Water Batteries, with Erik Steimle

Climate Break

Pumped Storage Hydropower as a Climate Solution

Pumped storage hydropower, also known as water batteries, are often used as a means to store excess renewable energy. For example, solar and wind may generate more energy than is needed during certain times of the day and less than what is needed at other times. As a result, water batteries are extremely useful as a way to store and release energy during peak demand periods or when renewable sources are unavailable (i.e, when the sun is down). This form of energy storage is used in many places across the country, and across the world, including Tennessee, Kentucky, and San Diego.

Current and Future Use of Pumped Storage Hydropower

In San Diego County, a proposed pumped storage hydropower project would connect a lake to large underground pipes which will “connect this lake to a new reservoir… 1100 feet higher in elevation” so that “when the sun is high in the sky, California’s abundant solar power will pump water into that upper reservoir.” When the sun is down, the water would be released to the lower lake, generating around ”500 megawatts of electricity for up to eight hours” which is “enough to power 130,000 typical homes.”

Similar projects are being implemented in other locations. In Kentucky, an old coal mine is being repurposed to be used as a water battery. This land has “hosted mining for at least 70 years” and this “project would deliver up to 287 megawatts of power for up to 8 hours, giving it more storage in the tank than the biggest lithium battery plants built thus far”. Additionally, Tennessee’s Raccoon Mountain, TVA stores the excess energy as gravitational potential energy and produces about “1700 megawatts of electricity” when in demand during the day. It takes extremely long for these projects to get approved because the investment is “more than 2 billion dollars for a large plant”. The project consists of three components: a lower reservoir “bounded by a 62 meter high dam” and “replenished as need to make up for evaporation;” an underground powerhouse which is “a 137-meter-long cavern” housing “three pump turbines;” and an upper reservoir which “would be some 600 meters across and bounded by a 53 meter high dam.”

Benefits of Water Batteries

Water batteries are incredibly useful for long-duration energy storage and can help balance fluctuations in renewable energy sources like solar and wind by providing power during peak demand periods. For instance, in San Diego, “the San Vincente project would store roughly as much electricity as batteries in 50,000 of Tesla’s long range Model 3 cars” and does not need materials like cobalt and lithium which are not only hard to find but create a lot of e-waste (and side effects with mining). Moreover, these projects fuel the economy and can create an abundance of construction jobs.

Challenges of Implementation

Pumped hydropower requires a lot of land, and flooding impacts habitat, and in some cases areas protected by indigenous tribes. The land and local ecosystem impacts can be very substantial. Moreover, water batteries require significant elevation difference between reservoirs to be effective so there are often geographic limitations to deployment. It can be extremely challenging to find places to build water batteries because they require specific topography as well as impacting the surrounding landscape. On top of this, these “facilities are expensive to build and take years to develop”. However, once they are in full structural integrity, they “store energy for far longer than lithium-ion batteries… and they last for many decades with minimal deterioration.”

Erik Steimle emphasizes that pumped hydropower/water batteries are a great way to generate energy in a more sustainable manner, however, he acknowledges that there are some downfalls of it . For example, pumped hydropower/water batteries must undergo extensive regulatory practices involving federal agencies that other types of energy storage and renewables do not, posing a barrier to widespread accessibility. Another benefit is the durability of this equipment, which can be useful for hundreds of years.

About our guest

Erik Steimle is the Chief Development Officer of Rye Development (tapped by DOE for the Kentucky project) and he is on the board of directors of the National Hydropower Association. Moreover, he has over twenty years of management experience in developing large-infrastructure renewable energy projects (especially in regards to hydropower).

Resources

• NPR: 'Water batteries' could store solar and wind power for when it's needed
• Canary Media: This Kentucky Coal mine could transform into pumped-hydro grid storage
• Science: How giant ‘water batteries’ could make green power reliable | Science | AAAS