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.

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.

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…