Long-duration energy storage (LDES) is crucial for zero-emission electricity grids, but its role in different grid types is unclear. This study uses the Switch capacity expansion model to analyze a zero-emissions Western Interconnect, exploring LDES value across 39 scenarios with varying generation mixes, transmission expansion, storage costs, and mandates. Key findings include LDES's particular value in predominantly wind-powered or hydropower-diminishing regions, cost-effectiveness of seasonal storage below US$5 kWh⁻¹, and significant electricity price reductions (over 70%) during peak demand with year-long storage mandates. Results offer grid planners valuable guidance on LDES's impact.

Martin Staadecker, Julia Szinai, Pedro A. Sánchez-Pérez, Sarah Kurtz, Patricia Hidalgo-Gonzalez