Power system planning under deep uncertainty: Integrating tidal energy for net-zero Northern Ireland

Achieving high renewable penetration is often hindered by resource variability, renewable curtailment, and deep uncertainties in long-term decarbonization planning. In coastal and islanded power systems with significant tidal potential, predictable marine resources such as tidal power can offer a valuable solution, enhancing system flexibility, reducing curtailment, and supporting progress towards net-zero objectives. In Northern Ireland, however, tidal energy remains underutilized, and limited operational flexibility continues to pose challenges for integrating large shares of renewables. To address these challenges, this paper proposes a robust multi-period power system planning framework that integrates tidal energy and energy storage using an Information Gap Decision Theory–Flexible Revision Multi-period Two-stage Stochastic Planning (IG-FRM-TSP) model. The framework explicitly accounts for uncertainties in demand growth, technology costs, and CO2 pricing, while optimizing the coordinated deployment of tidal, offshore wind, and hydrogen-battery storage. A novel Dispatch Down Reduction Index (DDRI) is introduced to quantify and reduce renewable curtailment, improving system efficiency and flexibility. Scenario analyses show that strategic co-deployment of tidal energy with offshore wind and storage can reduce curtailment to below 2 %, while achieving up to 80 % CO2 emissions reduction compared to business-as-usual scenarios, all while maintaining grid reliability. The results highlight that tidal predictability, combined with responsive storage and supportive policy incentives, plays a critical role in enabling cost-effective decarbonization pathways for islanded and coastal power systems. The proposed methodology offers a replicable approach for similar regions worldwide, emphasizing that operational coordination and market design—beyond capacity expansion—are essential to achieving net-zero goals.