This journal article was originally published in Applied Energy.
In the UK, many fossil fuel power stations are approaching retirement, yet these sites retain valuable brownfield assets, notably developed industrial land and high-capacity grid connections, and can be repurposed for low carbon generation. Repurposing such sites for low carbon generation could therefore offer three linked advantages: lower upfront capital requirements through reuse of grid connections and developed industrial land; shorter project delivery times by reducing permitting needs and avoiding lengthy grid-connection queues; and higher system value through the provision of dispatchable flexibility and improved asset utilisation.
This study examines repurposing end-of-life gas power stations into modular nuclear plants and further enabling hydrogen integration via high-temperature electrolysis, where the electricity-heat split is governed by endogenous reactor choice. A repurposing-oriented optimisation framework is proposed to embed inherited brownfield constraints, particularly land availability and grid-export limits, while co-optimising technology selection with hourly unit commitment and economic dispatch.
Under the selected representative-week simulations, results show that the repurposed modular nuclear can deliver system-level flexibility comparable to that of gas turbines while meeting brownfield constraints. Nuclear‑hydrogen integration further increases reactor utilisation by using co-located electrolysis as a flexible local demand for nuclear-derived electricity and heat, eliminating renewable curtailment and substantially reducing plant-level levelised cost of electricity (LCOE) relative to power-only repurposing under these simulations. Among the electrolyser options, high-temperature electrolysis coupling gives the lowest plant-level levelised cost of hydrogen (LCOH), while producing the largest hydrogen output with the lowest plant-level upfront investment. This advantage arises from the ability of high-temperature electrolysis to use both electricity and cost-effective nuclear heat, reducing reliance on electricity-priced input energy. Sensitivity analysis identifies nuclear and high-temperature electrolyser capital costs as the main upward cost drivers, while stack lifetime remains the key durability-related lever.
Overall, the findings indicate that brownfield nuclear‑hydrogen integration can provide a valuable pathway for converting retiring thermal power station sites into flexible low-carbon power and hydrogen production assets.