a) Electrical energy produced by coal-fired plant = 2000MW = 2000x106W Electrical energy produced by wind turbine = 300kW = 300x103W 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.