sed duxbury wind feasibility report

8/3/2019 SED Duxbury wind feasibility report

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TECHNICAL ANALYSIS FOR ON-SITE WIND GENERATION- DRAFT REPORT

Town of Duxbury, Massachusetts

October 20, 2011

Sponsored by:


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iDraft Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

Notice

This report was prepared by Sustainable Energy Developments, Inc. in the course of performing work

sponsored by the Massachusetts Clean Energy Center (MassCEC) Commonwealth Wind Incentive

Program: Community Scale Wind, pursuant to task order 10-1 executed November 19, 2010. The

opinions expressed in this report do not necessarily reflect those of the MassCEC or the Commonwealth

of Massachusetts, and reference to any specific product, service, process, or method does not constitute

an implied or expressed recommendation or endorsement of it.

Further, the MassCEC, the Commonwealth of Massachusetts, and the contractor make no warranties or

representations, expressed or implied, as to the fitness for particular purpose or merchantability of any

product, apparatus, or service, or the usefulness, completeness, or accuracy of any processes, methods

or other information will not infringe privately owned rights and will assume no liability for any loss, injury,

or damage directly or indirectly resulting from, or occurring in connection with, the use of information

contained, described, disclosed, or referred to in this report.

Acknowledgements

Rich Gross P.E. Inc. contributed to the development of an electrical interconnection plan for a wind

turbine at this site.

AWS Truepower, LLCprovided wind resource data that was used to calculate wind turbine output

estimates.

Disclaimer

This report is presented in response to the contract between the Town of Duxbury and Sustainable

Energy Developments, Inc. executed on 19 November 2010. The information and analyses presented

herein is based on wind development best practices, commercially available information and a preliminary

analysis of the Town of Duxbury electrical infrastructure. SED makes no guarantees, expressed or

implied as to the actual outcome of the processes described in this report.


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iiDraft Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

ABSTRACT

nalysis for On-Site

Wind Generation for the Town of Duxbury that occurred between November of 2010 and December of

2011. The study assessed and quantified the ability to install a wind turbine on Town-owned land

that would utilize virtual net metering to offset municipal accounts. Key aspects of wind project

development were examined including: site considerations; wind resource assessment and turbine output

modeling; wind generated electricity value; electrical system impact assessment; buildability; permitting;

development budgeting; total capital cost; operations & maintenance; timeline; an economic analysis; and

financing and ownership options.

The goal of this feasibility study was to identify and explore a wind energy project that would be

economically beneficial for the Town of Duxbury to pursue. The Town of Duxbury Wind Bylaw restricts

the allowable height of a wind turbine to 250 feet, which presents an obstacle to economically beneficialoutcome for the Town. There are currently no wind technologies under this height that would be an

economical option for the Town to purse. Therefore, SED explored two different wind turbine technology

options that would provide the best economic opportunity for the Town of Duxbury. One would involve a

Northwind 450kW, a wind turbine currently under development, but that would be much more economical

than other similarly sized technologies on the market. The other technology evaluated was a PowerWind

900kW, which would slightly exceed the height limit, but would provide a proven and readily available

wind turbine that would generate significant electricity savings for the Town of Duxbury. Proceeding with

a project utilizing either of these technologies would be the best pathway to forward to a successful wind

development.


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iiiDraft Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

KEYWORDS

On-site Wind Power

Wind Turbine

Wind Power

Wind Modeling

WindPro

WAsP

Town of Duxbury

Sustainable Energy Developments, Inc.

Northern Power Systems

Northern Power 450kW

PowerWindPowerWind 56 900kW

Virtual Net Metering


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ivDraft Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

ACRONYMS AND ABBREVIATIONS

agl -above ground level

amsl -above mean sea level

AEP -annual energy production

AEO -annual energy output

DEP -Department of Environmental Protection

ENF -Environmental Notification Form

EPA -Environmental Protection Agency

FAA -Federal Aviation Administration

FCC -Federal Communications Commission

ft -feet

kW -kilowatt

kV -kilovolt

kVA -kilovolt-amp

MEPA -Massachusetts Environmental Policy Act

Mass Highway -Massachusetts Highway Department

MassCEC -Massachusetts Clean Energy Center

MWh -Megawatt hours

m -meters

m/s -meters per second

MW -Megawatt

NPDES -National Pollutant Discharge Elimination System

NHESP -Natural Heritage and Endangered Species Program

NHGC -North Hills Golf Course

NOI -Notice of Intent

O & M -operations and maintenance

SED -Sustainable Energy Developments, Inc

USFWS -United States Fish and Wildlife Service

W/m2

-Watts per square meter

WAsP -Wind Atlas and Analysis Application Program


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vDraft Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

TABLE OF CONTENTS

Section Page

S EXECUTIVE SUMMARY S-1

1 WIND TURBINE SITING AND ENERGY YIELD ANALYSIS 1-1

1.1 BACKGROUND 1-1

1.2 NORTH HILL SITE DESCRIPTION 1-1

1.3 PROPERTIES ASSESSMENT 1-2

1.4 WIND RESOURCE POTENTIAL 1-4

1.5 SITING CONSIDERATIONS 1-6

1.6 SELECTED SITE EVALUATIONS 1-10

1.7 FINAL SCENARIO RECOMMENDATIONS 1-16

2 WIND RESOURCE ASSESSMENT AND TURBINE OUTPUT MODELING 2-1

2.1 WIND TURBINE SELECTION AND OUTPUT CALCULATION 2-12.2 VIRTUAL MET MAST INFORMATION 2-2

2.3 TERRAIN AND ROUGHNESS MAPS 2-3

2.4 WIND TURBINE POWER CURVES 2-3

2.5 SUMMARY OF MODEL RESULTS 2-5

2.6 FINAL TURBINE OUTPUT CALCULATIONS 2-6

3 INTERCONNECTION INVESTIGATION 3-1

3.1 RECOMMENDED INTERCONNECTION PLAN 3-1

3.2 NEXT STEPS 3-2

4 WIND GENERATED ELECTRICITY VALUE 4-1

4.1 TOWN OF DUXBURY ELECTRICITY DATA 4-1

4.2 GREEN COMMUNITIES ACT AND NET METERING 4-2

4.3 CALCULATING NET METERED CREDITS 4-3

4.4 IMPLICATIONS OF NET METERING 4-5

4.5 ELECTRICITY RATE ESCALATION 4-6

5 BUILDABILITY 5-1

5.1 TRANSPORTATION 5-1

5.2 SITE ACCESS AND STAGING 5-1

5.3 FOUNDATIONS AND GEOTECHNICAL CONSIDERATIONS 5-3


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6 PERMITTING AND REGULATORY ANALYSIS 6-1

6.1 FEDERAL REGULATIONS 6-1

6.2 STATE REGULATIONS 6-9

6.3 LOCAL REGULATIONS 6-17

6.4 RECOMMENDATIONS 6-19

7 PERMITTING TOOLBOX 7-1

7.1 SOUND PROPAGATION REPORT 7-1

7.2 SHADOW FLICKER ASSESSMENT 7-3

7.3 SUMMARY OF FINDINGS 7-7

8 CAPITAL COSTS 8-1

8.1 ESTIMATED CAPITAL COSTS 8-1

8.2 OPERATION AND MAINTENANCE 8-58.3 PROJECT TIMELINE 8-6

9 ECONOMIC ANALYSIS 9-1

9.1 BASELINE ECONOMIC ANALYSIS 9-1

9.2 SENSITIVITY ANALYSIS 9-2

10 FINANCING, OWNERSHIP AND OPERATIONS

10.1 MUNICIPAL BOND 10-1

10.2 LEASE MODEL 10-310.3 THIRD PARTY OWNERSHIP 10-4

10.4 CONCLUSION 10-9


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viiDraft Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

FIGURES

FIGURE PAGE

Figure 1-1 North Hill Area with Property Lines 1-2

Figure 1-2 Property Designations with Legend 1-3

Figure 1-3 Municipal Open-Space Properties with Outline 1-4

Figure 1-4 Wind Resource Grid and Eligible Municipal Properties 1-5

Figure 1-5 Wind Resource Grid with Areas Identified 1-6

Figure 1-6 Wind Turbine Technologies 1-10

Figure 1-7 Site 1 NHGC with Setbacks 1-11

Figure 1-8 Site 2 Kettle Hole with Setbacks 1-13

Figure 1-10 Site 3 DPW West with Setbacks 1-15

Figure 1-7 Recommended Wind Turbine Locations 1-17

Figure 2-1 VMM Information 2-2

Figure 2-2 70m VMM Wind Roses and Weibull Distribution 2-3Figure 2-3 PowerWind 56 900kW Manufacturer Supplied Power Curve 2-4

