How Do Water Wheels Generate Power?

Water wheels have been used for over 2,000 years. In an overshot wheel, water is delivered to the top, filling buckets that descend under gravity, turning the wheel — this type is the most efficient, converting up to 85–90% of the water's potential energy. Undershot wheels are placed directly in a river current, with water pushing flat paddles at the bottom. Breastshot wheels receive water at about axle height, combining features of both. Historically, water wheels powered grain mills, sawmills, and textile factories. While largely replaced by turbines, small water wheels and micro-hydro turbines are experiencing a revival for off-grid renewable energy generation, producing anywhere from a few hundred watts to tens of kilowatts.