Easy# Hydropower Plants: Efficiency and Calculation

APES-PXD4UY

Hydropower plants have very high efficiency, with most producing electricity at about 90% efficiency. This means 90% of the gravitational potential energy in the water entering the turbine is turned into electrical energy. A large hydroelectric plant produces $1.8 \times 10^9$ Joules of electricity per second.

Assuming the plant is 90% efficient, calculate the number of Joules of gravitational energy per second that were in the water as it entered the turbine.