Altamont Wind (Summit) Blade Throw Analysis

Transcription

1 Summit Wind Blade Thrw 4-25.dcx PRINIPALS Thedre A Barten, PE Margaret B Briggs Michael E Guski, M Dale T Raczynski, PE indy Schlessinger Lester B Smith, Jr Rbert D O Neal, M, INE Andrew D Magee Michael D Hward, PWS Duglas J Kelleher AJ Jablnwski, PE Stephen H Slcmb, PE David E Hewett, LEED AP Dwight R Dunk, LPD David. Klinch, PWS, PMP Samuel G. Mygatt, LLB ASSOIATES Richard M. Lampeter, INE Maria B. Hartnett Geffrey Starsiak 3 Mill & Main Place, Suite 250 Maynard, MA April 25, 2017 Epsiln Ref Tdd R. Hpper Directr f Develpment SALKA LL 402 W. Bradway, Ste 400 San Dieg, A Via at thpper@salkaenergy.cm Subject: Dear Mr. Hpper: Altamnt Wind (Summit) Blade Thrw Analysis Epsiln Assciates, Inc. (Epsiln) has been retained by SALKA LL t cnduct a blade thrw analysis fr the Summit Wind Prject in Alameda, alifrnia. Epsiln has cnducted blade thrw analyses fr prjects in alifrnia, including Alameda, Slan, Kern, ntra sta, and Ls Angeles. The purpse f the analysis is t assess ptential blade thrw distances using cmmn assumptins and determine if, in the rare event a blade is disldged frm a turbine, it culd cllide with a sensitive receptr (e.g. residence), r passing vehicle, transmissin line, r adjacent parcel. Fr this analysis, a ttal f thirty tw (32) site lcatins were evaluated; nt all f these site lcatins will be used in the final design. Tw turbine mdels were analyzed, ne f which will be selected fr the final design. Epsiln used the fllwing characteristics in the blade thrw analysis: Turbine Mdel: Vestas GE Hub Height: 95 meters 90 meters Rtr Diameter: 110 meters 116 meters Blade Length: 54 meters 56.9 meters Maximum rtatinal speed: 14.9 rpm 15.7 rpm Blade center-f-gravity frm center: 16 meters 16 meters alculatins in the alifrnia Energy mmissin s Permitting Setback Requirements fr Wind Turbines in alifrnia, prepared by the alifrnia Wind Energy

2 Mr. Tdd Hpper 2 SALKA, LL April 25, 2017 llabrative, Nvember 2006, reprt number E , (the E reprt ) were used as a guide t calculate blade thrw. The calculatins fllw the simple ballistics mdel predictin in Sectin f that reprt, which has precedent in several permitted prjects. Epsiln is unaware f any ther state r lcal standards fr blade thrw analyses utside f this reprt. The key assumptins in the calculatins are stated belw, and are the same nes used in blade thrw analyses fr ther recently apprved wind prjects. The calculatins are fr the release f an entire blade at the maximum nminal rtr speed. They d nt address thrw f a blade fragment r rtr verspeed cnditins, bth f which are less likely 1, but either f which culd cause a blade thrw range lnger than shwn in the analysis. T prvide cntext, the likelihd f a blade fragment r verspeed failure is estimated at apprximately ne-third and ne ne-hundredth that f an entire blade failure, respectively 2. Aerdynamic frces, assumed t be much smaller than the rtr s weight, were nt included in the mdel and the blade was assumed t travel and land in its riginal plane f rtatin. A cnsideratin f aerdynamic frces r ut-f-plane prjectin wuld invlve mre cmplex cmputatinal fluid dynamics (FD) mdeling, requiring much mre detailed infrmatin than is currently available (i.e., blade gemetry, weight distributin, air flw, etc.) and intrduce a significant amunt f uncertainty. Additinally, blade thrw was assumed t ccur anywhere in a 360- degree directin arund each wind turbine (independent f wind directin). The E reprt ntes that the maximum range in a vacuum is achieved when the release angle is 45 (page 21). Hwever, this is nly true fr an bject that is released and lands at the same elevatin. In practice, turbines are placed n twers at elevated lcatins t increase the height f the rtrs, and this additinal height gives bjects 1 Rademakers & Braam, Guidelines n the envirnmental risk f wind turbines in the Netherlands, March 2004, Table 1 2 H. Braam and G.J. van Mulekm, Analysis f Risk-Invlved Incidents f Wind Turbines. Translated by J. M. Hpemans and.p. Van Dam and included as Attachment 1 in Permitting Setback Requirements fr Turbines in alifrnia Prepared fr the alifrnia Energy mmissin (E) by the alifrnia Wind Energy llabrative (WE), Nvember 2006, E , Table 6.1.

