# A hydroelectric generating plant is supplied from a reservoir of capacity 3.6 × 106 m3 at a head of 100 m. Find the total energy available in kWh if the overall efficiency is 75%.

A hydroelectric generating plant is supplied from a reservoir of capacity 3.6 × 10

^{6}m^{3}at a head of 100 m. Find the total energy available in kWh if the overall efficiency is 75%.### Right Answer is:

735750

#### SOLUTION

**Given **

overall efficiency = 75%

Reservoir capacity (V) = 3.6 × 106 m3

Water Head (h) = 100 m

Now to calculate the potential energy, we know that

Density of water = 997 kg/m3

g = 9.8 m/s2

Potential energy = E = mgh

**E = D × V × g × h** (∵ mass = density × Volume)

Put all these in formula of potential energy, we get

E = (D × V) × 9.8 × 100

E = 997 × 3.6 × 106 × 9.8 × 100

E = 3517416 × 106 J

E = (3517416 / 3600) x 103 kWh

E = 977060 kWh

Hence, total output energy can be calculated as

E’ = 977060 x 0.75

**∴ E’ ≈ 732795 Wh ≈ 732.7 kWh**