A wind turbine consists of a few essential components that convert the wind’s kinetic energy into electrical energy. To determine how much energy will be available for conversion, one has to take factors such as the wind speed and the swept area of the turbine into account. Any wind farm project requires planning to establish how much power and energy output can be expected of each turbine to determine whether the project will be economically viable.
How to calculate expected wind energy
- It is crucial to know how much energy a wind turbine can produce in different conditions. To do this, one can calculate the rotational power produced at rated wind speed in a wind turbine. Rated wind speed is the minimum wind speed required for a wind turbine to produce power.
- The Betz Limit or Betz Law theory concludes that a wind turbine cannot convert more than 16/27, or 59.3%, of the wind’s kinetic energy into mechanical energy by turning a rotor. This theory establishes that the maximum power efficiency, or power coefficient, of any wind turbine design is 0.59.
- The power coefficient of each turbine type is unique and will be unique in the wind speed the turbine is operating in.
- The true maximum power efficiency is usually lower than the Betz Limit at 0.35-0.45, even in premium wind turbines.
- Once other factors of the wind turbine system, such as the gearbox, bearings, and generator, are taken into account, only about 10-30% of the wind power is converted into electrical energy.
Although turbine designers usually define expected wind turbine power, there is a relationship between various factors that affect wind speed power more than the rated wind speed. To understand any income that might be lost by the down-time of the turbine, it is vital to know turbine behavior at different wind speeds. Understanding these factors will also help with noticing any problems with the turbine when it is producing lower energy values than expected.