Update | Fusion revisited


Four years ago, Arthur D. Little published its first report on the prospects for fusion energy, entering a debate that was just beginning to gain traction. A new report, Unlocking fusion energy: navigating challenges & opportunities in fusion energy commercialization, summarised here, revisits the topic, offering an updated perspective on fusion energy, assessing its current status, and illuminating the path to commercialisation


Stephan Ruehl, Michael Kruse, Lars Ole Nowak, and Artur Korinski Arthur D. Little


The combination of increasing electricity demand and the need to decarbonise power generation is leading to a growing supply gap as baseload fossil fuelled power sources are decommissioned. Intermittent renewables alone cannot bridge this energy-supply gap. The total capacity of announced renewable projects is below predicted electricity demand, which the International Energy Agency (IEA) predicts will expand by around 4% per annum. By their nature, intermittent renewables are also unable to deliver the consistent, baseload power required in an always-on world, even with the addition of battery storage. While nuclear fission is a candidate to step up, large cost and time overruns on recent projects, coupled with safety concerns are major challenges to its adoption. Small modular reactors (SMRs) are promising, but, as yet, are unproven, with no deployments in Western countries to date.


All of this is leading to a reassessment of fusion energy as a future option for the supply of clean, safe and sustainable energy. Previously seen as a technology perpetually at least 30 years away from reality, the combination of recent scientific breakthroughs and growing market need are attracting increased investment and interest from both governments and the private sector. The first commercial grid-connected fusion power plants are now expected to come online in the 2040s. Unlike nuclear fission, which splits atoms to release energy, fusion energy combines light atomic nuclei (usually hydrogen isotopes of deuterium and tritium) under extreme conditions to form heavier nuclei. The gas becomes a plasma (a hot, charged gas made of positive ions and free-moving electrons with unique properties compared to solids, liquids, or gases), and the nuclei combine to form a helium nucleus and a neutron. The process releases energy as high- energy particles, as shown in Figure 1. As envisioned in future power plants, fusion is similar to the physical process that occurs in stars like our sun. However, it requires extremely high temperatures (more than 100 million degrees Celsius) to overcome particle repulsion and generate fusion plasma. The plasma must be kept at high temperatures and maintained in a stable state. In addition to ignition and plasma control, the efficiency of the energy cycle is crucial in order to ultimately generate more energy than the entire system consumes (called the “breakeven point”). When commercialised, fusion energy offers the ability to supply scalable, limitless green power with minimal waste and high safety levels. It can


Figure 1. The fusion process Source: Arthur D. Little, International Atomic Energy Agency (IAEA), Max Planck Institute


be deployed anywhere and delivers constant, baseload energy with a minimal environmental impact.


The fusion technology landscape There are essentially five technology approaches to successfully achieving fusion: 1. magnetic confinement fusion energy (MFE); 2. inertial confinement fusion energy (IFE); 3. magneto-inertial confinement fusion energy; 4. hybrid magnetic/electrostatic fusion energy; 5. muon-catalysed fusion energy.


Of these, MFE and IFE are the most advanced in terms of energy gain, leading to the creation of a number of well-funded start-ups building on the work and investment of public research projects. In our analysis, half of the 47 fusion start-ups currently operating are focused on MFE, with 20% following an IFE path.


MFE is the most researched fusion energy technology, with scientific projects stretching back to the 1980s, including the Joint European Torus (JET) project and its successor, ITER, which is scheduled to be completed in 2034. MFE confines high temperature plasma using magnetic fields, with the aim of retaining it for long enough to achieve a scientific energy gain, expressed as having a fusion energy gain factor (Qsci Qeng


) of greater than one, and ultimately > 1. 12 | May 2025| www.modernpowersystems.com


IFE takes a different approach. Typically, fuel is confined through focused, high-energy lasers which implode small quantities of fuel pellets injected into the chamber. This produces plasma, which is the medium where fusion reactions occur, releasing energy. Using IFE, the US National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory first successfully achieved scientific energy gain (Qsci


improved this to a Qsci


> 1), in 2022. Further experiments figure of 2.4, generating


2.4x more energy than used to power the process, despite relying on low-efficiency lasers. These breakthrough results demonstrated the viability of fusion energy and sparked global interest and investment from governments and the private sector. Reflecting the commercial potential, Bloomberg in 2021 estimated that the fusion energy market could achieve a $40 trillion valuation by 2050. Further scientific advances have followed. In January 2025, China’s EAST (“artificial sun”) reactor sustained plasma at over 100 million°C for 1066 seconds, setting a new record for high temperature plasma confinement. This milestone stood for just a month, with France’s WEST tokamak, operated by CEA, sustaining plasma for 1337 seconds in February 2025.


Public sector support for fusion While governments have funded fusion programmes for many decades, their focus


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