HARNESSING WIND ENERGY AND TURNING IT INTO ELECTRICITY
Wind energy is captured and turned into electricity by a wind turbine. The rotors (or blades) of a modern wind turbine typically consist of three blades. The energy captured by the blades steadily rotating is transferred to an electrical generator. The generator, together with a gearbox, transformer and other control equipment, is housed in what is known as the 'nacelle' of the turbine, as shown in the chart below.
The towers are mostly tubular and made of steel or concrete, generally painted white. The blades are made of glass-fibre reinforced polyester. They are white because it is inconspicuous under most lighting conditions. The finish is matt, to reduce reflected light.
Although a wind turbine is designed to operate continuously across a range of wind speeds, it does not always generate electricity at its rated capacity (e.g. a 1.65 MW turbine has a rated capacity of 1.65 MW while its actual generation of electricity at any given time may be less than 1.65 MW). A wind turbine normally does not generate electricity if the wind speed is below a certain level, the "cut-in speed". As wind speed increases, the wind turbine will gradually increase its electricity output until it reaches its rated capacity. When the wind speed rises to a certain threshold, the "cut-out speed", the wind turbine will shut down in order to protect itself from the forces exerted by high wind conditions.
A modern wind turbine is designed to generate high quality, network compatible electricity for more than 20 years, with remote monitoring and relatively low maintenance. During their lifetime wind turbines produce no greenhouse gas emissions. It takes a turbine just three to six months to produce the amount of energy that goes into its manufacture, installation, operation, maintenance and decommissioning after its lifetime.
Design efforts are currently focused on addressing grid compatibility, further improvements to acoustic performance and the emerging offshore market. There have been three major trends in the development of wind turbines in recent years:
- Larger capacity and taller turbines
- Increased efficiency
- Decreased investment costs
The Global Wind Energy Council forecasts that the wind energy sector will grow at an average rate of 18.5% p.a. between 2011 and 2015. It forecasts that a total of 459,000 MW of wind energy capacity will be installed by the end of 2015, an increase of 133% from the 197,039 MW of installed capacity at the end of 20101.
To find out more, view our Frequently Asked Questions (FAQ) section.
1 - "Global Wind Report: Annual Market Update 2010", The Global Wind Energy Council, April 2011.