University of Wisconsin-Madison spinoff company Type One Energy has published a comprehensive and robust physics basis for a practical fusion pilot power plant. The advance is an important and promising milestone that brings fusion power closer to reality.
This groundbreaking research was presented in a series of six peer-reviewed scientific papers in a special issue of the prestigious Journal of Plasma Physics, published in March 2025.
The articles serve as the foundation for the company’s first fusion pilot plant project, which Type One Energy is developing. Type One Energy is partnering with the Tennessee Valley Authority utility as a probable partner in this endeavor. Fusion energy, the process that powers the sun and stars, is a long-sought-after way to produce limitless clean and safe energy.
The new physics design basis for the pilot power plant is a robust effort to realistically consider the complex relationship between challenging, competing requirements that all need to function together for fusion energy to be possible. Those requirements include plasma performance, power plant startup, construction logistics, reliability, and economics using actual power plant operating experience.
“With this work, we showed there are no showstoppers for Type One Energy’s pilot power plant,” says Chris Hegna, vice president of stellarator optimization for Type One Energy and a professor of nuclear engineering and engineering physics at UW-Madison. “We demonstrated that our design optimization procedure simultaneously satisfied all the requirements without any notable shortcomings. For every kind of plasma physics question that might arise, we had a good answer for how to handle it.”
Hegna is a co-founder of Type One Energy along with UW-Madison Electrical and Computer Engineering Professor Emeritus David Anderson, who served for decades as the director of the Helically Symmetric eXperiment (HSX), a stellarator fusion reactor in the College of Engineering at UW-Madison. Anderson and Hegna are building upon major research advances from HSX as they develop Type One Energy’s power plant design.
The new physics solution makes use of the operating characteristics of highly optimized stellarator fusion technology using modular superconducting magnets. A stellarator is a type of fusion reactor that uses complex, helical magnetic fields to confine the plasma, thereby enabling scientists to control it and create suitable conditions for fusion. This technology is already being used with success on the world’s largest research stellarator, the Wendelstein 7-X, located in Germany, but the challenge embraced by Type One Energy’s new design is how to evolve the design for use as a pilot plant.
Led by Hegna, widely recognized as a leading theorist in modern stellarators, Type One Energy performed high-fidelity computational plasma physics analyses to substantially reduce the risk of meeting the pilot power plant’s functional and performance requirements.
“We’ve developed a very robust solution and stress tested it, showing that our design doesn’t require us to be living on the edge of disaster,” Hegna says.
This research was developed collaboratively between Type One Energy and a broad coalition of scientists from national laboratories and universities around the world, including UW-Madison, which is one of the world’s top-ranked fusion energy research universities. Paul Wilson, a professor of nuclear engineering and engineering physics at UW-Madison, and members of his research group are co-authors on two of the Journal of Plasma Physics papers, contributing expertise in neutronics and fuel-cycle modeling.
“One of the joys of being at UW-Madison is that we have lots of world-class experts in many different areas walking around our hallways, and Type One Energy is able to work closely with them and benefit from their expertise through collaborative research agreements,” Hegna says.
The company made use of a spectrum of high-performance computing facilities, including access to the highest-performance U.S. Department of Energy supercomputers such as the exascale Frontier machine at Oak Ridge National Laboratory, to perform its physics simulations.
This work was supported by Type One Energy. The researchers gratefully acknowledge their use of computing resources and facilities funded by the U.S. Department of Energy, including: the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC 05-00OR22725, using awards for computing time on Summit and Frontier; the National Energy Research Scientific Computing Center (NERSC), a Department of Energy Office of Science User Facility, using NERSC awards FES-ERCAP27470 and FES-ERCAP0031820 for computing time on Perlmutter; the Argonne Leadership Computing Facility, a U.S. DOE Office of Science user facility at Argonne National Laboratory, which is supported by the Office of Science of the U.S. DOE under Contract No. DE-AC 02–06CH11357, using an award for computing time on Polaris provided by the U.S. Department of Energy’s (DOE) Innovative and Novel Computational Impact on Theory and Experiment (INCITE) Program.
Chris Hegna is the Harvey D. Spangler Professor in nuclear engineering and engineering physics.
Paul Wilson is the Grainger Professor of Nuclear Engineering and chair of the Department of Nuclear Engineering and Engineering Physics.
David Anderson is the Jim and Anne Sorden Professor Emeritus in electrical and computer engineering.
Portions of this article were originally published by Cambridge University Press and Type One Energy.
Featured image caption: Conceptual design for Type One Energy’s fusion plant. Credit: Type One Energy.