Figure 2-4 Northern Power 450kW Manufacturer Supplied Power Curve 2-5

Figure 2-5 Summary of Model Result 2-5

Figure 2-6 Assumed Losses 2-6

Figure 2-7 Final Output Calculations 2-7

Figure 4-1 12-Month Electric Usage Data (kWh) 4-2

Figure 4-2 Ten Largest Electric Accounts in Town of Duxbury 4-2

Figure 4-3 NSTAR 33-General Annual (G-1) Delivery Service Charges 4-4

Figure 4-4 Utility Derived Electricity Value Year 1 4-5Figure 4-5 Projected Electricity Rates ($ per kWh) 4-6

Figure 6-1 Airports in Proximity of Proposed Development 6-2

Figure 6-2 Airports within a Ten-mile Vicinity 6-2

Figure 6-3 FCC Communication Paths Geosearch Results 6-4

Figure 6-4 Point to Point Communications 6-5

Figure 6-5 Local Communications 6-6

Figure 6-6 DOD long Range Radar Tool 6-7

Figure 6-7 Federal Regulations 6-8

Figure 6-8 Priority Habitats in Proximity of the Proposed Locations 6-10

Figure 6-9 Estimated Habitats in Proximity of the Proposed Locations 6-11

Figure 6-10 Protected or Listed Species for the Town of Duxbury 6-12

Figure 6-11 National Wetlands Inventory 6-13

Figure 6-12 Nationally Registered Historic Sites within Five Miles 6-14

Figure 6-13 Nationally Registered Historic Site Details within Five Miles 6-15


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Figure 6-14 State Regulations and Policies 6-16

Figure 6-15 Publicly Owned Land Overlay (POLO) District 6-17

Figure 6-16 Comparison of Turbine Variance Needs 6-18

Figure 6-17 Town Permits and Approvals 6-19

Figure 7-1 Sound Levels at 8 m/s for One (1) PowerWind 56 900kW

Wind Turbine at Site 1 7-2





Figure 7-4 PowerWind 56 Shadow Flicker Map Site 1 7-5



Figure 8-1 Estimated Total Project Costs 8-1Figure 8-2 Estimated Design Costs 8-2

Figure 8-3 Estimated Construction Capital Costs for PowerWind 900kW 8-3

Figure 8-4 Estimated Construction Capital Costs for PowerWind 900kW 8-4

Figure 8-5 O&M Costs Comparison 8-6

Figure 8-5 Project Timeline for Wind Turbine Development 8-7

Figure 9-1 Unleveraged IRR, Payback and Savings at a 3% Energy Escalation 9-2

Figure 9-2 Scenario 1 900kW Sensitivity Analysis with Variable Energy Escalation Rates 9-2

Figure 9-3 Scenario 2 450kW Sensitivity Analysis with Variable Energy Escalation Rates 9-3

Figure 9-4 Scenario 1 900kW Sensitivity Analysis with Variable Annual Energy Production 9-3Figure 9-5 Scenario 2 450kW Sensitivity Analysis with Variable Annual Energy Production 9-3

Figure 9-6 Scenario 1 900kW Sensitivity Analysis with Capital Costs 9-4

Figure 9-7 Scenario 2 450kW Sensitivity Analysis with Capital Costs 9-5

Figure 10-1 IRR, Year 1 and Year 20 Savings for Scenario 1 with Municipal Bond 10-2

Figure 10-2 Cash Flow of Bond Financed Wind Turbine Project at 3% Escalation 10-2

Figure 10-3 Town of Duxbury Economic Benefits for Lease Model Scenario 1 10-3

Figure 10-4 Cash Flow of Lease Model Scenario 1 10-4

Figure 10-5 20-Year Economic Benefit at Varying Retail Electricity Escalation Rates for $0.125/kWh

PPA at 3% Escalation with ITC 10-5

Figure 10-6 Energy Savings with $0.125/kWh PPA Escalating at 3% with ITC 10-6


PPA at 0% Escalation with ITC 10-6

Figure 10-8 Energy Savings with $0.155kWh PPA Escalating at 0% with ITC 10-7


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PPA at 3% Escalation without ITC 10-7

Figure 10-10 Energy Savings with $0.195 PPA Escalation at 3% without ITC 10-8


PPA at 0% Escalation without ITC 10-8

Figure 10-12 Energy Savings with $0.245/kWh PPA Escalating at 0% without ITC 10-9

APPENDICES

Appendix A WindPRO Model Runs

Appendix B Electrical One-line Diagram E-2

Appendix C Utility Rate Description

Appendix D Preliminary Development Plan D-1

Appendix E FAA Determination

Appendix F Town of Duxbury Community Wind Facilities Bylaw

Appendix G Shadow Flicker Analysis

Appendix H Output Pages from Cash Flow Models


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S-1Draft Report

Technical Analysis for On-Site Wind Generation for the Town of Duxbury

EXECUTIVE SUMMARY

After completing a thorough technical feasibility study, Sustainable Energy Developments, Inc. (SED) has

determined that the installation of an economically viable wind power installation in the Town of Duxbury

is dependent upon: access to appropriately sized wind turbine technology and/or building community

support necessary to secure a height variance from the 250 foot height restriction established by the

no currently available wind turbine which would generate significant economic returns for the Town. This

issue may be overcome by the introduction of new wind turbine technologies, currently being tested for

rbine project.

SED therefore identified two wind turbine technologies that would provide favorable economic returns for

use in this technical assessment. Neither of these technologies is an ideal or immediate fit for the project.

The Northwind 450kW is currently undergoing testing at the National Renewable Energy Laboratory inGolden, CO and is not expected to be commercially available until the summer of 2012 at the earliest.

The PowerWind 900kW is problematic because the shortest tower option would excees

height limit by 26 feet. These technology issues can be navigated efficiently through a transparent

development process A wind energy

installation in the Town of Duxbury possesses the technical characteristics necessary for a feasible,

is to pursue a larger project that would require a variance, because such a project will provide significantly

greater financial benefits for the Town without imposing significant impacts to the environment or

neighboring land uses. SED further recommends that this project proceed into the business planningphase in preparation for a public vote on whether to proceed with obtaining a design and construction

grant from the MassCEC.

Site Considerations: Only property owned by the Town of Duxbury located in the area of North Hill, not

designated as conservation land was contemplated for potential wind turbine locations. There were

numerous development factors considered to identify appropriate locations for a wind turbine installation

in the North Hill area. SED first identified properties owned by the Town of Duxbury within an area of

roughly 1000 acres between the North Hill Golf Course, North Hill Marsh Wildlife Sanctuary, the Town

Hall and DPW Yard and Mayflower Cemetery. Once these properties were identified, SED overlaid a

wind resource grid to determine those areas with the highest wind speeds that would best support an

installation and three specific areas were selected: North Hill Golf Course, Kettle Hole and DPW West.


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S-2Draft Report


SED then applied additional criteria to determine most appropriate location to install a wind turbine within

each identified area. These included: setbacks from residences; setbacks from sensitive habitats;

Duxbury Community Scale Wind Facilities Bylawsetbacks; interconnection; accessibility; and wind

turbine technology.

The Town of Duxbury Wind FacilitiesBylaw establishes a minimum setback distance equal to 1.1 times

the overall height of the wind turbine from the nearest property line and private or public way; and a

minimum setback distance equal to 2 times the overall height of the wind facility from the nearest existing

residential or commercial structure not owned by the applicant. SED also applied wind industry standard

setbacks based on the scale of wind turbine being considered.

The Bylaw also restricts height of a wind turbine to 250 feet (76m) from the base of the wind turbine to the

tip of the rotor blade at its highest point. This height restriction greatly limits the available wind turbine

technologies that could be considered for this project that would provide a worthwhile economic benefits

to the Town. Therefore, SED identified two wind turbine technologies to be considered for installation in

the Town of Duxbury, a Northwind 450kW and a PowerWind 900kW. The Northwind 450kW wind turbine

is currently under development and will not be commercially available until late 2012, but on a 50-meter

(76 feet) tower would not exceed the 250 foot height limited established by the Bylaw and due to its

advanced design would be more cost effective than other similarly sized technologies. The other wind

turbine considered, was a PowerWind 900kW on a 59-meter (194 feet) tower, which is a proven and


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S-3Draft Report


readily available technology. This wind turbine would slightly exceed the 250 foot height limit, but the

stronger economic returns it would provide may be enough to justify a variance for the additional height.

