Visualization of the proposed SPARC tokamak experiment. Using high-field magnets built with newly available high-temperature superconductor, this experiment would be the first controlled fusion plasma to produce net energy output. Visualization by Ken Filar, PSFC Research Affiliate

What is the big picture? What is the news?

MIT will collaborate with a new private company to build the world's highest-performing superconducting magnets for fusion energy. The magnet research will be based on High-Temperature Superconducting (HTS) technology that has only recently become commercially available. Once the magnet technology has been developed, the magnets will be used to build SPARC, which aims to be the first device to generate a fusion plasma that produces more energy than it consumes.

Who is funding the work?

The work will be funded by Commonwealth Fusion Systems (CFS), currently headquartered in Cambridge, Massachusetts. More information is available on the CFS website.

Why should people be interested in fusion energy?

Fusion offers the possibility of unlimited, carbon-free electrical power. It is the same natural process that powers our sun and other stars.

If the magnet research is successful, what comes next?

The next step will be to design and build SPARC, the first device that will generate a fusion plasma that produces more energy than it consumes, and demonstrate that fusion energy can be developed in time to provide carbon-free power to combat climate change.

Where would this fusion experiment be located?

Various sites will be considered, but given the facility’s anticipated size, we know that it would have to be located outside of Cambridge.

Will we then have fusion electric power plants?

No, not yet. Even though SPARC will, if successful, yield net energy and large amounts of power from fusion, it is intentionally designed as a pulsed experiment and would not convert its fusion energy into electricity. The next step would be to build a net-electricity producing fusion pilot plant, based on this new magnet technology — while its details are to be determined, we call this device ARC (Affordable Robust Compact)

On this path, how long would it take before fusion energy is on the grid?

MIT scientists and their collaborators believe that ARC — a fusion pilot plant that would produce electricity continuously — could be built and operating in about 15 years.

What is Commonwealth Fusion Systems?

Commonwealth Fusion Systems (CFS) is a new LLC created by former MIT staff and students to commercialize fusion energy and related technologies. CFS has attracted investments from several companies, venture capital firms, and individuals to support its work.

CFS intends to collaborate with MIT and sponsor research. CFS will also carry out research and development at its own facilities.  

Visit CFS website.

How will this collaboration work?

The collaboration is structured to bolster fusion research and education at MIT while building a strong industrial entity that will aim to commercialize fusion energy.

The collaboration will work like many other industrial sponsored research projects at MIT: MIT researchers propose research projects to CFS and CFS agrees to fund them. In some cases, MIT and CFS personnel will work side-by-side on research projects, each bringing their own unique skills to the problem. If any intellectual property is generated as part of the research, CFS will have the option to license and commercialize it.

As at any for-profit company, investors in CFS will share in any value created from commercializing fusion energy production and spinout technologies. MIT’s role would be to carry out the research sponsored by CFS and train students.

Will MIT have equity in CFS?

Yes. Universities often hold equity in companies that license their technology. MIT’s equity in CFS is non-voting, to maintain the independence of CFS from MIT.

Are current MIT students or employees involved in CFS?


Why is MIT moving from the traditional federally funded model for fusion work to this privately funded model?

MIT is augmenting, not moving away from, its fusion funding model in order to support two complementary activities: research and commercialization. It will continue to carry out fusion energy science research with government funding while simultaneously partnering with the private sector to accelerate fusion commercialization.

The government has traditionally funded basic research on fusion science and technology, but cannot directly support commercialization in this or any other field. The spin-out of government funded basic research into the commercial sector is entirely consistent with the essential roles and missions of each.

Though privately funded, the MIT SPARC team intends to remain fully engaged with the overall national and international fusion programs. Meeting the challenge of developing practical fusion energy will require the active participation of universities, private industry and the government. We feel that it is essential to continue public support of the basic science that underpins fusion energy and even more urgent given the accelerating interest from the private sector.

At the same time we note that government investments in fusion are incommensurate with the existential threat posed by climate change, and the accompanying need to develop scalable, carbon-free energy sources as quickly as possible. On a path determined by current levels of federal research funding, fusion energy would be unlikely to come online, and help mitigate the effects of climate change, much before the end of this century.

This new model seeks a much more rapid development path, one that could develop fusion power in time to address the growing threat that humanity faces from climate change.

What are the basic principles of fusion energy?

Fusion is the process by which light elements, like hydrogen, combine to form heavier elements, like helium, releasing enormous amounts of energy. It is the source of energy for the sun and all the stars. To fuel this process, matter has to be heated to extremely high temperatures – roughly 100 million degrees.

How would someone use fusion power plants to produce electricity?

The fusion reaction is simply a new source of heat. This heat would be used to create steam, and the steam would drive a turbine and electrical generator — which is the way most electricity is produced. The heat can be used for other purposes too, such as fuel production.

