FAQ
Q: What is fusion energy?
A: Fusion, the physical process that powers the sun, occurs when light atoms like hydrogen combine to form heavier atoms like helium. That releases tremendous amounts of energy. Fusion is hard to reproduce on Earth, but CFS machines use a design called a tokamak to do so. Fusion releases no carbon dioxide or other greenhouse gases. Because fusion is clean, reliable, and safe, with abundant fuel, it could be the last energy source humanity needs.
Q: Who is Commonwealth Fusion Systems?
A: CFS, based in Massachusetts, spun out of MIT in 2018 to commercialize fusion energy. The company is based in Devens, Massachusetts, where it’s building a fusion machine in collaboration with MIT. That machine, SPARC, will demonstrate fusion power viability by producing more fusion energy than it uses to start and sustain the process. The company has raised more than $2 billion to date. Key to the company’s approach is a technology called high-termperature superconductors that enable powerful electromagnets that make fusion power plants smaller and more economically competitive.
Q: Why is CFS commercializing fusion energy?
A: CFS believes that access to clean, abundant, affordable energy and an environment preserved for future generations are fundamental human rights. ARC advances this view with a business that meets the world’s growing energy needs. ARC will provide round-the-clock power regardless of wind, weather, or season and can be built where power demand is high. Its abundant fuel improves energy security. All the fuel required to operate ARC for decades will fit on a truck.
Q: How will CFS make fusion energy work with SPARC and ARC?
A: We use powerful electromagnets to confine and control our fusion fuel, turning the hydrogen into a highly energetic cloud of particles called a plasma housed in a donut-shaped machine called a tokamak. We’ll heat the plasma to about 100 million degrees Celsius so it becomes energetic enough for fusion to occur. For fuel, we’ll combine two forms of hydrogen, deuterium and tritium, to form helium and energetic neutrons. We’re demonstrating this technology with a fusion machine called SPARC that’s under construction now in Devens, Massachusetts.
The company’s next tokamak is a power plant called ARC that’ll put about 400 MW of power onto the grid in Chesterfield County, Virginia. It'll feature a “blanket” of molten salt that captures the neutrons’ energy. The resulting heat is transferred to water that drives a conventional steam turbine to generate power. The neutrons also create tritium in the blanket that supplies the power plant’s fuel needs in a closed cycle.
Q: What does a fusion power plant look like?
From the outside, the ARC power plant will reside in buildings with about the same size and appearance as a big-box retailer. To the electric grid, an ARC power plant will resemble a gas plant with the ability to provide power on demand, but without any fuel piped in or greenhouse gases or pollution going out.
Q: How is fission, usually called nuclear power, different from fusion?
A: Fission and fusion are completely different physical processes with different fuels, facilities, risk profiles, and thus different regulations. Fission, usually called nuclear power, captures the energy released when heavy atoms like uranium split apart. Fusion captures energy when light atoms like hydrogen combine to form heavier elements. Unlike with fission, there’s no possibility with fusion of a runaway chain reaction or meltdown. Spent nuclear fission fuel is highly radioactive and long-lived (10,000 years), whereas fusion produces modest amounts of low-level, short-lived (50-100 years) byproduct materials.
Q: Is fusion energy safe? How will it be regulated?
A: Yes. With fusion energy, there’s no possibility of runaway chain reactions or meltdowns, and there’s no long-lived, highly radioactive waste like that from nuclear fission. Tritium is weakly radioactive, so to store and handle it, CFS will use well-established technology and processes and will comply with applicable regulations. If any air enters the tokamak’s interior, it immediately and safely stops the fusion process. US regulations treat fusion power plants similarly to how they treat particle accelerators, not nuclear fission plants — an approach that recognizes fusion’s inherent safety and supports its rapid scaling. ARC will require a radioactive materials license from Virginia.
Q: What are the benefits of fusion energy?
A: Fusion energy has many of the characteristics of an ideal power source:
- Clean: no carbon dioxide or other greenhouse gas emissions;
- Safe: no possibility of runaway chain reactions or meltdowns and no long-lived, highly radioactive waste like that from nuclear fission;
- Firm: provides power around the clock regardless of wind, weather, or season;
- Scalable: modular and power-dense plants take up less space so they can be built near demand. That requires less power line infrastructure and ultimately makes their power more affordable; and
- Secure: with fuel that’s abundant and available everywhere, fusion won’t rely on any geopolitically fraught supply chains. That can allow regions to effectively “own” their own energy. In fact, all the fuel required to operate the plant for decades will fit on a truck.
With these characteristics, many believe that fusion is not just the next new energy source, but the last energy source humanity will need.
Q: What fuel does a fusion power plant use?
A: Our design uses two forms of hydrogen, deuterium and tritium as our fuel. Hydrogen is the most abundant element in the universe. Deuterium is easily extracted from seawater, and fusion and fission both can be used to produce tritium. Fusion power plants will fuse deuterium and tritium to generate heat that’s converted to electricity.
Q: How will ARC affect the climate change fight?
A: Fusion power plants will be an incredibly important tool in fighting climate change: they can be the most scalable, deployable, and affordable source of firm, zero-carbon power. Because of this, ARC power plants will become the backbone of future power grids, providing the firm power traditionally provided by gas or coal plants. ARCs can leverage some of the existing infrastructure of those traditional plants and be sited much closer to areas that need power, speeding up deployment to meet the growing demand for firm, zero-carbon power. ARCs can also be an excellent complement to wind and solar in those regions where those power sources are plentiful. The end result is that fusion power has the chance to avoid gigatons of greenhouse gases (GHGs) while making energy abundant and affordable, ushering in energy prosperity for all.
Q: How does fusion energy affect energy independence?
A: Because its fuel can be filtered from ordinary seawater, fusion increases energy security: Regions using fusion power aren’t dependent on natural resources that lie elsewhere on the globe. Fusion also can boost economic competitiveness with reliable, affordable energy that businesses value. ARC will be a scalable energy technology that can be replicated at many locations, leading to not just independence, but to abundance and sustainable economic growth. And, although China has an active fusion energy program of its own, developing fusion is a chance for the US to prove its technical leadership.