Energy yield for co-located offshore wind and tidal stream turbines

Deployment of co-located wind and tidal stream turbines is proposed as a method for reducing cost of electricity generation from either technology individually. Energy yield for wind turbines is modelled using a standard eddy viscosity wake model in OpenWind and for tidal turbines using a method of self-similar superposition of wake deficits. A case study of the MeyGen site in the Pent-land Firth is considered for co-location. Wind resource data for 01 January 2012-01 May 2015 is from the Met Office 1.5 km UKV model and corrected to 8 weeks of WRF data at 400 m resolution using a measure-correlate-predict method. 7 km current data from FOAM for the coincident period is corrected to 8 months of 150 m ADCIRC model data using linear regression. Yaw strategy is considered for the tidal turbines, finding that although a continuous yaw strategy generates highest yield, a strategy of changing yaw during slack-tide only offers a suitable compromise with mechanical complexity and 10% loss in energy yield. 7 months of wave buoy data is also used directly for studying sensitivity of an H-s shutdown criterion towards energy yield, with a 5% reduction when H-s shutdown is set at 2.5 m compared with 3.5 m. Co-location of 12 MW wind capacity to a 20 MW tidal array results in a 75% increase in annual energy yield, compared to operating the tidal turbines alone.