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Eltex t1_j0ocl5n wrote

Reply to comment by mufasa_lionheart in Switzerland’s Giant “Water Battery” Starts Working by Wagamaga

You mean like every elevated storage tank in the world?

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prtt t1_j0p2w5e wrote

You mean with the tiny minuscule detail that this is the largest example of it, by a significant margin?

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mufasa_lionheart t1_j0ql7ko wrote

No, most elevated storage isn't at this scale and also doesn't harness power on the way down as that would defeat the purpose of the elevated storage.

The difference between "elevated storage" (I'm assuming you are referring to things like municipal water towers) and "pumped storage" is the form of energy that it was built to store.

With "pumped storage" the stored energy is electricity in the form of potential energy. Excess grid power is used to move water from one reservoir (like a lake, not a tank) to another with a higher elevation (like up a mountain, not a tower, like 1000 feet difference, not 100). Then, once more energy is needed, they change the potential energy into electricity using turbines as the water moves to the lower reservoir. They repeat this process as needed.

This process requires massive amounts of water, and a huge elevation change to store meaningful amounts of electricity. It also requires massive pumps/turbines to take advantage of the cyclical price of grid power.

With "elevated storage" the stored energy is water pressure in the form of potential energy. This is done both to provide water pressure to higher elevation homes without the need for huge pumps and to equalize the demand for water pressure. They use a small (compared to pumped storage ones) pump to maintain a water level in the water tower which typically maintains a higher level of pressure than the pump provides.

This requires relatively low power pumps because physics gets leveraged and the tank provides a buffer to higher demand than the pump can keep up with. The tank only needs to be large enough to provide a safe buffer for peak water demand. The pump only needs to be large enough to have enough volume to easily keep up with average water demand and enough pressure to get that volume up to the tank. There also aren't any turbines impeding the outflow because that would lower the available water pressure and because the outflow could only produce a negligible amount of electricity.

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