Important Events in the Evolution of Wind Turbines
- The earliest antecedent of the wind turbine is the Persian windmill. This device is at least 1,500 years old, and consists of a number of blades sticking out of a vertical axis. Half of the blades are shielded from the wind so that when it blows, it pushes against only half of them, causing them to rotate about the axis. The Persian windmill was used to mill grain and pump water.
- The next great innovation in the development of the modern wind turbine came 800 years later, with the development of the European windmill. This version had blades mounted on a horizontal axis. All of the blades were exposed, making it more efficient than the Persian version. There were various designs to the blades of the European model, and some gave the blades lift, making them faster.
- In the mid 19th century the meteorologist Poal la Cour conceived of adapting the windmill to produce electricity. The first working wind turbine was built in 1888 by Charles Brush. The Brush Machine, as it was known, included a new innovation: a gearbox that increased the speed and power of the turbine's rotation. It produced 12 kilowatts of electrical energy.
- In 1922, the engineer S. J. Savonius went back to the original Persian windmill design to create an alternate style of wind turbine. The Savonius turbine was a vertical axis turbine with rounded scoops that presented more resistance on one side of the turbine than the other. These turbines always faced into the wind and experienced less wear and tear than the models based on the European design. In 1931, George Darrieus invented vertical axis blades that were more efficient than the Savonius type. Some engineers believe that vertical axis turbines will prove capable of producing more energy more efficiently than the standard horizontal axis turbine.
- During World War II, several companies developed powerful new two- and three-blade turbines. These turbines also featured the first alternating current generators, which were more efficient at transmitting electricity over long distances than the conventional direct current generators. These were the first modern wind turbines.