Meanwhile in Germany:
I’ve been to a hydro storage plant and I know how it works. It stores power by pumping water into an upper reservoir when there is excess power and then letting it through turbines at peak demand. Overall, it achieves about 80% efficient energy storage whose capacity scales very cheaply as opposed to battery storage, and can respond to demand in a minute.
However, it never generates power in the usual sense so it should show up negative on an overall chart. Is this a real time one? I don’t think so because it says “past 12 months”.
Could a dam lake be counted as hydro storage? That wouldn’t require energy spending to pump water up, but it can work as a “cache”?
Nope, that’s just regular hydroelectric. All hydro power plants have valves to control the flow and they do adjust them on demand, for turbine/filter maintenance, and/or hydrological event control.
Also, dam lake is a misnomer because lakes are naturally occurring. The correct term is reservoir. However, a reservoir can be natural and not dammed, like the oldest Czech pumped storage power plant at Černé jezero, which I visited. (The reservoir is a beautiful mountain lake and unfortunately, nature preservationists capped the water level changes to 4 cm, limiting capacity.)
