Question

Pumped-storage hydroelectricity is a type of hydroelectric energy storage used by electric power systems for load balancing. The idea is to pump water from a lower elevation reservoir to a higher elevation reservoir when electricity demand is low and inexpensive, such as at night. During periods of high electrical demand, such as during the day, the stored water is released through turbines to produce power. (a) (5 points) If water of density ows by gravity from the higher elevation reservoir (a) to the lower one (b) at a steady ow rate Q over a height H, what is the loss in energy associated with this ow? (b) (5 points) If this same amount of loss is associated with pumping the water from the lower reservoir to the higher one at the same owrate, determine the power required to run the pump. 3

Answer 1

A) energy loss E = pgQtH

Where p = density in kg/m3

g = gravity acceleration in m/s2

Q = flow rate in m3/s

t = time taken for flow in sec

H = height of flow in m

B) power required to run pump;

P = pgQH

Step-by-step explanation:

Detailed explanation and calculation is shown in the image below