Survey of Energy Resources 2007
Wind Energy - Resource and Potential
Winds are generated by complex mechanisms involving the rotation of the earth, heat energy from the sun, the cooling effects of the oceans and polar ice caps, temperature gradients between land and sea and the physical effects of mountains and other obstacles. Some of the windiest regions are to be found in the coastal regions of the Americas, Europe, Asia and Australasia. Most mountain regions are also windy, while the interiors of large land masses are generally less so. The total resource is vast; one estimate suggests around a million gigawatts (Cole, 1992) 'for total land coverage'. If only 1% of the area was utilised, and allowance made for the lower load factors of wind plant (15-40%, compared with 75-85% for thermal plant), the wind-power potential would still correspond, roughly, to the total worldwide capacity of all electricity-generating plant. The offshore wind resource is also huge, with European resources, for example, capable of supplying all the European Union's electricity needs, without going further than 30 km offshore.
The locations of the 'best' onshore wind resources, based on maps by Czisch (2001), are summarised in Fig. 12-1, which shows that wind energy resources are well distributed.
The progress and prospects for wind energy may be assessed by examining the projections for 2010 as set out in the European Commission's White Paper on renewable energy (EC, 1997). Wind was set a European target of 40 GW by 2010, 16 times the capacity in 1995, but the target was realised by 2005. The only other renewable energy to achieve its goal by 2005 was large-scale hydro - which was set a much more modest growth target (a 10% increase over 1995).
World wind energy capacity has been doubling about every three and a half years since 1990, as shown in Fig. 12-2. It is doubtful whether any other energy technology is growing, or has grown, at such a rate. Total world wind capacity at the end of 2006 was around 72 000 MW and generation from wind was around 160 TWh, which roughly equates to the annual consumption of electricity in Sweden. Germany, with over 20 000 MW, has the highest capacity, but Denmark, with over 3 000 MW, has the highest level per capita and wind power accounts for about 20% of Danish electricity consumption.
Wind energy is being developed in the industrialised world for environmental reasons and it has attractions in the developing world as it can be installed quickly in areas where electricity is urgently needed. In many instances it may be a cost-effective solution if fossil fuel sources are not readily available. In addition there are many applications for wind energy in remote regions, worldwide, either for supplementing diesel power (which tends to be expensive) or for supplying farms, homes and other installations on an individual basis.
Most world wind capacity is located at onshore sites, but offshore wind farms have been completed, or are planned, in Denmark, Ireland, Sweden, Germany, the United Kingdom and elsewhere. Offshore wind is attractive in locations such as Denmark and the Netherlands where pressure on land is acute and windy hill-top sites are not available. In these areas offshore winds may be 0.5 to 1 m/s higher than onshore, depending on the distance. The higher wind speeds do not usually compensate for the higher construction costs, but the chief attractions of offshore are that it is a large resource with a low environmental impact.