3 Mr. Tdd Hpper 3 SALKA, LL April 25, 2017 a further distance t fall. That further distance means that a flatter release angle will achieve the maximum range. Epsiln evaluated elevatin data fr the prject area, derived frm USGS Digital Elevatin Mdel (DEM). Fr each prpsed turbine lcatin, Epsiln determined the maximum elevatin drp within 800 feet frm the turbine base. That elevatin drp ranges frm 30 t 88 meters depending n the turbine lcatin. Fr each turbine lcatin, Epsiln cnducted the blade thrw calculatin cnservatively assuming the blade wuld fall t that lwest elevatin (irrespective f the directin thrwn). T accunt fr this variatin in terrain height surrunding the wind turbines, a variety f release angles were mdeled. Bth verhand and underhand release angles were calculated. Fr the Vestas turbines, calculating the maximum thrw distance fr release f entire blade at the maximum rtr speed, accunting fr the maximum elevatin drp at each lcatin, cnservatively neglecting air resistance, results in a maximum distance (depending n lcal terrain) between 141 and 163 meters, which is up t 1.1 times the Ttal Turbine Height (TTH). Fr the GE turbines, calculating the maximum thrw distance fr release f entire blade at the maximum rtr speed, accunting fr the maximum elevatin drp at each lcatin, cnservatively neglecting air resistance, results in a maximum distance (depending n lcal terrain) between 146 and 173 meters, which is up t 1.2 times the TTH. The attached Figures 1 and 2 shw the maximum calculated blade-thrw radii as shaded circles arund each wind turbine fr the Vestas (Figure 1) and the GE (Figure 2) turbines. Again, nt all f these turbine lcatins will be used. Based n a review f the aerial phtgraphy, the maximum blade thrugh distances will nt extend t the traveled radways in the vicinity f the Prject (Altamnt Pass Rad, Interstate 580, Vasc Rad, publicly-accessible sectins f Dyer Rad and Gecken Rad). Similarly, transmissin lines in the prject area are als beynd maximum blade thrw distances fr bth turbine mdels, based n available data. Finally, the maximum blade thrw distances predicted fr each turbine d nt extend t the 27 specific residential receptr lcatins prvided by yu. The true prbability f an impact depends n the number f blade thrw events ver the peratinal life f the prject, the effect f aerdynamic frces n the blade r blade fragment gverned by the principles f fluid mechanics and the laws f mtin,

4 Mr. Tdd Hpper 4 SALKA, LL April 25, 2017 the frequency distributin f wind speed and directin, rtr speed, the lcatin, number, size, and shape f each blade r fragment, and the number f receptrs likely t be lcated within the release area. The largest fragments wuld experience the highest aerdynamic drag frces and are mst likely t hit the grund nearest t the base f the turbine. As a result, the prbability f an impact with large fragments decreases significantly as ne mves away frm the turbine. T reduce the likelihd f blade thrw-related incidents, the Vestas and GE wind turbines, like mst mdern wind turbine technlgy, are designed t shut dwn autmatically under cut-ut wind speed cnditins higher than the rated wind speed at hub height. Bth turbine mdels als cme equipped with pitch cntrl t minimize system stress in all wind envirnments. If yu have any questins n this reprt, please cntact me at (978) , r by at ajablnwski@epsilnassciates.cm. Sincerely, EPSILON ASSOIATES, IN. A.J. Jablnwski, P.E. Principal

5 G:\Prjects2\A\4817\BladeThrw\blade_drp_Vestas.mxd LEGEND Wind Turbine Lcatin Alternate Wind Turbine Lcatin PG&E Transmissin Line Ptential Thrw Area 1,000 2,000 Feet R d 0 sc Scale 1:24,000 1 inch = 2,000 feet sta a r t n eda Alam Va Bundary WT5 WT2 WT1 ALT 1 WT6 WT7 WT3 WT8 WT4 WT9 WT31 WT10 WT33 WT27 WT11 ALT 32 WT32 WT12 WT13 ALT 13 WT14 WT15 WT16 WT19 ALT 17 Al WT17 WT18 ALT 18 t am Pa nt ss ALT 20 WT20 WT21 fs en G Dr e ck uf li n R d Bl L au g h WT22 Be ar re ek Dr Edge wate r Ln Livermre Summit Wind 580 Surce: Esri, DigitalGlbe, GeEye, Earthstar Gegraphics, NES/Airbus DS, USDA, USGS, AerGRID, IGN, and the GIS User mmunity Alameda, alifrnia Figure 1 Ptential Wind Turbine Blade Thrw Areas, Vestas V MW

6 G:\Prjects2\A\4817\BladeThrw\blade_drp_GE.mxd LEGEND Wind Turbine Lcatin Alternate Wind Turbine Lcatin PG&E Transmissin Line Ptential Thrw Area 1,000 2,000 Feet R d 0 sc Scale 1:24,000 1 inch = 2,000 feet sta a r t n eda Alam Va Bundary WT5 WT2 WT1 ALT 1 WT6 WT7 WT3 WT8 WT4 WT9 WT31 WT10 WT33 WT27 WT11 ALT 32 WT32 WT12 WT13 ALT 13 WT14 WT15 WT16 WT19 ALT 17 Al WT17 WT18 ALT 18 t am Pa nt ss ALT 20 WT20 WT21 fs en G Dr e ck uf li n R d Bl L au g h WT22 Be ar re ek Dr Edge wate r Ln Livermre Summit Wind 580 Surce: Esri, DigitalGlbe, GeEye, Earthstar Gegraphics, NES/Airbus DS, USDA, USGS, AerGRID, IGN, and the GIS User mmunity Alameda, alifrnia Figure 2 1 Ptential Wind Turbine Blade Thrw Areas, GE 2.5MW 116