As global wind power integration rapidly expands, some countries may find they lack high-quality wind resource maps and accompanying national/regional siting plans. Based on spatial planning frameworks (see Vestas policy on “Spatial planning for large-scale wind power integration”), national/regional siting plans identify specific on- and off-shore areas for long-term large-scale wind power developments. Good national/regional siting plans take into account economic, environmental, and public acceptance issues.
National/regional siting plans are built on the back of high-quality wind resource mapping, which is necessary for governments to identify the best wind sites in the country. Once the national/regional siting plan is developed, additional detailed wind measurements must be conducted at specifically identified wind sites in order to establish sufficiently reliable predictions of economic output from the planned wind power project. As a general rule, the higher the wind speed the more electricity a turbine can produce and thus the better economics in the project. In good wind sites modern on-shore wind turbines are competitive with electricity produced using fossil fuels.
National wind resource mapping:
Mapping of national wind resources typically takes 18-24 months and usually draws on existing meteorological data of wind speeds from different meteorological stations throughout the country. Governments typically finance national wind resource maps, as they are used by national and local authorities to plan for wind power’s integration in the national power supply system. There are several internationally recognized institutes capable of conducting the meso- and microscale modelling that is required for making national wind resource maps of sufficiently high quality.
Developing countries can apply for funds from different donor organisations to carry out high-quality wind resource mapping.
Vestas’ local measurement campaigns:
As a wind turbine manufacturer, Vestas typically is not involved in the actual siting of wind power projects, which is the project developer’s responsibility. In very few cases, however, Vestas also develops wind power projects. In these few cases, Vestas supplements national wind resource maps with additional site-specific wind measurements to produce a sufficiently detailed estimate of the economic output of the site. Local wind measurement campaigns take at least one year, depending on the availability of longer-term correlation data in the vicinity.
Vestas’ virtual risks maps:
The local measurement campaign also measures turbulence at the site. Certain sites might have sufficiently high wind speeds, but if there is too much turbulence at the site, it can reduce the turbines’ lifetime and thereby the economic output of the project.
Offshore sites:
For offshore turbines, local measurement campaigns take into account waves, currents and tidal conditions. The geotechnical survey is distributed over several years. The climatic and geological conditions of an offshore site are also site specific; meaning the exact same combination of conditions is not likely to be found elsewhere.
Vestas recommends that governments develop national wind resource maps using internationally recognized institutes capable of using meso- and microscale modelling programs and tools. Models such as Weather Research and Forecasting (WRF) are well suited for initial large-scale mapping. WRF is developed and maintained in cooperation between the Mesoscale and Microscale Meteorology Division of the US National Center for Atmospheric Research and the US National Centers for Environmental Prediction.
Based on the mesoscale wind resource maps, microscale wind resource maps can be produced by, for example, the Wind Atlas Analysis and Application Program (WAsP), which is developed by the Risø National Laboratory for Sustainable Energy (DTU) in Denmark.
Once a national wind resource map has been developed and a national/regional siting plan established, a local measurement campaign at identified sites must be conducted by the developer. This local measurement campaign must comply with International Electrotechnical Commission (IEC) recommendations.
In projects that use Vestas turbines, Vestas will conduct its own site assessment to evaluate the siting done by the developer.
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