Wind resource mapping
Wind energy has become a renewable energy source of increasing interest. Following this, more detailed knowledge of wind conditions are needed. Presently this mainly concerns the wind resource down to the 1 km scale, but more focus will during the comming years be needed on wind varibility on smaller scales. Also turbulence characteristics are becomming of more interest, both in relation to turbine loads, power production, and wake behaviour. The new wind resource mapping over Sweden using the MIUU-model, shows that also forested areas may be of interest for wind energy, but here the turbine industry is concerned about the expected increased turbulence levels in this environment. Thus more research on turbulence and wakes in high turbulence environments are needed.
The project 'Mapping the Wind Potential in Sweden' has produced a large database of meteorological parameters at different heights over the whole of Sweden with 1 km horizontal resolution. This database will here be used to extract further statistics of interest for wind energy applications. This will give the country wide variations of the Weibull parameters as regards annual averages, and for wind direction sectors, extreme winds for 50-100 years for different averaging times from 1 s to 1 hour, information on the turbulence intensity, and rearding the vertical wind skear. Methods to increase the resolution of the wind mapping from 1 km to 50-100 m will be developed. They will use information on the wind at 1 km scale as input to some other models giving the higher resolution.
Wind indeces are often used to relate wind energy production during a shorter time to conditions during a longer time. This is referred to as 'correction to normal conditions'. Similar corrections to normal conditions are also crucial to be able to use wind measurements made during shorter periods. Within the work with the new Swedish wind mapping question regarding this has arised. The natural has then been to start by looking for numbers in the Swedish 'driftstatistik' at Elforsk. This has the limitations of only giving one wind index for the whole of Sweden, while the geographical variations are large. A comparison with Danish statistics also show large differences. The need for a regionalized wind index is large and will be accomplished using new methods.
Mapping of Sweden 2009 (in Swedish)