“Of coarse what is not mentioned in my Lifted from wiki post is the cost in megawatts of pumping 27 billion US gallons 363 feet uphill at night.”
True. But it is an impressive project. I ran the numbers for the country based on their parameters. With 30 days of energy storage (amount required to get through worst-case bad spells), we’d need roughly 18,000 of the facilities (allowing for some down-time). The biggest immediate problem is finding or creating the storage reservoirs. In the case of this project, they had a huge lake on one side and high terrain on the other side, which was perfect for the application. Starts getting tougher to locate another 17,999 of them...
Do note that that facility doesn’t have 30 days of energy storage at max output. In a bad spell, as if the nukes go down, 27B gal reservoir, at 27MM gpm flow, gives you about 16 hours of water to empty. So multiply your 18M facilities by 45 to get your national 30 days of storage: 800M times that one facility!