Wind Turbine &

Rated Capacity

Tower

Height

Rotor

Diameter

Total Tip

Height

Bylaw

Setback from

Residential

Buildings

Recommended

Setback from

Residential

Buildings

Northern Power

450kW50m (164ft) 48m (157ft) 74m (243 ft) 150m (492ft) 244m (800ft)

PowerWind

900kW59m (194ft) 56m (184ft) 87m (276 ft) 175m (574ft) 305m (1000ft)

After evaluating the positive and negative aspects of the potential locations, three final sites wereidentified as the most developable locations for a wind turbine installation. All of the proposed sites meet

Bylaw and industry standard setback requirements.


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S-4Draft Report


From these locations, SED developed six potential development scenarios utilizing the two different wind

turbine technologies detailed to determine the logistical and economic viability of a development at the

Town of Duxbury.

Scenario Site Wind Turbine

1 North Hill Golf Course PowerWind 56 900kW

2 North Hill Golf Course Northwind 450kW

3 Kettle Hole PowerWind 56 900kW

4 Kettle Hole Northwind 450kW

5 DPW West PowerWind 56 900kW

6 DPW West Northwind 450kW

Wind Resource Assessment and Wind Turbine Output Modeling: The two different sized wind turbine

technologies were analyzed by creating a computer model with the industry standard modeling tool Wind

Atlas and Application Program (WAsP), created by the Danish National Laboratory, along with WindPRO,

created by EMD International A/S. A key input to the model was a representative year of wind data

derived from a Virtual Met Mast. Other key inputs to the model include wind turbine power curves for the

selected technologies, a roughness map, and a digital elevation model of the region. The following chart

is a summary comparison of the four scenarios analyzed.

Scenario Wind Turbine Gross MWh

Net MWh (AEP

minus 7.5% in

losses)

Mean Wind Speed

at Hub Height (m/s)

1 PowerWind 56 900kW 1,830.4 1,693 5.82 m/s (13.0 mph)

2 Northwind 450kW 1,167.5 1,080 5.48 m/s (12.3 mph)


4 Northwind 450kW 1,234.4 1,1425.61 m/s (12.6 mph)


6 Northwind 450kW 1,243.0 1,150 5.64 m/s (12.6 mph)


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Interconnection Investigation: SED commissioned an electrical interconnection plan for the project. It

was determined that the recommended interconnection for any of the three facilities would be into existing

three phase 23kV over-head distribution circuits located at the North Hill Golf Course (Sites 1 and 2) or

Town of Duxbury DPW Yard (Site 3). The 690V output of the wind turbine will be stepped up by a three

phase transformer at the base of the wind turbine. From there, the wire will run underground to the

overhead circuit at the Golf Course or DPW Yard. The wire runs for each site will be: 640m (2100ft) for

Site 1, 832m (2700ft) for site 2 and 518m (1700ft) for Site 3 respectively.

Utility Derived Electricity Value: SED evaluated 12+ months of electric bills and other supporting

i in order to determine the value of wind

generated electricity. The Town of Duxbury currently uses over 5.2 million kWh per year, most of which is

attributed to the Duxbury Public Schools. The Town of Duxbury is served by NStar and currently has a

supply contract with GEXA for $0.104/kWh. The average electricity rate that the Town of Duxbury

currently pays is valued at $0.18/kWh.

Based on the interconnection investigation, any of the proposed wind turbines, would not be

interconnected behind an existing meter and therefore virtual net metering will be employed. Based on

proceedings in the Mass DPU regarding the implementation of the Green Communities Act, the rate at

which the electricity produced by a wind turbine at North Hill -

1 Rate) calculated to be $0.16/kWh. This will be applied to every kWh generated by a wind turbine at

North Hill and the savings will then be allocated onto the

The scenarios presented will produce between 20% and 40% of the total electricity usage within the Townof Duxbury and net metering eligibility will provide that 100% of the wind generated electricity will be

valued at the G-1 Rate.

Buildability: The transport of equipment, site access, staging needs and foundation considerations were

explored for both the PowerWind 900kW and Northwind 450kW wind turbines. Site 1 will require an

access road to be built from the golf course parking lot that follows the edge of the driving range to the

proposed turbine site. Limited clearing will be necessary at the wind turbine site, with the potential

utilization of a small area of the golf course. Site 2 and 3 will require significant site work that includes

grading of the existing slope to provide a flat area for the installation of the foundation and clearing of

trees at the project site and for a permanent access road.

Based on the subsurface conditions typical to coastal regions of Massachusetts consisting of sand and

gravel deposits a spread footing type foundation is anticipated for use at each site.


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Permitting: SED analyzed local, state and federal permitting considerations for the installation of a wind

turbine in the Town of Duxbury at three identified sites. SED mapped out a permitting pathway for the

wind project to satisfy required permits and approvals. If the PowerWind 900kW wind turbine is pursued

a variance would be required to exceed the 25 . There do not

appear to be any other major permitting obstacles to development, although some additional

environmental studies will be necessary and public outreach through project specific public forums

combined with general wind education will be vital to project success.

Permitting Toolbox: SED performed initial assessments of the sound, shadow and visual implications of

a wind turbine installation at the sites considered. These studies suggest that any of three sites will have

limited or no discernible effect to neighboring residences. Site 1 will present some shadow and sound

effects to the North Hill Golf Course, but this will not affect the safety nor does SED feel it will adversely

affect recreation or ongoing operations at the golf course.

Development Budget Timeline and Total Capital Cost: Detailed design and construction budgets were

created for the different development scenarios. The following chart shows the design and construction

budgets for each scenario.

Town of Duxbury Scenario 1900kW

Scenario 2450kW

Scenario 3900kW

Scenario 4450kW

Scenario 5900kW

Scenario 6450kW

Total Design $249,830 $203,800 $268,390 $222,360 $263,390 $217,360

Wind Turbine Cost $1,664,000 $997,000 $1,664,000 $997,000 $1,664,000 $997,000

Total Construction $1,106,500 $882,000 $1,372,500 $1,140,000 $1,211,500 $1,001,000

Total Project Cost $3,020,330 $2,082,800 $3,304,890 $2,359,360 $3,138,890 $2,215,360

SED has presumed that the design phase could begin as early July of 2012. Depending on how this

proceeds, construction could begin by the spring of 2013 and be completed later that summer.

Economic Analysis: The wind turbine output predictions, current wind generated electricity value and

total capital costs were compiled to produce unlevered pro-formas. The following chart is a comparison

of the economic returns for the six development scenarios in a baseline economic scenario of 3.0%

energy escalation rate, including MassCEC Design and Construction funding.


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Scenario Wind Turbine SitePayback(years)

IRR 20 Year Savings

1 PowerWind 900kW 1 9.12 9.58% $3,776,304

2 Northwind 450kW 1 9.73 8.59% $2,194,047

3 PowerWind 900kW 2 9.65 8.74% $3,734,911

4 Northwind 450kW 2 10.51 7.56% $2,171,931

5 PowerWind 900kW 3 9.17 9.51% $3,905,279

6 Northwind 450kW 3 9.73 8.58% $2,348,763

Each of the scenarios examined appears to have favorable economics in this baseline scenario.

Scenarios 1 and 2 at Site 1 demonstrate the strongest economics and additional sensitivity were applied

to each.

Financing, Ownership and Operations: SED analyzed three different financing and ownership

scenarios utilizing the PowerWind 900kW to demonstrate how each would benefit the Town of Duxbury in

relation to a varying dispersal of risk. The most financially beneficial option to the Town of Duxbury would

be to self finance the project through issuing a municipal bond. This scenario could generate significant

energy savings, but the Town would take on the risk of developing and owning the project.

Alternately, the opportunity for third party ownership structure for this scenario could generate long-term

savings for the Town of Duxbury and provide very little upfront risk. A lease structure could be the most

practical solution, as risk would be shared between the Town and a third party. In this model, the ThirdParty would develop and own the project, while the Town makes an annual lease payment, as well as

maintenance costs in exchange for all of the electricity generated by the wind turbine. These lease and

maintenance payments would be less than the value of energy savings and could save the Town over

$2

Conclusion & Recommendation: This project has many of the aspects necessary for the successful

development of an on-site wind project. Based on the results of this study SED recommends that the

Town proceed into the business planning phase to prepare for a decision on whether to proceed with

design and construction in the spring 2012 Town Meeting. SED recommends that the stronger economicbenefit of installing a PowerWind 900kW justifies obtaining a variance of 26 feet on the Wind Bylaw and

would be the best path for the Town of Duxbury to pursue.


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1-1Draft Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

WIND TURBINE SITING AND ENERGY YIELD

SECTION 1

Appropriate and effective siting of a wind turbine is the most critical aspect of wind energy development.

