1. Wind turbines in regions exposed to tropical cyclones Niels-Erik Clausen, Søren Ott and Per Nørgård, Risø National Laboratory Niels-Jacob Tarp Johansen, DONG Energy Anaflor Candelaria and Samuel Hernando, PNOC-EDC, Philippines Søren Gjerding, Tripod

2. EWEC 2007 7-10 May Milan, session BW4 Outline Tropical cyclones Tropical cyclones and wind turbines Extreme wind from tropical cyclones Impact on design and cost Conclusions Cat. 4 tropical cyclone IVAN 15 Sept 2004 at landfall near Luisiana, USA (NASA/GSFC)

3. EU-ASEAN Wind project Feasibility assessment and capacity building for wind energy development in the Philippines, Vietnam and Cambodia. Project period: Feb. 2005 – Dec. 2006 Risø National Laboratory (coordinator)Denmark Innovation Énergie DéveloppementFrance Mercapto ConsultDenmark PNOC Energy Development CorporationPhilippines Institute of EnergyVietnam Ministry of Industry, Mines and EnergyCambodia The project is financially supported from the EC-ASEAN Energy facility through the ASEAN Energy Centre in Jakarta. Contract 125-2004.

4. EWEC 2007 7-10 May Milan, session BW4 4 A tropical cyclone Initially a rotating collection of thunderstorms over a warm sea water surface. Tropical depression <17 m/s Tropical storm 17-32 m/s Tropical cyclone >32 m/s (hurricane, typhoon) Average 48 TC per year globally (20 - 35 years data)

5. EWEC 2007 7-10 May Milan, session BW4 5 Geographical distribution of tropical cyclones The Philippines NW Pacific average 17 TC per year

6. Sea water temperatures Sea water temperatures in May 2001. Source: MODIS Ocean Group, NASA/ GSFC and Miami University) T > 26.5  C

7. 7 Damaged wind farms Japan: Miyakojima wind farm after being hit by a typhoon Sept. 2003 (right) Gujarat, India 1998 (left and top)

8. EWEC 2007 7-10 May Milan, session BW4 8 NorthWind, Bangui Bay, Philippines This wind farm have survived two typhoons but with damage to cabling (flooding) Photo by NorthWind 57 km 69 kV transmission line to substation Power back-up for yaw system

9. EWEC 2007 7-10 May Milan, session BW4 9 ASEAN wind case study St. AnaDinagat Island

10. EWEC 2007 7-10 May Milan, session BW4 10 Sta. Ana, Philippines The mast is located 10 m asl Measurement heights 10 and 27 m

11. EWEC 2007 7-10 May Milan, session BW4 11 Tropical storm near Sta. Ana in 2005 NE SW

12. 12 Analysis of typhoon best track data Only parts of tracks with V max > 50 knots are shown 2004 1977-2005 2006 2005 Data Japan Meteol. Agency JMA

13. EWEC 2007 7-10 May Milan, session BW4 13 Estimation of U 50 1.Choose a grid of observation points (e.g. 1x1  ) 2.For each typhoon track find the smallest distance from the observation point to the track 3.Calculate the corresponding V max using a model for dist. versus V (Holland’s model). Neglect V max if below 50 knots 4.Find all the yearly maxima 5.Repeat for observation points in the grid covering the NW Pacific 6.Find U 50 from the 28 yearly maxima at each grid point assuming a Gumbel distribution

14. 14 Extreme wind atlas for Western N Pacific U 50 10 min average 10 m above sea based on JMA typhoon tracks 1977-2005

15. 15 Comparison with Philippine Structural Code 3 sec gust 10 m height land (3 cm) 10 min av 10 m height over sea

16. EWEC 2007 7-10 May Milan, session BW4 16 Cost impact from typhoon design Assumptions for simple cost model Grid connection costs are disregarded The foundation contributes about 1/6 of the total costs The rotor, the nacelle, and the tower contribute each about one 1/3 third of the remaining 5/6 The rotor-nacelle-assembly is basically design-driven by fatigue Approx. 1/2 of the tower and foundation costs are assumed driven by extreme loads The extreme load driven costs are assumed proportional to the load, which is proportional to the square of the mean wind speed V av and the load safety factor γ f

17. EWEC 2007 7-10 May Milan, session BW4 17 Estimated impact on wind turbine cost In the standard IEC 61400-1 the partial safety factor is 1.35, and for wind turbine class IA V ref = 50 m/s This is the reference For typhoon area we estimate the partial safety factor of 1.7 leading to cost increases of: 50-year wind 60 m/s: 20% 50 year wind 70 m/s: 30%

18. Met mast Wind farm Sta. Ana 30 MW wind farm U 50 was found to 67 m/s in 80 m height

19. EWEC 2007 7-10 May Milan, session BW4 19 Conclusions U 50 can be estimated from best track data Cost increase est. 20-30% for wind turbines Next steps Improved knowledge of site design data Ground measurements of TC pass Assess impact on design (cost model) Design guidelines and application examples

20. Thank you for your attention More info at www.aseanwind.eu or at the Risø stand F012 Wednesday 9 May 15:30