Our "pumped hydro" is an old quarry that they let fill with water from a nearby river, and then pump the water back out. The pumps exist because the quarry is u

Our "pumped hydro" is an old quarry that they let fill with water from a nearby river, and then pump the water back out. The pumps exist because the quarry is used for water retention, but they are also used to just waste energy. I don't know the specifics, but I know they do that when electricity prices go negative. I didn't know turbine bypass was a thing though. Why does the utility purchase load if they can bypass the turbines? Do transformers need a certain amount of load on them? The pumped hydro facility in Ludington, MI is kind of close by, but I suspect it might be a little too far away to provide peaking power for Chicago.