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what is Australia’s wind energy resources?

Australia has some of the best wind resources in the world. Australia’s wind energy resources are located mainly in the southern parts of the continent (which lie in the path of the westerly wind flow known as the ‘roaring 40s’) and reach a maximum around Bass Strait . The largest wind resource is generated by the passage of low pressure and associated frontal systems whose northerly extent and influence depends on the size of the frontal system. Winds in northern Australia are predominantly generated by the monsoon and trade wind systems. Large-scale topography such as the Great Dividing Range in eastern Australia exert significant steering effects on the winds, channelling them through major valleys or deflecting or blocking them from other areas (Coppin et al. 2003).

Deflection of weaker fronts from frontal refraction around the ranges of the Divide in south eastern Australia creates winds with a southerly component (‘southerly busters’) along the east coast. In addition to the refractions by topography and heat lows over northern Australia, other major factors influencing wind resources are seasonal and diurnal variation in wind speed. Winds are strongest in winter and spring in western and southern Australia but the monthly behaviour differs from region to region. Variations in average monthly wind speed of up to 15-20 per cent over the long term annual average are not uncommon. There may be similar daily variations at individual locations, with increased wind speeds in the afternoon (Coppin et al. 2003).

Meso-scale maps show that Australia’s greatest wind potential lies in the coastal regions of western, south-western, southern and south-eastern Australia. Coastal regions with high wind resources (wind speeds above 7.5m/s) include the west coast south of Shark Bay to Cape Leeuwin, along the Great Australian Bight and the Eyre Peninsula in South Australia, to western Victoria and the west coast of Tasmania. Good wind resources extend hundreds of kilometres inland and many of Australia’s wind farms (current and planned) are located some distance from the coast. Inland regions of Western Australia, South Australia and western Victoria all have good wind resources. Areas with high wind potential also lie along the higher exposed parts of the Great Dividing Range in south-eastern Australia, such as the Southern Highlands and New England areas.

The New South Wales Wind Atlas (Sustainable Energy Development Authority, NSW 2002) shows that the areas with the highest wind energy potential lie along the higher exposed parts of the Great Dividing Range and very close to the coast except where there is significant local sheltering by the escarpment. The best sites result from a combination of elevation, local topography and orientation to the prevailing wind. Significantly, the map shows that some inland sites have average wind speeds comparable with those in coastal areas of southern Australia.

The Victorian Wind Atlas (Sustainable Energy Authority Victoria 2003), shows a modelled average wind speed of 6.5m/s across the state with the highest average wind speeds (> 7m/s) found in coastal, central and alpine regions of Victoria (figure 9.8). The atlas also presents modelled average wind speed data in relation to land title (national parks, other public land and freehold land), land use and proximity to the electricity network. Effective wind resources are defined as those located within a commercially viable distance from the electricity network. The atlas delineates corridors within 10 and 30km of the network. It presents wind resource maps for each of the local government areas in relation to the electricity network according to land title.

Local topography and other variability in the local terrain such as surface roughness exert a major influence on wind speed and wind variability. Wind speed varies with height and with the shape and roughness of the terrain. Wind speed decreases with an increasingly rough surface cover, but can be accelerated over steep hills, reaching a maximum at the crest and then separating into zones of turbulent air flow. There are also thermal effects and funnelling which need to be considered when assessing wind resources. All of these effects impact on capacity factors (Coppin et al. 2003; ESIPC 2005). Australia’s high capacity factors reflect the large development potential.

Because of these factors meso-scale maps such as figure 9.8 do not account for fine-scale topographical accelerations of the flow. In particular, the effect of any topographical feature smaller than 3km is unlikely to be accounted for. In mountainous country, topographical accelerations (and decelerations) because of these finer scale features commonly exceed 20 per cent. As such, these maps are useful only for preliminary selection of sites: detailed assessment of wind energy resources for potential wind farm location sites requires integration of high quality monitoring measurements with a micro-scale model of wind flow incorporating the effects of topography and terrain roughness.