This siting assessment is a culmination of the results of numerous investigations performed and

presented throughout this study in order to determine the optimal location and configuration for a wind

energy development to be owned by the Town of Duxbury. A technical siting assessment must critically

examine how a wind turbine will interact with a surrounding community and investigate all reasonable

actions that may be taken to minimize potential negative effects while maximizing economic and

environmental benefits for the Community.

1.1 BACKGROUND

A preliminary site assessment administered by the MassCEC was performed for the Town of Duxbury

which evaluated all municipally-owned property for suitability to host a community-scale wind energydevelopment. The assessment identified municipal property near the North Hill Golf Course and Town

Department of Public Works as the most feasible locations for wind development. The area offers ample

space for siting a wind turbine and thereby minimizing effects to the surrounding community, and

environmental and recreational resources on-site and in the neighboring vicinity. This area identified in

the preliminary site assessment is the basis of further investigations for this technical and economic

analysis for on-site wind generation.

SED performed site visits, evaluated available property/satellite maps and applicable GIS data, analyzed

wind resource data, and participated in discussions with Town officials and the general public in order to

identify the most appropriate locations for a wind turbine development within this identified area, identified

for the remainder of this study as North Hill. This siting process accounts for several considerations

including but not limited to: regulatory and development setbacks; current land uses and classifications;

and available site wind resource. From these details the most appropriate sites and the scale of preferred

technology was determined. Only property owned or administered by the Town of Duxbury was

considered within this analysis.

1.2 NORTH HILL SITE DESCRIPTION

The area encompassing North Hill represents the largest contiguous open space in the Town of Duxbury

with over 1000 acres of land divided between municipal, recreational and conservation classifications.

North Hill is predominantly wooded, with some wetlands distributed throughout. The signature

conservation feature in the area is the North Hill Marsh Wildlife Sanctuary, a 117 acre parcel owned

jointly by the Massachusetts Audubon Society and the Town of Duxbury, managed as part of the North

River Wildlife Sanctuary. The sanctuary is centrally located in the North Hill area and contains the North

Hill Pond and numerous recreation trails.


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Several conservation and historic areas are designated throughout this portion of the Eastern Greenbelt,

including the Knapp Town Forest and the Waiting Hill Preserve. In addition to the extensive network of

recreational trails throughout, this area hosts the North Hill Golf Course (NHGC), a nine-hole municipal

golf course managed by Pilgrim Golf, LLC. The North Hill area adjoins with the Duxbury Town Hall,

Department of Public Works (DPW), the Senior Community Center, the Mayflower Cemetery and the

Town Transfer Station properties. The area evaluated for wind turbine development is bordered by

Tremont Street to the east, Mayflower Street to the south, Lincoln Street to the west and West Street to

the north.

Figure 1-1 North Hill Area with Property Lines

1.3 PROPERTIES ASSESSMENT

To determine appropriate wind turbine locations, SED first established a baseline criteria to identify whatsites would be considered:

1. Property must be owned by the Town of Duxbury;

2. Property must not be designated Conservation Land or Open Space;

3. Property must have a high enough wind resource to satisfy the MassCEC funding requirement.


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Utilizing maps from the Massachusetts Oliver Program1 and the Town of Duxbury GIS platform, SED

determined the ownership and usage designation for the numerous lots within the defined North Hill area

see Figure 1-2. Designations include Municipally Owned, Conservation, Audubon and Historical Property.

Areas outside of the considered area consist of single family residences and some additional

conservation and historically designated land. There are roughly 20 parcels owned by the Town of

Duxbury within this area (see Figure 1-3). Municipal properties were also identified south of Mayflower

Street between Round and Island Creek Ponds; these properties were not included in the preliminary site

assessment and therefore will not be considered for this siting assessment.

Figure 1-2 Property Designations with Legend

In addition to Conservation Land and Open Space areas, the Knapp Town Forest, the Mayflower

Cemetery, and the Senior Community Center property have also been excluded from consideration.

1The MassGIS online data viewer:http://www.mass.gov/mgis/mapping.htm.
http://www.mass.gov/mgis/mapping.htmhttp://www.mass.gov/mgis/mapping.htmhttp://www.mass.gov/mgis/mapping.htmhttp://www.mass.gov/mgis/mapping.htm


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Figure 1-3 Municipal Open-Space Properties under Consideration with Outline

1.4 WIND RESOURCE POTENTIAL

In order to be eligible for MassCEC funding a wind energy project requires a wind speed of at least 5.6

m/s (12.6mph) between hub heights of 50m (164ft) and 59m (194ft) and 5.8 m/s (13mph) between hub

heights of 60m (195ft) and 69m (226ft). To identify the available wind resource of the North Hill area an

analysis was performed utilizing data obtained through a Virtual Met Mast (VMM) provided by AWS

Truepower (See Section 2). This VMM data was used to generate a wind resource grid of the North Hill

area that provides a visual representation of wind speeds at a height of 60m (195ft). The resource grid

provides a useful tool for micro-siting wind turbines by identifying areas where electrical generation can

be maximized based on the available wind resource. The combination of the wind resource grid with the

identified eligible properties overlay results in several areas where the wind resource would be supportiveof a wind turbine installation.


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Figure 1- 4 Wind Resource Grid and Eligible Municipal Properties

Properties located within the green shading of Figure 1-4 meet the minimum requirement established by

the MassCEC; and would therefore would be best suited for siting a wind turbine based upon available

wind resource. Of these areas, three in particular were determined to be a far enough distance from

residential areas to minimize possible effects that a wind turbine could generate. These will be referred to

as:

Area 1) North Hill Golf Course

Area 2) Kettle Hole

Area 3) DPW West


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Figure 1- 5 Wind Resource Grid with Development Areas Identified

1.5 SITING CONSIDERATIONSThe three areas identified were then evaluated to determine which location within would provide the most

ideal wind resource for an economically viable wind energy project. Additional siting criteria were then

applied to refine specific wind turbine locations and establish development options for the Town of

Duxbury. Appropriate wind turbine siting assures minimal interference results upon nearby properties,

existing buildings and/or residences, and allows for ease of access for construction and staging purposes.

The following is a brief description of these considerations with respect to wind turbine development in the

North Hill area.

SetbacksSetbacks are used to avoid or minimize potential disturbances associated with sound and/or any

resulting shadow flicker effect , as well as to minimize potential disruption to the surrounding area and

natural habitat. Setbacks for residences, conservation areas and wetlands, historic areas, and recreation

areas and trails have been considered to determine appropriate locations to site a wind turbine within a

speicific area.


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Residences and Unoccupied Buildings There are numerous residential neighborhoods

surrounding the North Hill area that were considered throughout siting efforts; these are primarily

located to the east and south. Industry standard setbacks based upon the scale of a proposed wind

turbine were used to determine the appropriate setback distance (See Figure 1-6). For non-

residential, unoccupied buildings, the standard setback employed is 1.1 times the total tip height of

the wind turbine. Another setback metric is drawn from the MassCEC which requires the performance

of an ambient sound study during the feasibility phase if a residence falls within 3.5 times the total tip

height of the proposed wind turbine.

Environmental and Recreational Resources SED consulted with a variety of resources to

determine where these critical areas are located within the North Hill area, including but not limited to:

the National Wetlands Inventory (NWI), MassGIS data and the Town of Duxbury GIS platform.

The North Hill Marsh Wildlife Sanctuary is the defining feature of this area, and is therefore taken intoconsideration in relation to each of the potential sites. SED recommends consultation be initiated

with the Mass Audubon Society, however, based upon past experience, and, that this is a single wind

turbine project it is unlikely that the Sanctuary will experience significant impacts by the envisioned

development.

The North Hill area has many recreational uses and numerous trails throughout. The NHGC is a

prominent recreational facility owned by the Town of Duxbury within proximity to the proposed

development.

Typical concerns associated with a wind turbine development include shadow flicker, general

aesthetic visibility, and ice throw. Shadow flicker and visibility will be discussed in later sections.

Icing on wind turbine blades is common in Northern areas of North America, but less likely in coastal

regions such as in Duxbury due to the moderating effects of the ocean. Wind turbines have been

proven to coexist with recreational and other uses and will pose little risk to the safety of existing land

uses with proper planning and education.2 It is important however to minimize project encroachment

on these resources in order to avoid disrupting intended activities.

Buildabilty and Interconnection - Understanding the logistics of how a wind turbine project is built,

including the staging area, foundation, access road construction/upgrades and interconnection is vital

when considering how to site a wind turbine. Any obstacles associated with these could cause major

delays or cost increases that could impact a SED examined each site

2Hull Wind I: adjacent to the high school football field. The Massachusetts Maritime Academy: close proximity to the school. IBEW:located in the parking lot.


