The role of new nuclear power in the UK's net-zero emissions energy system

Swift and deep decarbonisation of electricity generation is central to enabling a timely transition to net-zero emission energy systems. While future power systems will likely be dominated by variable renewable energy (VRE) sources, studies have identified a need for low-carbon dispatchable power such as nuclear. We use a cost-optimising power system model to examine the technoeconomic case for investment in new nuclear capacity in the UK's net-zero emissions energy system and consider four sensitivity dimensions: the capital cost of new nuclear, the availability of competing technologies, the expansion of interconnection and weather conditions. We conclude that new nuclear capacity is only cost-effective if ambitious cost and construction times are assumed, competing technologies are unavailable and interconnector expansion is not permitted. We find that bioenergy with carbon capture and storage (BECCS) and long-term storage could reduce electricity system costs by 5–21% and that synchronous condensers can provide cost-effective inertia in highly renewable systems with low amounts of synchronous generation. We show that a nearly 100% variable renewable system with very little fossil fuels, no new build nuclear and facilitated by long-term storage is the most cost-effective system design. This suggests that the current favourable UK Government policy towards nuclear is becoming increasingly difficult to justify.