Hydropower

Energy Cast Podcast: “World’s largest battery” storage solution

Energy Cast Podcast: “World’s largest battery” storage solution
(1,200 feet above rests the upper reservoir. The water level can drop 106 feet. )

Energy Cast is a podcast featuring some of the top experts across all links in the energy industry chain, including renewables, generation and more! Jay Dauenhauer created the show and has been hosting Energy Cast for several years.

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We cover energy storage technologies a lot on this podcast.  Probably no other storage solution has the track record of Pumped-Storage Hydropower.

Dominion Energy’s Bath County Pumped Storage Station in Virginia  is not only the largest pumped hydro facility, it’s the “world’s largest battery.”  And at 3,000 megawatts (MW), it’s the 10th largest power plant in the U.S.  Hoover Dam, by comparison, produces only ⅔ the power of Bath County.

I was given the special opportunity to visit this facility last spring.  Sean Fridley, my guest and Station Director, has also managed coal plants in his career.  For him this was a special honor.

Pumped Storage works by moving water between two reservoirs of different elevations.  In Bath’s case, there is 1,200 feet of head between the upper and lower reservoirs.

The upper reservoir is about 265 acres and drops over 100 feet when depleted.  The lower reservoir is 555 acres and drops 65 feet.  Neither lake fully drain.  This is called the “Conservation Pool,” and is vital in cases of drought.

The water that produces and stores energy is called the “Power Pool.”  During hot summer peak periods, all six turbines move 13 million gallons of water a minute.  Bath is capable of maintaining this production for 10 hours.  What’s amazing is that the pumping (storing) is capable of moving all that water to the upper reservoir in about 11 hours.

“One of the most interesting features of this station is that we’re nimble,” said Fridley.  “We’re able to start in 15 minutes.  That’s faster than any gas facility and definitely faster than any coal facility.”

Bath begin operations in 1985, making it much younger than a lot of other hydropower operations.  My guest in Episode 21 was commemorating a century of operations.

When operations began back then, the focus was on keeping baseload generation (i.e. coal, nuclear) busy when demand wasn’t high.  Even today that the remains focus, unlike my guest from Episode 57 developing a Compressed Air Energy Storage plant to regulate the 20% renewable mix in Texas.

“If you’re looking at creating a pot of stew, you’ve got different vegetables that go in there,” said Fridley. “One’s coal, one’s nuclear, one’s gas.  You don’t really know what you’re dipping out to pump Bath County, but we assume that as more and more renewables come on, we’re using that to pump with.”

Dominion says they have plans to build a “sister” pumped hydro facility in southwest Virginia one day, hopefully in the 800-MW range.

They have also received visitors from around the world, such as China and Switzerland.  Other countries have experimented with pumping seawater into an upper reservoir. (This article was originally posted in June 2019).

Energy Cast Podcast is hosted biweekly by Jay Dauenhauer.

Learn more about the podcast here.

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