Fusion power experience rates are overestimated

Abstract Fusion power plants (FPPs) are viewed as a promising source of firm low-carbon electricity, attracting large investments. However, their future cost is highly uncertain. Current projections assume widely varying starting costs and highly arbitrary experience rates (ERs) of 8–20%. Here, leveraging recent insights from innovation literature, we examine the currently assumed ER range for FPPs by linking technological characteristics of the two dominant fusion approaches, magnetic fusion and laser-based inertial fusion, to ERs. We find that FPPs’ large unit size, extraordinary complexity and intermediate need for customization are empirically linked to ERs of 2–8%, which are much lower than currently assumed for FPPs. When paired with the expected high initial capital costs, the results raise questions about the viability of FPP in future net-zero energy systems. We urge for the adoption of ERs for FPPs that are justifiably lower than currently assumed in cost projections, energy system modelling and investor valuations, and for the research community to explore alternative fusion designs with greater cost reduction potential.