Making a battery out of nothing but water

Energy storage can take more than one form. Batteries are the obvious place but there are others. One of the places has been air stored in caves under pressure. Another has been water at elevated levels.

Energy storage by lifting water so it can fall back down to run a generator is not new. It is not only an old idea, but it's been a huge economic success. The problem with the idea is that to pay off, large amounts of water and land have to be used for the reservoir. That means to pay off, there has to be a natural formation where water can reside up high and also down low so the water can be shuttled back and forth between them. To build such a large formation would be economically unfeasible.

Being so large, these formations are usually not hard to spot. So when they were all the rage in the 50's and 60's, all the obvious ones were taken. But there are still a few promising places. One of them is in Oregon where the idea is not to use solar or wind whenever it is available to pump water up from a lower reservoir. But to use electric pumps when the rates are low and sell the generated electricity back when the rates are high.

Sure, that idea won't last forever, but it might pay off.

The problem in this case is the water pumped into the upper reservoir will be ground water. And after it falls through the generator it will be lost eventually to the ocean. But ground water cannot be re-charged once the space has been lost. And ground water can be used for other things because it is clean. This is why the two reservoir solution is more popular.

There may be a few good places left for energy storage by lifting water. But there won't be many. And even with the addition of all the remaining water storage areas it won't make much difference to the energy needs of the nation. So it would be better to take a long term view and leave the ground water and rate shifting tactics in lieu of more efficient and sustainable solutions.