Bridging plans and energy paths: A multi-nodal prospective analysis of the Spanish electricity generation and transmission system

Abstract

National energy system decarbonisation plans increasingly rely on optimisation models to identify cost-effective power system pathways. These models typically do not incorporate renewable energy projects currently under development, as defined by European regulatory processes. This paper assesses how different planning approaches can be integrated within a spatially explicit electricity-sector capacity expansion model based on PyPSA-Eur, using a myopic model from 2025 to 2050. The analysis compares a cost-optimal baseline, National Energy and Climate Plan (NECP) targets, and a deployment-driven scenario based on projects under development, enabling a more realistic assessment that bridges the gap between plans and energy pathways.

The Spanish power system model is implemented by replacing default PyPSA-Eur datasets with a national georeferenced power plant database derived from official administrative registers and complementary sources, and by representing transmission constraints under conservative line ratings.

The results indicate that the NECP trajectory can be integrated within the model and extended over a long-term horizon, leading to a system characterised by high photovoltaic penetration. Differences across scenarios are reflected in battery capacity, being 32 GW for the Optimised scenario, 22 GW for the NECP scenario and 27 GW for the Authorised scenario, curtailment levels, reaching 32 TWh in the NECP scenario and 25 TWh in the other two alternative scenarios in 2050, and nodal self-sufficiency, with the lowest value being 18% in the Optimised scenario in 2037 and the highest value 68% in the NECP scenario in 2033. The Authorised scenario performs comparably in terms of system costs for the year 2050, while improving spatial balance and reducing curtailment relative to the cost-optimal pathway.