HomeMy WebLinkAboutAtmautluak Wind Renewable Energy Project Wind-Diesel Power System Conceptual Design Report - Jul 2012 - REF Grant 7040002Wind-Diesel Power System
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Contents
Contents ................................................................................................................................................. 1
Introduction ............................................................................................................................................ 6
Project Planning ...................................................................................................................................... 6
Project Management .......................................................................................................................... 6
Location and Description .................................................................................................................... 6
Access ................................................................................................................................................. 7
Economy ............................................................................................................................................. 8
Geology .............................................................................................................................................. 8
Climate ............................................................................................................................................... 8
Flooding ............................................................................................................................................ 10
Local Infrastructure ........................................................................................................................... 10
Water Infrastructure ...................................................................................................................... 10
Wastewater Infrastructure ............................................................................................................ 11
Electricity/Communication Infrastructure ..................................................................................... 11
Solid Waste Disposal ..................................................................................................................... 12
Fuel Storage Areas ........................................................................................................................ 12
Small Structures ............................................................................................................................ 13
Boardwalks and Roads .................................................................................................................. 13
Wind-Diesel Hybrid System Overview .................................................................................................. 14
Wind-Diesel System Components ......................................................................................................17
Supervisory Control System .......................................................................................................... 18
Synchronous Condenser ................................................................................................................ 19
Secondary/Interruptible Loads ...................................................................................................... 19
Storage Options ............................................................................................................................ 20
Wind Turbine Options ....................................................................................................................... 22
Vestas V17 ..................................................................................................................................... 22
Northern Power Systems Northwind100 ....................................................................................... 22
Community Energy Use ........................................................................................................................ 23
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Heating/Diesel Fuel ........................................................................................................................... 23
Transportation .................................................................................................................................. 24
Electricity .......................................................................................................................................... 24
Water/Sewer ..................................................................................................................................... 26
Power Cost Equalization Data ........................................................................................................... 27
Atmautluak Wind Energy Resource ...................................................................................................... 29
Initial Environmental Review................................................................................................................. 30
Alaska Pollution Discharge Elimination System ................................................................................ 30
US Fish and Wildlife Service .............................................................................................................. 31
Federal Aviation Administration ....................................................................................................... 31
Determination of No Hazard to Air Navigation .............................................................................. 31
Alaska Department of Natural Resources.......................................................................................... 31
Alaska Coastal Management Program Consistency Review .......................................................... 31
State Historic Preservation Office (SHPO) consultation ................................................................ 32
US Army Corps of Engineers ............................................................................................................. 32
Wetlands and Waterways .............................................................................................................. 32
Fisheries ............................................................................................................................................ 32
Vegetation ........................................................................................................................................ 33
Avian Resources ................................................................................................................................ 33
Yellow-billed loon (YBLO) ................................................................................................................. 34
........................................................................................................... 35
Bats ................................................................................................................................................... 37
Other Mammals ................................................................................................................................ 37
Federally Listed Species .................................................................................................................... 37
Cultural Resources ............................................................................................................................ 37
Site & Powerhouse Assessment ............................................................................................................ 37
Atmautluak Joint Utilities- Existing Power System ........................................................................... 38
Waste Heat Recovery ........................................................................................................................ 39
Intertie Options ................................................................................................................................. 40
North Site ......................................................................................................................................... 40
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South Site ......................................................................................................................................... 40
Geotechnical Report ......................................................................................................................... 41
Review of Existing Geotechnical Information ................................................................................ 41
Design Configurations .......................................................................................................................... 44
Conceptual Design Components ....................................................................................................... 45
Cold Climate Considerations ............................................................................................................. 48
Rime ice ........................................................................................................................................ 48
Glazed Ice ...................................................................................................................................... 48
Very Cold Temperatures................................................................................................................ 49
Wind Turbine Foundation Considerations ......................................................................................... 49
Construction Considerations ............................................................................................................. 49
Modeling Assumptions ......................................................................................................................... 50
Electrical Load Data .......................................................................................................................... 50
Thermal Load Data ........................................................................................................................... 51
Wind Data ......................................................................................................................................... 51
Diesels .............................................................................................................................................. 52
Fuel Price .......................................................................................................................................... 52
Economics ......................................................................................................................................... 52
Wind Turbine .................................................................................................................................... 53
Rough Order of Magnitude (ROM) Cost Estimates ............................................................................ 53
V17 Configuration .......................................................................................................................... 53
NW100 Configuration .................................................................................................................... 53
Cost Estimates .............................................................................................................................. 54
Modeling Methodology......................................................................................................................... 55
V17 Configuration (2 Turbines) .......................................................................................................... 56
NW100 Configuration (2 Turbines) .................................................................................................... 59
Single Turbine Configuration ............................................................................................................ 62
Modeling Conclusions ........................................................................................................................... 64
Estimated Annual Renewable Fraction and Capacity Factor ............................................................. 64
Estimated Annual Wind Energy Production ...................................................................................... 65
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Estimated Fuel Savings ..................................................................................................................... 65
Cost of Energy and Benefit/Cost Ratio .............................................................................................. 65
Recommendations ................................................................................................................................ 68
Appendix A: Atmautluak AEA Wind Energy Resource Report .............................................................. 70
Appendix B: Atmautluak Proposed One Line .........................................................................................71
Appendix C: Atmautluak Distribution Maps .......................................................................................... 72
Appendix D: HOMER Model Inputs ...................................................................................................... 73
Appendix E: Northern Power NW100B Arctic Specification Sheet ........................................................ 74
Appendix F: Vestas V17 Specification Sheet ......................................................................................... 75
Appendix G: Atmautluak Powerplant Site Visit .................................................................................... 76
Appendix H: Geotechnical Report ......................................................................................................... 77
Figure 1: Location of Atmautluak ........................................................................................................... 7
Figure 2: Village of Atmautluak illustrating typical boardwalk and grass ................................................. 8
-2009 .................................... 9
Figure 4: Timber utility posts have been cut off near the ground surface and attached to H-piles.. ....... 12
Figure 5: Pile Support Fuel Storage Facility ........................................................................................... 13
Figure 6: Installed Wind Projects in Alaska ............................................................................................ 14
Figure 7: Low Penetration Wind-Diesel Configuration........................................................................... 15
Figure 8: Medium Penetration Wind-Diesel Configuration .................................................................... 16
Figure 9: High-Penetration Wind-Diesel Configuration ......................................................................... 16
Figure 10: Synchronous Condenser at Kokhanok ................................................................................. 19
Figure 11: Screen of a Secondary Load Controller Depicting the Frequency Control Function .............. 20
Figure 12: Battery Systems from Kokhanok and Wales ........................................................................ 21
Figure 13: Kokhanok V17s Courtesy of Marsh Creek .............................................................................. 22
Figure 14: Unalakleet NW100 Turbines ................................................................................................ 23
Figure 15: PCE Trending Data - kWh Generated and Fuel Consumed .................................................... 24
Figure 16: PCE Trending Data-Cost of Fuel and Efficiency .................................................................... 25
Figure 17: PCE Trending Data- Fuel Cost per kWh and non-PCE Residential Rate................................. 25
Figure 19: Wind Frequency Rose and Total Wind Energy Rose ............................................................. 29
Figure 20: Monthly Wind Speed Profile ................................................................................................ 30
Figure 21: Yellow-billed Loon Range Map. (Alaska Department of Fish and Game, 2012) .................... 35
Figure 22: Spectacled Eider Critical Habitat Map. (USFWS, 2004, Spectacled eider). ............................ 36
..................................... 36
Figure 24: Atmautluak Joint Utilities Powerhouse ................................................................................. 38
Figure 25: Atmautluak Powerplant-Interior .......................................................................................... 39
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Figure 26: Aerial Photo of Atmautluak with Proposed Site and Distribution Lines ................................ 43
Figure 27: Conceptual Layout of Hydronic Heating Loop for District Heating System ........................... 45
Figure 28: Conceptual Wind-Diesel System One-Line Diagram (See Appendix B for Larger Drawing) .. 47
Figure 29: Daily Electric Load Profile .................................................................................................... 50
Figure 30: Monthly Load Profile ............................................................................................................ 51
Figure 31: Thermal Load Monthly Profile-Assumed............................................................................... 51
Figure 32: Wind Resource Monthly Profile ............................................................................................ 52
Figure 33: Atmautluak Deferrable Load ................................................................................................ 56
Figure 34: V17 HOMER Configuration ................................................................................................... 57
Figure 35: Monthly Average Electric Production by Source .................................................................. 57
Figure 36: AC Primary Load (Blue) and Excess Electricity from 2 V17 Turbines(Purple) ......................... 58
Figure 37: Renewable Penetration from 2 V17 Turbines (%) and AC Primary Load (kW) ....................... 59
Figure 38: NW100B HOMER Configuration .......................................................................................... 60
Figure 39: NW100B Configuration Monthly Average Electric Production per Source ............................ 60
Figure 40: AC Primary Load (Blue) and Excess Electricity from 2 NW100 Turbines (Purple) .................. 61
Figure 41: AC Primary Load (kW) and Renewable Penetration (%) from 2 NW100 Turbines ................. 62
Figure 42: 1 NW 100 - AC Primary Load (kW) and Renewable Penetration (%) ...................................... 63
Figure 43: AC Primary Load (Blue) and Excess Electricity from 1 NW100 Turbine (Purple) .................... 64
Table 1: Increase in Mean Seasonal and Annual Temperatures in Bethel, 1949-2009 .............................. 9
Table 3: Atmautluak Joint Utilities Monthly Data for 2009 ................................................................... 27
Table 5: PCE Data (* Denotes Derived Numbers Based on Average Efficiency) .................................... 28
Table 6: Wind Resource Characteristics ................................................................................................ 29
Table 7: Atmautluak Joint Utilities existing diesel generators ............................................................... 38
Table 8: Atmautluak HOMER Model Cost Assumptions for System Fixed Costs................................... 54
Table 9: Atmautluak Wind Turbine Associated Costs ........................................................................... 55
Table 10: Summary of Wind Turbine and System Costs Broken Down Per Turbine .............................. 55
Table 11: Estimated Fuel Savings with Various Configurations .............................................................. 65
Table 12: Results of HOMER Modeling for Atmautluak Wind-Diesel System Alternatives, Cost of Energy
.............................................................................................................................................................. 66
Table 13: Final Conclusions Based Upon Multiple HOMER Models and Analysis.................................... 67
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Intr oduction
The Village of Atmautluak received $100,000 through Round IV of t
Renewable Energy Fund. This funding allowed for the completion of this Conceptual Design Report
and will enable the Village of Atmautluak to pursue Design and Construction Funding. A Wind
Resource Report was completed by the Alaska Energy Authority in 2007 and a Wind-Diesel Feasibility
Study was completed by WHPacific in September 2011.
The Village of Atmautluak is interested in the installation of wind turbines primarily to reduce diesel
fuel consumption. In addition, other benefits include:
reduced long-term dependence on outside sources of energy;
reduced exposure to fuel price volatility;
reduced air pollution resulting from reducing fossil fuel combustion;
reduced possibility of spills from fuel transport & storage; and
reduced overall carbon footprint and its contribution to climate change.
Project Planning
Project Management
The Atmautluak Traditional Council has executive oversight of this project and will provide the
administrative and financial management systems. The Village of Atmautluak has hired WHPacific to
complete the conceptual design phase and Atmautluak will also work with WHPacific to continue
through the final design of the project. A general contractor will be selected through the standard
RFP/bid process with WHPacific continuing with project management oversight through the
construction/installation and commissioning of the wind-diesel system.
Location and Description
Bethel at 60.866940
north latitude and 162.273060 west longitude. It is on the west bank of the Pitmiktakik River in the
Yukon-Kuskokwim Delta. The population of Atmautluak is 305 people (2000 Census). As of February 7,
1996, the village uses a traditional village council government. Atmautluak resides in the Calista
Region. Figure 1 indicates the location of Atmautluak, Alaska.
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Figure 1: Location of Atmautluak
years; most villagers maintain the
traditional subsistence and fishing lifestyle. Atmautluak was settled in the 1960s and incorporated in
1976; in 1996 the city was dissolved in favor of the traditional village council government.
The 2000 US Census places the population of Atmautluak at 294; this is up from 258 in 1990 and 219 in
1980. No population data is available from before 1980. Nearly 96 percent of the population is all or in
part Alaska Native. There are 64 housing units in the community.
Access
A State-owned 3,300-foot-long by 60-foot-wide gravel airstrip is available year-round. Scheduled air
service to and from Bethel is available daily. The area is accessible during the summer by skiffs
navigated along the waterways. During winter four wheelers, snow machines, and dog sleds are used.
Also during the winter, a trail exists to Nunapitchuk.
Most transportation within the community is accomplished using timber boardwalks (Figure 2). These
boardwalks keep the residents and ATVs out of the tundra, and prevent the development of very
muddy travel ways on the ground. Boardwalks serve pedestrians as well as ATVs. Boardwalks in the
community must be adequate to serve the four wheelers that haul waste to the sewage lagoon.
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Figure 2: Village of Atmautluak illustrating typical boardwalk and grass
Economy
The school, retail businesses and the village government provide cash income to supplement the
subsistence lifestyle. Thirty-one residents hold commercial fishing permits. The per capita income for
Atmautluak is listed as $8,500 and the median household income is $37,917. Nearly 70 percent of
residents qualify as living above the poverty level.
Geology
Atmautluak is located within the physiographic province known as the Yukon Kuskokwim Lowlands,
characterized by flat terrain with slow-moving, meandering rivers and numerous lakes and ponds. The
soil in the area is covered by a thick sequence of Quaternary deposits, consisting of interstratified
alluvial and marine sediments, generally consisting of silt and sand.
Climate
The area experiences summer and winter temperature ranges of 42 to 62 and -2 to 19 degrees
Fahrenheit, respectively. Also for this area, there is an average of 16 inches of precipitation and 50
inches of snowfall.
Global warming is currently impacting Alaska and will continue to impact it in a number of ways. These
impacts include melting polar ice, the retreat of glaciers, increasing storm intensity, wildfires, coastal
flooding, droughts, crop failures, loss of habitat and threatened plant and animal species. In
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Atmautluak, the expected impacts could include thawing permafrost, increased storm severity, and
related infrastructure damage to roads, utility infrastructure, pipelines and buildings. Extremes in
weather patterns could contribute to increased erosion.
The effects of climate change can potentially exacerbate melting permafrost which contributes
significantly to ground failure or destabilization of the ground. Such phenomena are addressed later in
the section on foundation considerations. Figure 3 shows the mean annual temperature fluctuation
since 1950.
Figure 3: -20091
Table 1: Increase in Mean Seasonal and Annual Temperatures in Bethel, 1949-2009
Winter +6.6 degrees F
Spring +4.8 degrees F
Summer +2.3 degrees F
Autumn +0.0 degrees F
Annual +3.5 degrees F
1 Alaska Climate Research Center, Geophysical Institute, University of Alaska Fairbanks
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Flooding
Flooding can result from many causes including excessive rainfall, snowmelt, rising groundwater, and
ice jams. The Division of Homeland Security and Emergency Management2 compiles a summary of
State funds spent on disaster relief, called the Disaster Cost Index. No declared disasters are listed for
Atmautluak specifically. The following list of previous occurrences of flood disasters in the Lower
Disaster Cost Index, as revised in February 2009.
Lower Kuskokwim, September 4, 1990 A severe storm compounded by high tides caused extensive
flooding in coastal communities of the Kuskokwim and Bristol Bay areas and along the lower
Kuskokwim River. The flooding caused damage to both public and private property. The disaster
declaration authorized assistance to local governments, individuals and families affected by the
flooding.
06-215 2005 West Coast Storm declared October 24, 2005 by Governor Murkowski then FEMA
declared (DR-1618) on December 9, 2005: Beginning on September 22, 2005 and continuing through
September 26, 2005, a powerful fall sea storm produced high winds combined with wind-driven tidal
surges resulting in severe and widespread coastal flooding and a threat to life and property in the
Northwest Arctic Borough, and numerous communities within the Bering Strait (REAA 7), the
Kashunamiut (REAA 55), the Lower Yukon (REAA 32) and the Lower Kuskokwim (REAA 31) Rural
Education Attendance Areas including the cities of Nome, Kivalina, Unalakleet, Golovin, Tununak,
Hooper Bay, Chevak, Mekoryuk and Napakiak. The following conditions existed as a result of this
disaster: severe damage to personal residences requiring evacuation and sheltering of the residents; to
businesses; to drinking water systems, electrical distribution systems, local road systems, airports,
seawalls, and other public infrastructure; and to individual personal and real property; necessitating
emergency protective measures and temporary and permanent repairs.
Most structures in the community are built on pilings because of the permafrost, the marshy ground,
and the threat of flooding.
Local Infrastructure
Water Infrastructure
In 2004, the Alaska Department of Environmental Conservation (ADEC) prepared a source water
assessment for the Atmautluak water system. A source water assessment is prepared to identify
potential and current sources of contamination with the public drinking water supplies. In this report,
they identify a single well, located under the washeteria structure, as being the source of drinking water
2 Division of Homeland Security & Emergency Management. Alaska All-Hazard Risk Mitigation Plan. Publication.
Anchorage: State of Alaska, Department of Military and Veteran Affairs, 2007. Print
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in Atmautluak. Water is available in Atmautluak through a limited plumbing system that serves the
school and teacher housing, at the washeteria, or at a water distribution faucet located near the
washeteria.
Wastewater Infrastructure
Most of the black (toilet or sanitary) wastewater, as well as water from the school and teacher housing,
is taken to an unlined lagoon approximately 1,000 feet northwest of the town. The lagoon is located
approximately 600 feet north of the edge of the lake that borders the western part of town. The lagoon
is also approximately 400 feet southeast of another large lake. There is currently no wastewater
discharge permit for the lagoon on file with the Alaska Department of Environmental Conservation,
and it may be assumed that the lagoon does not discharge. An organic mass was observed on the
lagoon surface near the point that the honeybuckets are emptied. The water quality of the lagoon is
unknown.
In addition to the honeybuckets, there is an insulated wastewater line that connects the village to the
lagoon. The school, teacher housing, and washeteria are connected to this line. The line is primarily
gravity fed with one lift station located in the central part of the town. The lines are primarily supported
on biped structures placed on wooden pads on the ground.
Most of the houses in the community operate on a honey bucket system, with several honey bucket
dumping stations located around the town. The material in the dumping stations is collected regularly
and transferred to the sewage lagoon
Historically, the wastewater from the town, and in particular the school and teacher housing, was
disposed of in an unlined lagoon in the central part of town, approximately 200 feet from the primary
water well. This lagoon is fenced to prevent access to the area.
A new, wastewater treatment plant has been constructed to treat the wastewater from the school and
the teacher housing. Michael Willyerd, principal at the Joann A. Alexie School, stated that it is the
intent of the school district to discharge the treated water into the old lagoon in the central part of the
community, although this has not been finalized.
Electricity/Communication Infrastructure
The buildings in the community are served by power and telephone lines located atop wooden poles
(Figure 4). Most, if not all, of these poles have been cut off at the base and attached to steel H-piles.
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Figure 4: Timber utility posts have been cut off near the ground surface and attached to H-piles..
The Village reports that this was done to provide additional stability to the poles, which were beginning
to show signs of frost jacking and tipping.
Two towers were observed to the west of the runway. Several of the guy lines appeared to be slack,
which may reduce the stability of the towersparticularly in high wind events.
Solid Waste Disposal
Solid waste from Atmautluak is taken approximately one mile upstream of the village for disposal. The
main disposal area is a partially fenced pond located several hundred feet back from the Pitmiktakik
River. This area is not a permitted landfill by the Alaska Department of Environmental Conservation.
The landfill is located across the river and far enough away from the village that it likely does not
present a direct potential health impact to thecommunity.
Fuel Storage Areas
Diesel for power and heat, as well as gasoline, is stored on an elevated fuel storage platform in the
central part of the community (Figure 5). This structure is founded on steel piles and appears to be in
good condition. Fuel lines leaving the structure generally consist of steel pipe that is placed on the
ground surface with occasional wooden blocks placed underneath to provide some support. The pipes
are physically unprotected from traffic and are often located within standing water.
