With nuclear capacity expected to be halved by 2030, large demand centers will increasingly rely on renewable energy imports.
MADRID (AURORA ENERGY RESEARCH)—Spain’s renewable energy sector has experienced significant growth, with installed capacity almost doubling in the last five years, according to Aurora Energy Research. However, this rapid expansion has placed increasing pressure on the country’s grid infrastructure, resulting in extremely localised grid curtailment. In certain areas, congestion is exacerbated, with 68% of curtailment concentrated in just ten provinces. Aurora’s analysis reveals that transmission constraints, and uneven distribution of renewable projects are key contributors to curtailment. As nuclear capacity declines and renewable energy continues to rise, addressing these challenges is crucial to ensuring a reliable and efficient energy system for the future.
The global analytics energy provider forecasts that grid curtailment will increase notably in regions such as Cáceres, Badajoz, and La Coruña. However, between 2027 and 2029, curtailment in Cáceres is expected to drop by over 30%, mainly driven by the phase out of nuclear power, leading to a similar reduction in Badajoz. In contrast, Zaragoza is forecasted to see curtailment increase to around 5% of total generation by 2030 (compared to 1.2% in 2025) due to rapid hydrogen deployment within an unprepared network. La Coruña’s curtailment could reach 7% of generation if the expected onshore wind buildout is realised.
Renewable integration and the challenge of grid capacity
Badajoz leads in installed solar PV capacity, while onshore wind is concentrated in Aragón, particularly in Zaragoza, which represents up to 12% of Spain’s total wind capacity. The rapid growth of renewables, with installed capacity nearly doubling in the past five years to 36 GW, and the approval of approximately 120 GW of new renewable capacity concentrated in areas that already have a large installed capacity of renewables is expected to create varying curtailment across regions. Moreover, demand is expected to grow 19% from 2025 to 2030. However, with demand being highly concentrated in big cities, far away from installed renewable capacity, Aurora’s model reveals that curtailment arises from transmission constraints.
Aurora forecasts a reduction in curtailment as key network infrastructure projects become operational. Reinforcements between Cáceres and Madrid are expected to reduce curtailment volumes in both Cáceres and Badajoz. Similarly, upgrades to connections between Lérida and Barcelona will help decrease curtailed volumes in the area. However, despite repowering lines projects, curtailment in Zaragoza is projected to remain significant due to the expansion of data centers and electrolyser buildout in the region. Spanish renewables are usually located far from demand centers putting a strain on the network and contributing to grid curtailment. The report shows that 25% of the Spanish demand is concentrated in Madrid and Barcelona, with remaining demand located along the coast. The 20 provinces with the least demand account for less than 15% of total demand, Aurora finds. With nuclear capacity expected to be halved by 2030 and fully decommissioned by 2035, large demand centers in Spain will increasingly rely on renewable energy imports. This shift underscores the need for a resilient grid capable of transporting power from high-generation areas like Cataluña and Extremadura to demand centers such as Madrid and Barcelona.
Aurora’s power flow modelling optimises the flow of power in Spain, addressing grid congestion and renewable integration challenges. Covering the transmission grid, it includes nodes, transformers, and lines. The model provides insights into future grid dynamics, helping stakeholders plan for renewable growth, nuclear phase-out, and rising energy demand through conservative planning for substations, lines, and transformers.
Christina Rentell, Research Lead France and Iberia at Aurora Energy Research, says:
“Grid curtailment in Spain varies greatly across regions, driven by the exact location of demand and supply growth, not just the absolute national increase. Because of this locational complexity, relying on historical data alone will not provide an accurate indication of future curtailment volumes, making a fundamental approach essential.”
Mario Prinetti, Grid Research Associate at Aurora Energy Research, says:
“Reinforcing the power system holds the key to integrating the ambitious renewable energy objectives set in Spain. Adequate planning and development play a crucial role in keeping curtailment low and reducing congestion management costs.”
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Established in 2013, Aurora Energy Research is a leading global provider of power market forecasting and analytics for critical investment and financing decisions. Headquartered in Oxford, we operate out of 15 offices worldwide covering Europe, North & South America, Asia, and Australia. Our comprehensive services include market outlook packages for energy industry participants, advisory support, and innovative software solutions. We foster diversity with a team of over 900 experts with backgrounds in energy, finance, and consulting, offering unparalleled expertise across power, renewables, storage, hydrogen, carbon, and fossil commodities. Our mission is to ease the global energy transition through widely trusted quantitative analysis and high-quality decision support
