[KaiserJeep]

Look, I think for the sake of this entire discussion, we should agree on some general principles. I would suggest:

1) Pumped hydro energy storage is practical and long-proven as a means of time shifting excess electrical energy. Indeed, it is fully mature and various hydropower dams have decades of operating experience. For those of you who do not know, Hoover dam has been in continuous operation since 1936 with an enviable safety record. Numerous engineering updates have been made including computer modeling of power grid ties, and computer modelling of long term power production. Lastly pumped hydro still comprises over 98% of the existing grid energy storage in 2018.

2) Construction of the pumps that pump uphill will utilize modern computer-aided design practices and losses in some similar and recently designed pumping stations in Norway are below 5%. This is about 1/3rd of the mechanical/electrical energy lost in the 1930's-era generators at Hoover dam, even after recent updates.

3) Performance of the dam and lake and pumping station would be maximized by having the lake full and the generators operating at 100% of capacity. At 100% head in terms of power generation, the dam and lake still retain about 35% extra capacity for flood abatement purposes, water would be buypassing the generators but the dam would not be in danger of breaching. Of course, as already noted, the water needed to fill the lake once to produce maximum head is not available in the area, this problem unless resolved would limit storage capacity and power production.

Source: IEEE Transactions on Power and Energy, which is unfortunately paywalled for non members. However I can provide additional details if needed.

[KaiserJeep]

You're an idiot. It all fits within the proposed $3B budget.

[KaiserJeep]

As you were told before and are ignoring, the river below the dam has more than enough capacity, due to earthen impoundments below Hoover that aid in water distribution. The water tunnel and pumping station are the major expenses.

[KaiserJeep]

I can't tell because the detailed design or the assumptions used for the proposal were not stated. However pumped hydro has almost a century behind it, it's the only significant technology in use, and there is already about 1.5GWh of grid storage implemented. Whatever lingering doubts you have would be unjustified.

The major problem with hydro energy production has always been it is limited by terrain and most of the best sites have been built already. The idea of reusing many of these hydro power plants and lakes for energy storage - even when as with Hoover they were not originally designed for such - is a good, low risk idea. Using wind and solar to pump water is also good, you re-use the power lines that already exist for the power plant.

It seems like an all round good idea to me, and it overcomes the intermittency problem that plagues renewable energy sources.

[Pops]

So the point is not to build storage until you have excess generation?

For what reason would you build excess generation if it has nowhere to go?

It's conversations like this among people who one would think grasp the situation that make me a doomer.

[KaiserJeep]

The point is to store power for baseline power consumption that is sourced from intermittent renewable energy and not from FF's. The renewable sources could be solar, wind, or hydro power. The storage battery is pumped hydro. Beyond that, there is a sizing that says that Hoover dam could be converted to a secondary purpose which is a pumped hydro battery, for $3B.

This seems like a good idea to me. But the only pieces already there are the dam and the power plant and the transmission wires. Everything else would have to be built, including the wind or solar plants.

[Simon_R]

I am afraid this conversation should have nothing to do with energy its just money

if the cost of selling the peak rate leccy makes up for the cost of the capex of the 3bn
bobs yer uncle. As they say hydro is for life.

the cost of the leccy is the cost of the pump (to top reservoir) at lowest rate + the VOM of the unit.

The advantage to the grid operator is that keeping thermals going longer drops the wholesale
rate as startup costs are reduced, so ... double bubble.

I would need to see the specifics, but the size of the downstream storage would be

(Rated Energy of plant / Energetic value of CuM of water ) * Hours to store

Excess water would be spilt.

you want to reduce evaporation, add floating solar plants.

Not sure the problem

Simon

[Plantagenet]

I'm warming to the idea of using Hoover Dam as a massive grid battery. However, I still don't see a solution to the problem of evaporation and water loss.

The Colorado River is already oversubscribed when it comes to water use. Already little to no water crosses the US border into Mexico---its all diverted for residential, agricultural and other uses.

If you take the water in Lake Mead, run it through the turbines in Hoover Dam, and then pump it back up into Lake Mead, more and more of the water will evaporate from Lake Mead each time it is re-pumped up there.

This means less water will be available to go down the Colorado---and there already isn't enough for the end users due to the drought. And this problem will get worse with time as global warming heats things up more and more.

What is the solution to the evaporation and water loss problem in Lake Mead?

https://www.hcn.org/articles/as-lake-mead-sinks-states-agree-to-more-drastic-water-cuts/image_large

Evaporaton and water loss from Lake Mead is already a big problem. States are already cutting their water use because of the drought and the evaporation...and re-pumping water back up into Lake mead will only result in even more evaporation losses. CHEERS!

[Pops]

$this->bbcode_second_pass_quote('Plantagenet', 'I')f you take the water in Lake Mead, run it through the turbines in Hoover Dam, and then pump it back up into Lake Mead, more and more of the water will evaporate from Lake Mead each time it is re-pumped up there.

[kublikhan]

$this->bbcode_second_pass_quote('baha', 'T')hey have a long way to go before there is any excess generation.

[KaiserJeep]

It's very discouraging, but AT LAST we seem to be focussing on the idea of using existing pumped hydro power plants and uphill water impoundments as storage for renewable energy. Now realize that the SIZE of the energy output is pre-determined by the generators present and the power distribution, also already present for the dam itself.

For existing dams, the remaining pieces are the lower altitude water impoundment, the pumping station and piping back to the high altitude water impoundment, and the sources of energy that are surplus to the needs of the local consumers, in the form of wind farms and solar arrays, or even solar thermal plants. TODAY the hydro power facility might be online during the day and offline at night, hydropower has the unique ability to be throttled up and down as needed quite rapidly.

TOMORROW after the build-out, the new wind farms and solar power surround the dam, the hydropower facility would be idled as the upper impoundment is filled via pumping from wind and solar, then online whenever the needs of the grid are excess to the online carbon-free power generation - such as at night or even a cloudy day, or a still day with no wind. The hydropower storage is matching grid capacity to grid demand always, and hopefully without needing to burn FF's or emit Carbon Dioxide. That is after all, what a battery does, it stores energy.

Seems like a good thing to me. Any opposed?

[evilgenius]

You don't have to pump water as far uphill if you change the scheme. Instead, pump it collectively from the Eastern US. Get it to a place where it can run downhill, all the way into the West. Run generators with it all the way downhill, for thousands of miles. There can be several downhill runs, for each region of the West that may need water. Instead of only thinking about power, this way you can also think about alleviating drought at the end cities.

[Simon_R]

@Baha … not only that, we could leave holes in them, and have a sort of summer 'ice fishing' deal, the tourist dollars alone would pay for the scheme.