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host a wind turbine with consideration for the staging and foundation, site accessibility, and distance to

points of interconnection. All sites would require construction of a 6m (20ft) wide paved access road to

allow for the transport of components.

Permitting Implications SED strives to work closely with clients, permitting authorities and

environmental advocacy groups to support smart community wind development. The many benefits this

type of development can bring are presented to all interested parties and all efforts are made to address

reasonable concerns associated with a wind turbine installation, particularly regarding construction near

sensitive areas. Permitting for a wind turbine at any of the proposed locations would require approvals

and or review at the federal, state and local levels.

Local Town of Duxbury local bylaws limit the overall scale and generating capacity for a

community-scale wind facility, largely due to the existing cap on the height of a wind turbine,

currently set at 250ft. The bylaw establishes a minimum setback distance equal to 1.1 times theoverall height of the wind turbine from the nearest property line and private or public way; and a

minimum setback distance equal to 2 times the overall height of the wind facility from the nearest

existing residential or commercial structure not owned by the applicant. The bylaw does however

allow the setback zone for Community-Scale Wind Facilities and or Wind Monitoring or

Meteorological Towers to fall within the limits of a Wetlands Protection Overlay District, and/or a

Flood Hazard Overlay District.

State Sites 1 and 2 are located within a Priority Habitat Area, which triggers review by the

Massachusetts Department of Natural Heritage. Due to the scale of the wind turbine and limitedarea that would be disturbed by construction, and the close proximity of the previously disturbed

nature of the existing golf course, this is not considered a fatal flaw to development.

Federal FAA approval will be a limiting factor in the scale of a wind turbine development. A

Notice of Presumed Hazard (NPH) for Site 1 has been issued and will limit the overall height of a

wind turbine based upon proximity to the Marshfield Airport and is considered representative of

the other 2 sites evaluated. The Not-to-Exceed Height is 317 feet (97m). The wind turbines

examined in this technical assessment would/would not exceed this limit. Appendix D: FAA NPH?

Wind Turbine Technology

SED actively performs technical reviews of wind turbine technologies with particular attention to their

compatibility with the distributed wind energy market. SED works with specific technologies in sizes

ranging from 10kW to 2MW, constantly reevaluating and updating the systems employed based on


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availability, cost competitiveness, performance and overall reliability. Employing a proven wind turbine

technology is crucial for the successful planning, development and operation of a wind energy project.

Much of the advances in wind turbine technology over the past decade have been geared towards

making larger technologies for utility-scale wind farm development. The big players such as GE, Vestas

and Gamesa have put their resources towards boosting production and capacity for these technologies

larger than 1MW. During this time, community wind developers have had to rely on older technologies in

the 100kW to 1MW range such as the Turbowinds 400kW, the RRB 600kW or Norwin 750kW just to

name a few. Most of these technologies are manufactured by other firms that have bought the rights to

these technologies and have made very few improvements. The benefit of these machines is that they

are proven and reliable, but the technologies have become outdated.

A shift is taking place though as smaller manufacturers recognize the potential of mid-scale wind turbines

in the community wind market. These firms are scaling down some of the advancements made in theutility-scale market to improve capacity factors, reliability and cost effectiveness. Examples include

permanent magnet generators that can cut down on maintenance costs or larger rotor diameters that

provide greater output in lower wind speeds. SED is working with several manufacturers at the forefront

of these upgrades to ensure that our clients are provided with most advanced technologies from firms like

Northern Power Systems and PowerWind that will improve economics and reliability. These will be the

technologies that take community wind into the future.

The Northern Power 450kW wind turbine is a mid-scale technology currently installed for testing

at the National Renewable Energy Laboratory in Colorado. This technology is based on thedesign of the highly successful Northern Power 100kW. This wind turbine is a gearless direct

drive machine that utilizes permanent magnet technology thus reducing the number of moving

parts and wear items. The wind turbine has a rotor diameter of 48m and will be available with a

hub height of 50m or 65m. The first commercial versions of this wind turbine will be available in

mid-2012. The 50m tower will be the option investigated in this feasibility study that will meet not

exceed the Town Bylawcurrent height restriction.

The PowerWind 900kW is the best mid-size wind turbine technology available on the market

today based on its performance and reliability history. The PowerWind 900kW is a horizontal axis

wind turbine available on a 59m or 71m steel, tubular tower with a rotor diameter of 56m or 60m.

The 56m rotor would be employed for the Town of Duxbury, as the Town of Duxbury is an

International Electrical Commission (IEC) Class II wind regime meaning that the 10-minute

average maximum 50-year extreme wind speed in this area is at least 95 mph. The 60m rotor is

designed for a Class III and would not meet the IEC standards for this region. It provides


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significant power production (65% of the 1.5MW class); lower construction costs; and much lower

long term maintenance and operation costs than utility scale (1 MW or larger) wind turbines.

Both of these wind turbines also possess the functionality to prevent ice shedding during major icing

events, while minimizing downtime associated with these events. Ice buildup on each blade is measured

to determine the conditions that would require the wind turbine to be shutdown, which is done through

analysis of natural oscillation frequencies of the blades which will change during icing events. The

system will shut down the wind turbine automatically in these events and also restart whenever the

conditions improve.

With consideration for and airspace restrictions from the FAA, SED focused

investigations on the Northern Power 450kW on a 50m tower and the PowerWind 900kW on a 59m

tower. While overall, the height of the PowerWind 900kW does Bylaw, the economic

returns are stronger a a variance for this height restriction.

Figure 1-6 Wind Turbine Technologies

Wind Turbine

& Rated

Capacity

Tower

Height

Rotor

Diameter

Total Tip

Height

Bylaw

Setback

from

Residential

Buildings

MassCEC

Ambient

Sound Study

Setback

Industry

Recommended

Setback from

Residential

Buildings

Northern

Power 450kW

50m

(164ft)

48m

(157ft)

74m

(243 ft)150m (492ft) 259m (851ft) 244m (800ft)

PowerWind

900kW

59m

(194ft)

56m

(184ft)

87m

(276 ft)175m (574ft) 305m (1000ft) 305m (1000ft)

1.6 SELECTED SITE EVALUATIONS

Area 1 - North Hill Golf Course The North Hill Golf Course (NHGC) is located on relatively flat terrain

above the North Hill Marsh area. SED did not consider siting the wind turbine within the confines of the

NHGC as a suitable option, so as to minimize disruption to the course during construction. When

considering the wind resource, the most suitable location appears to be in a thinly forested area south of

the 8th hole green and 9th hole tee that sits at an elevation of 24m (79ft).


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Figure 1-7 Site 1 NHGC with Setbacks

Residences and Unoccupied Buildings The proposed site is south and east of nearby residential

areas. The closest residential property line is 396m (1300ft) west, with the closest residential building442m (1450ft) north, both of which are associated with 72 Hounds Ditch Lane. There is also a facility

owned by the Duxbury Housing Authority north of the Club House at 75 Merry Ave which is 427m

(1400ft) from the proposed site. The closest non-residential building is the North Hill Club House, 396m

(1300ft) north of the proposed turbine site.

Environmental and Recreation Areas - The proposed wind turbine site is 177m (580ft) from the North

Hill Marsh Wildlife Sanctuary. There are wetland areas 76m (250ft) southwest and 146m (480ft)

southeast, both classified as Freshwater Forested Wetlands.

The proposed site would be within 30m (100ft) of the NHGC and 60m (200ft) from the North Hill Marsh

Pond Loop, a hiking trail that encircles the marsh. SED does not believe that these resources will be

adversely impacted by the presence of the wind turbine.

Buildability and Interconnection The proposed site would be accessed along the eastern edge of the

NHGC driving range. This route will require the construction of a suitable access road from the NHGC


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parking lot. The proposed location is relatively flat and has the necessary room, roughly one acre, to

support the wind turbine installation and staging area for the crane and other components. The clearing of

approximately 1/3 acre would be necessary to construct the access road and prepare the site for staging,

which will require use of the area between the 8th and 9th holes.

The existing electrical infrastructure at the NHGC and at the DPW is not substantial enough to handle a

behind the meter interconnection without significant modifications and upgrades. SED therefore

recommends that the wind turbine be interconnected directly into the existing distribution circuit near the

Club House as a new service and account.

Permitting Implications The proposed site meets setback

Wind Bylaw. The site is located within a Priority Habitat Area, which triggers review by the

Massachusetts Natural Heritage & Endangered Species Program (NHESP), but due to the scale of the

wind turbine, the limited area that will be disturbed by construction, and the close proximity to thepreviously disturbed nature of the golf course, this is not considered a fatal flaw. The only identified

federal implication is FAA approval based upon proximity to the Marshfield Airport four miles away.

