One method used to store energy during times of low demand is by pumping water uphill into a reservoir.

, of water during the low usage period?

b.  What is the total mass of water raised 97.4 m during this 267.0 minute period?

c. How long can the turbines produce 275.0 MW of power from the release of the mass of stored water calculated above? Assume the water sustains a friction loss of 51.9 m2/s2 on the way down to the turbine.

d. What is the efficiency of this process? (Assume that the pump and tubines operate at 100% efficiency, and the only loses are due to frictional loses within the pipes.) Efficiency is defined as the total energy recovered/ total energy input.