A Life Cycle Assessment of Closed-Loop Pumped Storage Hydropower in the United States

The United States is working hard to reduce harmful greenhouse gas emissions by 2050. One way to do this is by using renewable energy sources like wind and solar power. But these sources can be unpredictable, so we need a way to store the energy they produce. Pumped Storage Hydropower (PSH) is a technology that can help with this.

What is Pumped Storage Hydropower (PSH)?

PSH is a way to store energy by using two water reservoirs at different heights. When there's extra energy, water is pumped from the lower reservoir to the higher one. When energy is needed, the water is released back down, turning turbines to generate electricity.

The Study

The authors wanted to understand the environmental impact of PSH, especially the greenhouse gas emissions it might produce. They looked at new closed-loop PSH systems in the United States. Closed-loop means the water is self-contained in a two reservoir system, it doesn't connect to natural rivers or lakes; it just moves between the two reservoirs.

Interesting Findings

• Greenhouse Gas Emissions: The study found that the emissions from PSH range from 58 to 530 grams of CO2 equivalent per kilowatt-hour (g CO2e kWh–1). This means the amount of CO2 produced for every unit of electricity stored.

• Impact of Materials: The type of materials used, like concrete in construction, affects the emissions. Also, using existing sites (brownfield) instead of building new ones (greenfield) can lower emissions by 20%.

• Comparison with Other Technologies: PSH has the lowest life cycle greenhouse gas emissions compared to other energy storage options like batteries.

• Scenarios: The researchers looked at different scenarios, like the size of the facility, the material used for lining the reservoirs, and the mix of energy stored. They found that the source of the stored energy had the biggest impact on emissions.

Takeways from the NREL Effort

PSH is a promising technology for storing renewable energy and helping the United States reach its goal of reducing greenhouse gas emissions. It offers benefits over other energy storage technologies, but the way it's designed and where it's built can affect its environmental impact.

The study by Young, Heath, Augustine, Margolis, and Macknick, sponsored by NREL, helps us understand how PSH can be part of the solution to our energy and climate challenges. It also shows that careful planning and design can make it even more effective and environmentally friendly.

Authors

The study was conducted by researchers Katherine R. Young, Garvin A. Heath, Chad Augustine, Robert M. Margolis, and Jordan Macknick and was sponsored by the National Renewable Energy Laboratory (NREL), a leading organization in the United States that focuses on advancing renewable energy and energy efficiency technologies.