The price and emissions effects of extending nuclear lifetimes: evidence from Spain

As Spain approaches the first scheduled nuclear retirements—most notably, Almaraz in 2027—the debate over the implications of delaying the nuclear phase-out has reopened. This paper uses detailed simulations of the Iberian electricity market to assess the consequences of postponing Almaraz’s closure on wholesale electricity prices, renewable and storage profitability, and power sector $$\hbox {CO}_2$$ emissions. We test the robustness of our findings to alternative investment targets, electricity demand paths, and gas marginal costs. We caution against a purely static assessment: while extending Almaraz, holding everything else equal, lowers prices and emissions by displacing gas, it also depresses renewables’ captured prices and increases curtailment, weakening incentives to invest in renewables and storage. If the investment response is large enough, a delayed nuclear phase-out may ultimately lead to higher prices and higher emissions.