The urgent need to transition to clean energy is becoming increasingly clear to governments and enterprises across the globe. The United States has established a goal of achieving a carbon-neutral economy by 2050. Additionally, industry leaders like Amazon, Apple, and IBM have set large-scale sustainability goals. At the same time, several factors, such as digital expansion, an increased global user base, and energy-intensive technologies like artificial intelligence (AI), are contributing to increased energy demand. Simultaneously meeting demand and climate goals will demand innovative energy solutions using emerging and proven technologies. As the sector transitions toward a decarbonized grid due to the irregular nature of solar, wind, and other renewable energy sources, energy storage will be a critical concern. One solution is pumped storage hydropower, or “water battery,” the most mature and proven storage technology. In addition to supporting climate goals, hydropower storage contributes to increased grid reliability and provides stable employment opportunities to communities.

Pump hydropower energy and its role in sustainability

Pump hydropower storage is an energy storage system that utilizes gravity. There are two pump hydropower storage systems: open- and closed-loop. Open-loop systems are connected to a naturally flowing water feature, while closed-loop systems are not. Hydropower pump storage consists of two ponds at different elevations; for instance, one might be 500 feet higher than the other. Many pump storage systems are built into mountains, taking advantage of the natural elevation change.

When energy demand is low, extra electricity from the grid pumps water from the lower pond to the upper pond. Conversely, at times of high demand, the water is released from the upper to the lower pond, releasing energy. Today’s pump storage systems manage electricity at the state or interstate level. In the future, they may be capable of regulating regional or nationwide grids.

Because energy storage is an integral part of a grid powered by renewable energy, it is crucial to the energy transition. This is because the two primary renewable energy sources—solar and wind—are intermittent. At other times, however, solar and wind produce more energy than can be immediately used. This issue is addressed by storing excess energy and releasing it during low production and high demand. It also increases the efficiency of the grid by reducing waste.

Discussions about energy storage tend to focus on batteries. Yet, pump storage is a time-tested technology with several benefits over batteries. Lithium-ion batteries have capacity limits of around two to four hours and occasionally catch fire when overheated. Pump storage technologies use less land and do not require extractive mining for materials such as lithium. They are also long-term solutions. While batteries must be replaced after 15-20 years, pump storage facilities can operate for decades without replacing or recycling major components. In fact, the United States’ oldest pump storage facility has been operating since 1929. Based on the viability of pump storage, the International Energy Association (IEA) has identified hydropower as one of the most important resources for managing the seasonal variability of renewables.

Benefits of pump storage

Integrating pump storage into an electric grid enables increased reliability of the energy supply, making blackouts less likely and improving the grid’s resilience to extreme weather. Because weather events increase in frequency in response to climate change, integrating pump storage into energy grids is extremely important. While hydropower currently provides only six percent of the energy in the United States, it provides 46 percent of the nation’s “black start capacity,” or the ability for an energy source to go back online after the rest of the grid temporarily fails. The increased resilience provided by pump storage can also manage sudden increases in energy demand, manage grid frequency, and address fluctuations in spot energy prices, ensuring that consumers can rely on readily available, consistently priced energy to meet their needs.

Secondly, implementing pump storage facilities can provide economic benefits to individuals and communities. Pump storage facilities provide long-term, well-paying jobs, many of which are in rural areas. As coal plants increasingly close, former mine sites can be converted to pump storage facilities, employing former coal workers. For example, in Bell County, Kentucky, an inactive coal mine was converted to the Rye Development Pump Storage Project, bringing over $1.5 billion and 1,500 construction jobs to the community. On a state and federal level, pump storage facilities are long-lasting, reducing long-term transmission infrastructure costs.

Challenges in implementing pump storage

The benefits of pump storage are numerous, but obstacles remain to building new pump storage infrastructure, particularly in the United States. New pump storage projects have prolonged development timelines, and the regulatory compliance process is lengthy. Large U.S. infrastructure projects typically require government support, though many are managed by quasi-governmental organizations like the Tennessee Valley Authority. The approval of new projects depends, at least in part, on political and economic trends. Each pump storage project must receive a license from the Federal Energy Regulatory Commission licensing process, an in-depth process that can take four to six years. The National Hydropower Association is pushing to streamline and standardize this process, potentially reducing it to under two years.

The future of pump storage and the clean grid

While the focus remains on energy sources such as solar and wind, it’s essential to understand that storage is equally critical when designing future energy infrastructure. Hydropower pump storage has been in use for more than 100 years in the United States, and technologies continue to improve. In fact, within a decade, excess energy produced in states like California could serve the needs of consumers in other parts of the country. Today, pump storage can enhance grid resilience while aiding in the transition to a zero-carbon grid. Companies such as Iron Mountain, Bayer, and others have already integrated hydropower and pump storage into their plans to decarbonize their operations. As many other companies, from Microsoft to Amazon, announce plans to move towards carbon neutrality, the benefits of considering pump storage in their plans are numerous. Although hydropower pump storage requires some upfront investment of money and time, the long-term benefits, including a more resilient grid and sustainable job growth, make it a sound investment in a world transitioning to green energy.

About the Author

Ushakar Jha, PE, MIEEE, MASCE, is a licensed engineer with over two decades of experience in hydropower and pump storage. His expertise includes design engineering, detailed project planning, project cost estimation, power production modeling, and project management. Ushakar has spent the last decade advancing hydropower and pump storage projects at the leading hydropower development company Rye Development. As the vice president of project engineering at Rye, Ushakar is responsible for overseeing all technical dimensions of the projects. Ushakar has both bachelor’s and master’s degrees in civil engineering and an MBA from the Hult International Business School. For more information, contact ushakar@ryedevelopment.com.