Wind energy is increasingly being developed in forested areas, setting special requirements for energy yield assessments. It is crucial to collect temporal information on forest growth and cutting and spatial data on tree height, forest density, and clearings. However, the high-resolution data may violate the homogeneous assumptions of flow models, so the whole model chain needs careful considerations for accurate energy yield assessments in forested areas.

In a new paper, Floors et al. (2021) use openly available satellite-based data to generate 20m-resolution maps of tree height and forest density at eight 40x40km sites. The satellite data is an alternative to globally available but coarsely resolved land cover data sets and expensive aerial Lidar campaigns. Floors et al. (2021) then derive the roughness length and displacement height using three forest canopy models, improving the traditional manual assessments that can be uncertain and time-consuming. Finally, the authors introduce a new forest model in WAsP that better utilize the high-resolution data.

Wind observations from 65 met masts are used to evaluate the new satellite-based approach and WAsP forest model. Results show that maps based on satellite data are comparable to expensive aerial Lidar scans and lead to markedly lower prediction errors than standard land cover databases. However, a couple of sites, characterized by highly varying vegetation, do not show improvements. This may be caused by how the high-resolution forest data is aggregated to the coarser model domain.

Floors, Rogier, Merete Badger, Ib Troen, Kenneth Grogan, and Finn-Hendrik Permien. 2021. “Satellite-Based Estimation of Roughness Lengths and Displacement Heights for Wind Resource Modelling.” Wind Energ. Sci. Discuss. [Accepted], April. https://doi.org/10.5194/wes-2021-28.