The New York Metropolitan Area has 7 million households.
The average electricity consumption per household is 24 kWh/day.
A 24 meter diameter, 9 meter high tank of molten salt can store 400 MWh of extractable energy. This tank has a volume of 4071.5 m3 and can provide electricity to 16,667 households.
The tank volume required to provide electricity for 7 million households is 1,734,461 m3. That is a tank 210 meters in diameter and 50 meters high.
Two tanks are normally required for liquid thermal storage systems, one hot and one cold.
This only considers residential electricity consumption. Industrial and commercial electricity consumption is about 3 times higher.