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Figure 5: Pile Support Fuel Storage Facility
Small Structures
Most of the structures in the community are built on pile foundations with an exposed air space under
the structure to reduce the heat transfer between the structure and the ground. Most of the observed
piles were wooden piles that were 8 to 16 inches in diameter. For a few structures, including newer
houses and the fuel storage platform, steel piles are used. A few residences, as well as most of the
smokehouses or smaller structures, are founded on timbers placed on the ground surface. Several of
these structures have undergone significant differential settlement.
Boardwalks and Roads
Boardwalks are used to protect the tundra and provide a walking and driving surface between most of
the structures in the village. These boardwalks appear to be founded on shallow piles located along the
length of the paths. The boardwalks were observed to undulate up to approximately six inches
(primarily settlement) in isolated areas, but were generally usable without difficulty. Evidence of
damage due to localized frost jacking was not observed.
In areas between the runway and the northern part of the village, a gravel surface road is present. The
driving surface of the road was visually estimated to be approximately 1 to 5 feet above the surrounding
grade. It is not known if the road is insulated. Community members state that the road has been
undergoing some settlement in recent years.
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Wind-Diesel Hybrid System Overview
As of December 2011, there is a total of 15.3 megawatts of wind energy installed throughout the state
of Alaska of which 93% are remote, isolated wind-diesel hybrid systems. There are now over 24 wind-
diesel projects in the state alone, making Alaska a world leader these technologies. There are a variety
of system configurations and turbine types that are currently being used and accordingly there is a
spectrum of success in all 24 of these systems. As experience and statewide industry support has
increased so has overall system performance. Figure 6 below indicates the locations of the installed
wind projects in Alaska.
Figure 6: Installed Wind Projects in Alaska
Some communities, such as in Perryville, have decided to install redundant small wind turbines
(Skystream 2.4 kW) in order to allow local laborers to easily take down and service if and when needed.
However, the economic benefit is not as great for this type of system because the opportunity to have
economies of scale is limited. Therefore, when an ultimate system configuration is selected it is
important to clearly understand the priorities and values of the client which may include but are not
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limited to economic viability ease of maintenance, diesel fuel offset for thermal energy and percentage
renewable energy.
Other communities, such as Kodiak Island, have chosen to install large scale turbines (GE 1.5 MW)
which greatly reduces the installed cost on a per kilowatt basis and increases the overall amount of
wind energy in their community. Kodiak Island has an aggressive goal of being 95% renewable by 2013
and they are in line to reach this target. To install a system of this size cranes must be used and Kodiak
Electric Association is more reliant on the outside expertise of GE if and when there are issues. To
reduce this dependency Kodiak Electric has sent their technicians outside for training.
In addition to turbine size, systems are configured to have different percentages of renewable
contributions. Some communities such as in Nome have less than 10% of their energy coming from
wind while others have significantly higher percentages. Figure 7 indicate the configuration and key
points on using a low penetration, wind-diesel system.
Figure 7: Low Penetration Wind-Diesel Configuration3
Many of the AVEC communities, Toksook Bay for example, have 24% of their energy from wind. Figure
8 indicates the configuration and key points on using a medium penetration, wind-diesel system.
33 Ginny Fay, Katherine Keith
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Figure 8: Medium Penetration Wind-Diesel Configuration
Other communities, such as Kokhanok, are more aggressively seeking to offset diesel used for thermal
and electrical energy. They are using configurations which will allow for the generator sets to be
turned off and use a significant portion of the wind energy for various heating loads. The potential
benefit of these systems is the highest, however currently the commissioning for these system types
due to the increased complexity, can take longer. Figure 9 indicates the configuration and key points
on using a high-penetration, wind-diesel system.
Figure 9: High-Penetration Wind-Diesel Configuration
The above system descriptions can be summarized in Table 2 below. The level of instantaneous
penetration is important for power quality design considerations. The annual amount of wind energy
on the system is considered the average penetration level and helps to provide a picture of the overall
economic benefit.
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Table 2: Categories of Wind-Diesel Penetration Levels
Penetration
Category
Instantaneous
Penetration
Level
Average
Penetration
Level
Operating characteristics and system requirements
Low Less than 50% Less than 20%
Diesel generation runs full-time
Requires little or no changes to existing diesel control
system
All wind energy generated goes to the primary load
Medium 50% to 80% 20% to 50%
Diesel generation runs full-time
Requires relatively simple new control system with
automation and set-point control, and secondary
loads such as electric boilers
At high wind power levels, secondary loads are
dispatched to absorb energy not used by the primary
load, or wind generation is curtailed
High 80% to 200% 50% to 100%
Diesel generation may be shut down during periods
of high wind power levels
Requires sophisticated new control system and
additional components (including demand-managed
devices and more advanced controls to regulate grid
voltage and frequency)
At high wind power levels, secondary loads and/or
demand-managed devices are dispatched to absorb
energy not used by the primary load.
High-
Diesels Off
200% and
above
Greater than
50%
Diesel generation will be shut down during periods of
high wind power levels
Requires sophisticated new control system,
additional wind capacity, and additional components
(including demand-managed devices and more
advanced controls to regulate grid voltage and
frequency)
At high wind power levels, secondary loads and/or
demand-managed devices are dispatched to absorb
energy not used by the primary load.
Wind-Diesel S ystem Components
Listed below are the main components of a medium to high-penetration wind-diesel system:
Wind turbine(s)
Tower and foundation
Power line (including transformers and cabling)
Managed load devices
Power control electronics
Communications and monitoring systems
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Supervisory Control System
Medium- and high-penetration wind-diesel systems require fast-acting real and reactive power
management to compensate for rapid variation in village load and wind turbine power output. A wind-
diesel system master controller, also called a supervisory controller, would be installed inside the
existing Atmautluak power plant, or in a new module adjacent to it. The supervisory controller would
select the optimum system configuration based on village load (demand) and available wind power.
Two examples of a wind-diesel system supervisory controller are the ABB distributed control system
and the Sustainable Power Systems master control system. Both are pre-configured to operate with
multiple diesel gen-sets, wind systems, and demand-managed devices. The ABB system is broken into
several layers of operation, with each controller device in communication with the others:
Station Controller: schedules each of the lower units, performs remote control functions and
stores collected system data
Generation Controller: monitors and controls a single diesel generator
Demand Controller: monitors, controls, and schedules demand-managed devices such as a
synchronous condenser or electric boiler, to insure that sufficient generation capacity is online.
Feeder Monitor: monitors vital statistics of the distribution feeder, including ground fault
information
Wind Turbine Controller: monitors the wind turbine it is connected to, and dispatches wind
turbines depending on the wind-of wind
energy.
The Sustainable Automation control system uses many similar components to the ABB system.
Functions of the Sustainable Automation Hybrid Power System Supervisory Controller include:
Diesel dispatch: starting and stopping the diesel generator(s) according to the diesel capacity
required
Wind turbine dispatch: allow/inhibit wind turbine operation as necessary
Secondary load dispatch: determining the required amount of power sent to the secondary load
at any given instant
Diesel status monitoring
Wind turbine status monitoring
Performance data logging: kWh and run-time totals, alarms, etc.
Fault detection and annunciation
Provide for remote access via dialup or internet connection
Several Alaskan electrical engineering and construction firms have also been involved with wind-diesel
power systems. Electric Power Systems, Inc. of Anchorage has been working with Kotzebue Electric
Association on their large wind diesel project and has also worked with Cordova electric on a hydro-
diesel project. They have extensive power generation and PLC control experience.
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Synchronous Condenser
A synchronous condenser, sometimes called a synchronous compensator, is a specialized synchronous
electric motor whose shaft is not attached to anything, but spins freely. Its excitation field is controlled
by a voltage regulator to either generate or absorb reactive power as needed to supp
support is essential for a wind-
For a power system the size of Atmautluak (Figure 10) is considered to be a
more economic option for voltage and reactive power support than a flywheel as discussed below.
Figure 10: Synchronous Condenser at Kokhanok
Secondary/Interruptible Loads
Secondary load, or rapidly shift
winds, is required for a wind-diesel hybrid power system to operate reliably and economically. The
secondary load converts excess wind power into thermal power for use in space and fluid heating.
Electric heating, either in the form of electric space heaters or electric water boilers, should be explored
as a means of displacing stove oil with wind-generated electricity. It must be emphasized that electric
heating is only economically viable when using excess electricity provided by a renewable energy
source such as wind, and not from diesel-generated power. It is typically assumed that one gallon of
heating fuel oil is equivalent to 41 kWh of electric heat.
An electric boiler is a common secondary load device used in wind-diesel power systems.
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Figure 11: Screen of a Secondary Load Controller Depicting the Frequency Control Function
As seen in Figure 11, a secondary load controller serves to stabilize system frequency by providing a fast
responding load when gusting wind creates system instability. Note the stability of the curve which
indicates rapid response of the controls.
Storage Options
Electrical energy storage provides a means of storing wind generated power during periods of high
winds and then releasing the power as winds subside. Energy storage has a similar function to a
secondary load but the stored, excess wind energy can be converted back to electric power at a later
time. There is an efficiency loss with the conversion of power to storage and out of storage. The
descriptions below are informative but are not currently part of the overall system design.
Flywheels
A flywheel energy system has the capability of short-term energy storage to further smooth out short-
term variability of wind power, and has the additional advantage of frequency regulation. However, a
flywheel system is much more expensive than a synchronous condenser. A Powercorp flywheel unit of
500 kW capacity, the smallest commercially available for a remote wind-diesel application such as
Atmautluak
storage technologies for the Alaska Energy Authority by WHPacific. This is the equivalent estimated
installation cost of an entire 200-kW Atmautluak wind-diesel system using a synchronous condenser.
Batteries
Battery storage is a well-proven technology and has been used in Alaskan power systems including
Fairbanks (Golden Valley Electric Association), Wales and Kokhanok. Kotzebue Electric Association will
be installing a 250kW battery storage system in 2011. Batteries are most appropriate for providing
medium-term energy storage to allow a transition, or bridge, between the variable output of wind
Storage for several hours or days is also possible with batteries, but requires more capacity (and more
Page | 21
cost). In general, the disadvantages of batteries for utility-scale energy storage, even for small utility
systems, are high capital and maintenance costs, and limited lifetime. Of particular concern to rural
Alaska communities is that batteries tend to be heavy to ship, and many contain toxic materials that
Because batteries operate on direct current (DC), a converter is required to charge or discharge when
connected to an alternating current (AC) system. A typical battery storage system would include a bank
of batteries and a power conversion device. The batteries would be wired for a nominal voltage of
roughly 300 volts. Individual battery voltages on a large scale system are typically 1.2VDC. Recent
advances in power electronics have made solid state inverter/converter systems cost effective and
preferable as a power conversion device. The Kokhanok wind-diesel system used a 300VDC battery
bank coupled to a grid-forming power converter for production of utility-grade real and reactive power.
The solid state converter system in Kokhanok was commissioned in the spring of 2012 and will be
monitored for reliability and effectiveness. Figure 12 highlights battery systems installed in Kokhanok
and in Wales.
Figure 12: Battery Systems from Kokhanok and Wales
There are a wide variety of battery types with different operating characteristics. Advanced lead acid
and zinc-
appropriate for
Alaska Center for Energy and Power. Nickel-cadmium (NiCad) batteries have also been used in rural
Alaska applications, such as the Wales wind-diesel systems. Advantages of NiCad batteries compared
to lead-acid batteries include a deeper discharge capability, lighter weight, higher energy density, a
Page | 22
constant output voltage, and much better performance during cold temperatures. However, NiCads are
considerably more expensive than lead-acid batteries. A November 2010 quote from Sustainable
Automation reported the equipment-only cost of a 250 kW/480 kWh capacity lead-acid battery system
would cost $315,000, not including shipping or other installation costs.
Wind Turbine Options
Vestas V17
Two V17s installed in Kokhanok, Alaska are shown in Figure 13 on lattice towers.
Several companies worldwide are now refurbishing the Vestas V17 wind turbines for resale. The
V17 model has a power rating of 90kW. The refurbished Vestas machines include a warranty.
Budgetary cost of a refurbished V17 is $300,000 which includes a tubular tower, controller, and
all ancillary equipment needed.
Vestas V17 turbines are presently installed and operating in Alaska. Kotzebue, Kokhanok and
Nikolski have installed these machines. The machine can be tilted up, if desired, thus not
requiring a crane for erection which can be a cost savings.
The Vestas V17 uses an induction type generator and stall regulation.
Figure 13: Kokhanok V17s Courtesy of Marsh Creek
Northern Power Systems Northwind100
Six Northern Power NW100B turbines from Unalakleet are shown in Figure 14.
The Northwind100 (or NW100) has a 100 kW nominal rated capacity
Output is 3 phase, 480 VAC, 60 Hz.
The NW1
Manufactured by Northern Power Systems of Barre, Vermont
Cost of NW100 Arctic (not including installation or shipping): $375,000
Page | 23
Figure 14: Unalakleet NW100 Turbines
The Alaska Village Electric Cooperative (AVEC) and Kotzebue Electric Association have extensive rural
Alaska experience working with the Northwind 100 (or NW100), which has proven more reliable than
other similar-sized turbines. -diesel installations,
including the three wind turbines that AVEC has installed at Kasigluk. The NW100 Arctic, a new version
of the turbine with additional features and design enhancements for cold-climate operation, is
recommended for the Atmautluak wind-diesel system.
Community Energy Use
Heating/Diesel Fuel
Diesel for power and heat, as well as gasoline, is stored on an elevated fuel storage platform in the
central part of the community. This structure is founded on steel piles and appears to be in good
condition. Fuel lines leaving the structure generally consist of steel pipe that is placed on the ground
surface with occasional wooden blocks placed underneath to provide some support. The pipes are
physically unprotected from traffic and are often located within standing water.
The price of residential heating fuel without taxes has increased over 100% since 2007 for many villages
in the Calista region. At one point, an estimated 60-70% of family disposable income went to energy
costs. In 2009, increasing energy costs led to a humanitarian crisis; where low income families were
unable to purchase fuel, electricity, and food from the local store. Local media attention resulted in
food drives and donations to villages in the Yukon Delta.
Page | 24
The reported retail rate for other fuels in Atmautluak was $5.45/gallon for heating fuel, $5.50/gallon for
gasoline.
Transportation
As previously stated, the area is accessible during the summer by skiffs navigated along the waterways.
During winter four wheelers, snow machines, and dog sleds are used. Also during the winter, a trail
exists to Nunapitchuk.
Boardwalks are used to protect the tundra and provide a walking and driving surface between most of
the structures in the village. These boardwalks appear to be founded on shallow piles located along the
length of the paths. In areas between the runway and the northern part of the village, a gravel surface
road is present. The driving surface of the road was visually estimated to be approximately 1 to 5 feet
above the surrounding grade.
Electricity
Electricity is provided by the Atmautluak Joint Utilities Company.
The buildings in the community are served by power and telephone lines located atop wooden poles.
Most, if not all, of these poles have been cut off at the base and attached to steel H-piles. The Village
reports that this was done approximately two years ago to provide additional stability to the poles,
which were beginning to show signs of frost jacking and tipping.
According to Atmautluak Joint Utilities, the diesel power plant generated 806,771 kWh in 2011, with an
average annual load of 92 kW. The peak load of the Atmautluak system is estimated to be about 150
kW.
Monthly generation and fuel consumption statistics for 2009 are presented in Table 3, and average
monthly electric loads for 2009 are graphed in Figure 15.
Figure 15: PCE Trending Data - kWh Generated and Fuel Consumed
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
900,000
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Fiscal Year
Atmautluak PCE Trending Data: kWh Generated and Fuel Consumed
kWh Generated
Diesel Fuel Consumed
Diesel Fuel Consumed
Page | 25
Figure 15 highlights how the kilowatt-hour generation varies significantly since 2002. This could be
indicative of partial reporting during 2004 and 2008. The decreasing trendline (black) does not warrant
a projected increase in annual electrical consumption during modeling.
During 2011, 53,865 gallons of fuel was used for power generation in Atmautluak, at an average diesel
generation efficiency of14.9 kWh per gallon (Figure 16-blue line).
Figure 16: PCE Trending Data-Cost of Fuel and Efficiency
Figure 16 indicates how the cost of fuel almost doubled in the past ten years (red line). The overall
system efficiency has stayed steady.
Figure 17: PCE Trending Data- Fuel Cost per kWh and non-PCE Residential Rate
The red line in Figure 17 indicates how the fuel cost per kilowatt-hour has increased and the blue line
depicts the cost of electricity before the power cost equalization subsidy is applied, if available. For
Atmautluak the reported pre-subsidy residential cost of electricity for 2011was $0.70 per kWh.
0
2
4
6
8
10
12
14
16
$-
$1.00
$2.00
$3.00
$4.00
$5.00
$6.00
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Fiscal Year
Atmautluak PCE Trending Data: Cost of Fuel and Efficiency
Cost of Fuel
Efficiency
Cost of Fuel
$0.0000
$0.1000
$0.2000
$0.3000
$0.4000
$0.5000
$0.6000
$0.7000
$0.8000
$0.9000
$-
$0.05
$0.10
$0.15
$0.20
$0.25
$0.30
$0.35
$0.40
$0.45
$0.50
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Fiscal Year
Atmautluak PCE Trending Data: Fuel Cost per kWh and non-PCE Residential Rate
Fuel Cost per kWh
Non-PCE Rate
Fuel Cost per kWh
Page | 26
Water/Sewer
The Calista Corporation indicates that the homes in Atmautluak currently do not have plumbing and
funds for a Master Plan for infrastructure development, which includes a new landfill, have been
requested4.
See earlier information about the Water Infrastructure for more information.
4 Calista Corporation, http://calistacorp.com/shareholders/village/atmautluak
Page | 27
Power Cost Equalization Data
Table 3: Atmautluak Joint Utilities Monthly Data for 2009
Month # Days in
Month
kWh
Generated
Monthly
Average Load
(kW)
Fuel Used
(gal)
Average Diesel
Efficiency (kWh/gal)
January 31 63,379 85 5,012 12.6
February 28 60,713 90 4,109 14.8
March 31 59,801 80 4,579 13.1
April 30 47,687 66 4,006 11.9
May 31 49,221 66 4,094 12.0
June 30 52,568 73 4,288 12.3
July 31 49,901 67 4,464 11.2
August 31 54,940 74 3,810 14.4
September 30 58,662 81 4,469 13.1
October 31 56,555 76 4,341 13.0
November 30 59,326 82 4,604 12.9
December 31 66,376 89 6,125 10.8
Annual 365 679,129 78 53,901 12.6
As is typical for Alaskan communities, the electrical load is highest during the winter (Figure 18).
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Figure 18: Average Monthly Electric Load of Atmautluak Joint Utilities for 2009
Table 4: PCE Data (* Denotes Derived Numbers Based on Average Efficiency)
Fiscal Year Total kWh
Generated
Total Fuel Used
(gallons) Avg. Price ($) Diesel
Efficiency(kWh/gal)
2002 851,700 62,276 1.58 13.68
2003 795,345 57,630 1.34 13.8
2004 475,326 59,098 1.80 13*
2005 637,221* 49,017 2.19 13*
2006 700,752* 53,904 2.46 13*
2007 701,103* 53,931 3.22 13*
2008 546,475 51,029 3.01 10.71
2009 658,951 53,409 3.99 12.34
2010 701,103* 58,821 13*
2011 806,771 53,865 3.36 14.98
-
10
20
30
40
50
60
70
80
90
100
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Page | 29
Atmautluak Wind Ener gy R esource
January 2007 wind resource assessment in Atmautluak, included in
Appendix A, over
13 months between October 21, 2005 and December 4, 2006 from a 30-meter NRG met tower in
Atmautluak, the annual average wind speed recorded was 7.16 m/s (16.0 mph) with north identified as
the prevailing wind direction. Taking into account the local air density and wind speed distribution, the
average wind power density for the met tower site is 477 W/m2. The month of highest average reported
wind speeds during this period was February, and the month with the lowest average wind speeds was
September. Table 6 provides a breakdown of wind characteristics.
