike a capsule filled with heavy hydrogen. China is also working on a larger version of this system.
SPARC uses the magnetic confinement method. It relies on a tokamak—a machine shaped like a donut. Inside the tokamak, strong magnetic fields compress hydrogen gas into a hot plasma. The gas contains two hydrogen isotopes: deuterium and tritium. When heated to extreme temperatures, the atoms fuse and release energy.
This is the same approach being used at ITER, the massive international fusion project in France.
To make fusion happen, SPARC will need to heat the plasma to between 180 million and 270 million degrees Fahrenheit. The pressure inside the machine will also need to reach five to ten times the Earth’s atmospheric pressure.
Clean, Safe, and Abundant—Fusion’s Many Advantages
Fusion offers many benefits over traditional nuclear power.
Unlike fission reactors, fusion reactors do not face the risk of runaway chain reactions. They are also much easier to shut down in case of a problem.
“If you were to blow a breath of air onto the plasma, you would kill it,” explained Brandon Sorbom, Commonwealth’s chief science officer. “If a meteor hit the plant and broke the vacuum chamber, everything would shut down instantly. There’s no meltdown risk like we saw at Fukushima or Chernobyl.”
Fusion also produces no long-lasting radioactive waste. Traditional nuclear plants must safely store their waste for thousands of years. Fusion does not have this issue.
The fuel for fusion—deuterium and tritium—is also widely available. Deuterium can be extracted from seawater. Tritium can be bred from lithium, a metal used in batteries.
However, lithium supplies are limited and in high demand. As more countries invest in battery technologies and electric vehicles, securing lithium may become a major challenge.
