Wind Resource Estimation Research Articles

Offshore wind resource estimation from satellite SAR wind field maps

A wind resource estimation study based on a series of 62 satellite wind field maps is presented. The maps were retrieved from imaging synthetic aperture radar (SAR) data. The wind field maps were used as input to the software RWT, which calculates the offshore wind resource based on spatial averaging (footprint modelling) of the wind statistic in each satellite image. The calculated statistics can then be input to the program WAsP and used in lieu of in-situ observations by meteorological instruments. A regional wind climate map based on satellite SAR images delineates significant spatial wind speed variations. The site of investigation was Horns Rev in the North Sea, where a meteorological time series is used for comparison. The advantages and limitations of these new techniques, which seem particularly useful for mapping of the regional wind climate, are discussed. Copyright © 2005 John Wiley & Sons, Ltd.

Evaluation of the wind-resource estimation program WAsP for offshore applications

The increasing interest in harvesting offshore wind energy requires reliable tools for the wind resource estimation at these sites. Most commonly used for wind resource predictions on land as well as offshore is the WAsP program. It has been validated extensively for sites on land and at the coast. However, due to the lack of suitable measurements there is still a need for further validation for offshore sites. Data from ongoing measurements at prospective wind farm sites in the Danish Baltic Sea region are available now. The wind resources estimated from these measurements are compared to WAsP-predictions. They agree well. The only deviation found is for two sites, which are located at about the same distance, but on different sides of the island Lolland. Here the measurements show a difference in the wind resources, which is not predicted by WAsP. A direction-dependent comparison explains this deviation. Wind speed ratios of several pairs of stations are modeled with WAsP for 12 directional sectors and compared with the measurements. Deviations in the directional wind speed predictions were found to correspond with the length of the sea fetch: For smaller sea fetches WAsP seems to slightly over-predict the wind speed, while for long fetches of more than 30 km an under-prediction is found. An analysis of the vertical wind speed profiles at three sites indicates that a combination of different effects is responsible for the correlation between sea fetch and model behavior. Effects of atmospheric stability as well as a fetch dependent sea surface roughness have to be taken into account.

Wind power meteorology. Part II: siting and models

The data used in wind power meteorology stem mainly from three sources: on-site wind measurements, the synoptic networks and the reanalysis projects. Wind climate analysis, wind resource estimation and siting further require a detailed description of the topography of the terrain—with respect to the roughness of the surface, near-by obstacles and orographical features. Finally, the meteorological models used for estimation and prediction of the wind are described; their classification, inputs, limitations and requirements. A comprehensive modelling concept, meso/microscale modelling, is introduced and a procedure for short-term prediction of the wind resource is described. Copyright © 1998 John Wiley & Sons, Ltd.