Table 5: Wind Resource Characteristics
Variable Value
Mean Annual Wind Speed 7.16 m/s
Mean Annual Power Density 477 W/ m2
The met tower was located at W (NAD83 coordinates converted from
NAD27 coordinates in 2007 AEA wind resource report), at 4 meters elevation, or about 800 feet
southeast from the North Site.
Figure 19: Wind Frequency Rose and Total Wind Energy Rose
As seen in the Wind Frequency Rose (Figure 19) the majority of the winds are from the northwest and
the northeast. This is consistent with the Total Wind Energy Rose. The south winds, while less frequent
than the northern winds, are high energy winds.
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Figure 20: Monthly Wind Speed Profile
Figure 20 indicates that the strongest winds occur during the winter months which dovetail nicely with
the village electric load.
Initial Environmental Review
The environmental permitting steps below are based on the publication Alaska Wind Energy
Development: Best Practices Guide to Environmental Permitting and Consultations , a study done by the
URS Corporation for the Alaska Energy Authority in 2009.
Alaska Pollution Discharge Elimination System
State regulations (18 AAC 83 APDES) require that all discharges, including storm water runoff, to
surface waters be permitted under the Alaska Pollutant Discharge Elimination System (APDES) permit
program, which aims to reduce or eliminate stormwater runoff that might contain pollutants or
sediments from a project site during construction. The construction of one or more wind turbines, and
the connecting access road and power line, in Atmautluak would likely disturb one acre or more of soil,
nstruction General Permit (CGP) and have a
Storm Water Pollution Prevention Plan (SWPPP). The construction contractor must submit a Notice of
Intent (NOI) to Alaska Department of Environmental Conservation (DEC) before submitting a SWPPP.
The DEC issues the final APDES permit for the project after review and public comment periods.
Page | 31
US Fish and Wildlife Service
Atmautluak is located in an area that is mapped by the Anchorage US Fish and Wildlife Service
for listed species under the Endangered Species
Act (ESA). Anchorage Fish and Wildlife
l
Atmautluak Traditional Council must also be aware of USFWS regulations and guidance under the
Migratory Bird Treaty Act, which prohibits the taking of active bird nests, their eggs and young. USFWS
The bird
window in the Atmautluak area is May 5 to July 25 except for Canada geese and swan habitat where the
window begins April 20 and for black scoter habitat where the window closes August 10. Clearing
before or after these dates is allowed. Clearing and construction activity during the window is not
allowed.
The USFWS Wind Turbine Guidelines Advisory Committee developed guidelines and recommendations
for wind power projects to avoid impacts to birds and bats. These recommendations were sent to the
Secretary of the Interior in March 2010 and should be referred to during design and construction.
Federal Aviation Administration
Determination of No Hazard to Air Navigation
Atmautluak Traditional Council will be required to file an FAA Form 7460-1 (Notice of Proposed
Construction or Alteration), as the proposed wind turbine site(s) are less than one mile from the
Atmautluak airport. Obstruction lighting on the wind turbine(s) is likely to be required.
Alaska Department of Natural Resources
Alaska Coastal Management Program Consistency Review
The Alaska Department of Natural Resources (ADNR)-administered Alaska Coastal Management
Program (ACMP) evaluates projects within the Coastal Zone, which includes Atmautluak, for
consistency with statewide standards and other local Coastal District enforceable policies. The ACMP
consistency review is a coordination process involving all federal and state permitting authorities within
the Ceñaliuriit Coastal Resource Service Area (CRSA), where Atmautluak is located.
The project design consultant will, on behalf of Atmautluak Traditional Council, fill out a Coastal Project
Questionnaire (CPQ) and consistenc
Page | 32
Ocean Management (DCOM). After a public comment and review period, DCOM will issue a final
consistency determination.
State Historic Preservation Office (SHPO) consultation
The project design consultant will complete a consultation under Section 106 of the Historic
Preservation Act with the State Historic Preservation Office (SHPO), to receive a letter concurring that
a wind project would affect no historic properties.
US Army Corps of Engineers
Because
much or all of the proposed wind turbine site(s) in Atmautluak are located on wetlands, Atmautluak
Traditional Council must receive a Section 404 permit from the Alaska District USACE.
Wetlands and Waterways
The project area was reviewed for the presence and distribution of wetlands and aquatic resources. The
US Fish and Wildlife Service (USFWS) National Wetland Inventory Wetland Mapper (2012) was used to
identify wetlands and water bodies in the project area.
Current data is not available on the Wetland Mapper for Atmautluak, Alaska. However, there is digital
information available on this site for nearby and similar landscapes.
The area is characterized by Freshwater Emergent wetlands with many Lake, Freshwater Pond, and
Riverine features. In wind energy development projects, wetland loss is largely due to road
construction and foundations for wind turbines. The NWI Wetland Mapper indicates complete coverage
of the proposed project area by freshwater emergent, freshwater pond, lakes, and rivers. All of these
features and resources are regulated by the US Army Corps of Engineers (USACOE). Fill placement and
other discharges of construction materials into these features requires a section 404 permit from the
Army Corps and may require mitigation and/or restoration of impacted habitats.
Fisheries
Atmautluak is located on the west bank of the Pitmiktalik River (AWC code 335-10-16600-2197-3115).
Fish collection records provided by the Alaska Department of Fish Game on the interactive Fish
Resource Monitor indicate use of project area waterways by resident and anadromous fish species
(2012). Records indicate the occurrence of sheefish (Stenodus leucichthys) and whitefish (Prosopium
cylindraceum). The Pitmiktalik River is a tributary to the Johnson River (335-10-16600-2197) which also
contains sheefish and whitefish. The Johnson River is leads to the Koskokwim River (335-10-16600)
which contains Chinook (Oncorhynchus tshawytscha), Coho (Oncorhynchus kisutch) , Chum
(Oncorhynchus keta), Pink (Oncorhynchus gorbuscha), Sockeye (Oncorhynchus nerka), Arctic lamprey
Page | 33
(Lampetra camtschatica), humpback whitefish (Coregonus oidschian), least cisco (Coregonus said),
Pacific lamprey (Lampetra tridentrate), sheefish, and whitefish.
There are numerous small and large lakes in the area. The prominent large lake in the area,
Nunavakanukakslak Lake, includes wetland areas that nearly surround the land where Atmautluak is
located. This lake also contains sheefish and whitefish.
Waterway crossings, in-water structures or any impact to fish and essential fish habitat will require a
Fish Habitat Permit from ADF&G and may trigger the need for mitigation activities and implementation
of specific BMPs during project operation, maintenance, and development. The project vicinity is
within the range of Essential Fish Habitat for a number of salmonid species. Project impacts to EFH
waters may require consultation with the National Marine Fisheries Service.
Vegetation
The vegetation community that dominates the lands surrounding Atmautluak is classified as wet-sedge
and moss community wetlands (Raynolds et al., 2005). This plant community is dominated by
emergent wetland vegetation with few woody species.
Avian Resources
Avian species which are commonly known to be at risk of impacts at wind farms are falcons, passerines,
and large birds such as geese. Pre-construction surveys of bird use in planned turbine placement areas
may be needed depending on consultation feedback from the USFWS and Park Service Biologists.
In the case that site-specific monitoring becomes a part of this wind energy project, it may include
studies on bird use and flight patterns near proposed sites, different species that frequent the site,
flight altitude of bird species, and specific times of year birds frequent the area, and known power line
collisions.
The Migratory Bird Treaty requires consultation with USFWS if there may be a potential impact to
migratory bird species protected by the Act. The Bald and Golden Eagle Protection Act additionally
prohibits harm, possession or take of bald and golden eagles and requires a permit through USFWS if
potential impact to bald or golden eagle, or if it is necessary to move a golden eagle nest.
-
windows established by the USFWS under the Migratory Bird Treaty Act. Apply the Yukon-Kuskokwim
Delta timing window guidelines to project planning: The project area no-clearing window in which
vegetation removal should be avoided is May 5th July 25th. If an active nest (indicated by eggs, live
chicks, or presence of adults on nest) is encountered at any time, including before or after no-clearing
window, leave it in place until young hatch and depart. For black scoter habitat the window extends to
Page | 34
August 1. Black scoter nesting habitat consists of dense thickets of knee-high or taller dwarf birch and
willow, along lakes and ponds in coastal and upland tundra. Canada geese and swan habitat: begin
April 20th.
Yellow-billed loon (YBLO)
Atmautluak is within or near the range of the Yellow-billed loon (Gavia adamsii). YBLO nest in coastal
and inland low-lying tundra with permanent fish-bearing lakes and forage in nearshore and offshore
waters near their breeding grounds during summer. Migration routes are thought to be primarily
marine (USFWS 12-Month Finding, 2006, pp.22-23), but during spring and fall migration, these birds
use coastal waters, rivers, and large inland bodies of water (Audubon, n.d., Natural History).
YBLO is a candidate for federal listing under the Endangered Species Act. Breeding is thought to be
limited by available habitat. These birds are shy and will flee their nest if disturbed, leaving eggs or
young vulnerable to predation. Gravel extraction and road construction are two of the main
conservation concerns for YBLO, and their habitat is sensitive to infrastructure development
disturbance, wetland filling, hydrology alterations or thermokarst action (USFWS Conservation
Agreement, 2006).
Page | 35
Figure 21: Yellow-billed Loon Range Map. (Alaska Department of Fish and Game, 2012)
(Polysticta stelleri), or Spectacled eiders (SPEI) (Somateria fischeri), both of which are federally
listed as Threatened (Figures 22 and 23). The use of the project corridor by these species may be
considered in future consultation efforts for the project and should be reviewed with USFWS
personnel prior to final site determination and development.
Page | 36
Figure 22: Spectacled Eider Critical Habitat Map. (USFWS, 2004, Spectacled eider).
Figure 23: Eider Critical Habitat M
Page | 37
Bats
While some bat species do occur in portions of Alaska, the project area is not in current range of any bat
species.
Other Mammals
The project corridor is expected to be within the range of numerous large and small mammals. Further
consultation and analysis of the effects of turbine placement is needed to ensure limited disruption to
migrations and habitat access on a specific site basis.
Other large mammals that may be in, or pass through the area include, wolf (Canis lupus), moose (Alces
alces), wolverine (Gulo gulo), caribou (Rangifer tarandus) Arctic fox (Alopex lagopus), snowshoe hare
(Lepus othus), and a number of other smaller mammals.
Federally Listed Species
There are no federally listed or candidate species with critical habitat in the Atmautluak area. Although
eider and yellow-billed loon may be in or pass through the area on a seasonal
basis.
Cultural Resources
Atmautluak is a subsistence and fishing village with a population around 275 people (2010 census). It
mo for thousands of years, though not settled until the
government in 1996.
The community has a school with 110 students, and one health clinic. Residents use treated well water,
and water from the Pitmiktakik River. The village has electricity, but does not have plumbing.
Site & Powerhouse Assessment
Brian Yanity, formally of WHPacific visited Atmautluak on September 2nd, 2010 to assess the diesel
power generation system, switchgear and ancillary equipment, as well as inspect possible wind turbine
sites. Atmautluak Joint Utilities staff provided tours of the existing diesel powerhouse, the prospective
wind turbine sites, as well as documentation and drawings. Daniel Waska, Atmautluak Tribal
Administrator at that time, presented a map with potential wind turbine sites identified by the
. Dennis Sharp completed a site visit on February 3rd,
2012 to obtain further detail on the powerhouse. Edward Nicholi, current Tribal Administrator, met
with Mr. Sharp. Both field visit reports, with photos of the wind sites and powerhouse, are attached as
Appendix G.
Page | 38
During the site visit, the wind-diesel project concept and pending grant proposal to the Alaska Energy
Traditional Council. At the community meeting, several residents expressed support for wind energy,
saying
concerns were expressed other than a question about how the state grant funds would be
administered.
Atmautluak Joint Utilities- Existing Power System
The cost of fuel purchased by Atmautluak Joint Utilities in 2010 was reported as $3.3688/gallon
(although some fuel purchased for $5.20/gallon was shipped in during the winter of 2010 due to a
temporary fuel shortage). The reported pre-subsidy retail cost of electricity for 2010 is $0.69860/kWh.
The existing three diesel generator sets in the power plant (Figure 24) are detailed in Table 7.
Figure 24: Atmautluak Joint Utilities Powerhouse
Table 6: Atmautluak Joint Utilities existing diesel generators
Gen-set
# Capacity Generator Engine
1 180 kW
225 kVA
Marathon Electric
MangaPlus 432PSL1268 (older generator)
Serial # LM-217323-TO95
John Deere 6081HF070
Serial # RG6081H296673
2 250 kW
313 kVA
Marathon Electric
MangaMax DVR 433RSL4019
Serial # WA-568180-0109
John Deere 6081HF070
Serial # RG6081H296672
3 117 kW
146 kVA
Marathon Electric
MangaPlus 431CSL6202
Serial # 705888-0209
John Deere 4045HF485
Serial # 4045HF485
Page | 39
The total generation capacity is 547 kilowatts.
The engines, control systems, and two of the generators were installed in 2008 by Marsh Creek LLC
(Figure 25). The John Deere diesel engines have electronic isochronous governors. The power house has
automated switchgear, with Woodward easYgen 3000 generator control panels and Satek PM130EH
power meters.
Figure 25: Atmautluak Powerplant-Interior
The Atmautluak School has its own diesel generator that is connected to the local distribution system
of Atmautluak Joint Utilities. This generator is used as backup for the school if the community
powerplant is down. In addition, it serves to relieve energy demand on the Atmautluak Joint Utilities
rned on
for several days in August 2010 to reduce load on the overall community grid when the Atmautluak
Joint Utilities power plant was experiencing high temperatures on its diesel engines during relatively
warm weather.
Waste Heat Recover y
Presently there is no waste heat system on the generators. ANTHC is investigating installing a system
in the power house to provide heat to some facilities but it has not been finalized.
In the feasibility study it was proposed to install an electric boiler and secondary load controller in a
module adjacent the power plant, tie it into a new waste heat loop from the generators, and provide a
glycol loop to the store, tribal office, washeteria and school. The tribal office is presently heated by two
Toyo stoves which is not compatible with a glycol-based heating system. An entirely new heating and
ventilation system would need to be installed to add this building to the waste heat loop. The cost of
Page | 40
providing this system has not been investigated. The store heating system type was not verified on our
site visit.
The washeteria and school could be integrated into a glycol loop and are also the largest consumers of
heat in the community. The store and tribal office are adjacent to the proposed loop and could easily
be added to the system at a later date. This glycol loop would be run through arctic pipe above ground
in or adjacent to, an existing utilidor and boardwalk for a distance of approximately 900 feet. As an
alternative, dispatchable electric boilers could be installed in both facilities with a communications link
back to a secondary load controller at the power plant.
Intertie Options
Another possible alternative is the installation of one or more additional 100kW NW100 turbines at
farm in Kasigluk, with a new distribution line connecting the Kasigluk-
Nunapitchuk system to Atmautluak. The Kasigluk wind farm was installed in 2006 with three NW100
turbines, for a total of 300 kW of wind capacity, with a 3-mile distribution line connecting Kasigluk to
Nunapitchuk. A new seven mile distribution line is needed to connect Nunapitchuk to Atmautluak.
-village power line construction costs of $350,000/mile, this line would
cost about $2,450,000. It could be more expensive than this, because of the numerous lakes and ponds
between Atmautluak and Nunapitchuk. AVEC has had considerable success with wind-diesel interties
and this option should be considered for future development. The Atmautluak Traditional Council is
focused on installing wind turbines in Atmautluak and therefore that is the focus of this CDR.
North Site
.
is located about 0.45 miles northwest of the
Atmautluak power plant and about 800 feet NW of the location where the met tower was installed
between 2005 and 2006. The site is located entirely on land owned by Atmautluak Limited, the local
village corporation. See Figure 25.
A 25 feet wide right-of-way easement exists through this site for a winter trail between Bethel and
Nunapitchuk that is no longer used but is recorded in BLM records. A different trail is now used in
winter. Atmautluak Traditional Council is working with BLM on this issue and is expected to resolve this
issue in the near future.
South Site
.
Page | 41
The South Site is also located entirely on land owned by Atmautluak Limited. A particularly marshy
area exists between the existing boardwalk/power line/homes and this site. After freeze-up this area is
more heavily used area than the North Site by snow machines. See Figure 26.
Geotechnical Report
In July 2012 Golder Associates completed a report (Preliminary Wind Tower Site Investigation and
Geotechnical Recommendations) describing the geological concerns with the installation of wind
turbines in Atmautluak. Field exploration occurred in February 2012 at two sites. The preliminary
conclusions show that both a pile foundation system and a gravity system would be feasible options at
both sites. The full report is available for review as Appendix H.
Review of Existing Geotechnical Information
Several soils investigations have taken place in Atmautluak over the years, although there is no local
repository of the soil information and the reports are scattered among local, state, and federal
agencies, as well as various consultants. In August 1997, the Alaska Department of Transportation and
Public Facilities5 conducted a geotechnical investigation in support of runway upgrades in Atmautluak.
The ADOT&PF identified Atmautluak as being in an area of discontinuous permafrost, which is
different from many documents, which identify the area as being in an area of continuous permafrost.
The report also states that the nearer the land is to the warming influence of the Kuskokwim River and
its sloughs and tributaries, the less likely that permafrost is present.
ADOT&PF conducted their drilling program in late March, when the depth of frozen penetration is
expected to be approaching its maximum depth. They drilled 17 borings near the runway to depth of
approximately 10 to 15 feet below the ground surface. They reported approximately 2 to 6 feet of peat
and organics overlying silt to the depth of the investigation. Massive ice was reported in several of the
borings.
Nine of the borings reported soils that were not frozen, although all but one were frozen at the base of
the boring. Most of the borings that were identified as having thawed soils had an unfrozen section
from the base of the seasonally frozen active layer 3 to 6 feet to a depth on the order of 7 feet. Most of
these borings are located in the half of the runway that is away from the village. In boring 17-96,
located at the far end of the runway away from the village, 3 feet of frozen soil was reported over 8 feet
of thawed, wet silt.
5 Alaska Department of Transportation and Public Facilities, 1997, Geotechnical report-Atmautluak airport
reconstruction. Project 51355/AIP 3-02-0379-01, 23 p.
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Shannon & Wilson conducted a subsurface soils investigation for the US Public Health Service in 1993 in
support of a proposed lift station and wastewater lagoon project6 . In that study, twelve borings were
drilled to depths between 12 to 35 feet. The locations are believed to be in the western to northwestern
part of the community. The borings were drilled in May 1993, and thus the active layer was frozen at
the time of investigation.
Frozen soils, peat and ice were observed in the borings to the depths explored. Ice-rich silts, organic
silts and peat layers were observed in most of the borings. Ice was reported in most of the silt and peat
samples observed, with the volume of the ice visually estimated to be up to 25 percent of the soil mass.
Moisture contents in these samples were generally in excess of 40 percent (with a few samples near 20
percent) and several were in excess of 100 percent by weight. Massive ice was observed in several of the
borings, up to approximately four feet thick. Based on the moisture content and visual ice reported in
these samples, these soils are anticipated to be thaw-unstable.
Gray, trace to slightly silty, fine sand (SP) was observed underlying the silts, organics, and massive ice at
depths ranging between 18 to 30 feet, where observed. In Boring DH-4, the sand was observed at
approximately 10 feet below the ground surface. Samples recovered were reported to be well-bonded,
with no visible ice. Moisture contents for samples of the sand were generally measured to be in the
range of 16 to 30 percent.
During this investigation, subsurface soil temperatures were measured using a thermistor string
installed in PVC casing in one of the borings. The results of the ground temperatures indicated warm
frozen soil with temperatures ranging between 31° and 32° between depths of 5 and 30 feet. However,
it may be that the soils had not returned to thermal equilibrium after the drilling and actual soil
temperatures may be lower.
Ground failure related to permafrost is a significant problem in Alaska. Permafrost is frozen ground in
which a naturally occurring temperature below 32 degrees Fahrenheit has existed for two or more
years. Approximately 85 percent of Alaska is underlain by continuous or discontinuous permafrost.
Permafrost can form a strong and stable foundation material if it is kept frozen, but if it is allowed to
thaw the soil can become weak and fail. Fine grained soils with high ice content are most susceptible to
thaw settlement. This may be caused by climate change or because of human activity that heats the
soil or removes insulating cover.
