ABSTRACT
Wind has been a source of energy all along history. The ancient Egyptians discovered the power of wind, which led to the invention of sailboats around 5000 BC. Although no one knows exactly who invented the first windmill, archaeologists discovered a Chinese vase dating back to the third millennium BC that had an image resembling a windmill. By 200 BC, the Persian, Chinese, and Middle Easterners used windmills extensively for irrigation, wood cutting, and grinding grains. They were often constructed as revolving door systems with woven reed sails, similar to the vertical-axis wind system used today. By the eleventh century, people in the Middle East were using windmills extensively for food production. During the period from the eleventh century to thirteenth century, foreign merchants who traded with the Middle East, and the crusaders who invaded the region, carried the windmill technology back to Europe. Figure 1.1 shows a nineteenthcentury renovated windmill in Europe. In Holland, windmills were also used to drain lands below the water level of the Rhine River. During this era, working in windmills was one of the most hazardous jobs in Europe. The workers were frequently injured because windmills were constructed of a huge rotating mass with little or no control on its rotation. The grinding or hammering sounds were so loud that many workers became deaf, the grinding dust of certain material such as wood caused respiratory health problems, and the grinding stones often caused sparks and fires.
