Closed-Loop Pumped Storage Hydropower Supply Curves
NREL has developed an interactive map and geospatial data showing closed-loop pumped storage hydropower (PSH) supply curves, which characterize the quantity, quality, and cost of closed-loop PSH resources.
Supply curves are available for 8-, 10, and 12-hour storage durations, dam heights of 40–100 meters, head heights of 200–750 meters, and a maximum conveyance length between upper and lower reservoir of 12 times the head height (leading to a maximum horizontal distance between reservoirs of 8250 meters for a 750-meter head height system).
Interactive Map and Geospatial Data
The closed-loop PSH geospatial data include storage duration, paired reservoir volume (gigaliter), capacity (megawatts), distance between reservoirs (kilometer), head height (meter), transmission spurline distance (kilometer), transmission spurline costs ($), and total cost ($/kilowatt). Data can be downloaded directly from the interactive map.
Supply Curves Development
NREL developed the PSH resource assessment and supply curves by adapting geospatial algorithms and a cost model developed for the Australia National University (ANU) Global Pumped Hydro Atlas. NREL adapted the model to reflect U.S.-specific inputs and modeling needs to better represent PSH technology development potential in tools such as NREL's Regional Energy Deployment System (ReEDS) model.
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 200-meter head height, a maximum 750-meter head height, discrete available dam heights of 40, 60, 80, and 100 meters, and a maximum conveyance length between upper and lower reservoir of 12 times the 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; glaciers and ice-covered areas, protected federal lands; urban areas; critical habitat areas; or are within 1000 feet of a wetland. Optional criteria can eliminate reservoirs intersecting roads or farmland or allow reservoirs intersecting ephemeral streams.
The remaining upper and lower reservoirs after applying technical potential criteria are paired by comparing upper and lower reservoir capacity to be within 10% of each other, applying the 12X 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 each combination of assumed storage duration (8, 10, or 12 hours in this data set) and optional technical potential criteria. 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. The figure below plots the supply curve of closed-loop PSH cost versus cumulative generating capacity for the contiguous United States for 8-, 10-, and 12-hour storage durations and the default assumptions for where to prohibit or exclude closed-loop PSH construction. Resource and cost data binned by cost ranges is also included in the NREL Annual Technology Baseline beginning in the 2022 data year.
The latest (2nd generation) data set includes several updates and changes. Incorporating stakeholder participation and review, the updated data better reflects the range of technical possibilities for designing closed-loop PSH in the United States. It also integrates updated geospatial data where possible and includes multiple scenarios for storage duration, dam height, and several site exclusion criteria. While some changes limit the range of system specifications to better capture realistic design constraints, multiple dam heights and a lower minimum head lead to many more sites being identified in the 2nd generation data set.
|Technical Characteristic||1st Generation Data||2nd Generation Data|
|Storage duration||10 hours||8, 10, and 12 hours|
|Minimum head||300 meters||200 meters|
|Maximum head||None||750 meters|
|Maximum distance between reservoirs||4.5 kilometers||Enforced by maximum length:head ratio|
|Maximum conveyance length:head ratio||16||12|
|Dam heights available||40 meters||40, 60, 80, and 100 meters|
|Reservoir search radius from an identified dam location||5.5 kilometers||7 kilometers|
|Reservoir volume similarity requirement||Within 20%||Within 10%|
|Technical Potential Criteria||1st Generation Data||2nd Generation Data|
|Glacier/ice exclusion||None||Enforced using National Land Cover Database 2019|
|Wetlands exclusion||Enforced using National Land Cover Database 2016||Enforced using National Land Cover Database 2019|
|Urban areas exclusion||Enforced for Global Human Settlement Layer 2019 Classes 30:13||Enforced for Global Human Settlement Layer 2019 Classes 30:12|
|Existing stream exclusion||All National Hydrography Data stream types excluded (persistent, intermittent, ephemeral)||Additional scenarios allow reservoirs on ephemeral streams|
|Roads exclusion||None||Additional scenarios prohibit reservoirs intersecting major highways in 2020 U.S. Census Bureau TIGER/Lines data|
|Agricultural land exclusion||None||Additional scenarios prohibit reservoirs on farmland, denoted as "cropped area" in 2018 U.S. Geological Survey Global Food Security-Support Analysis Data|
Learn more about NREL's renewable energy supply curves or check out this webinar demonstrating the resource assessment and supply curves tool.
Closed-Loop Pumped Storage Hydropower Resource Assessment for the United States, NREL Technical Report (2022)
Advanced Hydropower and PSH Capacity Expansion Modeling, NREL Technical Report (2022)