In a hydroelectric dam, water falls 33.0 m and then spins a turbine to generate electricity. What is ΔU of 1.0 kg of water? Suppose the dam is 80% efficient at converting the water’s potential energy to electrical energy. How many kilograms of water must pass through the turbines each second to generate 45.0 MW of electricity? This is a typical value for a small hydroelectric dam.