Permitting Setbacks for Wind Turbines and the Blade Throw Hazard - - PowerPoint PPT Presentation

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permitting setbacks for wind turbines and the blade throw
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Permitting Setbacks for Wind Turbines and the Blade Throw Hazard - - PowerPoint PPT Presentation

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Permitting Setbacks for Wind Turbines and the Blade Throw Hazard Scott Larwood California Wind Energy Collaborative UC Davis Doctoral Student California Wind Energy Collaborative California Wind Energy Collaborative 2004 Forum Palm

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SLIDE 1

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Permitting Setbacks for Wind Turbines and the Blade Throw Hazard

Scott Larwood California Wind Energy Collaborative UC Davis Doctoral Student

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SLIDE 2

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Organization

  • Purpose of Investigation
  • Setbacks for California Counties
  • Blade Failure Probabilities
  • Blade Throw Analyses
  • Conclusions
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SLIDE 3

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Purpose

  • Part of “Wind Plant Optimization” task for

California Wind Energy Collaborative

  • Study and Report on permitting issues

with regards to the blade throw hazard

– Seemed to be based on maximum range and a function of turbine size – Setbacks vary county to county – Setbacks can limit revenue with modern turbine heights

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California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Turbine Geometry

Rotor Diameter Hub Height Total Height

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SLIDE 5

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Example Parcel

  • One kilometer square parcel
  • Setbacks are three times overall height
  • Spacing requirements for turbine wakes

– Three-diameters crosswind – Ten-diameters downwind

  • Layouts for two turbine types

– Vestas V-47, 660 kW, 47-m Ø, 50-m HH – GE 1.5s, 1.5 MW, 70.5-m Ø, 65-m HH

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California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Vestas V-47 Layout

Setback 3X overall height 3D in-row spacing 10D row spacing Setback 3X overall height 1 km sq. meter parcel 10- V47 turbines 50 meter Towers Total Rating 6.6 MW Prevailing Wind

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California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

GE 1.5s Layout

Setback 3X overall height 2.9D in-row spacing Setback 3X overall height 1 km sq. meter parcel 3- GE1.5s turbines 65 meter towers Total Rating 4.5 MW Prevailing Wind

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California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Setbacks for California Counties

Property Line Dwelling Roads Reductions in Setbacks Alameda County 3x/300 ft (91 m), more on slope 3x/500 ft (152 m), more on slope 3x/500 ft (152 m), 6x/500 ft from I-580, more on sloped terrain maximum 50% reduction from building site or dwelling unit but minimum 1.25x, road setback to no less than 300 ft (91 m) Contra Costa County 3x/500 ft (152 m) 1000 ft (305 m) None exceptions not spelled in

  • rdinance can

be filed with county Kern County 4x/500 ft (152 m) <40 acres or not wind energy zone, 1.5x >40 acres 4x/1000 ft (305 m) off-site 1.5x With agreement from adjacent

  • wners to no

less than 1.5x Riverside County 1.1x to adjacent Wind Energy Zones 3x/500 ft (152 m) to lot line with dwelling 1.25x for lightly traveled, 1.5x/500 ft (152 m) for highly traveled. None Solano County 3x/1000 ft (304 m) adjacent to residential zoning, 3x from

  • ther zonings

3x/1000 ft (304 m) 3x Setback waived with agreement from owners of adjacent parcels with wind turbines

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SLIDE 9

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Blade Failure Probabilities

  • Types and Causes
  • References in the Literature
  • Alameda County Data
  • WindStats Data
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SLIDE 10

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Types and Causes

  • Types

– Root connection failure – Partial failure from lightning – Failure at outboard aerodynamic device – Tower strike – Partial failure due to defect – Extreme load buckling

  • Causes

– Unforeseen events out of design envelope – Failure of control system – Human error – Incorrect design for fatigue/ultimate loads – Poor manufacturing quality – Usually a combination of above

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SLIDE 11

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

References in the Literature

  • Putnam 1948

– 1.25 MW turbine, 750 ft (230 m) throw

  • SERI 1979

– Analysis at 1.2 × 10-2 per year

  • Eggwertz 1981 Sweden

– Estimate of 10-5 per year

  • De Vries 1989 Netherlands

– Netherlands 2 × 10-2 per year – Denmark 3 to 5 × 10-3 per year – US 3 × 10-3 per year

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SLIDE 12

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Alameda and WindStats Data

  • Operators in Alameda County notify Building

Official of Blade Throw

– Jan 2000 to Fall 2003, Kenetech 56-100s – 5.4 × 10-3 blade failures/turbine/year

  • WindStats Quarterly Publication

– Denmark 1993-2004; 3.4 × 10-3 failures/turbine/year – Germany 1996-2004; 1.5 × 10-2 failures/turbine/year Unclear if failure resulted in blade throw – No apparent time trends

  • Recommend using 10-2 per year as baseline

probability

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California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Blade Throw Analyses

  • Simplified Model
  • Literature
  • Recommendations
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California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Simplified Model

Ω Center

  • f

Gravity rcg θ V0 Impact X1 x y Gravity

  • Turbine Tip Speed

– –

  • Projectile Release

Velocity

– –

  • Projectile Range in

Vacuum

– –

  • Projectile Maximum

Range in Vacuum

– –

cg

r V Ω =

θ 2 sin

2 1

g V X =

g V X

2 max =

R Vtip Ω =

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California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Literature

  • Eggwertz 1981 Sweden

– Random Probability of blade failure position

  • MacQueen 1983 UK

– Upper limit of tip speed 310 m/s – Comparison to lightning strikes in UK 10-7 per year

  • Sørensen 1984 Denmark

– Comprehensive aerodynamic analysis shows limitations of other models – Study of three turbines of increasing size

  • Eggers 2001

– Closed form solutions for impact probabilities

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SLIDE 16

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Sørensen 1.5-2.0 MW Turbine Blade Throw Probabilities

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 100% 150% 200% 250% 300% Nominal Tip Speed Turbine Heights Blade Hazard Range Fragment Hazard Range Blade Max Range Fragment Max Range

Blade Fragment Hazard is 10^-4 Probability

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SLIDE 17

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Comparison of Analyses

Maximum Range of Full and Partial Blade Throw for Nominal Operating Condition 0.0 1.0 2.0 3.0 4.0 5.0 6.0 50 100 150

Overall Height (m) Range normalized by Overall Height

Full Blade Blade Fragment

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SLIDE 18

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Recommendations

  • Develop consistent analysis method to provide

guidance on setbacks

  • Failure 10-2; Overall hazard- 10-6 (one in a

million)

  • Study variety of current turbines
  • Use Sørensen’s model and Eggwertz probability

and impact method

  • Determine probability and range for failure tip

speeds

  • Validate with actual failure data and/or field test
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SLIDE 19

California Wind Energy Collaborative California Wind Energy Collaborative •

  • 2004 Forum Palm Springs

2004 Forum Palm Springs

Conclusions

  • Setbacks were based on collaboration with

industry but not applied consistently

  • Current regulations can “squeeze out”

modern turbines

  • Blade failure rate is surprisingly high and

not showing improvement

  • Blade throw has been studied extensively

but no setback guidance

  • Proposed approach to develop set back

guidance