The Helms Pumped Storage Plant in Sierra National Forest, California, has an upper reservoir with a surface area of 2 km2 and a depth of 75 m. The upper reservoir is 495 m higher than the lower reservoir (use this height for calculating potential energy, ignoring the additional depth of the upper reservoir). The average electricity use per capita in California is 8,000 kWh per year. At full capacity, the energy stored in the reservoir can supply the electricity needs for a small city for a full year without being recharged. What is the population of that city? The turbines are only 90% efficient at converting kinetic energy of water into electrical energy.
A) 12,000
B) 15,000
C) 18,000
D) 20,000