Global Wind Resources

Introduction:

Renewable Energy Technologies (RETs) have become multi-billion dollar industry from the realm of laboratories in recent years. At present, most of the large International Oil Companies (IOCs) have started serious business with renewables, like Shell and British Petroleum have individually committed US$500 million for renewable energy investment. Installed capacity of non-hydro RETs is already 60,000 MW [GEF 2001] and at present they are supplying 14 percent of the total global energy demand [WEA 2000]. The World Energy Council (WEC), Shell, the Intergovernmental Panel on Climate Change (IPCC) and several UN bodies expect a significant share of RETs in the future with major contribution from biomass, hydro, wind and solar energy (Mazharul Islam, Bangladesh).

The global wind energy potential, even excluding environmentally sensitive areas, is roughly five times current global electricity use. (CANWEA)

Anyone who has struggled to stay upright in a strong gale is aware of the intrinsic power of the wind. Indeed wind energy has been harnessed by people for centuries. The wind-mills with cloth sails used in many European countries are a good example, as are the multi-bladed windmills commonly seen on farms and in rural areas of Australia. The power of the wind is also used to propel sailing ships, cool homes on balmy NSW summer evenings, and fly kites. Recent research and development in harnessing the wind means that we can now generate electricity using wind energy. Modern machines that generate electricity from the wind work in much the same way as the more familiar European windmills of old. These modern machines are called wind turbines, as they produce electricity.

What is a wind turbine and how does it work?

A wind turbine is comprised of a tower, topped by an enclosure called a nacelle, and the rotor, which is the propeller-like structure connected to the nacelle. The nacelle houses an electrical generator, power control equipment and other mechanical equipment, which is connected to the rotor. The rotor blades are made out of light composite materials such as fibreglass. They are well researched and shaped to maximise the energy harnessed. The wind strikes these blades, and due to their shape, the wind causes the rotor to spin. When the wind is strong enough, the rotational energy in the rotor is converted to electrical energy within the generator. Towers are commonly made of steel tubes, although some earlier models used steel lattices. The height of the tower varies from turbine to turbine, and is determined by the length of the blades, size of the generator, and the need to access the smoother winds available further away from the ground.

How much energy is there in the wind?

Wind turbines can generate significant amounts of electricity. Wind electrical power is generally proportional to the speed of the wind cubed. This means that if the wind speed doubles, the power generated is multiplied by eight. Apart from the actual wind speed at a site, the length of the blades on the rotor also determine the amount of power produced. The longer the blade, the more wind it can harness. Wind turbines that are capable of generating 1 MW of electrical energy are now relatively common. A turbine this big could provide sufficient electricity to power approximately 300 homes, and save over 2000 tonnes of greenhouse gas emissions per year (http://www.seda.nsw.gov.au/).

Global Wind Resource Index>>