When windmills made their way to Europe in the 12th century AD they were immediately accepted as a way to harness the power of the wind to grind grain or to pump water that would be used for irrigation. These early devices often had either three or four windmill blades. It wasn't until several centuries later that farmers in the UK decided to add more blades or sails to what would come to be known as a multi-sail windmill. They quickly discovered that not only did windmills with more sails increase power and efficiency, but they also seemed to run smoother that windmills with fewer sails.
Another commonr problem the multi-sail windmills addressed was storm damage. In those days windmills were fairly fragile devices, and it was not at all uncommon for one or more windmill blades to be destroyed during a storm. This meant that the farmer either had to stop the mill and lose a day of grain production, or he had to continue on at half power. But, if he owned a multi-sail windmill, he didn't have to worry about sacrificing power or efficiency if one or even two blades had been damaged.
While they may not be as popular as they were in 18th century Europe, windmills are still used on farms and even on private residences to pump water from wells and to produce electricity. And as surprising as it might be, the debate over windmill blades is still alive and kicking today.
Most experts contend that home or residential windmills are incorrectly designed and are therefore inefficient. They say that the use of only three windmill blades for home windmills is senseless because residential windmills must be erected close to the ground and that means that they should have more than three blades to increase power and efficiency. They also claim that several large, slow-moving windmill blades create more power and thusly more electricity than three relatively small, fast-moving blades.
The number of windmill blades is also being debated by people who are constructing wind farms. A wind farm is an expanse of land that is home to hundreds of windmills or wind turbines whose job it is to create electricity for local residents. But unlike the small home windmill, a wind turbine is gigantic. Their windmill blades alone can reach up to 150 feet in length and they are attached to tall towers that stretch three- hundred feet into the sky. When a windmill is this large it must use only two blades because of the stress the wind and rotation puts on the metal. However, experts believe that many of these larger wind turbines are extremely inefficient and wasteful. And that for the cost it takes to build one huge wind turbine, you could construct 3 smaller wind turbines with more blades that would be far more efficient and would produce more electricity.
Unfortunately, however this centuries' old debate is not likely to be concluded any time soon. But if you are a homeowner who's thinking about installing a residential windmill, you owe it to yourself and your family to draw your own conclusions.
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