MIT researchers tackle the economic realities of fusion power

In the last decade, scientists have shown that fusion energy can work, as a physical process. Next question: Can it work economically?

A study co-authored by MIT professors Dennis Whyte and Andrew W. Lo proposes a framework for understanding what’s needed to make fusion energy commercially viable in the marketplace. The method considers the physical inputs needed to sustain controlled fusion energy production, as well as the cost of building power plants that can compete in energy markets.

“It’s all the things that come along with finding, allocating, and spending money at this scale,” says Whyte, a professor of nuclear science and engineering at MIT and a key driver of the field’s progress, who co-authored the paper. “This is critical to what we do. We should look at the economics. If we want this technology to actually be meaningful in the world economy, we have to start getting straight with ourselves about these topics.”

The goal of the paper, Whyte says, is to create “this framework, where are all the economics are clear, and then we understand what it would mean” for any fusion energy power plant.

Fusion energy harnesses the reaction that powers the stars: the fusion of light nuclei. It is often referred to as “plasma fusion,” as the fusion reactions generate fuel in a plasma state, often confined by magnets or initiated by powerful lasers. Whyte says the goal is to generate abundant energy while also offering society attractive safety, licensing, and siting options.

In 2022, researchers at the National Ignition Facility in Livermore, California, one of the U.S. national labs, achieved a reaction with positive energy gain. Venture funding has also poured into the field in recent years, although there are still many challenges regarding the construction of viable commercial fusion energy.

“It’s challenging to reduce complex scientific and engineering requirements to economic consequences,” Lo says. “But if we don’t do that, we’re not going to get the funding we need to achieve the impact we want.”

The open-access publication, “Criteria for the economic viability of fusion power plants,” appears online in the Journal of Fusion Energy. The authors are Whyte, who is the Hitachi America Professor of Engineering and a professor of nuclear science and engineering at MIT; Lo, who is the Charles E. and Susan T. Harris Professor and a professor of finance at the MIT Sloan School of Management; Rachel Bielajew, an analyst with Rutherford Energy Ventures and a researcher at MIT’s Plasma Science and Fusion Center; Maria Hancock and Riley Moeykens of Rutherford Energy Ventures; and Guinevere Shaw of Rutherford Energy Ventures and MIT’s Plasma Science and Fusion Center.

Whyte is a former head of MIT’s Department of Nuclear Science and Engineering and a former director of MIT’s Plasma Science and Fusion Center. He co-founded Commonwealth Fusion Systems, an MIT spinoff firm that is one of the leaders in the fusion industry. Whyte and Lo also co-founded Rutherford Energy Ventures, a consultancy and investment advisory firm, which is working with the U.S. Department of Energy’s Oak Ridge National Laboratory to build a consortium for new fusion research.

10 parameters, any power plant

The framework Whyte and Lo propose in the paper has 10 parameters for evaluating the economic viability of a fusion energy power plant. Some of these are scientific and physical, dealing with the energy consumed and produced in a given plant. Most of the parameters are in the realm of engineering and economics, such as the costs of plant construction.

A key inspiration for the framework is the so-called Lawson Criterion, derived in the 1950s, which describes the combinations of temperature, plasma density, and energy confinement time that can produce net energy from the plasma due to fusion, regardless of its absolute power or volume. Specifically it calculates a “plasma Q,” which is the ratio of fusion power produced to the external power required to sustain the plasma.

“The Lawson Criterion describes the scientific success of energy gain from fusion plasmas, while our framework generally describes economic Q, which is the ratio of capital gained to that expended,” Whyte explains.

The parameters in the framework describe engineering features of the fusion power plant such as power density, the efficiency of converting fusion power into an economic product, and the durability of components used in the energy conversion, in addition to costing and market parameters that assess the expenses and returns from invested capital. Or, as Whyte puts it, the framework is centered on what it takes to achieve a net-positive economic return, “but applied to practical power plant design.” In parallel to plasma Q, the economic Q described in the framework must be greater than 1 for basic viability.

Researchers have tried a variety of methods for generating and containing fusion energy. The paper’s framework, Whyte emphasizes, is “completely agnostic to whatever fusion concept you use, because the physical reality of fusion is that you expend money to build the capability to produce fusion power.” And the parameters do not depend on the size of any reactor being built; the framework is set up so that any inputs can be scaled to a given project or power output.

“It doesn’t matter whether the fusion power plant is a small or large, the bottom line is: In both cases you better have money coming out that exceeds the money going in, otherwise it’s not going to be around for very long,” Lo says.

One source of motivation for the paper, Whyte and Lo say, is to underscore the importance of accounting for all costs in fusion research as rigorously as possible. While researchers will be highly aware of the costs of basic experiments, estimating the costs of a fusion reactor is a somewhat different matter, but something leaders in the field have to be increasingly oriented around.

Fixing a missing link

That is certainly the case, the authors note, as new rounds of funding enter the fusion energy industry. Just last week, Commonwealth Fusion Systems obtained a new billion-dollar round of funding support from investors; it hopes to open its first working power plant in the 2030s, in the state of Virginia.

Lo acknowledges that there will be uncertainties and challenging decisions involved in the development of the very first commercial fusion reactor. If successful, though, the industry might follow the path of learning by doing that has been common in energy and other industries, helping plants become more economical over time.

“This pattern of learning by doing exists in all deep technology sectors,” says Lo, noting that sequencing a human genome is a million times cheaper right now than it was about 25 years ago. “We’re going to see the same thing, but maybe not to the same degree, in fusion energy.”

Lo has long worked to develop ways for scientific research to gain financial support in biotechnology — and is launching a new MIT Sloan educational program, called CATAPULT, to provide more tools for people in any field of study to translate their research advances into products.

When it comes to fusion, Lo says, “It’s pretty clear that economic viability is something we can start assessing now.” And while there might be thousands of particular decisions involved in building a commercial fusion plant, the authors think they have an overall approach that will let people quantify all that work.

“When you’ve got a framework to evaluate it in a quantitative way, it tells you about the literal worth of making a particular design decision. That seems to me at this moment of fusion development absolutely critical, and what we’ve been missing,” Whyte says.