Commonwealth Fusion Systems, Devens, Mass., is the first U.S. company working on a plan to use a full-scale fusion power plant for generation of nuclear energy to power the electric grid.

The Massachusetts-based fusion company is in the process of building a donut-shaped machine called a tokamak, which is scheduled to be operational late next year. The tokamak is a chamber where atoms are “smashed” together in 100-million-degree plasma. The nuclear fusion reaction of forcing two atoms to merge creates heat energy. This is the opposite of conventional nuclear energy—a fission reaction that splits atoms (typically uranium), producing nuclear waste. The fuel for fusion is derived from deuterium, found in seawater, and tritium, which is extracted from lithium.

If it proves successful by achieving net energy (producing more energy than it consumes to run), Commonwealth will build a 400-megawatt fusion power plant in Virginia to be named the Fall Line Fusion Power Station.

The 400-megawatt power plant would have similar capacity to a natural gas-fired plant and is smaller than nuclear fission reactors and most coal-fired plants. One benefit of smaller nuclear plants is that less fuel is needed, making them easier to build closer to grid infrastructure, even where the population is dense.

“You have the opportunity to put them close to load, put them close to the data centers, and sometimes closer to where people live,” said Rob Gramlich, founder and president of Grid Strategies, Washington, D.C. “You can fit a lot of power in a small area.”

Scientists throughout the United States and Europe have demonstrated, through numerous breakthroughs in recent years, that net energy gain from nuclear fusion is possible. The challenge is in sustaining it long enough to power electric grids and heating systems.

Commonwealth has applied to the nation’s largest grid operator, PJM Interconnection, to connect its future plant into its network, with the goal of approval by the 2030s because the application process with PJM takes four to six years to complete. PJM’s initial questions include how much fuel the power plant will need on-site, how much power and lead time it will need to turn on, and how intermittent the power will be.

Commonwealth Fusion CEO Bob Mumgaard said the timeline is “not that dissimilar from any of the other energy sources that people are talking about.” For example, the current wait time to build the gas turbines is over five years.

Similarly, the process of connecting a fusion power plant to the grid is about the same as that of connecting other types of power, according to Gramlich. The electricity is made the same way: hot water creates steam to turn turbines that create electricity. The only difference is how the water is heated.

Two buyers, Google and energy company Eni, are already lined up if the Virginia fusion plant is approved.