Wind Energy

A wind turbine

Wind energy is an indirect form of solar energy. It is estimated that between 1% and 3% of the solar energy that strikes the Earth is used in the creation of wind.

Wind is created by the uneven heating of the Earth's atmosphere. This effect creates high and low pressure systems in the atmosphere. Air moves from the high-pressure systems to low pressure systems, creating the winds that circulate the earth. The wind has kinetic energy. A wind generator converts kinetic energy to electrical energy.

Wind Power and Australia

At the end of 2006, Australia’s total installed wind energy capacity was 817 Megawatts (MW), comprising 563 wind turbines in 42 wind farms. (http://www.auswind.org/auswea/index.html, 18 May 2007)

Queensland’s largest wind farm is owned by Stanwell Corporation and located in the Atherton Tablelands in far north Queensland. It is the State’s largest wind farm. It consists of twenty turbines generating a total of 12 mW of electricity, while on Thursday Island two wind turbines each generate 225 kW.

The farm generates enough energy to power 3 500 homes per year.



Caption - The wind spinning turbines drives a generator to produce electricity. This electricity travels through a transformer into the local electricity network.

The above image of turbines at WindyHill Wind Farm is supplied courtesy of Stanwell Corporation Limited. http://www.stanwell.com/frame.asp?ContentURL=/sites/windyhill.asp

Technology

Wind power turns kinetic energy of the wind into mechanical energy in a turbine and then into electrical energy in a generator. Wind turbines are mounted on high towers to take advantage of better wind conditions away from the ground. Towers may be built from tubular steel, concrete or steel frame.

Propeller-like blades of a wind turbine turn in the wind. Blades need to be aerodynamic and be able to be pitched into any wind. They need a system to turn them to the optimal position with each wind change. Currently, turbine blades tend to be fibre glass and composite materials.

The generator is located inside the nacelle (cabin or housing) behind the blades. The turbine, as well as the blades, turns to meet the wind. A braking system for a wind turbine is essential to minimise damage in high winds and storms.

Not all the wind energy is converted into electrical energy. Some energy is wasted in the form of heat. Generators require cooling systems to reduce this heat.

The power generated by a wind turbine is dependent on the:

• length of the blades
• size of the generator
• wind speed.

• Wind energy is an indirect form of solar energy and is free
• It is a renewable energy source
• There are no dangerous emissions
• Wind power can be used in remote areas
• Wind power can be used in conjunction with other renewable energy resources

• Wind turbines need to be built where there is a reliable source of wind
• Wind speed can fluctuate and this means that electricity generation is not reliable
• Wind farms can be noisy and unappealing visually
• Wind turbines can be expensive to maintain.
• Energy storage devices such as batteries are necessary.