HiWinds: High resolution forecasts for wind energy applications
C. Sweeney (UCD, Republic of Ireland)
In a recent Irish government white paper entitled "Delivering a Sustainable Energy Future for Ireland"[1], the goals for renewable electricity generation were set at 15% of Ireland's electricity consumption by 2010, and 33% by 2020. To compare this goal with recent years, renewable energy made up 6.8% of the electricity supply in 2005, which was up from 5.2% in 2004.
The largest growth in renewable energy contribution in recent years has come in the form of electricity generated from wind power. In order to achieve the Government's renewable energy targets, wind power will continue to play an important role in Ireland's electricity generation.
The amount of energy available in the wind varies with the cube of the wind speed. A 10 m/s wind contains about twice as much energy as an 8 m/s wind. This 2 m/s difference is the typical size of errors in operational wind forecasts. Such errors in predicted wind speed result in substantial inaccuracies in the prediction of available energy. More accurate wind forecasts allow a greater confidence in predicting the amount of electricity generated by wind farms, thereby allowing a more efficient integration of wind energy into the national electricity supply grid.
The HiWinds project is focused on reducing the error in wind forecasted by numerical weather prediction (NWP) models, thus enabling better management of wind energy facilities. This is achieved by using existing forecast data to drive a non-hydrostatic NWP model which downscales, through nesting, to horizontal resolutions of 2 kilometres and lower. New sub-grid scale turbulence schemes are implemented in the model. The resulting wind forecast data are compared with existing operational forecast data as well as data from weather stations around Ireland to quantify improvements in the predicted winds under different driving scenarios.