What are the advantages of fusion energy?

The fuel for fusion — light elements like hydrogen — is sufficient on Earth to meet all of mankind’s needs for millions of years. Fusion doesn’t create greenhouse gases like carbon dioxide, or pollutants like sulfur dioxide or nitrogen dioxide, nor particulates like soot.

Compared to other clean energy sources like wind or solar, it would have a very small footprint: A fusion power plant would be approximately the same size as a conventional fossil fuel plant. Fusion plants can run around-the-clock; there is no requirement for massive energy storage systems. Fusion is also inherently safe because it does not rely on a chain reaction. These advantages have been recognized for decades.

Why are the magnets so important?

To make fusion work, the fuel must be heated to temperatures above 100 million degrees. Matter in that state is called a plasma – where the particles have net electric charge. To be kept hot, this plasma must be very well insulated from ordinary matter. Fusion devices use magnetic fields to provide the thermal insulation that is required. The stronger the magnetic field, the stronger the confining force on the charged particles in the plasma, the better the insulation, which enables a much smaller, better performing fusion device.

How much progress has been made so far?

Decades of research, worldwide, has taught us a tremendous amount about how fusion systems work. In terms of performance, there was a great period of progress from the late 1960s to the late 1990s. Performance increased by more than a factor of 10,000 times over those 30 years.

Why has that progress slowed in recent years?

Fusion performance increases with the size of an experiment, but so does cost and timeline. Until recently, the limitations of magnet technology required a coalition of almost all industrialized nations to fund and take the next step – namely producing a net energy fusion device. It took several decades for these nations to reach a consensus, commit the necessary funds, and begin construction in southern France of a device called ITER,. The current schedule calls for ITER producing net energy sometime around 2035.

What is new? What makes this new path possible now?

The SPARC approach uses a newly available superconducting material that allows operation at much higher magnetic fields than the previous state-of-the-art. Superconducting materials are required in fusion energy systems as no electrical power is required to operate the magnets that provide the plasma containment; the high magnet fields are critical because they dramatically reduce the volume of the plasma at a fixed fusion power output. This combination makes a net-energy fusion device, such as SPARC, much smaller and less expensive than if it were built with the previous magnet technology. As a result, smaller and much more streamlined organizations, such as MIT and CFS, can pursue net energy fusion devices. This is not to say success is guaranteed; but the cost and timescale to retire key technical risks becomes acceptable to private-sector investors.

When were High-Temperature Superconductors (HTS) first discovered?

These materials were discovered in 1986 by IBM researchers J. Georg Bednorz and K. Alex Muller, who won the 1987 Nobel Prize in physics for their discovery. Researchers at MIT’s PSFC quickly understood their potential for producing the high magnetic fields needed for fusion – however, it took more than 20 years for the raw superconducting material to be transformed into a useful industrial product. We see this as another great example of new technologies being discovered in laboratories, but eventually having real-world impact by commercialization.

Have magnets been built with this new superconductor?

Yes: Small-bore magnets have been built with fields up to 42 tesla, considerably higher than required for SPARC. This proves that the superconductor can operate at the fields needed for fusion. Still, significant research must be performed to make the large-bore/volume, high-field magnets that will be required for fusion.

When did HTS become available with the performance necessary for the SPARC mission?

Only in the last three to five years has the performance of the superconductor, and the ability to manufacture it in sufficient quantities, been adequate for fusion applications.

How confident are MIT scientists, CFS, and those investing in CFS that this will work?

MIT scientists and their collaborators are quite confident that once the magnet technology has been developed, the SPARC device can achieve the level of performance that we seek — namely, net fusion energy. We have this confidence because the assumptions used to predict the level of fusion power produced by SPARC are conservative – and based on an enormous worldwide database from a variety of fusion experiments.

Why doesn't ITER use HTS magnets?

HTS technology was not available during the time when ITER was designed — from roughly 1985 to 2005. ITER construction is now too far along to allow for such a significant change of course.

How does this effort relate to other fusion efforts, particularly ITER?

SPARC will be parallel and complementary to other international fusion efforts, including ITER, as well as other ongoing private-sector fusion endeavors. Decades of research worldwide in fusion science and technology, including that carried out in support of ITER, have already paved the way for much of the SPARC work. The science behind the two projects is different in that ITER is a moderate-field, moderate-density device, while SPARC is a high-field, high-density device.

Focusing on new high-field magnet technology is an alternate approach: Ultimately, fusion is far too important for scientists to allow its pursuit to have us putting all of our eggs in one basket, limiting ourselves to one approach or one experiment

The SPARC plan is driven by a focus on short-term commercialization, while U.S. interest in ITER lies in basic science. Right now, the U.S. has a fusion science program, but it does not have a fusion energy program.

Back to SPARC project page