Wind energy is a powerful and renewable source of energy that can be used to generate electricity. Wind turbines are the machines that convert wind energy into electricity, using the aerodynamic force of rotor blades that work like the wings of an airplane or the rotor blades of a helicopter. When the wind flows through the blade, the air pressure on one side of the blade decreases, creating lift and resistance. The lift force is stronger than the resistance, causing the rotor to rotate and turn a generator, which produces electricity. The amount of wind power generation has grown significantly over the past 30 years, thanks to advances in wind energy technology that have reduced the cost of producing electricity from wind.
Government requirements and financial incentives for renewable energy in the United States and other countries have also contributed to this growth. Wind turbines use blades to collect kinetic energy from the wind. The wind flows over the blades creating lift (similar to the effect on the wings of airplanes), causing them to rotate. The blades are connected to a drive shaft that rotates an electric generator, which produces (generates) electricity. The type of wind turbine generator required for a particular location depends on the energy contained in the wind and on the characteristics of the electrical machine itself. High-strength magnets are usually made of rare-earth materials, such as neodymium, iron (NdFe) or samarium-cobalt (SmCo), eliminating the need for field coils to provide a constant magnetic field, leading to a simpler and stronger construction.
Smaller or home-made wind turbines generally tend to use a low-speed permanent magnet direct current generator, or Dynamo, since they're small, cheap, and much easier to connect. Smaller wind turbines are used for applications such as battery charging, auxiliary power for boats or caravans, and for powering traffic warning signs. Larger turbines can contribute to domestic electricity supply and, at the same time, sell unused energy to the utility provider via the grid. An advantage of this arrangement is that the turbine does not need to point towards the wind to be effective, which is an advantage in a place where the direction of the wind is highly variable. Wind farms and nuclear power plants are responsible for between 0.3 and 0.4 bird deaths per gigawatt-hour (GWh) of electricity, while fossil-fuel power plants are responsible for approximately 5.2 deaths per GWh. Around the time of World War I, American windmill manufacturers produced 100,000 agricultural windmills every year, mainly for pumping water. These systems are called hybrid wind systems and are generally used in remote, off-grid locations (where there is no connection to the power grid) and are increasingly common in grid-connected applications for resiliency reasons.
When wind turbines of any size are installed in or near the place where the energy they produce will be used, they are called distributed winds. If the height of a roof-mounted turbine tower is approximately 50% of the building's height, it's close to the optimal level for maximum wind energy and minimum wind turbulence. Harnessing this powerful source of renewable energy can help reduce our dependence on fossil fuels and create a more sustainable future.