In earlier centuries, grain and oil windmills were needed to meet the basic food requirements throughout the Münsterland region, where my ancestors had a farm since 1287.
So, im the 18th century, they decided (but mainly due to inheritance problems) to sell the farm and built a windmill. After some successful business, they moved to the next larger town and built a new windmill, opened a trade in grain as well ... in the town centre (about 3,000 inhabitants in those days).
From about 1900, the windmill was only used as an auxiliary mill.
Wind turbines were first installed here in 1970's; since the 1980's we've got wind farms.