Leilões de Capacidade de Ligação à Rede e Armazenamento em Portugal Avaliação técnico-económica, repartição de encargos e aplicação do princípio do causador-pagador

This study assesses Portugal’s grid connection capacity auctions for renewable generation with co-located storage and stand-alone storage, announced in October 2026, from technical, economic and distributional perspectives. It examines the model’s contribution to the national electricity system and whether costs are allocated to the agents that cause them, in accordance with the cost causation principle. The methodology combines documentary and regulatory analysis, a literature review and illustrative financial scenarios, using 3 November 2026 as the cut-off date. Private profitability, changes in total system cost and the distribution of benefits and costs are assessed separately. The analysis identifies advantages in the competitive allocation of scarce connection capacity, investment mobilisation, technical requirements and municipal revenue transfers. Storage’s contribution to resource adequacy remains conditional on available energy, state of charge, location and the duration of system needs. In a hypothetical 100 MW/400 MWh exercise, net present values range from −€110.39 million to +€20.33 million; these figures are not forecasts for Portuguese projects. The results show that a positive arbitrage margin does not ensure investment recovery. Regarding cost allocation, the auction design assigns responsibilities and payments to developers but does not demonstrate that all net incremental system costs are covered. Sharing revenue with municipalities does not establish such coverage. The study concludes that auction assessment should incorporate location-specific incremental cost and benefit accounts, comparisons of alternatives providing equivalent services, and monitoring of performance and tariff impacts. The ex ante nature of the study precludes confirmation of realised benefits or a generalised breach of the principle. Full implementation remains to be demonstrated. Keywords: Energy storage; grid connection capacity auctions; power system adequacy; total system cost; cost causation principle; consumer protection; territorial justice.