Wind energy comes from moving air. Winds are driven by uneven heating of the Earth's surface. The Sun warms some areas more than others, creating pressure differences that set air in motion. Humans have used wind for sailing and milling for thousands of years. Today, turbines convert it into electricity.

Modern wind turbines are sophisticated machines. Blades shaped like aircraft wings generate lift as wind passes over them. The rotor turns a shaft connected to a generator through a gearbox. Sensors and motors adjust blade pitch and nacelle direction to capture the most wind. A single large turbine can power hundreds of homes.

Wind is one of the cheapest sources of new electricity. Costs have fallen sharply. Onshore wind is mature. Offshore wind is growing fast, especially in Europe and China. Wind is variable, so grids need storage and transmission. Public opposition to turbine views and noise exists but is often overstated. Most people who live near wind farms support them.

Common applications

• Onshore wind farms
• Offshore wind farms
• Distributed small turbines
• Hybrid wind and solar
• Wind-powered water pumping