1. Offshore wind resource assessment Colin Morgan and Graham Gow Garrad Hassan and Partners www.garradhassan.com/offshore

2. Scenario 1 Physical Modelling Immediate Cheap Least accurate Highly sensitive to station Accuracy very difficult to determine + Published estimates

3. Scenario 2 Physical and Statistical Modelling Rapid Increased cost Platform accuracy? Model accuracy in coastal zone? More time consuming + Published estimates

4. Scenario 3 Statistical Modelling Most accurate Mast may be used for later purposes? Costly Time consuming

5. Overall scheme Site free wind speed (ref. height) Hub height Ideal energy output Topo losses Wake losses Electrical losses Net Energy Output Other losses

6. Other Losses 1 - Unscheduled turbine downtime 2 - Waiting on weather time 3 - Scheduled WTG downtime 4 - Electrical system downtime 5 - Grid downtime 6 - Grid curtailment 7 - Environmental and Owner’s downtime 8 - Icing and blade degradation 9 - Columnar shutdown

7. Uncertainty in energy prediction 10-yr average (gross of availability)

8. Forecasting - Project Overview Co-funded by UK Government Scottish Power Utility Wind farm operator The Met Office Meteorological services Garrad Hassan Method development Project management

9. Project Aims Stimulate UK forecasting activity Validation under UK conditions Addressed to individual wind farms Market trading Geographically transferable

10. Method NWP to site-specific Statistical modelling Adaptive Multi-inputs wind speed direction temperature time of day etc. Site-specific models Site-specific forecasts Power models Power forecasts “ National ” Forecasts

11. Results - 12 hr wind speed forecast

12. Results - wind speed Improvement in error standard deviation over persistence

13. Results - 12hr power forecast

14. Results - power Improvement in error standard deviation over persistence

15. Implications for offshore projects Flexible adaptable tool of proven accuracy Increasing importance for large wind farms Operators (O&M scheduling) Owners Grid companies Scope for tuning “Learning” time Improved NWP modelling of offshore effects Refined downtime modelling and forecasting Portfolio effects

16. Construction Plant Market Survey and Database www.garradhassan.com/offshore/database