6 Shannon & Wilson, Inc., 1993, Geotechnical services, proposed lift station, honeybucket lagoon, sewage lagoon
and sewage pipeline, Atmautluak, Alaska K-1267, for Public Health Service, Alaska Area Native Health Service June
1993, 50 p.
Page | 43
Figure 26: Aerial Photo of Atmautluak with Proposed Site and Distribution Lines
North Site
South Site
Page | 44
Design Configurations
Low-penetration wind-diesel systems require the fewest modifications to the existing system.
However, they tend to be less economical due to the limited annual fuel savings compared to the total
wind system installation costs.
developed as a medium- or high-penetration system.
An electric boiler is a common secondary load device used in wind-diesel power systems. An electric
boiler (or boilers), coupled with a boiler grid interface control system, in a new module outside the
Atmautluak power plant building, would need to be able to absorb up to 200 kW of instantaneous
energy (full output of the wind turbines). The grid interface monitors and maintains the temperature
of the electric hot water tank and establishes a power setpoint. The wind-diesel system master
controller assigns the setpoint based on the amount of unused wind power available in the system.
Frequency stabilization is another advantage that can be controlled with an electric boiler load. The
boiler grid interface will automatically adjust the amount of power it is drawing to maintain system
frequency within acceptable limits.
The school, tribal building and washeteria represent the largest heating loads in Atmautluak. There is
no form of heat recovery presently employed at the diesel powerhouse, nor is there any kind of local
district heating system. Potential discretionary electric heating loads for a future wind-diesel system
identified during the site visit include:
Electric boiler system at the school
An electric boiler/recovered heat module could be installed next to the existing diesel
powerhouse, with a hot water pipe (hydronic heating loop) extending a length of approximately
washeteria and school (Figure 26). The central location of all of
these buildings, in relation to the existing power plant, could make a district heating system
economically feasible.
Page | 45
Figure 27: Conceptual Layout of Hydronic Heating Loop for District Heating System
Conceptual Design Components
Components of the conceptual Atmautluak wind-diesel system:
Two Vestas V17 or two Northern Power Systems NW100 Arctic wind turbines (Alternative A-
180 kW; Alternative B- 200 kW) installed on permafrost foundations.
The existing electrical distribution is provided by a 3-phase 12470Y/7200 volt overhead system.
This system is energized by a 225kVA pole-mounted transformer bank at the power house. The
3-phase section of the system extends south from the power house approximately 500 feet to
the school and washeteria and north about 500 feet where the phases are split in different
directions to serve residential loads. The majority of the distribution within the village is single
phase. Refer to Appendix C for more information.
To interconnect with the North Site the northern distribution branch would be upgraded to
three phase from the point of the split to its end approximately 1000 feet northwest. The poles
in this distribution currently have cross arms so it would be a relatively inexpensive upgrade.
From this point approximately 1000 feet of new poles and 3-phase conductors would be
Page | 46
required to extend the lines to the turbine site. This distribution could parallel the existing road
to the sewage lagoon to a point nearer the turbines to reduce installation costs.
installed adjacent to the existing diesel power plant building. The power line from the wind
turbine site would connect directly to this new building/module, which would house the
synchronous condenser (if needed), electric boiler/boiler grid interface, power control
equipment, and an insulated hot water tank. The hot water tank, as well as a pump connected
to the district heat system, could be also integrated into a new heat recovery system on the
existing diesel power plant.
The switchgear is fully electronic, using Woodward easYgen 3200 generator controllers, for
generator control and protection. However, some new electronic control systems and panels in
the existing power plant building will be needed for the ancillary components such as the
synchronous condenser and secondary load controller.
A district heating system (Figure 26), consisting of an insulated above-
in length, connecting the electric boiler/hot water tank near the powerhouse to the store, tribal
office, washeteria and school.
An electrical one-line diagram with these components is shown in Figure 28.
Page | 47
Figure 28: Conceptual Wind-Diesel System One-Line Diagram (See Appendix B for Larger Drawing)
Page | 48
Cold Climate Considerations
It is important to the take harsh climate conditions into consideration in Alaska. As the diesel
generators are typically housed in temperature controlled diesel powerhouses harsh climate conditions
would generally in addition to possible outside diesel fuel storage issues be a concern for the wind
turbines and meteorological sensors of a sub-arctic wind-diesel system. Today any commercial wind
turbine manufacturer will be able to supply their wind turbine with a cold climate package that may or
may not include a blade heating option.
Atmautluak is located in the transitional climate zone, which is characterized by long, cold winters and
mild summers. Winter temperatures average -2F to 19F and summer average temperatures between
42F to 62F.
es which causes an unknown percentage of
performance loss. It is currently unclear what the expected impacts of icing will be in Atmautluak.
There are three main phenomena that characterize the problems met by wind-diesel systems in arctic
and sub-arctic harsh climate conditions:
Rime ice
Rime ice is a meteorological phenomenon that arises in certain conditions. Sub-cooled, very small,
water drops are formed that hit the equipment (wind turbines and meteorological equipment) and
freeze into thick layers of ice that may take almost surreal shapes. They often lead to wind speed
sensors and wind vanes being frozen solid, preventing the wind turbine and system controllers to get
the data they need. The sensors may be heated (at a considerable cost) but even heated sensors may
not always be able to overcome rime ice.
Glazed Ice
Glazed ice is also a meteorological phenomenon that arises in certain conditions, but local or regional
characteristics determine which type of icing is relevant for a specific location. Also in case of glazed
icing subcooled water drops are formed that hit the equipment to form a kind of ice glazing on e.g.
wind turbine blades. Such ice glaze layers may be so extensive that they can cause unbalance of the
rotor, forcing the wind turbine controller to shut down the turbine until the glaze ice is melted. They
may also change the aerodynamics of the wind turbine blades to the extent that the wind turbine
controller shuts down the turbine to prevent overload / excessive power production. Wind turbine
manufacturers are beginning to supply blade-heating equipment to deal with that issue. The down time
and the corresponding loss of energy caused by these phenomena may be quite considerable.
Page | 49
Very Cold Temperatures
Very cold temperatures may, in arctic and sub-arctic applications, influence both wind turbine material
properties and lubrication demands, but that will usually be covered by the cold climate packages
provided by the wind turbine manufacturers.
A number of suppliers exist that can supply meteorological sensors (wind speed and direction sensors,
temperature gauges etc.) and met masts that can cope with arctic cold climate conditions.
Wind Turbine Foundation Considerations
Wind turbines installed in the Alaskan arctic require unique foundation design methods. The majority
of the ground in remote Alaska is permanently frozen complicating excavation and creating settlement
issues. Atmautluak is no exception to the rule.
Conventional concrete foundations cause the underlying soils to melt and settle resulting in structural
instabilities. To counteract this, specialized piles are used which incorporate passive refrigeration
techniques to prevent the melting of the surrounding ground. These piles are installed in a predrilled
hole and allowed to freeze back into place. Other options are conventional driven piles or non-
refrigerated freeze-back piles.
A detailed geotechnical report for Atmautluak can be found as Appendix H. The preliminary findings
determine that there is no contraindicative evidence for the installation of wind turbines.
The foundation layout will depend on the tower selected. For the Northwind 100, a single cluster of 6-8
piles would be installed and interconnected by a steel pile cap. The tower base for the turbine would be
attached to the center of this cap.
For the Vestas V17, if a lattice tower is desired, it would require four separate foundations to support
the four tower legs. At each of these locations, a single large pile or a group of smaller piles would be
installed and configured to support the tower leg.
The geotechnical report did yet not consider a Vestas V17 with a monopole tower.
Construction Considerations
Construction should most likely occur during the winter months when the tundra surface is fully frozen
and protected from surface damage from construction activities. If construction activities are planned
at other times of the year, specifically summer and fall conditions when standing water may be present
at ground surface, access roadways and construction pads may be required to protect the tundra
surface.
If access roads and construction pads are required, they may be constructed out of non-structural
mineral soil fill over a woven or non-woven geotextile separation fabric. The roadways and pads should
Page | 50
be designed by the project engineer to accommodate the expected construction and
operation/maintenance needs for the project. If locally available fine-grained or potentially wind or
water erodible materials are used for embankment construction, additional fill protection measures
may be needed.
It is essential that construction planning for the pile foundations include adequate time after installation
to allow for freezeback of the slurry backfill. If installation schedules do not allow for adequate cooling
prior to foundation loading, differential foundation movements may occur8.
Modeling Assumptions
HOMER software was used to simulate conditions at Atmautluak with two Vestas V17 or two
Northwind 100 wind turbines (based on wind resource information collected by the AEA met tower),
running in conjunction with the existing diesel power plant. This software can provide a comparison of
estimated fuel savings, levelized cost of electricity, and emissions from diesel-only and conceptual
wind-diesel configurations. HOMER calculates gross energy production with no allowance for power
plant downtime, turbine or generator maintenance, equipment curtailment or other reasons. The
HOMER Systems Reports for modeling the following six scenarios are included in the Appendix:
Three, two, one and zero (base case) Vestas V17 turbines at $4.40/gallon ($1.16/liter) fuel cost
Two, one and zero (base case) NW100 turbines at $4.40/gallon ($1.16/liter) fuel cost
Electrical Load Data
Electrical load profile information was obtained from Atmautluak Joint Utilities. The average load is 81
-hours per day.
The daily (Figure 29) and monthly (Figure 30) load profiles are detailed below.
Figure 29: Daily Electric Load Profile
8 Golder Preliminary Geotechnical Report. July 2012
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Figure 30: Monthly Load Profile
The annual electric energy consumption of approximately 806,771 2011
generation statistics) is fixed, and it is not assumed in the HOMER model to increase.
The generation-only cost of diesel-generated electricity at the Atmautluak power plant is $0.51
per kWh at $3.36 per gallon fuel cost, given a generation efficiency of 14.98 kWh per gallon
(based on Atmautluak Joint Utilities 2011 statistics).
The non-generation cost of electricity in Atmautluak is assumed to be $0.24 per kWh, which
combined with the assumed diesel generation cost of $0.51, is equivalent to the present retail
rate of electricity of approximately $0.70 per kWh (the diesel-only base case).
Thermal Load Data
Thermal load data for the powerplant was collected from Deering, Alaska. It was then scaled to
represent the likely thermal load, which the diesel gen-sets could meet for Atmautluak. As stated
above there is no current waste heat recovery system in place. Their thermal load has an average
demand of 49 kW and a peak of 171 kW. Excess electricity could offset the use of diesel fuel needed to
meet this demand. Excess electricity could also meet additional thermal loads outside of the
powerplant. The monthly (Figure 31) and daily (Figure 32) load profiles are detailed below.
Figure 31: Thermal Load Monthly Profile-Assumed
Wind Data
Data was collected every 2 seconds, but recorded at 10 minute averages, from October 21st, 2005 to
December 4th
Page | 52
density of 477 W/m^2 and an annual average wind speed of 7.16 m/s. The monthly profile is shown in
Figure 32.
Figure 32: Wind Resource Monthly Profile
Diesels
The diesel gen-sets are accurately represented based upon design drawings provided by Atmautluak
and confirmed during site visits.
The fuel curves are . Design parameters include a 30% minimum
load ratio and an 18% heat recovery ratio.
For purposes of the HOMER model, only the two newest existing diesel gen-sets in the Atmautluak
power plant will be used: Generator 2 (250 kW) and Generator 3 (117 kW)
Fuel Price
The diesel fuel cost of $4.40 per gallon is based on projections made by the Institute for Social and
Economic Research and is an acceptable medium range projection for the lifetime of this project. The
$5.48 price reflects the median value of the 2013 price of $3.85/gallon and 2033 price of $4.95/gallon9.
Economics
This project will be funded through a state grant program called the Renewable Energy Fund which is
managed by the Alaska Energy Authority. The cost projects detailed in this HOMER model reflect cost
of energy as if the true cost of the project was being paid by the community. Therefore, the cost of
energy does not accurately reflect how the cost of energy will ultimately change for the residents of
Atmautluak. That is a separate analysis. The purpose of this analysis is to determine which installed
system represents the greatest benefit to cost ratio.
The project lifetime is 20 years and a 3% discount rate.
9 ISER Fuel Projection Study
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Wind Turbine
The two wind turbines under consideration for this project are the Northern Power NW100B and
Remanufactured Vestas V17 sold by Halus and supported in Alaska by Marsh Creek. The wind turbine
costs were obtained by Marsh Creek and AVEC. They represent pure estimations as the geo-technical
reports and foundation designs are not yet complete. The O&M for wind turbines is $.0469 per kWh
which is used by the Alaska Energy Authority as an average to date.
$1,605,000 total installed cost for 2-Vestas V17 turbine (180 kW) wind system.
$2,310,000 total installed cost for 2-Northern Power Systems NW100 Arctic turbine (200 kW)
wind system.
Annual O&M costs are $4,900 for each Vestas wind turbine and $7,000 for each Northern Power
Systems wind turbine.
Assumed 100% wind turbine availability.
The wind turbine power curves have not been adjusted to account for air density.
Rough Order of Magnitude (ROM) Cost Estimates
The ROM cost estimates for V17 Configuration (two turbines) and NW100 Configuration (two NW100s)
are based on a review of cost estimates for similar-scaled wind-diesel projects in the Yukon-Kuskokwim
delta region, both existing and proposed.
V17 Configuration
Two Vestas V17 turbines would be mounted on standard 30 m tubular towers, installed atop a concrete
foundation designed for marshy, permafrost-laden soil.
Preliminary rough order of magnitude (ROM) cost estimate for 2 V17 turbines : $1,605,000
NW100 Configuration
Two Northern Power NW100 turbines would be mounted on standard 37 m tubular towers.
Preliminary rough order of magnitude (ROM) cost estimate for 2 NW100 turbines: $2,310,000
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Cost Estimates
A breakdown of the system costs in a variety of scenarios is detailed below in Tables 8, 9, and 10.
Notice that the fixed cost estimates are currently the same for both the North and the South site.
Therefore, all future modeling is assumed to be based upon the North Site
play a major consideration in site selection.
Table 7: Atmautluak HOMER Model Cost Assumptions for System Fixed Costs
System Fixed Costs North Site NW100 North Site V17s
3 Phase Line Upgrade and Extension $150,000 $150,000
Site Development $100,000 $100,000
Secondary Load Controllers $125,000 $125,000
2-100 kW Electric Boilers $75,000 $75,000
Synchronous Condenser $0 $115,000
SCADA Upgrades $100,000 $100,000
Mob/Demobilization $200,000 $160,000
System Fixed Costs Subtotal $750,000 $825,000
The Northwind 100 and the Vestas V17 are very different machines and therefore require different
components upon installation to complete integration. Additionally the NW100 is a new machine while
the V17 is remanufactured with new parts. Therefore, the cost of the NW100 turbine itself is higher
than that of the V17. However, the V17 requires additional ancillary equipment which the NW100s do
not. These differences are noted in Tables 8 and 9.
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Table 8: Atmautluak Wind Turbine Associated Costs
Wind Turbine
Specific Costs
North Site
NW100 North Site V17s
Turbines +
Inverter (V17s) $680,000 $300,000
Foundation,
Install, and Site
Access
$70,000 $50,000
Foundation
Materials $50,000 $50,000
Wind Turbine
Specific Costs $800,000 $400,000
These general development costs, turbine costs, and integration costs must all be wrapped up in the
first turbine, as noted in Table 10. Each additional turbine increases the benefit with only the
incremental cost of the turbine itself. For HOMER economic modeling the costs in Table 10 are used to
model the cost of energy for every possible system configuration over twenty years.
Table 9: Summary of Wind Turbine and System Costs Broken Down Per Turbine
Wind Turbine Cost Breakdown North Site NW100 North Site V17s
System Fixed Costs Subtotal $750,000 $825,000
Wind Turbine Specific Costs $800,000 $400,000
Grand Total for First Turbine $1,550,000 $1,225,000
Grand Total for 2 Turbines $2,310,000 $1,605,000
Grand Total for 3 Turbines n/a $1,985,000
Modeling Methodology
HOMER does not effectively model the potential and value that excess wind energy offers when
meeting the thermal needs of a rural Alaska community. One option for modeling a dispatchable load
Page | 56
is to require that a certain thermal load be met, considered a deferrable load, but the load must be met
throughout the year. This means that if the wind cannot meet those needs the diesel gen-sets must
generate the electrical energy to do so. Therefore, the user must know to a degree of certainty, what
the heating load is and wrap that cost into the overall operating costs of the system.
Therefore different models were developed to compare a system configuration with an electric
deferrable load and one without. Even with a dispatchable energy source, not all the energy generated
by the wind can be consumed by both the electric community load and the thermal load. In comparing
the two models a picture of the quantity and timing of the excess wind electricity can be obtained. The
usable excess electricity can then be provided with a value based upon the forecasted cost of diesel
fuel.
In order to have a reasonable percentage of renewable energy on the grid, there will be a need to install
one or more deferrable loads to take up the excess electricity produced by the wind turbines. A
deferrable load is an electrical load that must be met within some time period, but the exact timing is
not important. HOMER serves the deferrable load only when the system is producing excess electricity.
In order for the deferrable load to capture all of the excess electricity it is necessary to have a 171 kW
peak load with the ability to capture 1,181 kWh per day. This would require an annual load of 431,065
kWh or 1,470 MMBtu to be met. Another way to look at this load is that during the winter months, the
electric boilers must be able to absorb an average of 49 kW 24 hours a day. Figure 33 displays the
deferrable load input.
Figure 33: Atmautluak Deferrable Load
V17 Configuration (2 Turbines)
Vestas V17 turbines were modeled, as configured in Figure 34, with all the assumptions detailed above.
Page | 57
Figure 34: V17 HOMER Configuration
Two V17 turbines will produce 484,465 kWh per year with a capacity factor of 30.7% with 100%
availability. This configuration provided the greatest cost benefit ratio of 1.07 and a fuel savings of
94,998 gallons. A breakdown of the monthly average electric production, by source, is shown in Figure
35.
Figure 35: Monthly Average Electric Production by Source
Given the available thermal and electrical load there are still significant amounts of excess wind
generated electricity. The need to curtail turbines will reduce the capacity factor to 25% with 100%
availability.
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Figure 36: AC Primary Load (Blue) and Excess Electricity from 2 V17 Turbines(Purple)
As shown in Figure 36, the amount of wind energy on the system creates a maximum wind penetration
of 293%. The times of highest penetration are during the summer months of June, July, and August
when the electrical and thermal loads are the lowest. A secondary load base could be created in the
summer to increase the overall benefit of the wind project and increase overall system stability. In this
situation and energy storage system could capture excess wind energy during peak wind, storing it for
times of low wind. In utilizing the remaining excess (Figure 37) electricity for thermal energy the benefit
cost ratio of this configuration would be 1.092 with an additional savings 2,072 gallons of heating fuel
per year.
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Figure 37: Renewable Penetration from 2 V17 Turbines (%) and AC Primary Load (kW)
NW100 Configuration (2 Turbines)
Northwind NW100B turbines were modeled, as configured in Figure 38, with all the assumptions
detailed above.
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Figure 38: NW100B HOMER Configuration
Two NW100 turbines will produce 654,972 kWh per year with a capacity factor of 37.4%. This
configuration provided the second highest modeled cost/benefit ratio of 1.04 and a fuel savings of
119,115 gallons. A breakdown of the monthly average electric production, by source, is shown in Figure
39.
Figure 39: NW100B Configuration Monthly Average Electric Production per Source
Given the available thermal and electrical load there are still significant amounts of excess wind
generated electricity. The need to curtail turbines will reduce the capacity factor to 28%.
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Figure 40: AC Primary Load (Blue) and Excess Electricity from 2 NW100 Turbines (Purple)
As with the V17 Configuration, the amount of wind energy creates a high amount of maximum wind
penetration-up to 359% (Figure 41). The times of highest penetration are during the summer months of
June, July, and August when the electrical and thermal loads are the lowest. A secondary load base
could be created in the summer to increase the overall benefit of the wind project and increase overall
system stability. In this situation and energy storage system could capture excess wind energy during
peak wind, storing it for times of low wind. In utilizing the remaining excess electricity for thermal
energy the benefit cost ratio of this configuration would be 1.094 with an additional savings 3,788
gallons of heating fuel per year.
