The POWER Interview: Designing a Net Energy Fusion System

Commonwealth Fusion Systems (CFS), a company commercializing fusion energy, recently announced a series of seven papers published and peer reviewed in a special edition of the Journal of Plasma Physics. The papers validate the company’s approach to commercial fusion energy.

CFS said the papers, written in collaboration with the Massachusetts Institute of Technology’s (MIT’s) Plasma Science and Fusion Center (PSFC), “are the first peer-reviewed publications from any private commercial fusion company that verify a compact fusion device will achieve net energy where the plasma generates more fusion power than used to start and sustain the process, the requirement for a fusion power plant.”

CFS in a news release said it is collaborating with MIT’s PSFC “to design and build SPARC, the world’s first net energy (Q>1) fusion system. SPARC is being designed with the collective and proven knowledge of the world’s fusion programs, using well-established plasma physics as well as cutting-edge tools that include advanced simulations, data analysis, and science from existing machines. These papers are the result of more than two years of work by the team to refine the SPARC design, which is now entering its final stages.”

Robert Mumgaard is CEO of Commonwealth Fusion Systems. Courtesy: Commonwealth Fusion Systems / Bryce Vickmark / MIT Department of Nuclear Science and Engineering Plasma Science and Fusion Center at MIT

Bob Mumgaard, PhD, CEO of CFS, in a statement announcing the work said, “These are concrete public predictions that when we build SPARC, the machine will produce net energy and even high gain fusion from the plasma. That is a necessary condition to build a fusion power plant for which the world has been waiting decades. The combination of established plasma physics, new innovative magnets, and reduced scale opens new possibilities for commercial fusion energy in time to make a difference for climate change. This is a major milestone for the company and for the global clean tech effort as we work to get commercial fusion energy on the grid as fast as possible.”

The CFS papers apply the same physics rules and simulations used to design the International Thermonuclear Experimental Reactor, or ITER, which is being built in France. CFS said it can “interpret results from existing experiments to predict SPARC’s performance based on the anticipated engineering design. The results show that SPARC will achieve its goal (Q>2) with considerable margin.”  ITER and SPARC are tokamaks, a device that uses a magnetic field to confine the fusion process. SPARC, though, “will use new high-temperature superconducting (HTS) magnets to enable a similar performance as ITER but built more than 10 times smaller and on a significantly faster timeline.”

The papers also predict that SPARC will likely achieve a burning plasma for the first time on Earth, which means the fusion process will be dominantly self-heating—a longtime goal of the world’s scientists.

The MIT group and CFS are building the advanced magnets “that will allow CFS to build significantly smaller and lower-cost fusion power plants,” according to the company, with the collaboration “on track to demonstrate a successful 20 Tesla, large-bore magnet in 2021. This magnet test, the first of its kind in the world, opens a widely identified transformational opportunity for commercial fusion energy.”

Mumgaard recently answered questions from POWER about his company’s work on commercial fusion energy.

POWER: Fusion energy has always seemed to be great in theory but difficult to accomplish in practice. What makes this project more practical and achievable?

Mumgaard: The world knows a lot of about fusion energy and has advanced it just below the point of making more power than it takes to operate using machines called tokamaks, machines that use magnetic confinement to insulate a plasma in which fusion happens. However, the scale has gotten in the way for this scientifically proven approach, the machines got large. CFS is taking decades of this proven fusion research and combining it with a new technological breakthrough that will allow us to achieve net energy from fusion for the first time in history, a requirement for a fusion power plant.

Our team has developed new groundbreaking high-temperature superconducting magnets and is working collaboratively with MIT’s Plasma Science and Fusion Center. These will be the strongest magnets of their kind in the world. We will use these advanced magnets to build a tokamak with a significantly stronger magnetic field. This will allow us to build devices 50 times smaller and as a result much faster and cheaper. Just recently, seven papers published and peer reviewed in the Journal of Plasma Physics validated this approach. These were the first peer-reviewed publications from a private fusion company that have predicted an approach to commercial fusion will work at a scale that is doable by a company.

POWER: Are private investors looking at fusion energy with an eye toward its enormous energy potential, or as a way to help combat climate change (or perhaps both)?

Mumgaard: The amazing thing about fusion energy is that you get both enormous clean energy potential and a new clean generation source to combat climate change. Our company is incredibly mission-focused and we have a team that is dedicated to making fusion energy work to combat climate change in a meaningful way. Our investors are the same. They understand that the world needs a fundamentally new clean energy source in order to power the world and also decarbonize.

POWER: Are there enough investors interested in this technology to keep research moving forward, or will government support be needed?

Mumgaard: The fusion industry at large has continued to grow and has seen a significant increase in investment. There is now almost $2 billion invested in private fusion energy companies. And while we expect to see private investment continue to increase, we are also seeing governments around the world such as China and the UK start to inject more and more funding into commercial fusion energy efforts. In order to compete with the global market, the U.S. needs to invest in commercial fusion. Recently, there has been language included in a House energy bill that would establish a public private partnership for fusion energy. This would be modeled after the NASA COTS [Commercial Orbital Transportation Services] program, which enabled the private space industry.  This would be incredibly important to accelerate the fusion industry here in the U.S.

POWER: Is the compact fusion reactor device a nod to being able to accomplish fusion energy in a shorter time period, as opposed to the larger-scale ITER project?

Mumgaard: CFS’ goal is to get clean fusion power on the grid as fast as possible. Our net energy fusion device, called SPARC, is the same design as ITER. However, because of our new breakthrough magnet technology we are able to build it 50 times smaller and as a result on a much faster timeline at significantly less cost. 

Darrell Proctor is associate editor for POWER (@POWERmagazine).

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