The most common sort of energy storage in the world's power grids is pumped water. It's pretty simple: when you have excess power you pump water uphill, and when you need extra power you let it flow back down. In Germany
they have hit on a scheme to do this in an old, 600-meter (2000-foot) deep coal mine. Not as much water is needed as in a traditional scheme because the vertical distance is so great, and there's no evaporation when it's under ground. This also provides a handful of jobs in a district where the decline of coal mining has hammered the local economy. Pretty clever.
A quick google search tells me that water turbines easily manage 80% efficiency, and larger systems can hit 95%. That's pretty darn good in terms of getting back the energy it takes to pump the water uphill in the first place.
ReplyDeleteUsing water to store excess energy in a stable state. A very elegant concept. I like it a lot.