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Figure 41: AC Primary Load (kW) and Renewable Penetration (%) from 2 NW100 Turbines
Single Turbine Configuration
Throughout the conceptual design the focus has been primarily on two turbines. From an economic
standpoint, the only viable solution is to install between 180-200 kW of wind turbines while meeting all
available thermal loads. However, there will be technical challenges associated with the high level of
renewable contribution on the system. These technical complications can be avoided by installing a
single turbine (90-100kW). As seen in Figure 42, the maximum percentage of wind contribution, using a
Northwind 100, is reduced to 179%. It should be noted that this is still a significant challenge for
integration. The annual renewable fraction is also reduced to 7%.
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Figure 42: 1 NW 100 - AC Primary Load (kW) and Renewable Penetration (%)
The level of excess electricity is also significantly reduced to 25,210 kWh per year as seen in Figure 43. It
will be made apparent in the next section that this is the least economically advantageous system
because the thermal benefit is cut back significantly. However, there are benefits to a more
conservative installation approach which are not apparent in the benefit/cost ratio.
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Figure 43: AC Primary Load (Blue) and Excess Electricity from 1 NW100 Turbine (Purple)
Modeling Conclusions
Estimated Annual Renewable Fraction and Capacity Factor
Renewable fraction (penetration level): 18% for V17 Configuration, 27% for NW100
Configuration.
Capacity factor on net wind production: 25% for V17 Configuration, 28% for NW100
Configuration.
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Estimated Annual Wind Energy Production
HOMER software estimated gross annual wind production to be:
484 MWh with 86 MWh excess electrical energy for V17 Configuration after meeting the
modeled thermal demand.
654 MWh with 159 MWh excess electrical energy for NW100 Configuration after meeting the
modeled thermal demand.
Estimated Fuel Savings
The total fuel savings, shown in Table 11, are highest (45,593 gallons) with the installation of two
Northern Power NW100 turbines. The installed capacity of 200 kW creates the greatest potential for
diesel fuel offset for both electrical and thermal uses. Two V17 turbines can save 37,500 gallons of fuel
annually.
Table 10: Estimated Fuel Savings with Various Configurations
Total Electrical
Fuel Consumed
Electrical Fuel
Saved
Thermal Fuel
Saved (With
100% Utilization
of Excess Wind
Energy)
Total Potential
for Fuel Savings
Gallons Gallons Gallons Gallons
2 NW100 42,983 31,509 14,084 45,593
2 V17 49,361 25,132 12,368 37,500
1 NW 55,461 19,031 10,888 29,919
1 V17 59,951 14,541 10,557 25,098
Existing Diesel
Only System 74,492 0 0
Cost of Energy and Benefit/Cost Ratio
As shown in Table 12, the V17 Configuration has the lowest levelized cost of energy. The V17
Configuration also has the best benefit cost ratio when considering the existing thermal and electrical
load in Atmautluak. The benefit cost ratios will improve if and when an additional thermal load can be
identified which attaches further value to the excess wind energy.
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Table 11: Results of HOMER Modeling for Atmautluak Wind-Diesel System Alternatives, Cost of Energy
System
Configuration
Levelized Cost-
of-Energy
($/kWh) $4.40
per Gallon
Benefit/Cost Ratio Using
All Excess Wind for
Thermal Load
Benefit/Cost Ratio
using Curtailment and
No Thermal Load
Benefit Cost
Ratio Meeting
Basic Thermal
Load
Base Case
(Diesel Only)
$0.40 1.00 1.0 1.0
V17
Configuration
(2 V17s)
$0.40 1.04 .91 1.01
NW100
Configuration
(2 NW100s)
$0.42 1.03 .90 .97
Table 12 also highlights the tremendous importance of including thermal load into the Atmautluak
system. Without the inclusion of thermal energy the benefit/cost ratios of installing wind turbines is
significantly reduced down to 0.91. This ratio is increased to 1.01 with the inclusion of a basic thermal
load including the powerplant and nearby buildings. If an additional dispatchable electric boiler is
installed at a remote site and all the excess electricity is absorbed the benefit/cost ratio increases to
1.04.
Table 13 summarizes the conclusions of numerous iterations of HOMER modeling. It is apparent that
installing two Northwind 100 s offsets the greatest amount of diesel fuel. However, the higher initial
capital cost of this configuration impacts the overall economic benefit in a negative way. The
installation of two v17 turbines offers the greatest economic benefit will still offsetting a significant
amount of diesel fuel.
The Adjusted Capacity Factor subtracts any unusable excess wind energy from the total wind energy
production prior to calculating the capacity factor. This is a realistic number to help understand overall
system performance. The Maximum Penetration is a critical design parameter. The system will have to
be engineered to absorb this percentage of wind energy. As apparent in earlier figures, this percentage
is highest in the summer months. Detailed solutions, beyond initial explorations in this conceptual
design report, will be engineered during the design and construction phase of the project.
Page | 67
Table 12: Final Conclusions Based Upon Multiple HOMER Models and Analysis
Turbine Renewable
Fraction Diesel
Total
Diesel
Consumed
for
Electricity
Wind
Production
Total
Diesel Fuel
Saved
(Electric+
Thermal)
Electrical
Fuel
Saved
Thermal
Fuel Saved
(With
100%
Utilization
of Excess
Wind
Energy)
% Liter Gallon kWh Gallons Gallons Gallons
2 V17 18% 186,583 49,361 484,465 27,201 25,129 12,308
2 NW100 27% 162,476 42,983 654,972 35,313 31,525 14,024
Base Case 0% 281,581 74,492 0 0 0 0
1 NW 12% 209,642 55,461 327,486 19,591 18,999 10,828
1 V17 5% 226,616 59,951 242,232 14,770 14,770 10,497
Turbine
Adjusted
Capacity
Factor
Maximum
Penetration
Usable
Excess
Electricity
Cost of
Energy
Initial
Capital
Operating
Cost with
Heat
Savings
Total NPC
w/20 Year
Heat
Savings
B/C
Ratio
% % kWh $ $ $ $
2 V17 25.0% 289% 86,837 $0.40 $1,605,000 $338,822 $6,587,652 1.04
2
NW100 28.0% 345% 158,763 $0.42 $2,310,000 $440,055 $6,682,890 1.03
Base
Case 0.0% 0% 0 $0.40 $0 $460,814 $6,855,753 1.00
1 NW 35.0% 172% 24,806 $0.43 $1,550,000 $378,177 $7,159,691 0.96
1 V17 29.0% 145% 10,923 $0.43 $1,225,000 $398,417 $7,145,125 0.96
Page | 68
Recommendations
The preliminary economic feasibility analysis by the HOMER software, based on the cost estimates
presented in this report, indicates that Atmautluak very likely would save on energy costs by installing
wind turbines with an installed capacity between 180kW to 200kW. Due to the high amounts of
renewable energy contributing to the isolated electrical grid ancillary components will need to be
installed in order to maintain system stability. An electric boiler heating system should be installed as
part of the wind-diesel system to use excess wind energy, possibly providing supplemental heat to the
store, tribal office, washeteria and school. An energy storage system could also be incorporated to
maximize the wind resource and for power quality control.
tmautluak concluded that the
December 4, 2006 from a 30-meter meteorological tower in Atmautluak, the annual average wind speed
recorded was 7.16 m/s (16.0 mph) with north identified as the prevailing wind direction.
Based upon economic analysis, it is recommended that Atmautluak wind resource be developed as a
medium- or high-penetration system, with two Vestas V17 turbines of 90 kW capacity each or two
Northern Power Systems NW100 Arctic turbines of 100 kW capacity each. While a single turbine
installation would be more simple from an engineering standpoint the economics are not practical.
Preliminary rough order of magnitude (ROM) cost estimates of the two turbine alternatives are listed
below:
$1,605,000 total installed cost for 2-turbine Vestas V17 (180 kW) wind system
$2,310,000 total installed cost for 2-turbine NW100 Arctic (200 kW) wind system
Preliminary estimates of annual diesel fuel savings are over 24,200 gallons for a 180 kW wind system
(42% reduction), and over 30,500 gallons for a 200 kW wind system (53% reduction).
The benefit/cost ratio for the two turbine V17 wind system over the existing configuration (no turbines -
$0 fixed system cost) is estimated at 1.04 over 20 years. The benefit/cost ratio for the two turbine
NW100 Arctic wind system over the base case is estimated at 1.03.
According to Atmautluak Joint Utilities, the diesel power plant generated 806,771 kWh in 2011, with an
average annual load of 92 kW. The peak load of the Atmautluak system is estimated to be about 150
kW. During 2011, 53,865 gallons of fuel was used for power generation in Atmautluak, at an average
diesel generation efficiency of 14.9 kWh per gallon. The reported pre-subsidy residential cost of
electricity was $0.70 per kWh. The total existing generation capacity is 547 kW, with modern diesel
generator sets.
Page | 69
power plant, and about 800 feet NW of the location where the met tower was installed. This North Site
is located entirely on land owned by Atmautluak Limited, the local village corporation.
There are no listed species under the Endangered Species Act (ESA) in the wind project area, so an ESA
consultation with US Fish and Wildlife Service is not necessary, although a consultation is needed under
the Migratory Bird Treaty Act. Other permits/approvals needed include a Form 7460-1 approval from
the Federal Aviation Administration, a Section 404 permit from the US Army Corps of Engineers, and a
consistency review by the Alaska Department of National Resources for the Coastal Zone Management
Program. Also, the construction contractor will be required to submit a Storm Water Pollution
Prevention Plan to the Alaska Department of Environmental Conservation.
The Alaska Energy Authority could provide funding for final design and construction through the
Renewable Energy Fund-Round VI grant program. Such a funding scenario could result in an
operational wind-diesel system in March 2014. This schedule also assumes that permitting and
regulatory approvals are simple due to the lack of significant environmental impacts, and are secured
by mid-2013. Other grant programs and funding sources besides Alaska Energy Authority are possible
such as energy project grant/loan programs of the US Dept. of Energy and the US Dept. or Agriculture-
Rural Development.
Page | 66
Appendix A: Atmautluak AEA Wind Energy Resource Report
www.akenergyauthority.org/programwind.html Page 1 of 9 December 2006
813 W. Northern Lights Blvd.
Anchorage, AK 99503
Phone: 907-269-3000
Fax: 907-269-3044
www.akenergyauthority.org
Wind Resource Assessment for
ATMAUTLUAK, ALASKA
Date last modified: 1/5/2007
Compiled by: Cliff Dolchok & James Jensen
SITE SUMMARY
Site #: 1045
Latitude (NAD27): 60
Longitude (NAD27): 162 16 53.6
Magnetic Declination: 14 31
Tower Type: 30-meter NRG Tall Tower
Sensor Heights: 30m, 20m
Elevation: 4.3 meters (14 ft)
Monitor Start: 10/21/2005 00:00
Monitor End: 12/4/06 10:50
Atmautluak lies on the west bank of the Pitmiktakik River in the Yukon-Kuskokwim
delta, 20 miles northwest of Bethel. Atmautluak is located in the Bethel Recording
District. (source: BearingSea.com)
WIND RESOURCE SUMMARY
Annual Average Wind Speed (30m height): 7.16 m/s (16.0 mph)
Average Wind Power Density (30m height): 451 W/m 2
Wind Power Class (range = 1 to 7): 5
Rating (Poor, Marginal, Fair, Good, Excellent, Outstanding, Superb): Excellent
Prevailing Wind Direction: North
In October 2005, a 30-meter meteorological tower was installed in Atmautluak.
The purpose of this monitoring effort was to evaluate the feasibility of utilizing
utility-scale wind energy in the community. The meteorological data collected
allows us to estimate the potential energy production from various types of wind
turbines.
Alaska Energy Authority ATMAUTLUAK, AK Wind Resource Assessment
www.akenergyauthority.org/programwind.html Page 2 of 9 December 2006
INTRODUCTION
On initial review, the community of Atmautluak appears to be a strong candidate for wind power. The wind
resource map below shows that Atmautluak is in close proximity to areas with wind resource ratings ranging from
Class 4 to Class 6. Areas of Class 4 and higher are considered suitable for utility-scale wind power development.
Source: AWS Truewind
Figure 1. Wind Resource Map of Alaska
With support from the Alaska Energy Authority, a 30-meter tall meteorological tower was installed in the village of
Atmautluak. The purpose of this monitoring effort was to verify the wind resource in Atmautluak and evaluate the
feasibility of utilizing utility-scale wind energy in the community. This report summarizes the wind resource data
collected and the long-term energy production potential of the site.
Alaska Energy Authority ATMAUTLUAK, AK Wind Resource Assessment
www.akenergyauthority.org/programwind.html Page 3 of 9 December 2006
SITE DESCRIPTION
The photos below document the meteorological tower equipment that was installed in Atmautluak.
Figure 2. Photos of the Met Tower Installation in Atmautluak, AK
The photos in Figure 3 illustrate the surrounding ground cover and any major obstructions, which could affect how
the wind flows over the terrain from a particular direction. As shown, the landscape surrounding the met tower site
is free of obstructions and relatively flat.
SW W NW N
NE E SE S
Figure 3. Views Taken from Met Tower Base
Table 1 lists the types of sensors that were used, the channel of the data logger that each sensor was wired into,
and where each sensor was mounted on the tower.
Table 1. Summary of Sensors Installed on the Met Tower
Ch # Sensor Type Height Offset Boom Orientation Arial view of equipment on tower
N
NE
E
SE
S
SW
W
NW
CH1, 30m anem
CH2, 30m anem
CH3, 20m anem
Tower
CH7, 30m anem
1 #40 Anemometer 30 m NRG Standard
2 #40 Anemometer 30 m NRG Standard
3 #40 Anemometer 20 m NRG Standard
7 #200P Wind Vane 30 m
9 #110S Temperature 2 m NRG Standard -
Alaska Energy Authority ATMAUTLUAK, AK Wind Resource Assessment
www.akenergyauthority.org/programwind.html Page 4 of 9 December 2006
WIND DATA RESULTS FOR ATMAUTLUAK MET TOWER SITE
Table 2 summarizes the amount of data that was successfully retrieved from the data logger at the met tower site.
There was a large amount of data loss during March due to icing of the sensors. A software program called
Windographer (www.mistaya.ca) was used to fill the gaps. Windographer uses statistical methods based on
patterns in the data surrounding the gap, and is good for filling short gaps in data. As such, the data from March is
the most questionable since Windographer had to fill large gaps in data.
Table 2. Data Recovery Rate for Met Tower Anemometers
Month Data Recovery Rate Data Loss Due to Icing
Oct. 2005 98.8% 19
Nov. 2005 85.5% 536
Dec. 2005 98.5% 66
Jan. 2006 94.7% 222
Feb. 2006 99.9% 4
Mar. 2006 27.5% 890
Apr. 2006 87.0% 488
May 2006 97.8% 95
Jun. 2006 100% 0
Jul. 2006 100% 0
Aug. 2006 100% 0
Sep. 2006 100% 0
Oct. 2006 97.7% 102
Nov. 2006 92.4% 302
Dec. 2006 99.6% 2
Wind Speed Measurements
The table below summarizes the wind speed data collected at the Atmautluak met tower site.
Table 3. Summary of Atmautluak Wind Speed Data, 30-meter Height
Annual Average 7.16 m/s
Highest Month February
Lowest Month September
Hour of Peak Wind 23
Max 10-minute average 23.1 m/s
Max gust 30.2 m/s
Alaska Energy Authority ATMAUTLUAK, AK Wind Resource Assessment
www.akenergyauthority.org/programwind.html Page 5 of 9 December 2006
The seasonal wind speed profile shows that the winter months are generally windier than the summer months. The
daily wind speed profile shows that wind speeds are typically greater in the afternoon and evening hours and
calmer in the morning. The data that makes up these graphs is listed in Table 4.
Table 4. Estimated Long-Term Wind Speeds at Met Tower Site, 30m Height (m/s)
Hour Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg
0 7.1 9.9 9.2 8.5 6.7 6.2 5.9 6.0 5.1 6.8 7.7 8.1 7.3
1 7.2 9.7 8.4 8.5 6.5 6.3 5.9 6.0 5.0 6.9 7.6 8.2 7.2
2 6.9 10.0 7.9 8.4 6.7 6.2 5.9 5.7 5.0 6.8 7.8 8.2 7.1
3 7.0 10.1 7.3 8.7 7.0 6.3 5.7 5.6 5.0 6.6 7.5 8.4 7.1
4 7.1 9.9 8.3 8.5 6.3 6.3 5.9 5.5 5.0 6.5 7.6 8.3 7.1
5 7.1 9.7 9.8 8.4 6.1 6.1 5.9 5.4 5.1 6.6 7.7 8.3 7.2
6 7.1 9.7 9.6 8.2 6.0 6.1 5.8 5.2 5.2 6.7 7.4 8.3 7.1
7 7.0 9.7 10.2 7.9 5.7 6.2 5.6 5.0 4.7 6.5 7.5 8.3 7.0
8 7.2 9.2 10.0 7.9 5.8 6.2 5.6 5.2 4.7 6.5 7.5 8.4 7.0
9 7.1 9.3 9.1 7.9 5.7 6.4 5.6 5.2 4.6 6.3 7.4 8.4 6.9
10 7.0 8.9 8.8 7.8 5.7 6.4 5.7 5.3 4.9 6.4 7.5 8.2 6.9
11 7.2 9.0 9.2 8.0 6.0 6.3 5.7 5.6 4.9 6.4 7.6 8.3 7.0
12 7.2 9.2 10.5 8.1 6.1 6.3 5.9 5.7 4.8 6.6 7.6 8.3 7.2
13 7.3 9.1 9.7 8.4 6.1 6.2 5.9 5.6 5.1 6.7 7.6 8.3 7.2
14 7.2 9.2 9.3 8.7 6.4 6.2 5.7 5.5 5.2 7.0 7.5 8.2 7.2
15 7.4 9.5 9.7 8.2 6.5 6.2 5.7 5.6 5.1 6.9 7.4 8.6 7.2
16 7.3 9.6 9.5 7.6 6.5 6.4 5.9 5.6 5.1 6.6 7.4 8.6 7.2
17 6.8 9.7 9.3 7.5 6.5 6.3 5.9 5.8 5.4 6.3 7.3 8.4 7.1
18 6.8 9.9 10.3 7.6 6.6 6.3 5.9 5.7 5.3 6.2 7.5 8.2 7.2
19 7.0 10.5 10.8 7.6 6.5 6.5 5.7 5.5 5.0 6.4 7.5 8.4 7.3
20 7.0 10.5 10.8 7.6 7.0 6.3 5.7 5.8 5.0 6.6 7.5 8.1 7.3
21 7.1 10.8 10.4 8.0 7.1 6.1 5.7 5.9 5.0 6.6 7.2 8.2 7.3
22 7.1 10.6 9.9 8.1 7.0 5.6 5.6 6.1 5.0 6.7 7.4 8.3 7.3
23 6.9 10.3 10.2 8.6 7.1 5.8 5.7 6.1 5.2 6.6 7.6 8.2 7.4
Avg 7.1 9.8 9.5 8.1 6.4 6.2 5.8 5.6 5.0 6.6 7.5 8.3 7.2
The estimated long-term average wind speed is 7.2 m/s (16.0 mph) at a height of 30 meters above ground level.
Wind Frequency Distribution
A common method of displaying a year of wind data is a wind frequency distribution, which shows the percent of
time that each wind speed occurs. Figure 4 shows the measured wind frequency distribution as well as the best
matched Weibull distribution, which is commonly used to approximate the wind speed frequency distribution.
Bin m/s Hrs/yr
1 72
2 290
3 518
4 728
5 962
6 1020
7 1019
8 952
9 826
10 676
11 487
12 359
13 278
14 190
15 122
16 83
17 60
18 41
Bin m/s Hrs/yr
19 24
20 16
21 10
22 8
23 4
24 4
25 4
26 2
27 1
28 2
29 1
30 1
31 1
32 0
33 0
34 0
35 0
Total: 8760
Figure 4. Wind Speed Frequency Distribution of Met Tower Data, 30-meter height
Alaska Energy Authority ATMAUTLUAK, AK Wind Resource Assessment
www.akenergyauthority.org/programwind.html Page 6 of 9 December 2006
The cut-in wind speed of many wind turbines is 4 m/s and the cut-out wind speed is usually 25 m/s. The frequency
distribution shows that about 90% of the time the wind in Atmautluak is within this operational zone.
