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Hydroelectric Projects: Pumped Storage Projects in the News

Jack H. (Nick) McCall Jr.'s picture
Retired Attorney, federal government

Retired Senior Attorney, Office of General Counsel, TVA, 2005-2021: Provided legal counsel and acumen to TVA in the drafting, negotiation, and interpretation of various contracts, especially...

  • Member since 2023
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  • Jan 17, 2023

A recent New York Times ("N.Y.T.") article focuses on the ongoing Tâmega project in rural Portugal.  See: "Is a Dam in Rural Portugal a Key to Our Alternative Energy Future?" by Stanley Reed and Matilde Viegas, January 3, 2023. Its authors point to "a kind of global renaissance in the technology, known as pumped storage, " as currently taking place. 

In reading and considering this article, it is worth recalling that pumped storage projects for hydroelectric power are not new technologies.

One leading example that may be  known to many is Tennessee Valley Authority's (TVA's) Raccoon Mountain pumped storage unit. Located outside Chattanooga, Tennessee, Raccoon Mountain’s four Allis-Chalmers pump-driven generating units have a combined installed capacity of 1,652 megawatts and a summer net dependable capacity of 1,616 megawatts. Its reservoir, located at the top of the mountain, contains approximately 107 billion gallons of water covering 528 acres of water surface, drawn from the adjacent Tennessee River.  As TVA reports: "With its 1.6 million kilowatts of capacity, the Raccoon Mountain Pumped Storage Plant generates 14 times more power than nearby Chickamauga Dam."

Raccoon Mountain is not a new facility. Its construction started in 1970, and Raccoon Mountain has been in safe and reliable operation since 1978.   In TVA's description: "The plant works like a large storage battery. During periods of low demand, water is pumped from [the Tennessee River's] Nickajack Reservoir at the base of the mountain to the reservoir built at the top. It takes 28 hours to fill the upper reservoir. When demand is high, water is released via a tunnel drilled through the center of the mountain to drive generators in the mountain’s underground power plant."

The N.Y.T. article notes that Iberdrola plans to install a large wind farm near the Tâmega pumped-storage project. The piece further speaks to how pumped storage units can fit in with wind and solar energy: "Pumped storage plants can also provide, in essence, energy insurance to install even more sources of clean power generation, aiding the effort to tackle climate change, analysts say. " The article's authors note the following among the downsides of such projects: "In Europe, the scope for building such huge facilities may be limited by high costs, long lead times and opposition from environmentalists and local residents objecting to flooding river valleys. And the flooding from dams can hurt the riverine habitats of fish, birds and plants and inundate antiquities."

Lead time is, of course, a highly significant consideration in scoping and building any pumped storage site.  The scope of earth and water displacement required can equally be considerable.  (For informational purposes: TVA's construction of Raccoon Mountain displaced some 10 million cubic yards of earth to build the reservoir. 12,000 feet of subterranean tunnels were constructed, and the plant's central hall is described as being "a space the size of a football field [carved] out of solid limestone.")  Naturally,  these projects are subject to geographic considerations and limitations. Obviously, to maximize the gravity-related effects vital to a pumped storage unit's operations, such a plant's reservoir requires siting on a suitable height adjacent to an ample water supply.  Droughts, of course, can exert a limiting effect on being able to maximize draws from nearby water sources, much as they can on other hydroelectric facilities.  

While environmental concerns arise in connection with the initial construction and operation of such facilities, it may be worth noting here that the lakes resulting from pumped storage projects can, in time, became a haven for many animal and bird species. The area around TVA's Raccoon Mountain facility is a State of Tennessee-designated wildlife observation area. The mountaintop is home to raccoons, whitetail deer, woodchucks, gray foxes and, moreover, a large wintertime population of bald eagles.

Finally, for existing hydroelectric plants looking into hydro-modernization opportunities and the possibility of expanding capacity, the N.Y.T. article raises the potential of using pumped storage as a useful expansion option for certain strategically sited dams: "[E]nergy companies may focus on upgrading existing hydroelectric facilities with pumps and other equipment so that they can keep reusing water that is lost when it flows through a conventional hydroelectric dam."

Not only worldwide, but equally in the U.S., the day of new pumped storage projects may have returned after a thirty-year hiatus. Such plants can offer some unique synergies for hydroelectric operators to consider and investigate. 


Mark Silverstone's picture
Mark Silverstone on Jan 18, 2023

Thanks for this interesting  information. 
Is there available any «catalogue» (of sorts) of feasible new opportunities for pumped storage in the US? Are there many such projects  at various stages of development at the moment? 

Jack H. (Nick) McCall Jr.'s picture
Jack H. (Nick) McCall Jr. on Jan 26, 2023

You are welcome, Mark. Besides Julian Silk's note (below) on the Tazewell County, Virginia project, other pending pumped storage hydro projects include sites in Montana (Gordon Butte ); Riverside County, California  (Eagle Mtn.) and  Klamath County, Oregon  (Swan Lake ). Unfortunately, I don't have a more complete listing of such pending projects. You might want to check out the following article (from last year, so likely a bit outdated):


Julian Silk's picture
Julian Silk on Jan 18, 2023

One that is planned but has not been approved is the PSH project in Tazewell County in southwest Virginia - 


Jack H. (Nick) McCall Jr.'s picture
Jack H. (Nick) McCall Jr. on Jan 26, 2023

Thanks, Julian; that's good information to know. 

Jim Stack's picture
Jim Stack on Jan 19, 2023

Pumped storage is very good. We even have some in Arizona as done by SRP that also has 7 large dams. That is very good in a desert area we live in.

  As you know Battery Storage is growing very fast and reacts in nano seconds. So it can work well with slower acting pumped storage. 

   Have you seen many example of this synergy ? 

Jack H. (Nick) McCall Jr.'s picture
Jack H. (Nick) McCall Jr. on Jan 26, 2023

Jim, I will have to defer to others on current thinking re: the battery storage-pumped storage synergy potential.  My knowledge on what TVA and electric utilities in the Southeast are/were thinking along these lines is now a little bit outdated (I retired from TVA awhile ago), but I'd welcome comments/updates from others. 

Jack H. (Nick) McCall Jr.'s picture
Jack H. (Nick) McCall Jr. on Feb 24, 2023

While this apparently transpired earlier today (I just learned of this): For those interested in pumped-storage projects, and in follow-up to my earlier posting, TVA may still be able and willing to share details about this very recent event in Pisgah, Alabama. More here:

Jack H. (Nick) McCall Jr.'s picture
Jack H. (Nick) McCall Jr. on Mar 27, 2023

FYI: in follow-up to this earlier thread, feel free to read National Hydropowr Association's recent article, "Seizing the Pumped Storage Moment", here:

Jack H. (Nick) McCall Jr.'s picture
Thank Jack H. (Nick) for the Post!
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