Sept Quarter, page-14

I’m on a train right now, so can’t give your post the attention it deserves. However Pumped Hydro has been used to stabilise the UK grid since the late 60s (they have a mega one in Wales) - basically in off peak you pump the water up and then using the same equipment you generator power when you have a demand increase. The cycle is about 75% efficient (round trip)

Thanks to the duck-curve of demand, google for more on that, it helps dramatically.

If you look at the AEMO price graphs you can see the opportunity to “buy” (or more likely not export) during the middle of the day then when the sun is going down (and grid demand coincidentally peaks as we all get home from work and make dinner) the pumped hydro exports electricity to the grid - chewing up all those delicious high rates.

Pumped hydro has much lower capital than battery, and it also has almost unlimited cycability. It is less quick to respond than battery, but much quicker than traditional generation.