How Do Windmills Work?

Video Transcript

"Hi I'm Steve Jones and I'm going to tell you a little bit how windmills work. Now windmills have been around for centuries and you may have seen the old style of windmill on a hill somewhere and if you go to Holland you see them everywhere and you'll see also the modern type of windmill. The principle is very much the same and it consists of sails in the case of an old mill you call them sails and here you have the blades of a propeller on a modern mill. Obviously the blades here are connected in the center and there is a top part of the mill which can rotate. This enables it to be set in the right direction so that the wind is coming through the sails to cause them to rotate. Normally in old mills this was a wooden structure and the sails were actually covered in literally they are sails and they are canvas just as on the sailing ship. The modern propeller blade is made with something like stresses carbon fiber. Now inside what we've got is with the rotation of the sales which is quite slow we have a gearing structure at the top to speed up the shaft and here we have a shaft which goes down into the mill to do whatever the mill is designed to do. Now a lot of people think mills only are designed to grind flour or should we say grind flour but in fact the first and most effective mills were designed to pump water and these were those in Holland, particularly where they were draining land and there were large amounts of water there and they had to keep the land dry because it was below sea level so they would actually attach this shaft to a rotary pump and it would pump water out of the boulders to keep the land dry. So that was the purpose of the windmills in Holland. Of course you could use them for grinding flour or grinding any other material that you wished to grind. Nowadays of course our windmill is different. Although it uses the same technology essentially, a pair of sails and a rotating generator at the top it actually is generating not rotation it is generating electricity. So the modern mill generates electricity instead of making flour or pumping water. So that's a little bit about how a windmill works."