I'd love to see the economics of that. The last system for example can supply about 4MW for an hour. It would be interesting to see the true lifecycle cost and who really is paying for it. In my experience, deep cycle batteries don't last all that long either..... Also I think the essential point of the argument was that such a system is a very exceptional case. It involves a negligible amount of the total grid.
-snip-
Don't know where TDD is-- but in NY-- Yes! Every night.
Here's one I watched them build in the 70's-
Jim
That may be what I read about years ago. By the way, I reside in beautiful Alabamastan. There's a lot of hydro power in the Northern part of the state along with some nuclear reactors. The TVA project from the last century did a lot to bring electricity to us Hillbillies. ^_^
TDD
And where did they get the power to run those "pumps" ?
I worked on this project as a young engineer.
I would imagine it comes from some of the water flowing through the generator, which would be the most logical source.
At least in the ones I'm familiar with it comes from power on the grid generated by turbines, waterfalls, and nukes that don't get shut down at night-- they normally just run the power to ground.
Jim
Cool, so that's the what's left of the cataclysmic impact that killed the French Canadian dinosaurs. ^_^
TDD
Ah, thermodynamics repealed!
No violation of thermodynamics involved.
It certainly is if you think you're doing this for a reason.
Actually they suffered heart failure from eating too much poutine.
The reason is to have more water available to supply more power during peak times during the day. Let's say you have
100MW of generating capacity from water flow from the normal flow of a river. The generator could supply 130MW if there were more water flow, but the river is only capable of 100MW. At night, the demand is only 60MW. So, at night you take the extra 40MW that isn't needed and use it to power pumps to move water to a reservoir upstream of the generator. The next day, when you need more than 100MW, you start releasing that extra water, boosting the generator output above 100MW.Nothing there violates thermodynamics and there is a reason for it. The power generating company has just help meet peak demand and gotten paid for electricity that it would otherwise have not been able to produce. Feel free to admit you're wrong at any time.
Good idea except it does not work that way. Even at 100% efficency, only the ammount of water going down hill can only pump the same ammount back uphill. If 100 MW of water is turning the turbins, it will take more than
100 MW to turn the pumps to get the water back to the top.For the system to work, it starts off like you say. The the flow of water going down hill is stopped at night. The pumps and the other users are supplied with power from other sources on the grid such as coal powered plants that have the excess capacity at night.
Don't be absurd. If you're pumping water by using falling water, there can be no gain. If you're using falling water at night to pump water during the day, where's the storage of that energy?
Good grief. Just store the water behind the dam and forget the whole thing.
It violates common sense.
Follow the example. It doesn't require 100% efficiency. You have a river that's flowing at 100MW an hour. During the day, there is a market for all that power. At night the demand is only 60MW. So, you could let that water pass by unused or use the 40MW available to pump water to a reservoir above the power plant. Then, during the day when you need more than 100MW, you release some of that water. You now have more than 100MW of water availble to turn the generator because you have EXTRA water beyond what the river supplies during that peak period. Hence you can produce more than 100MW of power during the day when you need it.
That's real nice. Let the river go dry at night. I'm sure the cities, towns, farmers downstream and all the farmers will be OK with that.....
You're not gaining energy. You're storing energy at night by pumping water up to a reservoir above the power plant. Then during the day, you're releasing the water, to get the energy back.
It's stored in the reservoir above the dam. If I expend energy to pump 100 gallons of water 500 ft higher, then later I can run that water back down the 500ft drop and into a generator, generating energy. If there were no losses you'd get all the stored energy back. But let's say it's only 75% efficient. In the example I gave, it doesn't matter, because if the river is flowing at
100MW and the plant only has demand at night of 60MW, then 40MW is going to waste. 40MW * 75% is 30MW of additonal power that the utility can sell in the peak daytime.Yeah, if there is a suitable dam area to contain the additonal water as part of the river ahead of the dam and IF you can throttle back the river withoug screwing up everything below it. You with Ralph on the idea of just turning off the river at night? But none of that has anything to do with your claim that the pumping system I described violates some law of thermodynamics, does it?
that's flowing at 100MW an hour. During the day, there is a market for all that power. At night the demand is only 60MW. So, you could let that water pass by unused or use the 40MW available to pump water to a reservoir above the power plant. Then, during the day when you need more than 100MW, you release some of that water. You now have more than 100MW of water availble to turn the generator because you have EXTRA water beyond what the river supplies
That makes no sense at all. You are saying let the water flow past the dam. Then pump it back up to the top ? It is not like getting the water down stream 10 miles or more from the dam. Why not just cut the flow back to the demand for power.
You're losing energy.
Then leave it there!
You're nuts.
Because there is no dam behind the falls? Think Niagara. How do you stop up the flow? During the day they can only deflect so much water into the generators - must maintain minimum flow over the falls. - Now they COULD build a "lake" a few feet higher than the inlet of the generator and only have to lift the water a small amount form ABOVE the falls overnight to fill the reservoir - which is then available to supplement flow during peak power periods the next day.
There are many situations where the same could be done, with a definite net gain in power output.
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