Pumped Hydro Energy Storage: It Takes A Heck of a Long Time


The most commonly used method of storing energy for the power grid is pumping water uphill and then letting the water move downhill to produce electricity when needed. It’s called pumped hydro, and like other energy storage systems, it can make the power network less volatile and help utilities avoid using expensive backup power plants. Rather than firing up last-resort plants when demand spikes, they can dispatch stored energy. But beyond the obvious fact that pumped hydro can only be implemented in hilly areas, the technology has another very serious hurdle: It spends years in regulatory and environmental review purgatory.

At a California Energy Commission conference last week, Michael DeAngelis, the manager of Advanced Renewable and Distributed Generation Technologies for the Sacramento Municipal Utility District (SMUD), discussed a 400 MW pumped hydro energy storage project called “Iowa Hill” near Placerville, Calif., that the utility is working on. The project has been under serious discussion since 2001, when SMUD started going through a relicensing process with FERC for dams and powerhouses in the Sierra Nevada region. But, according to SMUD documents, the site has been under consideration for pumped hydro “on and off since 1972, when Bechtel Corp. performed preliminary engineering on the Iowa Hill site.” DeAngelis said last week that if construction starts on the project this year, the best estimate for when it would start operating is 2015.


Between serious discussions and production, that’s over a decade. And that’s almost 40 years from basic concept to completion. At that rate, we can just wait for global warming to take effect before adding the crucial capacity of energy storage to the power grid. To be fair, as Better Place’s Sven Thesen pointed out at a recent energy storage conference, there are some really serious environmental implications of pumping water up and down mountains. But decades? Startups, start looking into alternatives like these eight technologies and this one that just uses a heat pump and gravel.


Lois Bailey-Hacker

Dear All, especially Fred P.
Your remarks on SMUD’s plans to use this project to make money leave something to be desired. Although SMUD is legally “non-profit”, they buy and sell power on the grid, earning profits for their owners, the rate payers. The fact that the CPUC has some control doesn’t negate that fact.
Also, membership in the Sierra Club really doesn’t mean much. The Sierra Club has spoken out strongly against the LEAPS project, but has refused to oppose Iowa Hill. Rumor has it was because they want to avoid the possibility of another SMUD project at a higher altitude.
The fact remains that even though SMUD bills itself as “green”, this project means the destruction of forest and habitat for the convenience of the Sacramento rate-payers.
P.S. Who did you work for?

Fred P.


There appears to be some misinformation being bandied about, primarily by those not ahving the technical background in hydro or pumped-storage.

1. Pumped storage requires differences in elevation to develop the kinetic energy caused by falling water. Those reservoirs are necessarily in hilly/mountainous areas and are at the surface. The generating units are in underground caverns (ie, below the surface of the lower reservoir) so they can pump the water uphill.

2. You can never have 100% efficiency in any method of energy conversion, so (no matter what) you will ALWAYS have a net loss. Taking into account evaporation losses from the exposed water surface and conversion losses, however, around 70%-85% of the energy used to pump the water into the elevated reservoir can be regained. This is currently the most cost-effective means of storing bulk energy on an operating basis, but capital costs and the presence of appropriate geography are critical decision factors.

Just releasing the water (as in a run-of-river hydro plant) does not have the bulk generation capacity that a pumped storage facility has. Depending on the watershed, a conventional hydro plant might only generate 10% to 20% of what a pumped-storage plant could generate…. and those are generally at the surface, not underground.

3. While wind and PV generation is fine, remember that the generation in an interconnected grid has to necessarily balance out (and exceed) the load. Also, variations in wind speed and weather can adversely impact the stability of the transmission grid, even taking into account the “smart grid” efforts being pushed today.

4. Stating that it’s “because they can sell energy at higher prices during peak hours” is ludicrous. While I’m not familiar with the ratemaking structures of organizations like SMUD, other utilities’ rates are under the auspices of the CPUC. Additionally, they have a relatively short startup/reversal time, so they’re able to balance load flows quicker and are able to address bulk power transfer and stability issues faster.

5. In California, generators can bid into the energy-only or ancillary services markets through the CAISO. Depending on the needs of the grid, ancillary services (AGC, spinning reserve, non-spin reserve and replacement reserve) can be more valuable not only to the generator (the utility) but to the grid itself. Lack of bulk power generation for short terms can require the CAISO to buy much more expensive power from outside the state, increasing the costs to the customer.

6. There are around 50-60 pumped-storage plants worldwide, with around 20% of them in the US. The most recent of these was completed in (I believe) the 1980s.

7. As far as methane contribution, the jury is still out. You may have some additional contribution for a year or so because of reservoir construction – but the decomposition will decrease over time. Also, the uphill runoff will not be affected – this would stay the same whether the facility were built, not built or a conventional hydro plant were built.

I would suggest that, before getting all “starry-eyed” and emotional about the issues, you take the time to gather ALL of the facts. You need to understand the ENTIRE situation, amd not just cherry-pick those issues of which you claim to have some knowledge.

Although I have been involved in the hydro generation area for about 40 years and am now retired, I have been able to look at the situations objectively – which is why I’ve also been a member of the Sierra Club for years.

Lois Bailey-Hacker

I live in the town of Camino, where SMUD plans to build this monstrosity of a project. There are functioning pumped storage projects in the U.S., but since the 1970’s the construction has all but ceased due to the massive environmental destruction caused by construction. In the case of SMUD’s proposed Iowa Hill project, they will blast and scrape the top off the hill, dispose of all “organic matter”, and blast a tunnel one thousand vertical feet down into the mountain, as well as a chamber for the three large turbines and a horizontal chamber to the lower existing reservoir.
Then, with the “spoil” from the tunnel blasting, SMUD will contruct a stone ring reservoir and line it with plastic.
In addition, a two mile long, 100 yard wide swath will be cleared through the El Dorado Nation Forest for the transmission lines.
Does this sound like an environmentally sound project? SMUD is certainly trying to sell it as such. In reality, it would consume more energy (pumping the water up to the top) than it could producef(releasing the water for power production during peak demand).
Iowa Hill is a money-maker for SMUD, though, and in these times of concern about energy supply, they’re doing a great job of selling this ugly beast of a project as a “green” project.
Do your research before you get all starry-eyed over this.


as far as global warming, its a net loss of energy wasted during pumping water. the utilities do it because they can sell energy at higher prices during peak hours. its not to help the environment


“But beyond the obvious fact that pumped hydro can only be implemented in hilly areas. . .”

This statement is incorrect. There are several pumped hydro systems currently in operation that make use of underground caverns and mine shafts in conjunction with ground-level reservoirs.

Katie Fehrenbacher

Charles, they didn’t mention that. Bruce, thanks, yes, pumped hydro is by far the most common form of energy storage for the grid in use today.

Charles R. Toca


Did they also mention the vast amounts of methane that will be produced by covering vegetation with water to decompose, and also the release of methane, gathered from uphill run-off, that occurs when water is released downhill for generation due to the pressure drop? Just wondering…


this is darkdreamer speaking let me say that i appriciate the fact that u guys are trying to save te earth

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