Copenhagen Offshore Wind 2005

The economic success of offshore wind farms in liberalised electricity markets strongly depends on reliable short-term (48 hours) predictions of their power output. In the EU-project ANEMOS for wind power forecasts, we investigate the short-term predictability of marine wind speeds and wind power. We found that the accuracies of wind speed predictions provided by the European Centre for Medium-Range Weather Forecasts, ECMWF and the German weather service DWD for the offshore sites Horns Rev and FiNO1 are similar or better than for single onshore sites considering that the mean producible power is twice as high as onshore. A weighted combination of the two forecast sources leads to reduced errors: This combined power prediction for a single site in the North Sea with a hub height of 100m shows a relative root mean square error of 16 % of the rated power for a look-ahead time of 36h, while the mean producible power amounts to 51 % of the rated power. A regional forecast of the aggregated power output of all projected sites in the German Bight with a total capacity of 25 GW benefits from spatial smoothing effects by an error reduction factor of 0.73, showing an RMSE of 3GW. 1