Fusion power plants are sites at which electricity could be generated via a process known as nuclear fusion, which entails the merging of two atomic nuclei into a single heavier nucleus. This process is known to generate very high amounts of energy, such as the energy required to light up the sun and other stars, yet its potential for the production of electricity has yet to be demonstrated.
Fusion power plants are often mentioned in political and environmental debates, with some claiming that they could eventually help to reduce greenhouse gas emissions associated with the energy sector and reduce the cost of electricity. However, building these power plants will likely be very expensive, and the extent to which they could be used to source electricity on a large scale remains poorly understood.
Researchers at ETH Zurich recently carried out a study aimed at further exploring the cost-effectiveness of two established fusion approaches, called magnetic fusion and inertial fusion. Their paper, published in Nature Energy, suggests that the costs of fusion technology will very likely decrease slower than earlier works predicted. Thus, fusion power plants might ultimately fail to compete with other renewable energy solutions.
“I follow the political debate about fusion in Germany, and it was interesting to hear the extremely low levelized cost of fusion power plants that were promised by some actors in the fusion space,” Prof. Tobias Schmidt, senior author of the paper, told Tech Xplore. “I wanted to understand this better. Our research group developed and tested a framework that can be used to understand why some technologies learn with higher experience rates than others. In this study, we applied it to fusion.”
Modeling the impact of nuclear fusion technology
As part of their study, Prof. Schmidt and his colleagues used a theoretical framework they created to compare two different types of fusion energy technologies with other energy solutions. They specifically focused on magnetic fusion and inertial fusion technologies.
Magnetic fusion equipment prompts nuclear fusion by confining hot plasma using powerful magnetic fields. Inertial fusion reactors, on the other hand, work by compressing fuel using lasers.
The researchers looked at how the size, complexity and customization of technologies influenced their rate of cost decline over cumulative production. Based on real data, they estimated experience rates for fusion systems (i.e., percentage cost reductions that would occur when the cumulative deployment doubles).
“Obtaining currently assumed experience rates for fusion power plants was rather straightforward,” explained Lingxi Tang, first author of the paper. “Essentially, a literature review of studies containing fusion power cost projections was conducted. Most studies make their assumed experience rates explicit while one study assumed costs for the tenth and the hundredth fusion power plant, allowing an implied experience to be calculated.”
Prof. Schmidt, Tang and their colleagues estimated that fusion power plants will likely have lower experience rates than many past studies assumed. In addition, their analyses suggest that the costs of fusion power plant infrastructure will decrease at a slower pace than that predicted in existing projections.
Challenging common assumptions about fusion energy
The results of this study suggest that current fusion energy models that investors and policymakers rely on are overly optimistic. To attain the forecasted benefits of fusion energy and maximize the impact of fusion power plants, energy engineers might need to develop alternative fusion reactors that are more cost-effective.
“Our paper is the first to provide an evidence-backed range of experience rates for fusion power plants and has notably shown a large discrepancy between previous ER assumptions and a sensible ER range for the technology,” said Tang. “These results would certainly raise doubts about current investment levels in fusion research, potentially reducing future funding for this technology, and instead redirecting funding to enabling the deployment of existing clean energy technologies.”
The analyses performed by Prof. Schmidt, Tang and his colleagues could inspire other energy researchers to further investigate the possible impact and limitations of existing fusion energy solutions. Meanwhile, the researchers plan to conduct new studies investigating the potential of other renewable energy solutions.
“Frankly, we do not plan to work more on fusion specifically,” added Prof. Schmidt. “However, we are still interested in the competition of clean energy technologies. To this end, we are also refining and testing the framework and applying it to other nascent technologies, such as electro-chemical CO2 capture from ambient air.”
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Publication details
Lingxi Tang et al, Fusion power experience rates are overestimated, Nature Energy (2026). DOI: 10.1038/s41560-026-02023-8.
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