Recommendation the North

Hill Golf Course Site - Site 1 - is suitable for a wind turbine development. Based on the site characteristics

and setbacks, a PowerWind 900kW or Northwind 450kW could be appropriately sited here. SED does

not anticipate a wind turbine will adversely impact recreational activities at the golf course or other trails in

the North Hill area. The wind turbine could co-exist with the golf course and has potential to become a

signature feature of the NHGC that would draw golfers from around the region.

Area 2 Kettle Hole This area is located between the Pond Loop Trail and Kettle Hole Trails. The

highest elevation within this area is 27m (90ft), and is centrally located within the parcel, which would

make it an ideal location for a wind turbine.


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Figure 1-8 Site 2 Kettle Hole with Setbacks

Residential and Unoccupied Building Setbacks The proposed site is centrally located within theNorth Hill Area and there are no residences or unoccupied buildings nearby. The closest residences are

518m (1700ft) to the northeast and south. The closest non-residential building is the NHGC club house

762m (2500ft) north.

Conservation Areas and Wetlands - The proposed site sits between an unnamed Conservation Area

and the Mass Audubon North Hill Marsh Wildlife Sanctuary, at 91m (300ft) and 113m (370ft) respectively.

The closest wetland is 91m (300ft) east and is a Freshwater Forest Wetland. However, no wetland areas

would be disturbed during an installation at this site.

A wind turbine at the proposed site will not encroach upon any major trails within the North Hill area. The

closest trail is the Pond Loop Trail 137m (450ft) west and Kettle Hole Trail 198m (650ft) east.

Consultation with the local historic commission is recommended since a section of the Pond Loop Trail on

the east side of the M

connected the Towns of Plymouth and Marshfield.


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Buildability and Interconnection The site access would be from the NHGC. An entirely new access

road over 1067m (3500ft) in length would need to be constructed, likely originating at the NHGC parking

lot and continuing through the Town Dumping Area. This route would require crossing some trails, but

identified wetlands and Conservation Lands could be avoided. A wetland delineation survey would be

needed for a development at this location. The project area itself is relatively flat. Clearing of at least one

acre for the foundation and staging area would be required; the access road would result in an additional

1.5 acres of cleared land.

Interconnection would be costly due to a long wire run and would follow the same route as the access

road with an interconnection scheme similar to that recommended for Site 1.

Permitting Implications A wind turbine at the proposed site meets the setback requirements

Wind Bylaw. Based upon the scale of proposed clearing and the disturbance

of greater than one acre, National Pollutant Discharge Elimination System (NPDES) coverage will berequired. For the State of Massachusetts, the EPA is the permitting authority for the NPDES.3 The federal

implication of FAA approval remains based upon proximity to the Marshfield Airport four miles away.

Recommendation Based on the demonstrated characteristics, it Kettle

Hole Site - Site 2 - is suitable for a wind turbine development utilizing a Northwind 450kW or PowerWind

900kW. Siting however, will add significant costs to the overall project due to the length of wire run and

access upgrades to be required. The amount of clearing necessary for the staging area and the

construction of an access road could pose an obstacle to development.

Area 3 DPW West This area is located west of the Duxbury Town Hall and DPW yard and is

predominantly forested and interspersed with some recreational trials. The highest point and prime

location for siting a wind turbine within the area is approximately 27m (90ft) above sea level.

3Applicants for National Pollutant Discharge Elimination System (NPDES) permits covering new or expanded industrial project

construction must submit information on the proposed construction. The information must describe the proposed or expandedprocess and its relationship to the existing facilities. The EPA will use the information to determine if new source performancestandards (NSPS) apply to the new construction. The New Source Determination (NSD) establishes whether or not the proposedconstruction is subject to environmental assessment under the National Environmental Policy Act of 1969, as amended (NEPA).These regulations and definitions are found in Sections 306 and 511(c) of the Clean Water Act and 40 CFR Parts 6, 122.2, and122.29.


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Figure 1-9 Site 3 DPW West with Setbacks

Residential and Unoccupied Building Setbacks The closest residential areas are to the north and

east of this proposed location. The closest residential property and residential building is at 102 Hounds

Ditch Lane, 366m (1200ft) and 405m (1330ft) to the northeast, respectively. The DPW Yard and Town

Hall are over 457m (1500ft) away from this site. The Duxbury First Parish Church is 548m (1800ft) east

of the proposed site.

Conservation Areas and Recreational Resources - The proposed site is 213m (700ft) away from two

unnamed Duxbury conservation areas that contain wetlands; these would not be disturbed at the

proposed location. The proposed site would pose little threat to recreation areas however trails in the areawould be crossed by the creation of an access road. The closest trail is a connector trail 30m (100ft) to

the north.

Buildability and Interconnection The proposed location would require the construction of an access

road originating at the DPW yard and extending 457m (1500ft). The proposed location is relatively flat

and has the area needed, roughly one acre, to support the wind turbine installation and staging area for


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the crane and other components. Interconnection costs would be high due to the wire run and would

follow the same route as the access road. The wind turbine would be interconnected at the DPW yard

onto the existing 23kV overhead circuit owned by NSTAR.

Permitting Implications The proposed site would meet the setback requirements established by the

Wind Bylaw. The site is not located within a Priority Habitat Area. Based upon the scale of

proposed clearing and the possible disturbance of greater than one acre, National Pollutant Discharge

Elimination System (NPDES) coverage would likely be required. The federal implication associated with

FAA approval proximity to the Marshfield Airport four miles away still remains.

Recommendation Based on the demonstrated characteristics, it is

would be suitable for wind development. However this site would add significant costs to the overall

project based upon the length of wire run and access upgrades required. The site could support a wind

turbine up to the 900kW scale, providing the Town Bylaw allows for a variance regarding the heightrestriction currently in place, as a 900kW would exceed the maximum allowable height.

1.7 FINAL SCENARIO RECOMMENDATIONS

SED has identified three possible sites that would be appropriate options for siting a wind turbine within

the Town of Duxbury. The locations are titled: Site 1-North Hill Golf Course (42.042803, -70.701576);

Site 2 - Kettle Hole (42.039523, -70.702537); and Site 3 - DPW West (42.037655, -70.698261).

Each potential site presents its own benefits and obstacles to development that should be carefully

stands out as the most developable location due to its accessibility and available area for staging both of

which act to limit total project costs. The proximity of the wind turbine to the golf course will require some

additional planning and outreach, but SED does not consider that this will be a detriment to the golf

course but rather a potential opportunity to market the green credentials of the golf course and attract a

broader base of recreationists.


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Figure 1-10 Recommended Wind Turbine Locations


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SECTION 2

WIND RESOURCE ASSESSMENT AND TURBINE OUTPUT MODELING

In order to calculate the anticipated Annual Energy Production (AEP) of the wind turbine for the Town of

Duxbury, SED used the wind industry standard modeling tools Wind Atlas and Application Program

(WAsP), created by the Danish National Laboratory along with WindPRO, created by EMD International

A/S. WindPRO is used for creating the model and reports and the WAsP program is used by WindPRO

for the wind flow calculations. For this analysis, SED input model data from the selected wind turbines

and potential sites. A single PowerWind 56 900kW wind turbine with a hub height of 59m (193.5ft), and a

rotor diameter of 56m (183.7ft); along with a single Northwind 450kW wind turbine with a hub height of

50m (164ft), and a rotor diameter of 54m (177ft) were explored at three potential sites.

2.1 WIND TURBINE SELECTION AND OUTPUT CALCULATION

SED selected the PowerWind 900kW wind turbine for this project as they are highly reliable, currently electricity consumption.

The Northwind 450kW wind turbine offers a smaller alternative option to the PowerWind with the

. To determine the

output of the wind turbines at each individual site, SED used the industry standard wind modeling

software, WAsP. The model was created by licensed and certified user: Scott Abbett, SED, USA using

WAsP version: 9.00.0153 and certified user Bill Court, SED, USA using WindPRO version 2.7.473.

In order to accurately calculate the output of the wind turbine at the Town of Duxbury, the WAsP and

WindPRO models considered:

A full year Virtual Met Mast (8760 hours) of wind data provided by AWS Truepower4

The turbine sites located at: (UTM Zone 19, WGS84)

o Turbine Site 1 NHGC 359186.0 E, 4655940.0 N

o Turbine Site 2 Kettle Hole 359085.0 E, 4655567.0 N

o Turbine Site 3 DPW West 359435.0 E, 4655353.0 N

A terrain map of the USGS 7.5 minute Quadrangle-Duxbury, MA

A roughness map for the USGS 7.5 minute Quadrangle-Duxbury, MA

The power curve of the PowerWind 56 900 kW wind turbine with a 56m (183.7ft) rotor diameter

and a 59m (193.5ft) hub height

The power curve for the Northwind 450 kW wind turbine with a 54m (177ft) rotor diameter and a

50m (164ft) hub height.

