If fusion is to contribute to decarbonizing electricity generation by mid century, the US must begin to construct a grid-scale pilot fusion-power plant well before a self-sustaining fusion reaction is first achieved, says a new report from the National Academies of Science, Engineering, and Medicine (NASEM). The report recommends that US researchers begin preparing multiple conceptual designs for such a plant now and aim to select a technological approach by 2028.
That date is well before ITER, the giant, internationally funded experimental reactor, is slated to begin experiments that could produce meaningful amounts of fusion energy. Although ITER is widely expected to eventually achieve a sustained fusion reaction, known as a burning plasma, it won’t do so until at least 2035, when initial experiments with tritium are due to get underway. ITER is solely a research facility and won’t produce electricity.
The NASEM report, released on 17 February, urged the US Department of Energy and the private sector to collaborate on the construction of a fusion pilot plant to begin operations in the 2035–40 time frame. The teams will also need to develop road maps for the enabling technologies.
The plant should produce more than 50 MW of electricity, enough to prove that fusion power is commercially viable. The initial goal will be to demonstrate output of 100–500 MW of electricity for 100 seconds or more. The second phase would produce more than 50 MW of electricity for three hours or more. Utilities will then have the information they need to proceed to build their own power plants, says Richard Hawryluk of Princeton Plasma Physics Laboratory, who chaired the NASEM committee that wrote the report.
“This plan is bold, but we believe it is achievable,” says Hawryluk. “The US has played a major role in the development of fundamental science of fusion; the US can now either take the lead in the technology or frankly let others take the lead.” The UK and China also have ambitious plans to develop grid-scale fusion power, he notes.
The committee was agnostic about which fusion approach—whether the mainstream tokamak or any number of alternative concepts pursued in the private sector—will be embodied in a pilot plant and recommended that multiple private–public teams float different proposals. But while acknowledging that there are other potential fusion fuel cycles, the report noted that the mainstream tritium–deuterium fusion reaction will require a method to breed tritium within the fusion reactor chamber. The world’s total commercially available tritium inventory of around 40 kg is on the same order as one year’s consumption by the proposed plant, it said. ITER will serve as a test bed for breeding tritium.
Apart from the further improvements in plasma characteristics that will be needed to produce power, other technology challenges stand in the path of a pilot plant. They include finding materials and structural components that can withstand the reactor’s high heat and high-energy neutron flux environment and discovering ways to continuously refuel the reactor while removing the helium by-product of the fusion reaction.
Developing high-temperature superconducting magnets with sustained performance at high field strengths will be key to building fusion reactors that are smaller than ITER, which is slightly taller than the Arc de Triomphe monument in Paris. ITER is using conventional low-temperature superconductors, which have lower field strengths than their high-temperature counterparts.
The committee emphasized that electric utilities must be convinced that fusion is both technologically viable and economically attractive. “What’s required from a pilot plant is to provide the technology and economic information so that decision makers can decide to build commercial systems,” Hawryluk says. “They need cost certainty, confidence it will work, regulatory certainty, and confidence that the public would support it.”
For fusion to be competitive in the US electricity marketplace, industry should be able to build a first-of-a-kind commercial fusion plant with an operational lifetime of about 40 years for $5 billion–$6 billion. The conceptual design that is selected in 2028 will provide a firm basis for cost and schedule estimates, Hawryluk says. “If the pilot plant can’t be built for less than the projected cost of a first-of-a-kind power plant or doesn’t have the potential to produce electricity at a competitive cost, we’ll acknowledge then that more innovations and research are needed to reduce the cost and prove the concept.”
Michl Binderbauer, CEO of the privately funded alternative fusion developer TAE Technologies, applauds the report’s emphasis on public–private partnerships. “You are combining the strength of a DOE lab or university program with the end-product focus of the private sector,” he says, rather than the “more meandering” academic process. “A tighter adherence to schedules will help to drive efficiency in the process.”
Richard Buttery, director of the DIII-D tokamak program at General Atomics, says that remaining a partner in ITER is still important even as the US fusion community tries to accelerate the timetable for a power plant. “There’s a huge amount we’ve solved already from ITER through the engineering of a full-on power plant–scale reactor,” he says. “We will learn an awful lot from ITER just from its early [pre-tritium] stages of operation in terms of making the plasma reliably and reaching performance parameters.”
ITER also provides a hedging opportunity for the US, adds Binderbauer. “You can run faster to fusion power than ITER’s program, but at the same time you can gain access to things that are useful.”
Stephen Dean, president of Fusion Power Associates, says the NASEM report indicates that a healthy US fusion program requires more than the science of burning plasma. “In the early 2000s [former DOE undersecretary for science] Ray Orbach eliminated most of the domestic US fusion technology effort and all of the power plant design studies in order to get [the Office of Management and Budget] and Congress to provide the money for the US to get back into ITER. The program then became ‘focused’ on the plasma science of burning plasmas.”
Dean and Binderbauer credit Paul Dabbar, the immediate past DOE undersecretary for science, for restoring an energy mission to the US program and reinvigorating federal support for non-tokamak fusion concepts.