Wind energy can be used to do work. When a boat lifts a sail, it is using wind energy to push it through the water. Farmers have been using wind energy for many years to pump water from wells using windmills. In Holland, windmills have been used for centuries to pump water from low-lying areas. Wind is also used to turn large grinding stones to grind wheat or corn, just like a water wheel is turned by water power.
Wind spins the large blades which turn generators to make electricity. Blowing wind spins the blades on a wind turbine just like a large toy pinwheel. The blades are attached to a hub that is mounted on a turning shaft. The shaft goes through a gear transmission box where the turning speed is increased. The transmission is attached to a high speed shaft which turns a generator that makes electricity. If the wind gets to high, the turbine has a brake that will keep the blades from turning and being damaged.
Wind turbines are being used to make electricity. Wind speeds must be 12-14 miles per hour to turn the turbines fast enough to generate electricity. The turbines usually produce about 50-300 kilowatts of electricity each. You can light ten 100 watt light bulbs with 1,000 watts.