Wind Direction
Wind power roses show the percent of total power that is available in the wind by direction. The annual wind power
rose for the Atmautluak met tower site is shown below.
Figure 5. Annual Wind Power Rose for Met Tower Site
Monthly wind power roses for the Atmautluak met tower site are shown below. The predominant wind direction
during the winter months is north, while the summer winds tend to come from the northwest. The wind rose for
March is not accurate due to the large amount of gap filled data.
Figure 6. Monthly Wind Power Roses for Met Tower Site
Alaska Energy Authority ATMAUTLUAK, AK Wind Resource Assessment
www.akenergyauthority.org/programwind.html Page 7 of 9 December 2006
Turbulence Intensity
Turbulence intensity is the most basic measure of the turbulence of the wind. Typically, a turbulence intensity of
around 0.10 is desired for minimal wear on wind turbine components. As shown in Figure 7, the turbulence
intensity from all directions is low and unlikely to contribute to excessive wear of wind turbines.
Dir Turbulence
Intensity
N 0.08
NE 0.10
E 0.09
SE 0.10
S 0.09
SW 0.08
W 0.09
NW 0.07
Ave 0.09
Figure 7. Turbulence Intensity Characteristics of Met Tower Site
Figure 7 plots the average turbulence intensity versus wind speed for the met tower site as well as for Category A
and B turbulence sites as defined by the International Electrotechnical Commission Standard 61400-1, 2nd Edition.
Category A represents a higher turbulence model than Category B. In this case, the met tower data is significantly
less turbulent than both categories across the whole range of wind speeds.
Wind Shear
Typically, wind speeds increase with height above ground level. This vertical variation in wind speed is called wind
shear and is influenced by surface roughness, surrounding terrain, and atmospheric stability. The met tower is
equipped with anemometers at 20 and 30-meter heights so the wind shear exponent can be calculated and used to
adjust the wind resource data to heights other than those that were measured. Results are summarized below.
Month Wind Shear
Jan 0.12
Feb 0.26
Mar 0.21
Apr 0.18
May 0.27
Jun 0.11
Jul 0.29
Aug 0.22
Sep 0.29
Oct 0.23
Nov 0.18
Dec 0.14
Ave 0.21
Figure 8. Wind Shear Characteristics of Met Tower Site
As shown, the wind shear varies by month, direction of the wind, and time of day. The average wind shear for the
site is 0.21. Typical values range from 0.05 to 0.25.
have a significant effect on wind power production.
Alaska Energy Authority ATMAUTLUAK, AK Wind Resource Assessment
www.akenergyauthority.org/programwind.html Page 8 of 9 December 2006
LONG-TERM REFERENCE STATION
The year of data collected at the met tower site can be adjusted to account for inter-annual fluctuations in the wind
resource based on long-term measurements at a nearby weather station. The weather station closest to
Atmautluak is the Bethel Airport ASOS, located about 20 miles to the southeast. The hourly measurements from
the met tower were not closely correlated with those from the Bethel airport weather station (correlation coefficient
of less than 0.60). Due to the poor correlation between the two sites no adjustments could be made. The fact that
just for inter-annual fluctuations in wind speed decreases the confidence in our wind speed
estimates. Longer period of monitoring would increase that confidence.
POTENTIAL POWER PRODUCTION FROM WIND TURBINES
Various wind turbines, listed in Table 5, were used to calculate the potential energy production at the met tower site
based on the data collected. Although different wind turbines are offered with different tower heights, to be
consistent it is assumed that any wind turbine rated at 100 kW or less would be mounted on a 30-meter tall tower,
while anything larger would be mounted on a 50-meter tower. The wind resource was adjusted to these heights
based on the measured wind shear at the site. Also, since wind turbine power curves are based on a standard air
density of 1.225 kg/m3, the wind speeds measured at the met tower site are adjusted to create standard wind
speed values that can be compared to the standard power curves
Results are shown in Table 5. Among the results is the gross capacity factor, which is defined as the actual
amount of energy produced divided by the maximum amount of energy that could be produced if the wind turbine
were to operate at rated power for the entire year. Inefficiencies such as transformer/line losses, turbine downtime,
soiling of the blades, yaw losses, array losses, and extreme weather conditions can further reduce turbine output.
The gross capacity factor is multiplied by 0.90 to account for these factors, resulting in the net capacity factor listed.
CONCLUSION
This report provides a summary of wind resource data collected from October 2005 through December 2006 in
Atmautluak, Alaska. Both the raw data and the processed data are available on the Alaska Energy Authority
website.
It is a rough estimate that the long-term annual average wind speed at the site is 7.2 m/s at a height of 30 meters
above ground level. Taking the local air density and wind speed distribution into account, the average wind power
density for the site is 451 W/m2. This information means that Atmautluak has an estimated Class 5 wind resource,
excellent The met tower wind data set was used to make predictions as to
the potential energy production from wind turbines at the site. The net capacity factor for large scale wind turbines
would range from 24 38%.
Alaska Energy Authority ATMAUTLUAK, AK Wind Resource Assessmentwww.akenergyauthority.org/programwind.html Page 9 of 9 December 2006 Table 5. Power Production Analysis of Various Wind Turbine ModelsWind Turbine Options Manufacturer Information Bergey 10 kW Fuhrlander FL30 30 kW Entegrity 15/50 65 kW Fuhrlander FL100 100 kW Northern Power NW100 100 kW Fuhrlander FL250 250 kW Vestas V27* 225 kW Vestas V47* 660 kW Tower Height 30 meters 30 meters 30 meters 50 meters 50 meters 50 meters 50 meters 50 meters Swept Area 38.5 m2 133 m2 177 m2 348 m2 284 m2 684 m2 573 m2 1,735 m2 Weight (nacelle & rotor) N/A 410 kg 2,420 kg 2,380 kg 7,086 kg 4,050 kg N/A N/A Gross Energy Production (kWh/year) Jan 2,374 11,188 18,740 36,259 29,575 82,121 74,145 248,272 Feb 2,374 11,432 20,290 38,523 31,354 86,292 77,962 256,118 Mar 2,506 11,959 20,609 39,481 32,170 87,654 79,595 263,588 Apr 1,657 7,677 11,686 23,300 19,040 50,789 46,499 162,511 May 1,807 8,349 12,932 25,632 20,950 56,579 51,642 179,533 Jun 1,436 6,686 9,837 19,789 16,153 43,187 39,464 139,897 July 1,250 5,907 8,477 17,139 13,954 40,128 36,619 130,924 Aug 1,791 8,311 12,795 25,407 20,753 62,436 56,969 196,264 Sep 1,910 8,860 14,030 27,645 22,598 67,342 61,685 209,774 Oct 2,071 9,626 15,415 30,273 24,726 70,964 64,580 219,479 Nov 1,892 8,712 13,709 27,106 22,153 63,305 57,723 197,903 Dec 2,165 10,121 16,466 32,146 26,267 73,911 67,079 227,042 Annual 23,233 108,828 174,985 342,696 279,693 784,705 713,961 2,431,302 Annual Average Capacity Factor Gross CF 27% 41% 30% 39% 32% 36% 36% 42% Net CF 24% 37% 27% 35% 29% 32% 33% 38%
Page | 4
Appendix B: Atmautluak Proposed One Line
Page | 5
Appendix C: Atmautluak Distribution Maps
Page | 6
Appendix D: HOMER Model Inputs
Page | 7
Appendix E: Northern Power NW100B Arctic Specification Sheet
Page | 8
Appendix F: Vestas V17 Specification Sheet
Page | 9
Appendix G: Atmautluak Powerplant Site Visit
1
Atmautluak Wind-Diesel Feasibility Study
Appendix B:Atmautluak Site & Powerhouse Field Visit Report
Brian Yanity visited Atmautluak on September 2, 2010 to assessthe diesel power generation system,
switchgear and ancillary equipment, as well as inspect possible wind turbine sites.Atmautluak Joint
Utilities staff provided tours of the existing diesel powerhouse, the prospective wind turbine sites,as
well as documentation and drawings.Daniel Waska, Atmautluak Tribal Administrator, presented a map
with potential wind turbine sites identified by the community: a preferred site and an “alternate” site
(see photos below).
The wind-diesel project concept, and pending grant proposal to the Alaska Energy Authority’s
Renewable Energy Fund,was presented at a community meeting hosted by the Atmautluak Traditional
Council.At the community meeting,several residents expressed report for wind energy, saying that a
reduction in the community’s overall diesel fuel consumption is highly desired.No concerns were
expressed other than a question about how the state grant funds would be administered.
Atmautluak Joint Utilities-Existing Power System
The cost of fuel purchased by Atmautluak Joint Utilities in 2010 was reported as $3.3688/gallon
(although some fuel purchased for $5.20/gallon was shipped in during the winter of 2010 due to a
temporary fuel shortage).The reported pre-subsidy retail cost of electricity for 2010 is $0.69860/kWh.
The reported retail rate for other fuels in Atmautluak was $5.45/gallon for heating fuel, $5.50/gallon for
gasoline.
The three diesel generator sets in the existing powerhouse (see photos below):
Genset
#
Capacity Generator Engine
1 180 kW
225 kVA
Marathon Electric
MangaPlus 432PSL1268 (older generator)
Serial # LM-217323-TO95
John Deere 6081HF070
Serial # RG6081H296673
2 250 kW
313 kVA
Marathon Electric
MangaMax DVR 433RSL4019
Serial # WA-568180-0109
John Deere 6081HF070
Serial # RG6081H296672
3 117 kW
146 kVA
Marathon Electric
MangaPlus 431CSL6202
Serial # 705888-0209
John Deere 4045HF485
Serial # 4045HF485
Total generation capacity: 576 kW
The engines, control systems and two of the generators were installed in 2008 by Marsh Creek LLC. The
John Deere diesel engines have electronic isochronous governors, and the the power house has
automated switchgear, with Woodward easYgen 3000 generator control panels and Satek PM130EH
power meters.
2
The Atmautluak School has its own diesel generator (see photos below), which isconnected to the local
distribution system of Atmautluak Joint Utilities. This generator is used as backup for the school if the
community power generation system is down, or to relieve energy demand on the Atmautluak Joint
Utilities power plant. For example, the power plant operator reported that the school’s generator was
turned on for several days in August 2010 to reduce load on the overall community grid when the
Atmautluak Joint Utilities power plant was experience high temperatures on its diesel engines during
relatively warm weather.
Heat Recovery and District Heat System Potential
There is no form of heat recovery presently employed at the diesel powerhouse, nor is there a ny kind of
local district heating system.
Potential discretionary electric identified heating loads for a future wind-diesel system:
Electric boiler system at the school
An electric boiler/recovered heat module could be installed next to the existing diesel
powerhouse, with a hot water pipe (hydronic heating loop) extending a length of approximately
900’ to the store, tribal office, washeteria and school.The central location of all of these
buildings, in relation to the existing power plant, could make a district heating system
economically feasible.
Existing electric heat trace system used for sewer and water lines.
Met Tower Site
Location:60° 51.686’ N, 162° 17.032’ W (NAD83 coordinates converted from NAD27 coordinates of the
site reported in the 2007 Alaska Energy Authority wind resource report, see Appendix A)
This is the location of the Alaska Energy Authority met tower installed in Atmautluak between October
2005 and December 2006.
Preferred Wind Turbine Site, “site 1”
Location (NAD83):60° 51.728’ N, 162° 17.225’ W
The community’s preferred wind turbine site, “site 1”, is located about 0.45 miles northwest of the
Atmautluak power plant, and about 800 feet NW of the location where the met tower was installed
between 2005 and 2006 (see coordinates above).The site is located entirely on land owned by
Atmautluak Limited, the local village corporation.
A 25’ wide right-of-way easement exists through this site for a winter trail between Bethel and
Nunapitchuk that is no longer used, but is recorded in BLM records. Today, a different trail is now used
in winter. Atmautluak Traditional Council is working with BLM on this issue, and is expected to resolve
this issue in the near future.
3
Preferred wind turbine site, facing north
Preferred wind turbine site, facing east
4
Preferred wind turbine site, facing southeast
Preferred wind turbine site, facing south
5
Preferred wind turbine site, facing southwest
Preferred wind turbine site, facing west
6
Alternate Wind Turbine Site, “site 2”
Location (NAD83): 60° 51.229’ N, 162° 17.102’ W
The site is located entirely on land owned by Atmautluak Limited, the local village corporation.
A particularly marshy area exists between the existing boardwalk/power line/homes and this site.After
freezeup,this area is more heavily used area than the preferred wind turbine site.
Alternate wind turbine site, facing north
7
Alternate wind turbine site, facing northeast
Alternate wind turbine site, facing east
8
Alternate wind turbine site, facing south
Alternate wind turbine site, facing west
9
Power Plant
Location (NAD83):60° 51.418’ N, 162° 16.748’ W
Atmautluak Joint Utilities powerhouse, with tank farm in the background
Atmautluak Joint Utilties powerhouse, interior
10
Atmautluak School
Location (NAD83):60° 51.410’ N, 162° 16.611’ W (pedestrian bridge over utilidor near school)
–
Utility pipes outside Atmautluak School
Utility pipes and generator/heat plant outside Atmautluak School
11
Utility pipes and generator/heat plant are outside Atmautluak School
Generator/heat plant area and fuel tank outside Atmautluak School
ATMAUTLUAK WIND STUDY SITE INSPECTION REPORT
February 3, 2012 Page 1 of 4
WHP PROJECT No.:
CONTRACTOR:
OWNER:
Inspector:
#5496
None
Atmautluak Traditional Council
Dennis Sharp
LOCATION:Atmautluak, Alaska
WEATHER:Clear,-30F, light breeze
PRESENT ON SITE:Edward Nicholai –Tribal Administrator; Harry Gilman –
Power Plant Operator (Atmautluak Joint Utilities)
EQUIPMENT ON SITE:
Arrived in Bethel at 8:00AM to an ambient temperature of -33F. This is too cold for the piston engine light aircraft to fly so waited in Yute Air’s
terminal for the temperature to warm up. About 12:30PM it had warmed up enough to fly and they began getting their aircraft ready.It was just
the pilot and I in a Cessna 172 for the 15 minute flight to Atmautluak where we arrived shortly after 1:00PM. Received a rid e from Owen,one of
the village airline agents,to the village tribal office on the back of his snowmachine.
Had a meeting with Edward Nicholai, Harry Gilman, and other interested parties about the different wind-diesel options. After presenting the
pros and cons of low, medium and high penetration wind configurations they migrated towards the medium penetration option. They would
like to maximize fuel offset while minimizing the complexity. They’re also concerned about maintainability, wishing the syst em to be simple
and easy to maintain with most repairs not requiring a service call from Anchorage as they feel the system is most prone to f ailing when
transport to the village from Anchorage is most difficult.Much time was spent looking at Table 8 of the WHPaci fic Atmautluak Wind-Diesel
Study which shows the estimated fuel savings of the two options analyzed in the report.
Harry then took me over to the power plant where I analyzed the existing generator sets and switchgear. The generator sets c onsist of 3 John
Deere diesel units with Marathon rotary generators. Generator set 1 is a John Deere 6081H with a 180kW Magnaplus 432PSL showing 7454
hours of operation on the controller. Generator 2 is a John Deere 6081H with a 250kW MagnaMax 433RSL showing 14148 hours of operation on
the controller (this conflicts slightly with the digital hour meter on the generator set which indicated 14399 hours). Generator 3 is a John Deere
4045H with a 117kW MagnaPlus 431CSL showing 251 hours of operation on the controller.The switchgear is fully electronic, using Woodward
easYgen 3200 generator controllers for generator control and protection. Harry reported that they have been having flickering power problems
with generator 3 so it has not seen much use. Additionally, the floor joists of the generator building are sagging in the middle under the
heaviest generator. Running generator 3 reportedly causes excessive vibration in the building.It is uncertain if these two issues are related.
Generator 2 was the only generator running at the time of the inspection. The easYgen showed 72kW of 480V 3-phase power being drawn at .94
power factor. Current readings were 107A for phase 1, 94A for phase 2 and 80A for phase 3.The generator was serving all of the loads in the
village except the school which is presently running on its own generator.The school has two 150kW Cummins generator sets in a
prefabricated enclosure on a deck that also includes the fire pump and water supply. One of those generators was running at the time of the
inspection to provide power for the school. The bar graph display indicated it was operating at about 50% capacity, or approximately 75kW, so
the total village load was approximately 150kW.
Distribution from the power plant to the village is provided by a bank of 3 75kVA step up transformers. The distribution voltage is 7200/12470Y.
The distribution line to the north runs approximately halfway to the primary wind turbine site.It appears that this line could be modified to
carry two circuits,the existing distribution line and the line from the turbine site to the power plant, for a possible cost savings over two
dedicated lines.
Investigated the possible users of waste heat or excess energy from the power plant that were identified in last year’s report. The boilers at the
school could easily be adapted to accept generator waste heat and serve as a load for an electric boiler. The washeteria was frozen and not
inspected but also has a boiler system. The store has a forced air furnace which could possibly accept a heat exchanger or be upgraded. The
tribal office has no central heating system but is heated by Toyos so is not a good candidate as an entire heating system wou ld need to be
provided for the building.
Took the scheduled 6:12PM Era flight back to Bethel and connected to the Alaska Airlines flight at 8:40PM. Arrived back in Anchorage about
10:00PM.
__________________________________________________ Date:02/07/12
Dennis Sharp, Electrical Engineer
ATMAUTLUAK WIND STUDY SITE INSPECTION REPORT
February 3, 2012 Page 2 of 4
easYgen 3200 Generator Controllers Generator 2 easYgen load display
Generator radiators Switchgear and generators 2 & 3. easYgen controllers are in
bay out of photo to right
Distribution transformer bank Village power plant and distribution feeders
ATMAUTLUAK WIND STUDY SITE INSPECTION REPORT
February 3, 2012 Page 3 of 4
Sagging floor joists on generator building Extra service drop transformer ID plate
Tribal office –Geoprobe drilling rig on right Distribution line heading north towards primary wind turbine site
School generator enclosure School generators
ATMAUTLUAK WIND STUDY SITE INSPECTION REPORT
February 3, 2012 Page 4 of 4
School generator display School boilers
School glycol circulation pumps
Page | 10
Appendix H: Geotechnical Report
Atmautluak Wind Turbine
Golder Associates Inc.
2121 Abbott Road, Suite 100
Anchorage, AK 99507 USA
Tel: (907) 344-6001 Fax: (907) 344-6011 www.golder.com
Golder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South America
Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation
July 2, 2012 113-95757
Mr. Dennis Sharp, PE
WHPacific
300 W 31st Ave
Anchorage, AK 99503
RE: PRELIMINARY WIND TOWER SITE INVESTIGATION AND GEOTECHNICAL
RECOMMENDATIONS - ATMAUTLUAK, ALASKA
Dear Dennis:
This report presents the results of the site exploration and geotechnical foundation recommendations
conducted by Golder Associates Inc. (Golder) for the proposed wind turbine sites in Atmautluak, Alaska.
view of existing geotechnical information from the Atmautluak area, a
site exploration of the selected wind turbine sites, geotechnical laboratory index testing, and wind turbine
tower foundation recommendations. Our services were completed in general accordance with our
proposal to WHPacific dated November 17, 2011. During the course of our work, we have consulted with
you and Mr. Edward Nickoli of the Atmautluak Traditional Council.
1.0 PROJECT DESCRIPTION
The proposed wind power generation project for Atmautluak consists of installing two to four wind turbines
at selected sites near the village. At the time of our investigation, two sites were identified by WHPacific
for the wind turbines. The preferred site is north of the village and an alternate site is southwest of the
village. Both of the sites are located approximately 1,500 feet from village primary infrastructure
(boardwalks and structures).
