Pumped storage |
pathways for systems below and above 25 MW. NLR said the updated model is intended to address ongoing challenges in comparing pumped storage projects across regions, where cost variability linked to geology, terrain and design choices can significantly influence feasibility assessments. Development of the model involved technical input and validation from HDR Inc. and Small Hydro Consulting LLC, providing industry perspectives across a range of project scales.
Conflicts and concerns In contrast to existing pumped storage hydropower
projects in the US that are open- loop and located on natural water bodies, a recent study has found that over 80% of proposed projects are closed-loop designs, due to their siting flexibility away from natural water bodies and purportedly lower social and environmental impacts.
Above: The Cortes La Muela Pumped Storage Hydropower Plant in Spain
storage hydropower. NLR says additional research and development is essential to help developers, policymakers, grid planners, and other stakeholders understand the technology’s costs, benefits, and opportunities, and so its researchers are developing open-source tools to bridge these critical knowledge gaps.
In partnership with the Hawaii State Energy Office,
Argonne National Laboratory, and Pacific Northwest National Laboratory, NLR is addressing the lack of detailed assessment, valuation, and characterisation of PSH opportunities in Hawaii. Leveraging previous experience modelling hydropower systems in Hawaii, the research team will use NLR’s PSH Supply Curves Tool to assess the value-added potential of PSH systems at four sites on publicly owned land across the islands of Oahu, Maui, Molokai, and Hawaii. With an interactive map and geospatial data, this tool shows pumped storage hydropower supply curves which characterise the quantity, quality, and cost of PSH resources. In addition, NLR has also released a web-based version of its PSH Cost Model, expanding access to a tool designed to support project screening, comparative analysis and early-stage investment decision-making. The new platform replaces spreadsheet-only access with an interactive interface that incorporates updated cost data, additional dam construction materials, liner options and multiple pump-turbine configurations. According to NLR, the web-based format is intended to improve usability while maintaining transparency through an open-source, component-level methodology. A key feature of the upgrade is the integration of NLR’s PSH Life Cycle Assessment tool, enabling users to assess capital costs alongside environmental impacts within a single analytical framework. The combined model allows developers and planners to evaluate trade-offs between design choices, cost structures and lifecycle impacts at a site-specific level. The cost model applies a bottom-up approach, generating estimates based on user-defined parameters such as reservoir geometry, hydraulic head, conveyance layout, dam type and indirect cost assumptions. Outputs include component-level and total plant costs, as well as performance parameters relevant to system sizing and grid services. The tool is structured to accommodate both large- scale and small-scale projects, with distinct calculation
22 | February/March 2026 |
www.waterpowermagazine.com However, issues over permitting and the consultation
processes, plus conflicts over siting, water resources, and Indigenous lands, are emerging more frequently given the planned expansion of pumped storage projects in the arid US West and near Tribal lands. And these issues and conflicts are not necessarily lowered by closed-loop technology, according to a research team from the Low Impact Hydropower Institute and Portland State University.
Drawing upon published research from both a
technical and social sciences perspective, the study by Karambelkar et al published in WIREs Water, considered the emerging importance, environmental and social impacts, and critical consideration of pumped storage in the US.
Recent figures show that the US currently has 43 PSH facilities with a total installed capacity of over 21GW – 26 of which are FERC-licensed facilities. Most of the existing FERC- authorised schemes became operational more than 30 years ago and span 20 states, with the greatest installed capacity located in California and Virginia. After a multi- decade stasis, the research team say the PSH project development pipeline in the US has seen a boom in recent years. There are currently 55 proposed projects with a combined installed capacity of over 36GW in various stages of evaluation and permitting. The arid US West dominates the landscape of this planned development due to suitable surface topography, proximity to states with high penetration of variable renewables, and the large electricity loads of the West Coast. The authors go on to claim that emerging opposition
to PSH illustrates that, in practice, PSH may not be universally accepted. Yet, limited critical or social science scholarly research has focused exclusively upon it. Due to the competitive nature of preliminary permitting, the public is typically not brought in for community consultation and comment until after pumped storage developers secure a site for further evaluation. At this point, the authors say, significant time, effort, and money may have been invested in developing plans for this predetermined location without the benefit of local collaboration or wisdom. Importantly, issues around Tribal consultation and consent have been a major theme in opposition to PSH development. The authors reiterate that the early stage of project development offers an opportunity to design projects that include community input and minimise trade-
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