Regensburg 2016 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 6: Additional Topics

UP 6.1: Hauptvortrag

Mittwoch, 9. März 2016, 11:45–12:15, H41

Estimating wind energy limits and atmospheric impacts at large scales from climate model simulations and first principles — Lee Miller and •Axel Kleidon — MPI Biogeochemie, Jena. Germany

Wind turbines generate electricity by removing kinetic energy from the atmosphere. When wind power is used at large scales, this removal results in reduced wind speeds that cannot be accounted for in large-scale wind power estimates derived from climatological wind speeds. Here we test how well wind power limits and this slowdown effect can be accounted for from first principles that are based on the momentum balance and the vertical downward flux of kinetic energy to the surface (VKE method). To do so, we apply VKE to the simulated control climate of a global climate model and compare the VKE estimates to the maximum wind power generation simulated by a set of sensitivity simulations ("GCM estimate"). On land, we find strong agreement between VKE and the GCM estimate, both with respect to generation rates (0.37 and 0.32 We m-2) as well as the reductions in wind speed by 42% and 44%. Over the ocean we find the GCM estimate to be about twice the VKE estimate (0.59 and 0.29 We m-2), yet wind speed reductions by 50% and 42% are comparable. We attribute this underestimation of generation rates to the common stable to neutral atmospheric conditions over the ocean. This offset between VKE and the GCM estimates over the ocean can be corrected for, so that VKE is a powerful approach to estimate more realistic wind power limits at large scales.