The challenges include designing magnetic fields to keep the plasma stable and away from reactor walls, building materials and components that
New regulatory and safety requirements make high energy power generation harder to and more expensive to run. New requirements (which are
Fusion energy may one day turn a pickup-truck-full of seawater into enough electricity to power Boston for a year, but not yet…. Freidberg, professor of nuclear science and engineering, has described how fusion energy may one day turn a pickup-truck-full of seawater into enough electricity to power Boston for a year. MIT researchers moved that day a little closer to reality when they announced recently that they have succeeded in using radio waves to mix the 50-million degree C plasma at their Alcator C-Mod fusion reactor, a tokamak (magnetically confined, doughnut-shaped nuclear fusion device) at the MIT Plasma Science and Fusion Center. Using a technique proposed more than 20 years ago at MIT (but had never been successfully tested), Institute researchers Yijun Lin and John Rice confined the plasma’s turbulence within a magnetic field “bottle” using something called the “mix-and-stir method.”. “Ours is the first definitive result showing that high-power radio waves can significantly affect the flow of the plasma,” said physicist Earl Marmar, division head of the Alcator Project.
Public sector efforts prioritize basic science, but fusion energy development requires an additional emphasis on technology and engineering research. Doing so may require significant public engagement, but little is known about public perception of fusion energy in the U.S. GAO developed four policy options that could help address these challenges or enhance the benefits of fusion energy. 34)** Implementation approaches: *Support facilities that address scientific and engineering challenges* *Support workforce development* *Assess sources of critical supplies and manufacturing capabilities* | * Could help fill critical research gaps on the path to fusion energy commercialization. GAO conducted a technology assessment on (1) the status, potential benefits, and limitations of fusion energy, (2) challenges that might affect the development or use of fusion energy, (3) policy options that might help enhance the benefits or mitigate challenges associated with fusion energy.
[Skip to Content](https://kleinmanenergy.upenn.edu/research/publications/bringing-fusion-energy-to-the-grid-challenges-and-pathways/#content). [Download PDF](https://kleinmanenergy.upenn.edu/wp-content/uploads/2025/10/KC-Digest-81-Bringing-Fusion-Energy-to-the-Grid.pdf). ](https://kleinmanenergy.upenn.edu/wp-content/plugins/a3-lazy-load/assets/images/lazy_placeholder.gif)](https://kleinmanenergy.upenn.edu/wp-content/uploads/2025/09/Fig-3.jpg)[](https://kleinmanenergy.upenn.edu/wp-content/uploads/2025/10/Fig-4.jpg). This category has over $2.5 billion in funding and 15 startups, such as TAE Technologies, Helion, and General Fusion.](https://kleinmanenergy.upenn.edu/wp-content/plugins/a3-lazy-load/assets/images/lazy_placeholder.gif)](https://kleinmanenergy.upenn.edu/wp-content/uploads/2025/10/Table-1-4.jpg). Historically, facilities like the [UR-LLE National Laser Users’ Facility](https://www.lle.rochester.edu/about-the-laboratory-for-laser-energetics/nluf/) (NLUF) program, the [DIII-D National Fusion Facility](https://science.osti.gov/fes/Facilities/User-Facilities/DIII-D), and Princeton’s [National Spherical Torus Experiment](https://science.osti.gov/fes/Facilities/User-Facilities/NSTX-U) have enabled hundreds of users to conduct experiments not possible at their home institutions, diffusing knowledge while harnessing national scientific ingenuity (U.S. Department of Energy 2024). “Promoting Fusion Energy Leadership with U.S. Tritium Production Capacity.” [_https://fas.org/publication/fusion-energy-leadership-tritium-capacity/_](https://fas.org/publication/fusion-energy-leadership-tritium-capacity/). “Major Funding Milestone for World-First Prototype Fusion Plant.” [_https://www.gov.uk/government/news/25-billion-for-world-first-prototype-fusion-energy-plant_](https://www.gov.uk/government/news/25-billion-for-world-first-prototype-fusion-energy-plant). “U.S. Department of Energy Announces Selectees for $107 Million Fusion Innovation Research Engine Collaboratives, and Progress in Milestone Program Inspired by NASA.” _[https://www.energy.gov/articles/us-department-energy-announces-selectees-107-million-fusion-innovation-research-engine](https://www.energy.gov/articles/us-department-energy-announces-selectees-107-million-fusion-innovation-research-engine)_. [More…](https://kleinmanenergy.upenn.edu/research/publications/bringing-fusion-energy-to-the-grid-challenges-and-pathways/#addtoany "Show all").
The sun, along with all other stars, is powered by a reaction called nuclear fusion. Today, we know that the sun, along with all other stars, is powered by a reaction called nuclear fusion. The amount of energy produced from fusion is very large — four times as much as nuclear fission reactions — and fusion reactions can be the basis of future fusion power reactors. On earth, we need temperatures exceeding 100 million degrees Celsius and intense pressure to make deuterium and tritium fuse, and sufficient confinement to hold the plasma and maintain the fusion reaction long enough for a net power gain, i.e. the ratio of the fusion power produced to the power used to heat the plasma. At the second United Nations International Conference on the Peaceful Uses of Atomic Energy, held in 1958 in Geneva, Switzerland, scientists unveiled nuclear fusion research to the world. The first international IAEA Fusion Energy Conference was held in 1961 and, since 1974, the IAEA convenes a conference every two years to foster discussion on developments and achievements in the field.
Achieving higher power densities in fusion reactors requires the development of as-yet-unknown materials or confinement concepts, due to the high heat fluxes which would occur at the plasma-facing components of the reactor. The first goal has been to reach what's called the break-even condition, which occurs when the amount of energy used to heat up the plasma is equal to the amount of energy that is produced by the fusion reaction. I will focus now on three specific areas where materials impact fusion reactor design: the plasma-facing region, where there is high heat flux and particles are impacting the metal structure; the plasma-diagnostic, heating, and magnet systems; and the structure of the blanket and first-wall region surrounding the plasma, which is the heart of the heat-extraction system. If you look at the sputtering behavior of various materials at fusion-relevant conditions (10-1,000 eV hydrogen ion energies), stainless steel is one of the worst possible plasma-facing materials.
Main problem: heat loss is too high. Think of fusion like baking a cake. You need to get the right ingredients together, heat them up and keep them hot long