All ways to fusion: a controversy mapping of the public-private shift in nuclear fusion research

Abstract Nowadays, it is said that nuclear fusion—a potentially clean and abundant source of energy that scientists have been pursuing for decades—has reached a pivotal point. The political economy of fusion research was once centred on the International Thermonuclear Experimental Reactor (ITER), an intergovernmental project intended to demonstrate the technoscientific feasibility of fusion energy. However, leadership in the fusion landscape has recently shifted towards a new movement of private start-ups that are planning to build their own proof-of-principle reactors, offering a faster, cheaper, smaller-scale approach than ITER. But what does this change in leadership from a government-led project to market-driven start-ups mean in practice? This study examines the discourse surrounding the shift from public to private fusion development by qualitatively analysing ‘bridging events’ in which fusion experts from ITER and start-ups publicly discuss their field of research, its prospects, and the pros and cons of handing over to the private sector. The analysis thus reveals that the two lines of research—ITER versus start-ups—are intertwined in a scientific controversy concerning the optimal size, design, cost, timeframe and innovation strategy for constructing a proof-of-principle fusion reactor. Both innovation strategies have their merits and limitations, which this study critically discusses.