the first power tool

[Doug Winterburn]

For solar, one method is salt - not table salt, but salt:

[John McCoy]

Leon wrote in news: [e-mail]:

Um, if you read upthread a bit, you'd see it's stored by pumping water uphill, and then letting it flow back down thru hydroelectric generators when it's needed.

Batteries, while theoretically possible, in practice are a lot more complicated than using water. They're used in a few places on a small scale. Other small scale storage mechanisms include compressed air, and electrolizing water into hydrogen and oxygen (later recombined in a fuel cell).

I'd guess pumped water makes up 99% of the electric utility energy storage capacity.

One of the problems with solar energy is that places which are good for large-scale solar tend to be flat, meaning that pumped water storage (for night time use) isn't possible. There's a fortune to be made for whoever figures out a good alternative.

John

[Leon]

That is pretty cool, not photovoltaic. I missed the salt part. I could see how rain during the night might hamper but there is probably not much problem with that considering where it is located.

[Leon]

Yeah I saw that.... but, If you run at 100% capacity/output, having 10% more water/fuel is not going to increase capacity. You still have the bottle neck of 100% capacity. Maybe I am mixing two different explanations here. And, it seems that if capacity is only 90 percent of demand, taping into 100% capacity to pump water back the the reservoir that it would be counter productive. Certainly there is a loss of capacity pumping the water back up stream than it produces.

Understood but batteries supplement/add to output. Recycling water does not add to on demand capacity, unless the lake is about to go dry.

Not arguing with you here, just kicking thing around.

[John McCoy]

Leon wrote in news:dJ-dndsU46Y [e-mail]:

I think I wasn't clear there.

Suspose the peak demand is 100MW - daytime, AC running in the summer, heat in the winter, businesses have all their machines and computers and whatnot running. And at night the demand is only 70MW, because people are sleeping, not using much electric equipment.

Now, suspose we design a powerplant with maximum capacity of

90MW. We're 10MW short of what's needed for peak demand, but we have 20MW extra at night. So we use some of that 20MW to pump water uphill at night, and in the daytime we let it run back thru a 10MW hydro generator. Thus we get the extra 10MW we need at peak demand times.

This all makes sense because:

a) powerplants are expensive, and the savings from building a 90MW plant instead of a 100MW plant pretty much covers building the pumping plant.

b) running a 90MW powerplant at 70MW is inefficient, and will consume almost as much fuel as running it at 90MW, so the power used for pumping is almost free.

John

[Leon]

But unless I am missing something here, It does not matter how much water is in the reservoir/lake because whatever water is there to begin with is enough to operate the power plant at capacity.

Unless the water goes to a different reservoir that does not naturally refill itself to power the smaller generator.

And FWIW I am picturing Lake Mead as the reservoir.

[Doug Winterburn]

There's a link at the bottom of the page that gives more on the tanks of "molten salt" at 700+ degrees...

[Markem]

There was a hydro plant in Missouri that was man made reservoir that failed, it was filled from a river.

[Leon]

Gotcha thanks

[John McCoy]

Leon wrote in news: [e-mail]:

Ah, I see the problem.

The site I'm familiar with, Cabin Creek in Colorado, is typical. There is one lake/reservoir above Georgetown, and another one about 800 vertical feet further up the mountain. They pump water from the lower one to the upper at night, and let it flow from the upper to the lower (thru the generator turbine) in the daytime.

The upper reservoir does get a little water from snowmelt, but that's lagniappe. Mostly it's the same water being pumped up and down every day.

John

[krw]

SO where are they going to pump the water to?

[Leon]

Gotcha.

[J. Clarke]

Some convenient natural or man-made feature that is above the surface level of the reservoir that feeds the main dam.

[Unquestionably Confused]

I was thinking - and I think John McCoy (and perhaps another poster) - of a different reservoir. It's not as if you were just standing there pouring water back and forth into the same two glasses.

If you view the water as fuel to run the generator (turbines) or ???, then by using the electricity generated which is in excess of that currently needed (low demand period at night?) to pump fuel (water) to that other reservoir which may not be filling by itself as quickly you now have an expanded source of "fuel" with which to run a different generator turbine or divert the water for irrigation purposes. Somewhat analogous, I think, to a storage battery. Electric "fuel" is stored in a cell, water "fuel" is stored in the reservoir.

[krw]

It's exactly analogous to a storage battery. The voltage on the battery corresponds to the height of the reservoir (both represent potential energy) and the flow of water to the current (kinetic energy). In both systems there are losses converting potential energy to kinetic energy and verse visa.

[Bill]

For as unstructured as its day is, it sure likes to go to bed at dusk. Posture/position/attitude are all there (my wife covers the cage). Up with the sun too, at least for our first 6 days so far. My wife is a good intermediary for us; she brought him in to watch Jeopardy with me for a few minutes tonight. It likes its Wooden ladder, and it's a good transport Tool.

[woodchucker]

Jumping in this very late in the thread, Just came back from Alaska 2 weeks ago. I thought they had a great use of water. Alaska is a rain forest in many areas (not all). They would run a pipe down from the high lakes only about 10-12" pipes and be able to power many homes from the force of the water in that small pipe. I imagine had a very good impeller design too. Very efficient.

[Bill]

Maybe I am just jealous that in the first 9 or 10 weeks of its life it has learned to keep "perfect" hours--something I have not done very well for over 50 years now. God works in mysterious ways...

[Bill]

Our Budgie jumped and hit his head tonight, and birds have thin bones. He was buried in sight of the area he surveyed through his window, along with his favorite ladder. Although he was only with my wife and I for a short time, he enriched our lives.

Bill

[Electric Comet]

hold on a second what wood did you choose for the coffin for the budgerigar did you use fasteners or glue