History & evolution from 644 A.D.to the 1990s. Purposes, technology, designs, theory, materials, efficiency, wind turbines.
Historically, wind energy conversion systems can be considered as one of man's earliest machines. Windmills, according to documentation, were used in... more
Historically, wind energy conversion systems can be considered as one of man's earliest machines. Windmills, according to documentation, were used in Persia as early as 644 A.D. to grind grain (5:9). Mechanically, the Persian windmill was a development of the watermill--an earlier machine used for turning grains into flour--and it looked a little like one turned up on end. A vertical shaft was set in a square tower, with sails set at right angles to the shaft at its top end. The wind passed through slots in the tower on to the sails, allowing the shaft to turn, as well as any machinery set at the bottom end (2:13). Traditionally, this principle travelled with the prisoners of Ghengis Khan to China, where horizontal mills with matting sails, but without the enclosing tower, were used to drive irrigation machinery. The Chinese discovered that if the