The cost estimates provided in the report are not intended to be exact numbers but reflect a representative cost based on ranges provided by various sources for the examined technologies. The analysis was done for energy storage systems (ESSs) across various power levels and energy-to-power ratios.
The cost categories used in the report extend across all energy storage technologies to allow ease of data comparison. Direct costs correspond to equipment capital and installation, while indirect costs include EPC fee and project development, which include permitting, preliminary engineering design, and the owner’s engineer and financing costs.
Cost metrics are approached from the viewpoint of the final downstream entity in the energy storage project, ultimately representing the final project cost. This framework helps eliminate current inconsistencies associated with specific cost categories (e.g., energy storage racks vs. energy storage modules).
The capital cost, excluding EPC management fee and project development costs for a 100 MW, 8-hour tower direct33 thermal storage system after stripping off cost for CSP plant mirrors and towers was estimated at $295/kWh, of which $164/kWh (or $1312/kW) corresponds to power block costs operating on a steam cycle (Lundy, 2020).
The 2020 Cost and Performance Assessment analyzed energy storage systems from 2 to 10 hours. The 2022 Cost and Performance Assessment analyzes storage system at additional 24- and 100-hour durations.
Looking at 100 MW systems, at a 2-hour duration, gravity-based energy storage is estimated to be over $1,100/kWh but drops to approximately $200/kWh at 100 hours. Li-ion LFP offers the lowest installed cost ($/kWh) for battery systems across many of the power capacity and energy duration combinations.