A stochastic policy assessment of Spain’s 81% renewable electricity target for 2030

Spain’s updated National Integrated Energy and Climate Plan (PNIEC) sets an ambitious target of sourcing 81% of national electricity generation from renewable sources by 2030. While official institutional roadmaps validate this target’s feasibility under central capacity plans and test grid adequacy under historical weather variations, they do not account for the joint probability of target compliance under broader capacity, fuel, and demand uncertainties. To bridge this gap, this study develops an independent and transparent probabilistic dispatch model for the Iberian electricity market using Julia (JuMP), calibrated on hourly market data (2020–2024). We embed a 10,000-iteration Monte Carlo framework to evaluate Spain’s 2030 pathway across five strategic configurations: Baseline, Nuclear, Optimistic, Climate Change, and No Batteries. Our simulations reveal a substantial target achievement gap: the Baseline scenario yields an expected renewable share of 73.75%, achieving the 81% target in only 9.06% of simulated futures. Even under an Optimistic configuration, combining accelerated storage deployment with enhanced demand flexibility, the compliance probability reaches just 14.51%. Furthermore, we formalize a Nuclear Paradox : retaining Spain’s 7.1 GW nuclear fleet yields the lowest wholesale prices (61.51 €/MWh) and carbon emissions (3.81 MtCO 2 ), yet its operational inflexibility crowds out variable renewables, reducing target compliance probability to exactly zero. Finally, while Loss of Load Expectation remains at zero across all scenarios due to the retention of backup gas capacity, our findings indicate that achieving the 81% target is heavily dependent on realizing the upper tail of the renewable capacity deployment distributions rather than variations in market prices.