Quote:
Originally Posted by AndrewJ
True, but one listener who obviously knew the full process and had thought it through indicated that it does provide an insurance backup, but is very inefficient.
When pushed about it, he mentioned a lot of the "spare/off peak" electricity used to pump the water back up the hill would actually be coming from coal, not renewables, ( as the pumps will be near the snowy system ) and there arent many nearby renewables.
Andrew
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Pumped Hydro doesn't need to be efficient to work. The market price during the day is generally at least 10 times what it is at night, so you only need a 10% system efficiency to make it viable.
The listener was correct though. At night, hydro and gas generally shut down. So you are left with (at a guess) 90%+ coal driving the pumps.
What is does do is allow the hydro systems to run for longer during the day, without the need to build new dams.