A 110 MW CAES plant stores compressed air in an underground salt cavern with a total volume of 1 million cubic meters.

A 110 MW CAES plant stores compressed air in an underground salt cavern with a total volume of 1 million cubic meters. The air is compressed from 100 kPa and 20°C to a maximum pressure of 9000 kPa and 20°C (a heat exchanger is used to cool the compressed air entering the reservoir.) A natural gas burner is used to heat the expanding air leaving the reservoir with a heat transfer efficiency of 99%. The CAES system has a round trip efficiency of 40% and requires 1.2 MWh of thermal energy from the natural gas burner to generate 1 MWh of electricity. At rated power the cavern has a compressed air discharge rate of 150 kg/s. The density of air at standard temperature and pressure is 1.177 kg/m3, the universal gas constant is 8.314 KJ/kgmol-K, and the molecular weight of air is 29. Assuming the reservoir is at full capacity and the pressure in the reservoir is maintained above 3000 kPa at all times, how long can the plant maintain an electrical output 110 MW (hr)?