Rotor blades on a wind turbine are turned by wind power, generating energy that is converted into electricity.
Most wind turbines consist of a rotor, mounted on a shaft connected to a speed increasing gearbox and high-speed generator. They range in capacity from several kilowatts to five megawatts and start operating in wind speeds as low as of around three/four metres per second (around seven miles per hour).
The longer the blades, the larger the area 'swept' by the rotor and the greater the energy output, so computers monitor and control every aspect of turbine operation to maximise wind capture. Larger machines also create increasing capital and operational efficiencies and, as they are modular, they can quickly be added to an existing site to increase overall system reliability and performance. In the UK Renewable Energy Generation Ltd. develops small embedded projects, typically of up to 10MW in size, and has five operating wind farms totalling 17.7MW of capacity.
It also owns a portfolio totalling over 200MW at various stages of development. In Canada REG is one of the largest wind developers with 70MW of wind projects under construction and a development portfolio of around 4000MW.