How Commonwealth Fusion Systems is designing its first fusion reactor

“AI factories and data centers require gigawatts of electric power,” said Siemens CEO Roland Busch today at CES 2026. “What if we had an energy source that was clean, safe, affordable, and practically limitless?”
There are several answers to that question, including wind and solar, but Busch was referring to fusion power, which heats and compresses atoms until they fuse, releasing tremendous amounts of energy in the process. Commercial fusion power is still years away, but several companies, including Commonwealth Fusion Systems (CFS), are in the process of building demonstration plants to prove the concept’s viability.
“In fusion, we’re developing an entire new industry,” said CFS co-founder and CEO Bob Mumgaard. “You can’t just go and buy a fusion plant or a fusion part.” To build the parts that will be assembled into a power plant, Mumgaard revealed that his company has been using Siemens software and tools to design and operate the systems.
Today, CFS also announced that, with the help of Nvidia, it will be building a digital twin of Sparc, its demonstration reactor. The company recently installed Sparc’s first 24-ton magnet at the reactor’s site in Massachusetts.
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