Closed-Loop Pumped Storage Hydropower Supply Curves

Resource potential is often assessed in terms of geographic (or resource), technical, and economic potential—each of which represents a succession of additional complexity and input assumptions that leverage similar data and a common analysis flow.

This closed-loop PSH resource assessment is accomplished by first applying high-resolution digital elevation models (30-meter resolution) to identify potential upper and lower reservoirs within the technology parameters specified by the NREL adaptation of the ANU model. Design specifications include minimum 300-meter head height, constant 40-meter dam height, and a maximum distance between upper and lower reservoir of 15X head height. This yields a large set of potential reservoirs with many overlaps.

Once the reservoirs are delineated, technical potential criteria are applied to appropriately limit the development areas. The current criteria eliminate any reservoirs that intersect existing water bodies and waterways; protected federal lands; urban areas; critical habitat areas; or are within 1000 feet of a wetland.

The remaining upper and lower reservoirs after applying technical potential criteria are paired by comparing upper and lower reservoir capacity to be within 20% of each other, applying the 15X distance criteria, and finally evaluating total paired system cost. The paired reservoirs are then optimized for lowest cost systems to develop a non-overlapping reservoir data set for an assumed storage duration (10 hours in this data set). Total costs include both hydropower site and transmission development. The site development costs are taken from ANU’s pumped hydro energy storage cost model with costs adjusted to align with industry expectations published in 2020 Grid Energy Storage Technology Cost and Performance Assessment, U.S. Department of Energy Technical Report (2020). In addition, transmission spurline costs are taken from NREL analysis supporting the ReEDS model. See ReEDS Model Documentation Version 2020, NREL Technical Report (2021).

Ultimately, this exercise results in a spatially resolved characterization of the technical potential quantity, quality, and cost of PSH resources, which can be sorted to represent a "supply curve" for a specific scenario—10-hour storage duration for closed-loop systems in this case. The supply curve of closed-loop PSH cost versus cumulative capacity for the contiguous United States is reproduced from the Closed-Loop Pumped Storage Hydropower Resource Assessment for the United States. Resource and cost data binned by cost ranges is also included in the NREL Annual Technology Baseline beginning in the 2022 data year.