4 AWS Truepower LLC based out of Albany, New York is an international leader and innovator in renewable energy technologyapplications, advanced atmospheric modeling and measurement, and engineering services for over 25 years.


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2.2 VIRTUAL MET MAST INFORMATION

SED contracted AWS Truepower of Albany, NY, to provide a Virtual Met Mast (VMM) data set, comprised

of a full year (8760 hours) of wind speed and direction data, for a location on the Town of Duxbury

property. Data from this VMM was then imported into WindPro in order to tabulate average wind speed

and direction data. AWS Truepower provides the following description of their VMM Product:

A Virtual Met Mast produces a representative calendar year of hourly wind speed, direction,temperature, atmospheric pressure, air density, and energy output. It is produced by makingmultiple refinements to coupled mesoscale and microscale model output, and then, using anestimated wind profile for the chosen site, scaling this data to a particular height (e.g. 40m). Thus,a complete climatology of typical conditions expected at the selected height above ground iscreated

mesoscale numerical weather model that resolves atmospheric phenomena at scales down to 1

3 km, establishes the general patterns of wind and weather in a region. These patterns reflect theinfluence of terrain, vegetation, oceans and lakes, solar heating, radiative cooling, convection,and many other factors. With output from MASS, MesoMap, a microscale wind flow model, isthen used to assess the wind resource at a higher resolution (typically 50 - 200 m, or grid sizes offrom less than 1 acre to about 10 acres). Existing long-term meteorological data is then used toverify output from MesoMap.

Figure 2-1 VMM Information

Data Source AWS Truepower

Height 50m & 70m

Location 359450.0 Easting (UTM -

WGS84)

Location 4655446.0 Northing (UTM

- WGS84)

Site Elevation 22m

Mean Wind Speed at 70m AGL

Mean Wind Speed at 50m AGL

6.18 m/s

5.68 m/s

Figure 2-1 provides a graphical representation of the WindPRO wind speed and direction in the form of

Wind Roses and Weibull Distribution for the 70m (229.6ft) VMM wind data. The Wind, Frequency and

Energy Roses describe wind direction, frequency and quantity of wind and turbine generated power from

each direction. It should be noted that in Figure 2-2 the energy rose is blank as it needs an associated

power curve in order to convert wind data to energy production. As depicted, the wind at the met mast

location is most frequently experienced at the southwest sectors. The Weibull Distribution (top left) is a

description of the number of hours in a year where certain wind speeds will exist at the meteorological


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tower location. A similar distribution is used in conjunction with the wind turbine manufacturer-supplied

power curve to determine the gross electrical output from a wind turbine at a particular site.

Figure 2-2 70m VMM Wind Roses (Bottom) and Weibull Distribution (Top Left)

2.3 TERRAIN AND ROUGHNESS MAPS

WAsP and WindPRO use terrain and roughness maps to accurately determine the way the wind flows

over the identified site. These maps are input into the model in order to calculate the local site effects.

The terrain map is a topographical representation of the area using 6.096m (20ft) contour lines. The

roughness map is a representation of the surface roughness and/or ground cover in the surrounding area

based on the WAsP roughness classification system. The area was modeled using a 23,500m (77,099ft)

by 23,750m (77,919ft) digital elevation model around the Town of Duxbury sites. The terrain map comes

directly from the US Geological Survey and the roughness map used in this model was obtained from

AWS Truepower.

2.4 WIND TURBINE POWER CURVES

In order for the WAsP and WindPRO models to work properly it is important to have an accurate power

curve for the turbine being considered for the project. A power curve indicates how much power the


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turbine will produce at different wind speeds. For this model, SED used the power curve for the

PowerWind 56 900 kW wind turbine with a 56m (183.7ft) rotor diameter along with the power curve for a

Northwind 450 kW wind turbine with a 54m (177ft) rotor diameter. The wind turbine manufacturer

provided the technical specifications needed to input the power curves into WindPRO. Figures 2-3 and 2-

4 are visual representations of the power curves for the PowerWind 56 900kW and Northwind 450kW

respectively as shown in WindPRO.

Figure 2-3 PowerWind 56 900kW Manufacturer Supplied Power Curve


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Figure 2-4 Northwind 450kW Manufacturer Supplied Power Curve

SUMMMARY OF MODEL RESULTS

Once all of the data inputs were completed, the WindPRO model was run with the PowerWind 900 kW

turbine and the Northwind 450 kW wind turbine at the identified locations. Figure 2-5 is a summary of the

results of this model.

Figure 2-5 Summary of Model Result

Site Identification Location [UTM, WGS84] TurbineHeight

[m]Wind Speed at

Hub (m/s)Net AEP[MWh]

Site 1 359186.0E, 4655940.0N PowerWind 900 59 5.82 m/s 1,830.4

Site 1 359186.0E, 4655940.0N Northwind 450 50 5.48 m/s 1,167.5

Site 2 359085.0E, 4655567.0N PowerWind 900 59 5.89 m/s 1,892.1

Site 2 359085.0E, 4655567.0N Northwind 450 50 5.61 m/s 1,234.4

Site 3 359435.0E, 4655353.0N PowerWind 900 59 5.91 m/s 1,893.3Site 3 359435.0E, 4655353.0N Northwind 450 50 5.64 m/s 1,243.0


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2.6 FINAL TURBINE OUTPUT CALCULATIONS

WAsP calculates turbine output assuming that the wind turbine is available 100% of the time and that

100% of the power produced by the generator makes it into the grid or is otherwise consumed on-site.

Realistically, a wind turbine experiences downtime for various reasons and not every single unit of power

-site. The following are

considerations used in WindPRO determining how much power a wind turbine will actually supply.

Assumed Availability: This assumed figure is based on generally accepted performance history for

wind turbine size classes and is the percentage of time that the wind turbine would be in working

condition. This figure takes into account the downtime for scheduled maintenance activities and assumes

that the wind turbine is properly cared for and maintained by professionals.

Electric Line Losses: The power generated at the turbine needs to run through a certain distance of

electric lines and two different transformers before it connects to the grid or is consumed at a facility.Through these conversions, a portion of power will be lost.

General Losses: This category includes downtime due to icing, other weather related events such as

high wind speed events and unscheduled maintenance.

Grid Failure: Without the electrical grid operating normally, a wind turbine cannot produce power

because it is a synchronous/induction generator that initially requires electricity to generate its own

electricity. Grid failure takes into account the time when the electrical grid is down due to scheduled or

unforeseen events.

Figure 2-6 Assumed LossesAssumed Availability (98%) 2.0%

Electric Line Losses 2.0%

General Losses 2.5%

Grid Failure 1.0%

Total Losses 7.5%

Therefore the power produced by a turbine as calculated by WindPRO needs to be reduced by 7.5%.

Figure 2-7 shows the remaining calculations to determine power output of the wind turbines that were

examined for the Duxbury site. The final values used for turbine output are shown in bold.


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Figure 2-7 Final Output Calculations

Site Turbine Rated PowerGross AEP from

WindPRO (MWh/yr)

Final net AEP after

losses (MWh/yr)

Site 1 PowerWind 900 kW 1,830.4 1,693

Site 1 Northwind 450 kW 1,167.5 1,080Site 2 PowerWind 900 kW 1,892.1 1,750

Site 2 Northwind 450 kW 1,234.4 1,142

Site 3 PowerWind 900 kW 1,893.3 1,751

Site 3 Northwind 450 kW 1,243.0 1,150


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3-1Final Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

INTERCONNECTION INVESTIGATION

SECTION 3

SED analyzed the existing electrical supply facilities, and the necessity for modifications associated with

interconnecting one (1) 450kW or one (1) 900kW to the utility grid at the Site 1 - NHGC.

3.1 RECOMMENDED INTERCONNECTION PLAN

Based on an analysis of the existing electrical facilities, consultation with Mr. Rich Gross P.E., and SED's

experience with similar wind turbine projects, an interconnection plan has been developed for proposed

turbine Site 1. Due to the similarity in approach for interconnecting a 450kW or a 900kW wind turbine, a

single plan has been developed and the minor differences based on wind turbine size are noted within the

plan. recommendations will minimize interconnection costs while maintaining the integrity of the

existing town and utility owned electrical systems.

