The Tesla Powerwall has 6.5 kwh = 23.4 M joules. Gravity potential energy = mgh. Suppose pool is 10 meters up, then you need 239,000 kg of water = 63K gallons

The Tesla Powerwall has 6.5 kwh = 23.4 M joules. Gravity potential energy = mgh. Suppose pool is 10 meters up, then you need 239,000 kg of water = 63K gallons or 8400 cu ft. This is a huge pool: 29 ft. x 29 ft x 10 ft. You could use the city water supply: borrow water through a turbine at night, and return it during the day :-) Or have pool up very high, for example on a cliff overlooking the Mediterranean: http://inhabitat.com/crazy-home-carved-into-a-coastal-cliff-has-a-swimming-pool-roof/ http://inhabitat.com/crazy-home-carved-into-a-coastal-cliff-...