Now, I don’t know how many of the 871 dams on federal land are in CA, but all the sites are listed in the linked article. Nor do I know how many of the non-used 80,000 dams are in CA. But I do know that we have dams that don’t run full speed year round due to lack of incoming water. We certainly could create some ‘dry season’ pump up storage in many of our dams and the dry season is when demand is highest. Night wind could be stored to power peak hour air conditioners.

We shouldn’t limit ourselves to thinking about CA as an isolated place. We’ve got a HVDC transmission line (the Pacific Intertie) running from Southern CA to the Northwest hydro facilities. And we’ve got the Intermountain Intertie running from SoCA to Utah. And plans underway to extend from Utah to bring abundant Wyoming wind to the Pacific Coast.

We’ve got some pump up storage being installed in the greater area. (I think there’s a SoCA project underway, but I’m not sure about that.)

Right now, I suspect pump up is less expensive for long term power shifting (night to day) than are batteries. But that could quickly change. There’s a storage battery company converting a large ex-Ford plant into a battery manufacturing plant. They must have a product that they think is going to be competitive.

10% loss savings seems high to me. But if it’s true then I’d think there’s money to be made by creating storage. Storage is going to likely be helpful both closer to point of generation and point of use. It means that transmission flows can be more moderate, making for smaller transmission lines.

“The 14% which had enough head but not adequate year round flow should be good candidates for pump-up storage.”

Do you know how many of those are in California?

Do you have any opinion of benefits of distributed energy storage by batteries v. centralized storage – hydro, etc.. One study I saw by AEP indicated a 10% savings in line losses by using distributed battery storage to store power at night when congestion on transmission wires is less.
http://tinyurl.com/yervzb4

I believe we’ll be more successful installing many megawatts of battery storage – flow batteries – near load then we will be trying to permit and build more central plant pumped hydro facilities.

http://www.usbr.gov/power/data/1834/Sec1834_EPA.pdf

In the US we have approximately 80,000 dams with about 2,400 (3%) used for power generation. We get 20% of all our electricity from those 2,400 dams.

If we use the federal findings as an indicator we might suspect that over 6,300 dams might be available to supply power to the grid and another 10,800 might serve pump-up storage purposes.

Furthermore, by using a technique called hydro uprating we can create 100% efficient “storage”. By taking a dam with adequate flow to supply one turbine and installing multiple turbines we can let water accumulate behind the dam when demand is low (the wind is blowing, the sun shining) and then when demand exceeds supply all the turbines can be put in operation to bring a lot of power on line quickly. This creates pump-up storage with out the energy loss from pumping by letting flow of the river recharge the energy supply.

http://neuralenergy.blogspot.com/2009/06/hydroelectric-uprating.html

At least two of the dams identified in the 2007 study are in the process of being converted to power producers and work underway on at least four others.

http://greeninc.blogs.nytimes.com/2009/08/19/retrofitting-non-electctric-dams-for-power/

Second, regarding the B&V report, I never quite understood how compressed air worked. At best, air compressors are, what, 85% efficient? Then turbines recovering the compressed air are, what, 85% efficient as well? So even before you begin to worry about finding relatively leak free underground caverns that are not heavily contaminated with methane to pump air in and out of you are starting with over 30% power loss just in the compression cycle.

Black and Veatch should be a little more concerned about their image as a legitimate engineering firm.

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Batteries might drop significantly in price. Sodium ion batteries with water-based electrolytes.

http://www.technologyreview.com/energy/24043/

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There are vast numbers of underground resources for installing CAES. From salt domes to limestone caverns, to played out oil wells, to empty/partly empty aquifers. There are few places in North America that do not have potential CAES sites.

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Pumped hydro. There’s a company called Riverbank which is in the process of building pump-up storage by creating underground caverns (looks like they intend to use a tunnel boring machine). That makes pump-up usable where there is some water available and it could be located close to available transmission lines.

http://www.riverbankpower.com/usercontent/projects/PRESS%20RELEASE%20-%20Riverbank%20Wiscasset%20Drill%20Test.pdf

I agree with the first two posters – flywheels for energy storage? Beacon flywheels are being built for $3,000 per kW, and they are $12,000 on a per kWh basis – and you only get 15 minutes of energy.

CAES is enhanced natural gas generation – assuming one can find a spot to build. What is the life-cycle cost, including fuel? And what’s the point in using natural gas generation to “store” renewable energy?

Pumped hydro is the best storage – but not practical given environmental and siting considerations.

NAS and flow batteries are the best solution for grid connected storage, and flow batteries are best for multiple cycle requirements of renewables.