At the time of our investigation, the wind turbine systems had not been selected. However, we
understand that Northwind 100 Arctic, Vestas V17/90, or Bergey BWC EXCEL S turbines are under
consideration. The three tower system options can be divided into two tower types, monopole
(Northwind) and lattice towers (Vestas or Bergey). Generally, in our experience, the monopole towers
develop greater structural foundation loads relative to lattice tower system. For purposes of this report,
we have assumed the Northwind 100 unit using a monopole tower will be the preferred wind turbine
system.
2.0 FIELD EXPLORATION
The field exploration was conducted February 3 through February 8, 2012 at the proposed wind turbine
sites in Atmautluak, Alaska. Three boreholes were advanced at the selected sites, two at the primary site
(ATT-1 and ATT-2) and one at the alternate site (ATT-3) to 40 or 50 feet below ground surface (bgs).
Geographic coordinates of select locations within the footprints of the two sites were provided by
WHPacific. Borehole locations were determined prior to field mobilization and geographic coordinates
were used to identify the borehole locations in the field using a hand-held GPS instrument.
The boreholes were advanced with a GeoProbe 6610DT direct push machine, owned and operated by
Discovery Drilling of Anchorage, Alaska. The GeoProbe was equipped with Macrocore direct push
sampling equipment. The GeoProbe is a direct push hydraulic machine that utilizes static weight and
percussion hammering to advance a smooth-walled rod with a leading sample barrel. The sample barrel
used for the project consisted of a barrel with 2.25-inch outside diameter (OD) with 1.5-inch inside
diameter (ID). Disturbed but representative samples were collected from the boreholes with a clear PVC
Golder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South America Golder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South America
Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation
The boreholes were advanced with a GeoProbe 6610DT direct push machine, owned and operated by The boreholes were advanced with a GeoProbe 6610DT direct push machine, owned and operated by
Discovery Drilling of Anchorage, Alaska. The GeoProbe was equipped with Macrocore direct push Discovery Drilling of Anchorage, Alaska. The GeoProbe was equipped with Macrocore direct push
sampling equipment. The GeoProbe is a direct push hydraulic machine that utilizes static weight and sampling equipment. The GeoProbe is a direct push hydraulic machine that utilizes static weight and
percussion hammering to advance a smooth-walled rod with a leading sample barrel. The sample barrel percussion hammering to advance a smooth-walled rod with a leading sample barrel. The sample barrel
used for the project consisted of a barrel with 2.25-inch outside diameter (OD) with 1.5-inch inside used for the project consisted of a barrel with 2.25-inch outside diameter (OD) with 1.5-inch inside
diameter (ID). Disturbed but representative samples were collected from the boreholes with a clear PVC diameter (ID). Disturbed but representative samples were collected from the boreholes with a clear PVC
Mr. Dennis Sharp July 2, 2012
WHPacific 2 113-95757
Atmautluak Wind Turbine
liner inserted in the sample barrel. The recovered soil samples were visually classified in the field
according to the Unified Soil Classification System (USCS) and representative portions were retained in
double sealed polyethylene bags to preserve their natural moisture contents.
Sealed and closed-end 1-inch diameter, schedule 80 PVC was installed in the boreholes for future ground
temperature measurements. The boreholes were backfilled with potable water and thawed soil cuttings.
Geographic coordinates of the borehole locations were recorded in the field with a hand-held GPS
instrument using WGS 84 datum.
On March 14, 2012, a Golder representative returned to Atmautluak to measure ground temperatures at
the wind turbine sites. An approximate one month lag between drilling and ground temperature
measurement was scheduled to allow for the dissipation of drilling induced heat. Ground temperatures
were measured in all three boreholes advanced on the project site on the same day using ice-bath
calibrated thermistors. Once set inside the PVC standpipes, the thermistors were allowed to thermally
attenuate for at least one hour prior to reading.
3.0 LABORATORY TESTING
The recovered soil samples were re-examined in the laboratory to confirm the visual field classifications.
Representative samples were selected and tested for natural moisture content, grain size distribution,
fines content (percent passing the U.S. Number 200 sieve size), plasticity (Atterberg Limits), and organic
content by ignition. Soil moisture content and grain size distribution (as percentages of dry weight), are
summarized on the borehole logs and are tabulated in the sample summary.
A vicinity map and general site plan with approximate borehole locations are presented in Figures 1 and
A-1 and A-2, respectively. Logs of boreholes are presented in Figures A-3 through A-5. A summary of
laboratory testing results and graphical grain size distributions are presented in Appendix A.
4.0 REVIEW OF EXISTING GEOTECHNICAL INFORMATION
Golder and Duane Miller Associates, LLC (DMA, now Golder) have conducted several geotechnical
investigations in Atmautluak, as summarized below. A report a third party geotechnical data near the
proposed wind turbine sites from our in-house files was also reviewed. Please note that third-party
geotechnical data are presented for informational purposes only since Golder is not able to verify the
quality of any third-party geotechnical data.
Wastewater Improvement Geotechnical Services, DMA, 2007 DMA drilled two test
borings west of the existing school with a Texoma drill rig using a 14-inch diameter disc
auger bit. The soils observed within the borings were frozen and encountered organic silt
at ground surface. Underlying the organic soils, mineral silt was observed to 30 and 31
feet bgs. Silty sand was reported from 30 feet bgs to the depths explored (31 feet bgs) in
one boring. Ground temperatures indicate frozen soil conditions from about 8 feet below
grade to the depths explored. Ground temperatures were measured at 31.5 degrees
Fahrenheit (°F) below 20 feet. Based on drilling action, a 6- to 8-inch marginally frozen
soil layer was inferred at 23.5 feet below grade in one borehole.
Water Storage and Washeteria Geotechnical Services, Golder, 2005 Golder
explored the area of the proposed new Washeteria and a 100,000 gallon water storage
tank. The site is located approximately 600 feet west of the existing Washeteria, past the
lift station. The test borings encountered silt with some silty fine sand. The borings were
generally frozen to the boring termination depths (31 and 50 feet bgs) with layers of
massive ice noted in the silts varying in depth and thickness. In boring G05-SB2, 1.5 feet
of unfrozen material was observed from 5 to 6.5 feet bgs. Ground temperatures were
29.5 to 30.5 °F below a depth of 8 feet.
explored the area of the proposed new Washeteria and a 100,000 gallon water storage explored the area of the proposed new Washeteria and a 100,000 gallon water storage
tank. The site is located approximately 600 feet west of the existing Washeteria, past the tank. The site is located approximately 600 feet west of the existing Washeteria, past the
lift station. The test borings encountered silt with some silty fine sand. The borings were lift station. The test borings encountered silt with some silty fine sand. The borings were
generally frozen to the boring termination depths (31 and 50 feet bgs) with layers of generally frozen to the boring termination depths (31 and 50 feet bgs) with layers of
massive ice noted in the silts varying in depth and thickness. In boring G05-SB2, 1.5 feet massive ice noted in the silts varying in depth and thickness. In boring G05-SB2, 1.5 feet
of unfrozen material was observed from 5 to 6.5 feet bgs. Ground temperatures were of unfrozen material was observed from 5 to 6.5 feet bgs. Ground temperatures were
Mr. Dennis Sharp July 2, 2012
WHPacific 3 113-95757
Atmautluak Wind Turbine
Bulk Fuel System Geotechnical Services, DMA, 1996 DMA investigated soil
conditions as part of a foundation study for the proposed fuel system upgrade. Two test
borings were drilled approximately 400 feet northeast of the Washeteria. One of the
borings had a 4.5-foot layer of organic silt overlying a predominately mineral silt with thin
layers of peat and organic silt at 7.5 and 9 feet, respectively. The second boring had a
4.5-foot layer of peat over layers of silt, peat, and organic silt. Ice layers were
encountered at 3 to 17 feet and the boring graded sandier near termination depth. Both
borings were frozen to a depth of 30 feet, the depth explored. Stable ground
temperatures below the depth of seasonal influence were between 30 and 31 °F below
14 feet.
Wastewater System Geotechnical Services, Shannon & Wilson Inc., 1993
Shannon and Wilson Inc. investigated the area soil conditions as a part of a study for the
proposed lift station, honey bucket lagoon, sewage lagoon and pipeline. They advanced
12 borings throughout the village but a site and boring location plan was not provided
with the report reviewed from our files. The boring logs showed an organic surface
overlying silt with areas of massive ice and peat throughout the investigation depths. In
general, the silt was found to extend to depths of roughly 25 feet bgs, overlying fine-
grained sand. In most cases the sand layer did not start until 25 feet bgs and deeper. All
borings were frozen, with lower visible ice contents observed in the sandier soils.
The subsurface conditions within the Atmautluak area are generally consistent with a surficial organic mat
of peat and organic silt to 4 to 5 feet bgs. Underlying the surficial organics is frozen mineral silt or silty
sand to depths of 30 to 35 feet bgs. The soils below the expected depth of seasonal thaw were generally
considered to be ice-rich permafrost to the depths explored.
5.0 CLIMATE DATA
Winter air temperatures are warming throughout most of Alaska including the Bethel region. Historical
and current design climate data including average thawing and freezing indices are presented in Table 1
for the Atmautluak area. The indices are calculated from data available by the University of Alaska
Fairbanks (UAF) Scenarios Network for Alaska and Arctic Planning (SNAP). Design indices are based on
the three coldest winters (freezing index) or warmest summers (thawing indices) observed during the
analysis period.
Table 1: Engineering Climate Indices for Atmautluak, AK
Design Index 1948-1978 1980-2009 2012 2042
(estimated)1
Average Air Temperature 28.5°F 30.5°F 32.8 °F
Average Freezing Index 3790°F-day 3250°F-day 2615 °F-days
Average Thawing Index 2500°F-day 2750°F-day 2910 °F-days
Design Freezing Index 4680°F-day 4350°F-day 3780 °F-days
Design Thawing Index 2810°F-day 3550°F-day 3685 °F-days
Note: 1) Projected by UAF SNAP, Global Climate Model ECHAM5, Emission Scenario A1B.
2) Air temperatures after 2009 are predicted from SNAP.
SNAP data was prepared by Rupp et al. (2009) and is distributed as two separate products. Historical
records were calculated using the PRISM model by combining climate data from multiple meteorological
records across the state of Alaska from 1901 to 2009, and modeled across the state in a manner that
2004). Forward-looking projections were prepared from 2009 to 2099 utilizing multiple global climate
models, and several carbon emission scenarios.
SNAP data was prepared by Rupp et al. (2009) and is distributed as two separate products. Historical SNAP data was prepared by Rupp et al. (2009) and is distributed as two separate products. Historical
records were calculated using the PRISM model by combining climate data from multiple meteorological records were calculated using the PRISM model by combining climate data from multiple meteorological
records across the state of Alaska from 1901 to 2009, and modeled across the state in a manner that records across the state of Alaska from 1901 to 2009, and modeled across the state in a manner that
2004). Forward-looking projections were prepared from 2009 to 2099 utilizing multiple global climate 2004). Forward-looking projections were prepared from 2009 to 2099 utilizing multiple global climate
Mr. Dennis Sharp July 2, 2012
WHPacific 4 113-95757
Atmautluak Wind Turbine
This report utilized the ECHAM5 global climate model results and the mid-range (A1B) carbon emission
scenario. The ECHAM5 global climate model was determined by the UAF SNAP group to have the
highest accuracy for Alaska.
6.0 SITE CONDITIONS
6.1 Site Surface Conditions
Two sites were selected by others prior to our arrival in Atmautluak. We understand the sites were
determined by WHPacific in consultation with village representatives, wind orientation, and other wind
turbine operational considerations. The primary site is located north of the village, east of the sewage
lagoon that serves the community. The site is generally level with little relief in the general area of the
wind turbines. The alternate site is southwest of the village and occupies a slight topographic rise that is
situated between two lakes north and south of the wind turbine site.
The area was covered with snow at the time of our investigation. Based on site photography developed
for the WHPacific Atmautluak Wind-Diesel Feasibility Study, dated November 17, 2010, the sites appear
to be covered with tundra vegetation including some lower lying wet areas. Standing water is visible in
photos presented in the feasibility report in the lower lying areas at the preferred wind tower site.
6.2 Subsurface Soil Conditions
The subsurface conditions observed at the wind turbine sites were generally similar. A surficial layer of
peat (Pt) and organic silt (OL) blanketed the site to depths ranging between 5 and 5.5 feet bgs at the
primary site and to 3.5 feet bgs at the alternate site. Mineral silt (ML) was observed underlying the
organics, and was found to extend between to 28 and 31 feet bgs at the primary site, and to 12 feet bgs
at the alternate site. At the primary site, a 2 to 4-foot thick layer of organic silt was observed beneath the
mineral silt. Poorly graded sand, poorly graded sand with silt or silty sand (SP, SP-SM, SM, respectively)
layer was observed at depths below 30 and 35 feet bgs at the primary site, and at 12 feet bgs at the
alternate site. Mineral silt layers were observed within the sand deposit, and ranged between 1.5 to 3 feet
thick in boreholes ATT-1 and ATT-3, respectively. In the boreholes that were advanced to 50 feet bgs
(ATT-01 and ATT-03), a silty sand layer was observed at 47.5 feet bgs in ATT-1 (primary site) and at 46
feet bgs in ATT-03 (alternate site).
Frozen soils were observed in the boreholes to the depths explored at the time of our fieldwork. Visible
ice was observed in the soil samples, generally consisting of ice as crystals (Vx), randomly oriented
formations (Vr) and occasionally as stratified ice lenses (Vs). The estimated volumetric ice content
generally decreased with depth. The observed visible ice content was highest in the near surface organic
soils, estimated to be between 10 and 60 percent by volume. Ice contents observed in the mineral silt
ranged between 20 and 55 percent in soils observed above 15 feet bgs, and decreased to between 5 and
20 percent below 15 feet bgs. Observed visible ice content in the poorly graded sand and silty sand was
consistently observed between 5 and 10 percent by volume. All volumetric ice contents are based on
visual estimates on select portions of recovered soil samples at the time of our fieldwork.
6.3 Ground Temperatures
Boreholes at each site in Atmautluak had ground temperatures of 30.5°F or colder below the depth of
seasonal variation. The preferred wind tower site had ground temperatures averaging 30.3 °F. The
alternate wind tower site had colder ground temperatures, with temperatures below the depths of
seasonal variation to 29.7°F. Measured ground temperature distributions are presented in Appendix C.
6.4 Laboratory Results
Figure B-1 presents the measured moisture content, as a percent of dry weight, by general soil type and
depth bgs. Moisture contents in excess of unfrozen state saturation are considered ice rich permafrost,
were measured in much of the organic and fine-grained deposits, consisting of peat, organic silt, and silt.
F. The F. The
alternate wind tower site had colder ground temperatures, with temperatures below the depths of alternate wind tower site had colder ground temperatures, with temperatures below the depths of
Measured ground temperature distributions are presented in Appendix C. Measured ground temperature distributions are presented in Appendix C.
Figure B-1 presents the measured moisture content, as a percent of dry weight, by general soil type and Figure B-1 presents the measured moisture content, as a percent of dry weight, by general soil type and
depth bgs. Moisture contents in excess of unfrozen state saturation are considered ice rich permafrost, depth bgs. Moisture contents in excess of unfrozen state saturation are considered ice rich permafrost,
were measured in much of the organic and fine-grained deposits, consisting of peat, organic silt, and silt. were measured in much of the organic and fine-grained deposits, consisting of peat, organic silt, and silt.
Mr. Dennis Sharp July 2, 2012
WHPacific 5 113-95757
Atmautluak Wind Turbine
The moisture content in the frozen sand deposit is not considered to be significantly in excess of unfrozen
state saturation.
Measured moisture contents in the peat averaged about 300 percent by mass. The moisture content
measured in the recovered organic silt samples ranged between 57 and 226 percent, and averaged 173
percent. Moisture contents measured in the mineral silt samples ranged between 24 and 628 percent,
and averaged 99 percent. The average moisture contents in the sand samples ranged from 21 to 27
percent, and averaged 24 percent. For presentation purposes, the moisture contents in Figure 1 are
terminated at 100 percent but as discussed above soil moisture contents in excess of 100 percent are
present in the recovered soil samples. The soil sample laboratory testing data presented in Appendix B
should be reviewed to augment the summary laboratory data presented in Table B-1 and on the borehole
logs.
Pore water salinity tests were conducted on selected samples at various depths throughout each of the
boreholes. The pore water salinities were less than 0.4 parts per thousand (ppt). Based on laboratory
test data, freezing point depressions due to pore water salinity is not expected to be a geotechnical
design concern at either wind turbine site. As a general point of reference, a pore water salinity of 10 ppt
decreases the freezing point of the pore water by 1°F.
Figure 3: Moisture Content by Soil Type and Depth
7.0 DISCUSSION
Of the three wind turbine options discussed by WHPacific, we understand two general tower types, a free
standing lattice (Vestas and Bergey) and monopole (Northwind) towers, are generally used to support the
wind turbine assemblies. Based on our experience, the monopole tower types will develop greater
foundation reaction loads, particularly overturning moments, than the free standing lattice towers.
Based on soil conditions and ground thermal states we encountered at the proposed wind turbine
locations, two foundation systems area considered feasible for the wind turbine foundations: a pile
foundation system and a gravity system. A gravity foundation would generally consist of a passively
cooled granular fill pad under a reinforced concrete tower base. However, all granular materials and
concrete required for a gravity foundation system will need to be imported to the village. The village has
limited barge access due to shallow water and lacks a local sand and gravel borrow sites. The pile
foundation will develop resistance to the tower base reactions through adfreeze bond strength in the
permafrost. While both foundation systems are generally feasible for the proposed wind turbine
foundations in this village, it is our opinion a pile foundation option has cost and constructability
advantages over a gravity based foundation system.
0
10
20
30
40
50
60
0% 20% 40% 60% 80% 100%
PT, OL ML SP-SM SM
Based on soil conditions and ground thermal states we encountered at the proposed wind turbine Based on soil conditions and ground thermal states we encountered at the proposed wind turbine
locations, two foundation systems area considered feasible for the wind turbine foundations: a pile locations, two foundation systems area considered feasible for the wind turbine foundations: a pile
foundation system and a gravity system. A gravity foundation would generally consist of a passively foundation system and a gravity system. A gravity foundation would generally consist of a passively
cooled granular fill pad under a reinforced concrete tower base. However, all granular materials and cooled granular fill pad under a reinforced concrete tower base. However, all granular materials and
concrete required for a gravity foundation system will need to be imported to the village. The village has concrete required for a gravity foundation system will need to be imported to the village. The village has
limited barge access due to shallow water and lacks a local sand and gravel borrow sites. The pile limited barge access due to shallow water and lacks a local sand and gravel borrow sites. The pile
foundation will develop resistance to the tower base reactions through adfreeze bond strength in the foundation will develop resistance to the tower base reactions through adfreeze bond strength in the
permafrost. While both foundation systems are generally feasible for the proposed wind turbine permafrost. While both foundation systems are generally feasible for the proposed wind turbine
foundations in this village, it is our opinion a pile foundation option has cost and constructability foundations in this village, it is our opinion a pile foundation option has cost and constructability
Mr. Dennis Sharp July 2, 2012
WHPacific 6 113-95757
Atmautluak Wind Turbine
For our geotechnical design analysis, we have assumed that the tower type selected for use on this site is
the monopole system used to support the Northwind wind turbines. If a different tower is being
considered, we should be contacted to verify or modify our recommendations for the selected tower.
Total tower base reactions (axial load, shear, torsion, and base moment) will need to be developed for
both transient and sustained load states, specifically for the proposed wind turbine system at this site. In
general, short-term (3-second) wind gust loads or heavy ice-loads during wind conditions are expected to
control the tower base reactions.
Foundation loading information was not available at the time of our submittal. However, our geotechnical
analysis is based on previous projects using Northwind wind turbine units on pile supported monopole
permafrost conditions within the Yukon-Kuskokwim area. For this site, we have
assumed that the monopole Northwind tower will connect to a concrete or steel foundation cap with at
least six foundation piles for support.
