A large coal-fired power station produces 2000 MW of electrical energy. A wind turbine with 33 m blades can produce 300 kW.
(a) How many turbines would be needed to replace the power station?
(b) Why, in actual practice, this number of turbines could not replace the coal-fired power station?
(a) Electrical energy produced by coal-fired plant = 2000MW
= 2000 x 106W
Electrical energy produced by wind turbine = 300kW
= 300 x 103W
No. of wind turbine required = 2000 × 106/300 × 103 = 6666.6
So, 6667 wind turbines would be needed to replace the power station.
(b) In actual practice, this no. of wind turbines could not replace the coal-fired power plant because the efficiency of wind turbines keeps changing due to changes in wind speed but the efficiency of steam turbines used in coal-fired power stations remains the same.