The Value of Long-Duration Energy Storage under Various Grid Conditions in a Zero-Emissions Future

Abstract Long-duration energy storage (LDES) is a key resource in enabling zero-emissions electricity grids but its role within different types of grids is poorly understood. Using the SWITCH capacity expansion model, we model a zero-emissions Western Interconnect with high geographical resolution to understand the value of LDES under 39 scenarios with different generation mixes, transmission expansion, storage costs, and storage mandates. We find that a) LDES is most valuable in majority wind-powered regions and regions with diminishing hydropower generation, b) seasonal operation of storage becomes cost-effective if storage capital costs fall below 5 $/kWh, and c) mandating the installation of enough LDES to enable year-long storage cycles would reduce electricity prices during times of high demand by over 70%. Our results provide grid planners with guidance on how LDES impacts and is impacted by energy storage mandates, investments in LDES research and development, and generation mix and transmission expansion decisions.