(266137) (Power} A large household air conditioner may consume 15.0 kW of power. What is the cost of operating this air conditioner 3.00 h per day 30.0 d if the cost of electricity is $0.110 per kW.h? A "kilowatt-hour" is a unit of energy equal to 1 kW multiplied by 1 hour: kJ/s x hr = kJ x (1 hr/1 s) = kJ x (3600 s/ 1 s) = 3600 kJ