European Use of Wind Power

In Europe, the windmill was one of the greatest scientific triumphs of the medieval age. Though the technology spread throughout Europe in the Middle Ages, it was especially important in northern and western Europe, particularly England, Scandinavia, Holland, Belgium, France and Spain. The earliest verifiable reference to a European windmill comes from a late twelfth century manuscript, while other evidence reveals the presence of windmills elsewhere in Europe in the thirteenth century. These European windmills differed from the earlier Persian model in their orientation—the Persian windmills rested on a horizontal plane, while the European models stood tall on a vertical plane. The earliest windmills in Europe appear to have been post mills, whose central body rested on a series of posts and could be rotated to match the changing direction of the wind. These were increasingly replaced in the fourteenth century and beyond by tower mills. Unlike the post mill, which rotated its entire body to meet the wind, the

blade mechanism of the tower mill was positioned at the top. The top could rotate to adjust to wind direction, but the main frame of the mill stayed in place. This allowed for the construction of sturdier frames, built out of brick or stone rather than wood. Stronger towers could support heavier and larger rotary blade mechanisms, which in turn allowed tower mills to capture more of the wind’s energy than post mills. Tower mills, however, were more expensive to build, and as such, both tower and post mill technology continued to be used throughout the Middle Ages.

Windmills were built to serve a variety of functions, such as raising water for irrigation or sawing wood. By far the most important function of windmills, however, was to grind grain for food. In this period, a typical western European family would consume about 1.2 bushels of wheat and barley per week. Grinding this amount of grain by hand was extremely time consuming, requiring about nine hours of labour.

A wind-powered mill, however, could do the job in about thirty minutes, freeing up time for other pursuits. The importance of wind power in grinding grain comes down to us in a revealing anecdote from a late twelfth-century manuscript in Suffolk, England. At the time, England was a feudal state, with the rights and obligations of both lords and peasants clearly defined by the law. Among the most important rights held by a lord was a monopoly on milling grain—the lord owned and operated the local mill, and peasants had little choice but to pay the lord an oppressive fee to have their grain processed. So long as mills were primarily water powered, it was difficult for peasants to challenge that monopoly, since the lord typically controlled access to the water. The evolution of windmills, however, gave some enterprising peasants the opportunity to build mills to grind their own grain, making free use of wind power that the lord could not hope to monopolize.

One such peasant was Herbert of Bury, who built a mill on his farm in 1180; when challenged by his lord, Herbert allegedly said, “The free benefit of the wind ought not to be denied to any man.” Herbert’s lord, and the law, disagreed, and the mill was dismantled. Herbert’s failure, however, should not obscure the fact that wind power posed a potent threat to the existing social and economic order. By declaring that wind was a resource that should be freely available for all to harness, Herbert was articulating a powerfully democratic ideal.

Wind was thus a crucial source of power for Europeans through the Middle Ages. Estimates vary, but at the peak of their importance, there may have been as many as two hundred thousand windmills operating in Europe. One historian estimates that wind provided Europeans with one quarter of their energy needs up through the dawn of the Industrial Revolution in the late eighteenth century.