Question

A hydroelectric power station takes its water from a lake whose water level if 50 m above the turbine. Assuming an overall efficiency of 40%, calculate the mass of water which must flow through the turbine each second to produce power output of 1 MV.

Answer 1

Potential energy = mgh

Efficiency = 40%

Useful work done = 40% of potential energy

= 40/100(mgh) = 0.4 x (m x 10 x 50)

= 200m

Power = work done pr second

1MW = 200 × mass of water flowing each second

1 × 10⁶w = 200 × mass of water flowing each second.

Mass of water flowing each second = 1 x 10⁶/200 = 5000kg