Existing Conditions

The primary electrical feeder for NHGC is a three-phase, 23kV overhead distribution circuit owned by

NSTAR5. The 23kV overhead circuit extends from West Street, up Merry Avenue, to a riser pole located

adjacent to the NHGC parking lot entrance and beside a gravel road leading to the NHGC maintenance

facilities. The circuit continues underground to a 150kVA transformer located adjacent to the maintenance

building at the west end of the course. The Club House appears to be electrically fed by a single phase

line originating from the three-phase 23kV overhead circuit. The single-phase circuit follows the northern

edge of the parking lot and terminates after approximately three spans at a pole north-east of the Club

House.

Interconnection Plan

The recommended interconnection plan includes all of the necessary protective equipment (relays and

disconnects) and interconnection of the wind turbine into the existing three-phase 23kV overhead circuit

currently feeding the golf course. The 690 Volt out-23kV by a new,

1000kVA three-phase transformer for a 900kW, or 500kVA three-phase transformer for a 450kW (located

at the base of wind turbine); transferred below ground approximately 2100ft via three, 1/0 AWG,

aluminum cable, under the parking lot and to a new riser pole located off the western side of the Club

House. The circuit will then be transferred over-head via three, 1/0 AWG, aluminum cable and

interconnect into the exiting three-phase 23 kV overhead circuit at NSTAR Pole # 459/9 located south-

west of the golf course parking lot. New poles for transferring the overhead circuit and for locating

protection and metering equipment will be installed between the new riser pole and existing NSTAR Pole

5 NSTAR is a Massachusetts based electric and gas utility


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3-2Final Report - Technical Analysis for On-Site Wind Generation for the Town of Duxbury

#459/9 as needed. Mr. Gross has developed a conceptual one-line for the proposed interconnection

approach for both the 900kW and 450kW wind turbines.

Since the generator will not be connected behind an existing service account, new service will be required

and a new account created with NSTAR for the turbine circuit. In addition, a new four quadrant meter will

be installed as well as any utility required protection equipment, such as a recloser and/or fused cut-outs,

deemed necessary by NSTAR.

Interconnection for Proposed Turbine Sites 2 and 3

The interconnection of turbines placed at the proposed turbine locations 2 or 3 will be very similar to the

approach described above. A turbine at Site 2 will interconnect at the same location as described above

for Site 1 and with identical protection equipment. The wire run, however, will increase from approximately

1700ft to 2900ft due to the increased distance from the proposed point of interconnection at the golf

course. A wind turbine at Site 3 will include all the same protection and electrical components asdescribed above but instead would interconnect into the existing three-phase 23kV over-head circuit

located at the DPW facility. The DPW buildings are fed by the same distribution circuit as the NHGC. As

with interconnection at the golf course, due to the size of the proposed generators and the capacity of the

existing electrical infrastructure at the DPW, it is recommended that the wind turbine be directly

connected into the existing 23kV distribution circuit and considered a new service account with NSTAR.

3.2 NEXT STEPS

During project design, an Interconnection Application will be filed with NSTAR for the proposed

interconnection approach. NSTAR will perform an initial review of the requested interconnection and willdetermine if the request can proceed under the Expedited or Standard Process based on set screening

criteria. The ability to proceed under the Expedited Process depends on the size of the generator,

component certifications (IEEE, UL, etc), condition

associated impact of interconnecting the generator onto the distribution circuit. Costs associated with the

interconnection process have been included in the Capital Costs in Section 8 of this report. During the

interconnection application process system modifications, additional reviews or studies may be found to

be necessary, but these are not reflected in the costs provided as part of this study.

A detailed description of the interconnection process can be found in

effective date October 1, 2009 and is available on the NSTAR website.


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WIND GENERATED ELECTRICITY VALUE

SECTION 4

The value of electricity generated by a wind turbine will play a significant role in determining the final

configuration for a wind project owned by the Town of Duxbury. Wind generated electricity values for

municipalities significantly improved when net metering provisions were enacted and will now allow theTown of Duxbury to aggregate and offset municipal loads with power produced from a single wind turbine

project, for multiple meters under the same distribution company and located in the same ISO-NE load

zone (also known as virtual net metering). This legislation will allow the Town of Duxbury to utilize all of

the electricity produced by a wind turbine installation to offset electricity use of any Town owned

accounts.

4.1 TOWN OF DUXBURY ELECTRICITY DATA

In order to determine the value of a wind energy generating facility for the Town of Duxbury, SED first

examined cumulative consumption data for all Town-owned accounts. Conservatively, SED has assumed

that electrical usage for the Town will not change significantly from its current level over the projected

lifespan of a wind turbine. Figure 4-1 shows the total electricity consumption of approximately 70 Town

accounts for the 12 months leading to December of 2009 6. Town accounts are billed at several rate

classes for various meters; the most commonly experienced rate for the largest Town accounts include:

33-GeneralAnnual and 84-SEMA Medium General TOU. This will prove significant if the wind generated

electricity is used to offset usage for specific accounts. For 2009, Duxbury utilized in excess of 5 million

kWh across all facilities. Based on an analysis of the provided electricity bills, SED determined the total

electricity usage for the Town, as well as the average retail electricity cost per kWh. Figure 4-1 is amonthly break down of electricity usage across all town accounts for the year 2010.

6 The Town provided copies of electricity bills reflecting annual usage for approximately seventy Town metered electricity accounts;while dates vary slightly from account to account, the overall cumulative data provides an overall representation of the electricityused by the Town for the year 2009.


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Figure 4-1 12-Month Electric Usage Data (kWh)

Month Consumption (kWh)

January 468,508

February 483,166

March 462,166

April 425,997

May 444,978

June 408,385

July 347,257

August 386,505

September 423,415

October 441,819

November 458,698

December 488,100

Total 5,238,994

Of these 70 accounts, there are 10 that represent 80% of the total usage in the Town of Duxbury. These

include but are not limited to the High School, Intermediate School, Town offices, Senior Center, library,

fire station, pool, police station, water department, pump stations, town lighting, and traffic signals (Figure

4-2).

Figure 4-2 Ten Largest Electric Accounts in Town of Duxbury.

Account Name2010 Electric Usage

(kWh)

Duxbury High School 1,244,320

Chandler School 618,971

Duxbury Middle School 616,000

Alden 515,090

Duxbury Free Library 322440

Off Evergreen 236,640

Tremont St. 168,240

Percy Walker Pool 150,400

10 Mayflower 132,400

Wright 115,760


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4.2 GREEN COMMUNITIES ACT AND NET METERING

In 2008, the Green Communities Act, which contained legislation to significantly expand net metering in

Massachusetts, was signed into law. The passage of this legislation and its implications on net metering

has made Massachusetts a national model for stimulating the expansion of on-site renewable energy

generation. Under these regulations, customers are classified into tiers based on the size of their

electricity generator (under 60kW, between 60kW and 1MW, or 1MW to 2MW per unit). Any of the wind

turbine sizes contemplated in this Study for the Town would be categorized as a Class II Net Metering

Facility. Net metering allows customers with their own electricity generation capabilities to quantify the

flow of electricity through the use of a bi-directional meter. Net metering allows th

generation to be allocated by the utility to other Town-owned facilities or through payment of net metering

credits and the utility is required to purchase or provide value for this excess energy. The rate that the

utility is required to purchase the excess electricity does not include the demand side management or

energy conservation charge (ECC), or the renewable energy charge (REC).

In late 2010, the Massachusetts Department of Public Utilities (DPU) adopted an amended definition for

"a net metering facility of a municipality or other governmental entity.

is eligible for up to a 10 MW net metering, so long as the individual project does not exceed 2MW. Based

upon this new definition, a net metered wind facility must be owned by the Town, must be either a Class II

or Class III facility, or the Town must utilize all of the output of the facility. Based upon the annual

consumption data provided, the Town will easily be able to utilize all of the energy produced by the two

technologies contemplated in this Study. Based on the anticipated load and newly enacted net metering

regulations, the Town could pursue a project up to 2MW in size.

4.3 CALCULATING NET METERED CREDITS

Interconnecting a net metered wind turbine for the Town of Duxbury will be governed in this case by the

Metering Credit as determined in Section 1.06 (1) of the M.D.P.U. No. 163. For a Class II municipally

owned net metered facility credits will be equal to the product of excess kWh, by time-of-use if applicable,

in a billing period (monthly), that is aggregated over a period of a year. The net excess generation will be

monetized and Net Metering Credits will be calculated based on the excess kilowatt hours (kWh)

the Utility distribution charges, which include the default service kWh charge, distribution kWh charge,

transmission kWh charge and transition kWh charge. Net Metering Cred

sed duxbury wind feasibility report

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