It does not pollute the environment since any carbon-dioxide or any other harmful gases are produced.
a) Birds might be injured by the rotating wings.
b) The move of the rotor produces some noise and thus must be placed at a certain distance from residential areas.
c) The cost of construction and maintenance of wind generators is still high, and therefore the electricity produced from them is more expensive compared to electricity produced in thermoelectric or nuclear factories.
Though the research done in this area may reduce this cost.