I suppose I should have clarified that I meant "lake Mead if at capacity" which it isn't.
Stored energy (in a fixed gravitational field) is the product of height and mass. Hoover dam has a "hydraulic height" of 576 feet according to a government website, though the average height of any given drop of water is less than that because the lake is deep (or it was, anyways).
The thing about lake Mead is that the volume of water is absolutely huge. I don't think there are any mountaintop reservoirs anywhere close to it because though the altitude difference could be a lot more, it's hard to store large amounts of water on a mountaintop.
If we estimate that the average height of water in Lake Mead is 400 feet and it holds 26 million acre feet, then a pumped hydro storage system with 4,000 feet of altitude difference would need to hold 2.6 million acre feet to be equivalent. I'm pretty sure there's nothing like that in the U.S. The Bath County Pumped Storage Station in Virginia has an upper reservoir of about 35.6 thousand acre feet and a vertical distance of 380 meters (1,246 feet).
There are dozens of such reservoirs in the Sierra Nevada range in California. None of them will take as much water as Lake Mead, but they don't need to.
Sweden has lots of high mountains that may have shallow reservoirs built cheaply on top of. Reservoirs with earthen dikes are radically cheaper than the sort of dams needed for traditional hydro power, and may be placed almost anywhere, because they do not need or destroy a watershed. Lots of small ones, placed close to users, are better than one big one like Lake Mead.
Stored energy (in a fixed gravitational field) is the product of height and mass. Hoover dam has a "hydraulic height" of 576 feet according to a government website, though the average height of any given drop of water is less than that because the lake is deep (or it was, anyways).
The thing about lake Mead is that the volume of water is absolutely huge. I don't think there are any mountaintop reservoirs anywhere close to it because though the altitude difference could be a lot more, it's hard to store large amounts of water on a mountaintop.
If we estimate that the average height of water in Lake Mead is 400 feet and it holds 26 million acre feet, then a pumped hydro storage system with 4,000 feet of altitude difference would need to hold 2.6 million acre feet to be equivalent. I'm pretty sure there's nothing like that in the U.S. The Bath County Pumped Storage Station in Virginia has an upper reservoir of about 35.6 thousand acre feet and a vertical distance of 380 meters (1,246 feet).