A coal-fired power station and an offshore wind turbine both generate electrical power.
The coal-fired power station produces 1.5 GW1.5\text{ GW}1.5 GW of electrical power, and a single offshore wind turbine produces 7.5 MW7.5\text{ MW}7.5 MW of electrical power.
Give one environmental advantage of using wind turbines instead of a coal-fired power station to produce electricity.
Coal-fired power stations are still in general use. Explain why offshore wind turbines have not totally replaced them.
In your answer, you should refer to the power outputs of both sources.