Fusion — clean, carbon-free energy the world desperately needs

Without question, the world desperately needs more clean, carbon-free energy and fusion seems like an ideal source. Fusion is the process which powers the sun and the stars by combining light elements like hydrogen into heavier ones like helium, producing prodigious amounts of energy. 

The question before us is whether we can harness this process on earth and make it into a practical power source in time to make a difference. We also need to ask ourselves a hard policy question: Is the U.S. looking toward a future where it makes and sells fusion power plants into a multi-trillion dollar energy market or one where it buys them from others?

The fuel for fusion would come from water and lithium, in essentially an inexhaustible supply, but the advantages of fusion energy go well beyond an abundance of fuel. It also dispenses with other pollutants that plague fossil fuels, as well as the hazards of mining, refining and transportation. Fusion would provide electricity from large central stations, simply replacing the heat from combustion with another energy source, so it would run all day in any weather, eliminating the need for expensive energy storage systems or extensive modification of our electrical grid. With these potential advantages, it is no surprise that the quest for fusion power has consumed the efforts of scientists and engineers around the world for decades.

However, despite tremendous progress in the science and technology, a practical demonstration of fusion has remained out of reach. So what has changed? One answer is that a new technology has emerged out of the lab and into industrial maturity. High-temperature superconductors were discovered in the mid-1980s but only in recent years have they been manufactured in a form and in quantities suitable for fusion. The other factor is a surge of interest and investment in fusion from the private sector. Together, these alter the landscape and offer the possibility of a dramatic speed-up in the development of this new energy source.

To explain the impact of superconductor development, we need to understand a bit about how fusion power works. The most important thing to know is that to make the fusion process go, we need to get the fuel up to unimaginably high temperatures — somewhere in the neighborhood of 200,000,000 degrees. Remarkably, achieving these temperatures in the laboratory (albeit quite large well-equipped laboratories) is now fairly routine. What has slowed progress is the scale of the devices that will be required for the next step. A consortium of nations including the U.S. is currently building such an experiment, called ITER. ITER is an enormous machine that will cost 10s of billions of dollars to complete and won’t begin fusion experiments until about 2035.

Achieving and maintaining the needed temperatures requires isolating and insulating the fuel from ordinary matter. At these extreme temperatures, the electrons in the fuel atoms are all stripped from their nuclei and the gas becomes a plasma, the fourth state of matter. Plasma is an excellent conductor of electricity, which allows it to be shaped and confined by magnetic fields. So magnetic fields provide thermal insulation and, crucially, the quality of that insulation improves as the field’s strength is increased. Make the magnetic field higher and a fusion machine of a given performance can be made smaller. So though huge, ITER is as small as it could be given the magnet technology that was available in the 1990s, when it was designed. Today, with the new superconductor, experiments can be built with more than twice the magnetic field opening up the possibilities of a new class of fusion machines. A team at our MIT research center is collaborating with the startup company, Commonwealth Fusion Systems, to design and build SPARC — just such a device. When operating, it will be the first fusion experiment to create and confine a plasma that produces net fusion power — a goal of the world’s research program for more than 60 years. 

The SPARC project is just one example of many privately funded fusion initiatives. More than two dozen companies are pursuing similar goals, exploring a variety of magnetic configurations and technologies. For the first time, a fusion industry association (FIA) has been formed to advocate for policies that will accelerate development. This represents a clear break from the past when essentially all funding for fusion came from national governments and should be seen as a natural step for a technology in the progression from basic research to practical applications. The work being carried out in the private sector stands on foundations built by years of patient research at universities and national labs. Commercial interest in this case is a signature of success and provides validation for the underlying publicly funded program. Investors in the private sector place a greater value on speed and are prepared to take greater technical risks than governments. They are also better equipped to build supply chains and optimize production processes. So the emergence of a private fusion sector offers opportunities for new sources of funding and faster development cycles. This is how a new technology gets to market.

Bridging the gap between the level of technical maturity that government funded programs can deliver and the level required for commercialization — the so-called “valley of death” — will still be challenging for the fusion industry. New programs funded by the Department of Energy’s (DOE) Office of Science and ARPA-E have begun to strengthen the engagement between private and publicly funded research. The House of Representatives has recently passed legislation, H.R. 4447, that authorizes the creation of milestone-based public-private partnerships. This program, based on the highly successful NASA Commercial Orbital Transportation Services (COTS), which launched the private space industry, is awaiting publication of a DOE analysis and action by the U.S. Senate. Movement on this legislation could boost the chances for success in the quest for fusion energy and provides a timely opportunity for the U.S. to take leadership in a critical new technology.

Martin Greenwald is the deputy director of MIT Plasma Science & Fusion Center.