Basically, any amount (other than zero) depending on the amount of power you wish to generate. Windo power is usually used to drive a wind turbine but these can vary greatly in size and output.
Actually, it is so profitable and in demand, that you can lease your land for windmill companies, one windmill for every quarter acre, and still use the land for things, like cattle raising.
Wind turbines in large farms are usually situated in one of three places: Offshore - Huge wind-farms which can make use of the raw ocean windsCountryside - Usually on top of hills or at the bottom of...