Hydropower Developers and Operators Can Use the Tool To Select Sites, Components,
and Specifications That Minimize Emissions

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The National Renewable Energy Laboratory (NREL) has developed a first-of-its-kind tool that enables hydropower operators and developers to estimate the greenhouse gas emissions
associated with building and operating closed-loop pumped storage hydropower (PSH)
facilities.

Closed-loop PSH generates and stores electricity by moving water between an upper
and lower reservoir. It is an established technology that accounts for most of today’s
grid-scale energy storage.

As part of the clean energy transition, low-carbon renewable energy sources such as
solar and wind are being rapidly deployed on the electric grid. However, because these
generation sources are variable, grid-scale energy storage is needed to help balance
energy supply and demand.

It is also important for the construction and operation of the storage technology
to be low carbon. With PSH, for example, there can be greenhouse gas emissions due
to diesel-powered construction equipment, the use of concrete and steel, and the local
grid electricity mix powering the pump to move water to the upper reservoir.

In 2023, an NREL research team published a study showing that PSH is the smallest emitter of greenhouse gases compared to four other grid-storage technologies—compressed-air energy storage, utility-scale
lithium-ion batteries, utility-scale lead-acid batteries, and vanadium redox flow
batteries. The finding suggests that PSH could offer substantial climate benefits
by playing a key role in accommodating wind and solar generation.

Recognizing this potential, the NREL team used the data and methods from the 2023
study to create the Pumped Storage Hydropower Life Cycle Assessment tool. PSH developers and anyone interested in PSH deployment can use this web-based, interactive
application to determine the greenhouse gas emissions of a PSH facility over its lifetime.
Lifetime emissions vary depending on numerous site-specific factors, such as construction
materials, components, and especially the grid electricity mix used to operate the
facility.

Users can input specifications for PSH facilities at varying levels of detail. Examples
of specifications include the reservoir volume, dam material and dimensions, number
and capacity of turbines, and length of the transmission line that connects the PSH
system to the grid. Users can compare different PSH scenarios side-by-side and view
the emissions by component, material, and life-cycle phase. The idea is to help users
determine the sites, specifications, and configurations that minimize emissions.

“The tool’s ultimate goal is to show how PSH can contribute to overall greenhouse
gas emissions reductions and make the clean energy transition as clean as possible,”
Stuart Cohen said.

The U.S. Department of Energy Water Power Technologies Office supported the development
of the tool.

Access the Pumped Storage Hydropower Life Cycle Assessment tool and learn how to use it. Have questions about the tool or want to collaborate with
NREL on PSH project development? Contact Stuart Cohen.