Abstract

In 2011, the Swiss Federal council and Parliament decided on the phase out of Switzerland’s five nuclear energy plants (BFE n.d.) and launched the “Energy Strategy 2050” which envisages a significant expansion of electricity production from renewable sources including wind energy. Much of the current wind resource assessment at the regional and national scale is based on mean decadal wind speeds at 1000m interpolated using approximately 200 measurement stations spread across the county and projected onto topography based on a statistical model. This methodology is however unsatisfactory to account for the complex, highly localized thermo-topographic flow phenomenon occurring at sub-diurnal timescales that could be harnessed for wind energy production. A prime example of such flows is katabatic winds that form when outgoing long wave radiation cools air at higher elevations. The cooled, high density wind then drains downslope under the influence of gravity. These winds combined with channeling effects of valleys they can reach speeds up to 50m/s. Due to their topography and the jet-stream, the Alps also form a barrier that often separates colder air from warmer air. The pressure gradient that is caused by this temperature difference accelerates the air when it flows through this barrier resulting in ‘pass-winds’ that have been shown to be attractive sites for wind energy generation. In this study we provide evidence for a need of systematic re-assessment of the national wind energy potential by describing such by performing high-resolution simulations using the WRF-LES for certain canonical topography features in the Swiss Alps – namely, (a) Valleys ( e.g: Rhine Valley), (b) Mountain Passes ( e.g: Flüelapass) and (c) Glaciers (e.g: Arola glacier system). We force these simulations using the Meteoswiss COSMO-2 reanalysis data to study ‘real-world’ scenarios. The simulations are validated using relevant weather station data and standard exclusion principles for wind resource development are applied to provide a realistic picture of the additional wind resource discovered.

Details

Actions