Recently installed Northwind 100 wind turbine units in Quinhagak reportedly developed unfactored total
design loads of 70 kips uplift and 100 kips compression per pile. The Quinhagak Northwind 100 wind
turbines were 120 feet tall with 68.5-foot rotors using a design wind speed to 133 miles per hour (3-
second gust). The tower base geometry consisted of an approximately 15-foot center-to-center diagonal
spacing between six foundation piles. We have used these unfactored pile reactions in our analysis and
the Atmautluak site. Actual unfactored design loads for the Atmautluak wind turbine systems need to be
determined and provided to us as part of our final design analysis. The Atmautluak wind turbine
unfactored design loads may be significantly different from our assumed loading conditions discussed
above.
The foundation piles will need to resist the structural foundation loads as well as the seasonal frost uplift
force. The frost uplift force is developed within the active layer due to the expansion of the water within
the soils during freezing and can be significant in the Atmautluak area. Sustained (dead) loads in excess
of the frost uplift force are not expected for the wind turbine units being considered for this village.
However, if the sustained loads on the foundation pile are in excess of the frost uplift force, we should be
notified to verify that pile embedment is sufficiently deep to resist any creep related foundation
movements.
Adfreeze piles installed by driven or drilled and slurried installation methods could be used. Driven H or
open end pipe piles are expected to have a reduced adfreeze bond strength relative to drilled and slurried
adfreeze piles due to the in-place silty soil adfreeze bond along driven piles. The required embedment
depth below the existing tundra surface for driven piles may also develop concerns for pile damage during
installation depending on pile geometry and pile installation methods.
Pipe piles with or without the addition of a helical wrap installed using drilled and slurried methods may be
used to support the foundation. The helical wrap effectively increases the diameter of the pile by moving
the potential adfreeze failure plane from the surface of the pile into the slurry along outside diameter of
the helices. The addition of helices generally decreases the required pile embedment relative to piles
without helices. The helices are placed on the pile sufficiently below the active layer to prevent frost
forces developing under the helices. Depending on final design loads, the embedment of the foundation
piles without helices may be sufficiently deep that construction may require specialized construction
equipment and significantly increase construction costs.
The subsurface conditions at the site are generally frozen well-bonded silt and fine sand with some
organic surface soils. These conditions along with the measured ground temperatures are conducive to a
drilled and slurried adfreeze pile foundation system. Drilled and slurried adfreeze pile may be backfilled
with either silt or sand and gravel aggregate slurry. However, if mineral silt is used for the slurry
aggregate a considerable reduction in adfreeze bond strength, relative to a sand and gravel slurry
aggregate, should be expected. A sand and gravel slurry aggregate is preferred.
The preferred and alterative wind tower sites are undeveloped with an undisturbed tundra mat at ground
surface. To reduce frost uplift loads under the foundation base, the pile cap should be slightly elevated
The subsurface conditions at the site are generally frozen well-bonded silt and fine sand with some The subsurface conditions at the site are generally frozen well-bonded silt and fine sand with some
organic surface soils. These conditions along with the measured ground temperatures are conducive to a organic surface soils. These conditions along with the measured ground temperatures are conducive to a
drilled and slurried adfreeze pile foundation system. Drilled and slurried adfreeze pile may be backfilled drilled and slurried adfreeze pile foundation system. Drilled and slurried adfreeze pile may be backfilled
with either silt or sand and gravel aggregate slurry. However, if mineral silt is used for the slurry with either silt or sand and gravel aggregate slurry. However, if mineral silt is used for the slurry
aggregate a considerable reduction in adfreeze bond strength, relative to a sand and gravel slurry aggregate a considerable reduction in adfreeze bond strength, relative to a sand and gravel slurry
The preferred and alterative wind tower sites are undeveloped with an undisturbed tundra mat at ground The preferred and alterative wind tower sites are undeveloped with an undisturbed tundra mat at ground
surface. To reduce frost uplift loads under the foundation base, the pile cap should be slightly elevated surface. To reduce frost uplift loads under the foundation base, the pile cap should be slightly elevated
Mr. Dennis Sharp July 2, 2012
WHPacific 7 113-95757
Atmautluak Wind Turbine
above the tundra surface and the tundra mat at ground surface should be left undisturbed as discussed
below. For this reason, we have assumed that construction will occur in the winter months, when the
tundra is frozen and can support the construction loads without damage. Alternatively, construction mats
or gravel access roads could be constructed across the wind tower sites to provide a stable platform for
construction over thawed ground. However, granular fill is not readily available in the Atmautluak area.
Imported fill may be required to construct access roadways and construction working pads.
Monopole wind towers may be sensitive to lateral loads and overturning moments. In general, the lateral
load or moment applied to the top of the pile will be resisted by the underlying frozen soils at the site. The
greater the vertical distance between the applied load and the point of fixity within the permafrost soils,
the larger the stresses within the foundation pile above the point of fixity. If the internal stresses within the
foundation pile are significant and present a concern to the project structural engineer, larger
dimensioned piles may be necessary or insulation may be added at the ground surface to reduce the
active layer thickness.
The permafrost must be maintained at or below the recommended design temperature throughout the
project design life to support the tower loads. With warming climate conditions and the general reduction
in freezing indices expected in the Atmautluak area, passive subgrade cooling systems (thermosyphons)
should be placed in the annulus of each foundation pile to remove heat and preserve the existing
permafrost. Passive subgrade cooling may also reduce the pile embedment requirements relative to non-
passively cooled piles, particularly if ground insulation is used under the tower base footprint.
We have assumed that construction will take place during the winter months when the tundra surface is
frozen. If construction is planned when the active layer is thawed, standing water may be present at
ground surface and access roadways and construction pads may be required.
8.0 ENGINEERING RECOMMENDATIONS
The following discussion presents the recommendations for the drilled and slurried foundation piles for
Northwind 100 wind turbines on monopole tower. If a different wind turbine/tower system is being
considered, such as a freestanding lattice tower, we should be contacted to verify or modify our
recommendations. Geotechnical recommendations for drilled and slurried pipe piles with a 2-inch wide
helical wrap connected to a common pile/foundation cap are presented for three different pipe riser sizes.
Nominal pipe diameters of 14, 16 and 18 inches, excluding the 2-inch helix wrap, were selected for our
analyses based on the expected allowable bending stress and constructability considerations related to
developing axial capacity.
8.1 Idealized Soil and Ground Temperature Profile
Soil conditions are generally consistent among the boreholes advanced in Atmautluak. The following
idealized soil profile was used as a basis for the design of the wind tower foundation. Moisture contents
are averages of laboratory testing results. Dry unit weights were determined from measured moisture
contents assuming saturated conditions and on our engineering judgment.
Table 2: Idealized Soil Profile
Depth of Layer Soil Type Moisture Content
Total Unit
Weight
0 5 feet Pt/OL 150% 125 pcf
5 30 feet ML 50% 120 pcf
30 50 feet SP/SP-SM/SM 25% 120 pcf
Notes: 1) pcf = pounds per cubic foot
Based on the profile and climate conditions discussed above, the active layer thickness is expected to be
5 feet, as calculated by Army Corps of Engineers methods (TM 5-852-6). If insulation is placed at ground
Based on the profile and climate conditions discussed above, the active layer thickness is expected to be Based on the profile and climate conditions discussed above, the active layer thickness is expected to be
-6). If insulation is placed at ground -6). If insulation is placed at ground
Mr. Dennis Sharp July 2, 2012
WHPacific 8 113-95757
Atmautluak Wind Turbine
surface, the active layer thickness and resulting frost uplift force will decrease. With 4 inches of surface
insulation with a thin fill cover, the active layer decreases to about 1 to 1.5 feet below the insulation at
surface. Calculations were completed using the estimated design thawing indices for the 2012 to 2042
period presented in Table 1.
The ground temperature profile used in our analysis is based on the warmer ground temperatures
observed at depth during our field exploration. A ground temperature of 30.5°F was used as a baseline
foundation design temperature below the depth of seasonal variation (10 to 15 feet). However, if 4-inches
of rigid insulation is placed under and around the tower foundation footprint, the depth of seasonal
variation decreases to approximately 5 to 10 feet bgs.
8.2 Foundation Loading
The pile embedment is controlled by either the structural loading for long or short-term loading conditions,
or the frost uplift force. The unfactored structural foundation loads for the Northwind 100 wind turbine
system were discussed previously for a 6 pile foundation cap geometry similar to the units recently
installed in Quinhagak, 100 kips compression and 70 kips uplift per pile for short-term loading scenarios.
Long-term (sustained) foundation loads are not expected to control the foundation pile embedment depth.
Frost uplift force is caused by the expansion of pore water within the active layer soils during freezing.
The assumed pressure that develops within the active layer due to frost uplift at this site is 40 pounds per
square inch (psi) acting on the circumference of the pile through the active layer. Table 3 presents the
estimated unfactored frost uplift force on select pile sizes for an active layer thickness of 5 feet. The
reduction in active layer thickness due to surface insulation results in lower estimated frost uplift forces to
the values presented in Table 4.
Table 3: Frost Uplift Force Table 4: Frost Uplift Force with Surface
Insulation
Pile Size
(nominal diameter)
Frost Uplift
Force
Pile Size
(nominal diameter)
Frost Uplift
Force
14-inch riser 106 kips 14-inch riser 32 kips
16-inch riser 120 kips 16-inch riser 36 kips
18-inch riser 136 kips 18-inch riser 41 kips
8.3 Axial Capacity
The structural and frost uplift forces will be resisted by the adfreeze bond within the slurry at the radial
edge of the helical wrap attached to the pile. In this analysis we have assumed the foundation pile
consist of 14, 16 and 18-inch pipe riser diameter open or closed-end piles with an additional 2-inch
helices attached radially to the exterior of the pile. Piles should have helices attached to the pile below an
embedment below tundra surface of 7.5 and 5 feet for tundra and insulated surface conditions,
respectively. Pile diameter and wall thickness may be governed by lateral loads and allowable pile head
deflection.
To achieve the requested design loads, the piles should be installed to the minimum embedment depth
below existing tundra surface is presented in Table 5. Minimum embedment depths are presented for
pipe piles with a 2-inch wide helical wrap installed with drilled and slurried methods using imported sand
and gravel aggregate for the slurry backfill. The minimum recommended embedment depths are based
on maintaining the existing tundra surface and insulated surface conditions encountered in our
geotechnical boreholes. For geotechnical purposes, we have assumed a nominal 16-inch pitch for the 2-
inch helix wrap. The minimum recommended pile embedment depths include a factor of safety of at least
two based on the assumed unfactored per pile axial compression and uplift design loads discussed
previously.
below existing tundra surface is presented in Table 5. Minimum embedment depths are presented for below existing tundra surface is presented in Table 5. Minimum embedment depths are presented for
pipe piles with a 2-inch wide helical wrap installed with drilled and slurried methods using imported sand pipe piles with a 2-inch wide helical wrap installed with drilled and slurried methods using imported sand
and gravel aggregate for the slurry backfill. The minimum recommended embedment depths are based and gravel aggregate for the slurry backfill. The minimum recommended embedment depths are based
maintaining the existing tundra surface and insulated surface conditions encountered in our maintaining the existing tundra surface and insulated surface conditions encountered in our
geotechnical boreholes. For geotechnical purposes, we have assumed a nominal 16-inch pitch for the 2-geotechnical boreholes. For geotechnical purposes, we have assumed a nominal 16-inch pitch for the 2-
inch helix wrap. The minimum recommended pile embedment depths include a factor of safety of at least inch helix wrap. The minimum recommended pile embedment depths include a factor of safety of at least
two based on the assumed unfactored per pile axial compression and uplift design loads discussed two based on the assumed unfactored per pile axial compression and uplift design loads discussed
Mr. Dennis Sharp July 2, 2012
WHPacific 9 113-95757
Atmautluak Wind Turbine
Table 5: Minimum Pile Embedment Below Existing Tundra Surface
Pile Riser
Diameter
Outer
Diameter with
2-inch helix
wrap
Minimum Pile Embedment (feet)
Non-insulated
Tundra Surface
4-inch Rigid Insulation
Placed at the Ground Surface
14 inches 18 inches 32 feet 27 feet
16 inches 20 inches 30 feet 25 feet
18-inches 22 inches 28 feet 23 feet
For design purposes, we have estimated a total settlement at the pile cap in the range of 1-inch in 20
years. However, this settlement will depend on the ground temperatures and pile installation methods
being consistent with the geotechnical foundation recommendations.
The piles should be installed within a drilled borehole with a diameter 4 to 6 inches greater than the
exterior diameter of the helix wrap. The boreholes should be drilled with a dry auger or air rotary drill
system. Drilling muds or other fluids should not be used. Thawing of the permafrost with steam, water of
other fluids should not be allowed. Unfrozen soil or free water below the active layer is not expected
within the pile boreholes. However, if unfrozen soil or free water is present or caving of the borehole
sidewall is encountered, we should be notified. Depending on the construction schedule, portions of the
active layer may be unfrozen. If so, temporary casing through the active layer may be required to control
sidewall caving and water inflow. The piles should be protected from corrosion through the active layer.
Corrosion control measures should be coordinated with the structural engineer.
Prior to installation, the pile should be free of snow, ice, oil, or other deleterious matter. The piles should
be plumb and checked for horizontal and vertical position prior to the placement of the slurry. Wedges or
other devices can be used to hold the piles in place until the slurry is placed and frozen.
In order to ensure long-term performance of the foundation, passive cooling is recommended adjacent to
the foundation piles. Since the pile caps are expected to be relatively close to final grade, the passive
subgrade cooling may require installation within the borehole annulus. For this project, passive cooling
systems consist of a two-phase liquid-vapor system (Thermoprobe) developed and manufactured by
Arctic Foundations, Inc. (AFI). The Thermoprobes should be 3.5-inches in diameter systems with a 70
square foot condenser and installed to at least 20 feet below the existing tundra surface, or as
recommended by AFI.
A closed-end standpipe should also be installed adjacent to the foundation pile within the borehole
annulus and oriented directly opposite the passive subgrade cooling system to permit ground temperature
measurements. The standpipe should consist of a closed-end, 1-inch diameter schedule 40 (or
equivalent) HDPE pipe installed to the base of the foundation pile. Prior to slurry placement, the
standpipe conduit should be capped and attached to the pile to reduce movement during slurry
placement.
The annulus of the borehole should be backfilled with slurry. The slurry aggregate should consist of a
clean, well-graded sand and gravel. The sand and gravel aggregate will most likely require importing to
Atmautluak. The sand and gravel slurry material should contain less than 10 percent material (dry weight
basis) finer than the U.S. No. 200 sieve size, and 40 to 60 percent (dry weight basis) gravel less than 1-
inch size. All slurry aggregate should be processed to less than 1-inch nominal diameter. The slurry soil
must be fully thawed prior to mixing and placement. The temperature of the mixed slurry should be at
40°F ± 5°F at the time of placement. The slurry should be saturated and have a consistency equivalent to
a concrete slump of 5 inches ± 1-inch using potable water. A representative portion of the slurry
aggregate should be submitted to Golder for testing to assure proper gradation and freezing point
depression materials are not present.
Atmautluak. The sand and gravel slurry material should contain less than 10 percent material (dry weight Atmautluak. The sand and gravel slurry material should contain less than 10 percent material (dry weight
basis) finer than the U.S. No. 200 sieve size, and 40 to 60 percent (dry weight basis) gravel less than 1-basis) finer than the U.S. No. 200 sieve size, and 40 to 60 percent (dry weight basis) gravel less than 1-
inch size. All slurry aggregate should be processed to less than 1-inch nominal diameter. The slurry soil inch size. All slurry aggregate should be processed to less than 1-inch nominal diameter. The slurry soil
must be fully thawed prior to mixing and placement. The temperature of the mixed slurry should be at must be fully thawed prior to mixing and placement. The temperature of the mixed slurry should be at
F at the time of placement. The slurry should be saturated and have a consistency equivalent to F at the time of placement. The slurry should be saturated and have a consistency equivalent to
a concrete slump of 5 inches ± 1-inch using potable water. A representative portion of the slurry a concrete slump of 5 inches ± 1-inch using potable water. A representative portion of the slurry
aggregate should be submitted to Golder for testing to assure proper gradation and freezing point aggregate should be submitted to Golder for testing to assure proper gradation and freezing point
Mr. Dennis Sharp July 2, 2012
WHPacific 10 113-95757
Atmautluak Wind Turbine
The slurry should be placed in lifts of approximately 3 feet with each lift being densified with a concrete
vibrator as the slurry is placed. Densification is required to assure the slurry completely encases the
helices and is full contact with the pile sidewall. The piles should be installed so that the centerline point
of the pile is within one half inch of the horizontal design location, or as required by the structural
engineer. Load should not be applied to the piles until the slurry is fully frozen, which can be confirmed
using a thermistor string in the HDPE pipe. The borehole annulus must be protected from infilling with
snow, water and other deleterious matter.
8.4 Lateral Pile Capacity
Lateral loading of the piles due to shear load applied to the foundation from wind loading has been a
concern in previous wind tower projects. The project structural engineer can further clarify the lateral
loading on the foundation piles.
The bending moment imposed on the piles depends on the lateral load imposed at the top of the pile and
the height of the top of the pile above the point of fixity. For permafrost conditions, the pile can be
assumed to be a cantilever above the point of fixity. For this site, the point of fixity during the summer
months is considered to be 0.5-foot below the active layer depth. The nominal active layers for the tundra
and insulated surfaces are expected to be 5 and 1.5 feet below tundra surface, respectively. During the
winter months, when the ground is fully frozen, the point of fixity is 0.5 feet below the existing tundra
surface.
For example, assuming a 16-inch diameter pipe pile with a 0.375-inch thick wall is used to support the
tower with 4-inches of rigid insulation installed at the ground surface. To reduce the bending stress within
the piles, the pile/foundation cap connection is no more than 1-foot above the final grade. For design
purposes, a 5 kip lateral load is applied at the pile cap. If so, the estimated pile head deflection for a free
head condition is approximately 0.2 inch at the pile cap. If rigid insulation is not included, lateral
deflections on the order of 0.5 to 0.75 inches at the pile cap can be developed.
Some partial fixity may be feasible depending on the pile cap design. If some partial fixity is developed, a
reduction in the estimated lateral deflection can be achieved. Refinement in the estimated lateral capacity
and deflection can be determined once final design loads are provided to us.
8.5 Ground Surface Insulation
Insulation should be placed on the site if a Northwind 100 wind turbine and monopole tower system is
being considered. A geotextile fabric should be placed at ground surface to protect the insulation. Four
(4) inches of extruded insulation (rigid insulation) should be placed over the existing ground surface
underlying the foundation pile cap. The insulation should have a compressive strength of at least 40-psi
at 5 percent strain. At each tower location, the rigid insulation should be installed under the entire
foundation footprint and extend at least 6 feet radially outward from the piles. The insulation should be
installed as two layers of 2-inch thick insulation with overlapping and offset vertical joints.
The insulation will require protection from UV radiation, weather, and damage. One option is to cap the
insulation with a mineral soil fill. If a fill cap is planned, it should be at on the order of 8 to 12 inches thick.
Depending on the type of mineral soil used, armor rock or geosynthetic erosion protection systems may
also be required. Final grades should be designed to direct water away from the foundation.
If fill is not used, the insulation should be anchored to the surface and protected from degradation and
damage. We should be notified if a mineral soil cap is not planned to design an anchoring system for the
insulation. Duckbill anchors or other systems can be used to anchor the insulation from floating.
Geotextiles and synthetic liners may be used to protect the rigid insulation from UV radiation, weather and
site damage. The project civil engineer should be contacted to develop rigid insulation measures.
If fill is not used, the insulation should be anchored to the surface and protected from degradation and If fill is not used, the insulation should be anchored to the surface and protected from degradation and
damage. We should be notified if a mineral soil cap is not planned to design an anchoring system for the damage. We should be notified if a mineral soil cap is not planned to design an anchoring system for the
insulation. Duckbill anchors or other systems can be used to anchor the insulation from floating. insulation. Duckbill anchors or other systems can be used to anchor the insulation from floating.
Geotextiles and synthetic liners may be used to protect the rigid insulation from UV radiation, weather and Geotextiles and synthetic liners may be used to protect the rigid insulation from UV radiation, weather and
site damage. The project civil engineer should be contacted to develop rigid insulation measures. site damage. The project civil engineer should be contacted to develop rigid insulation measures.
Mr. Dennis Sharp July 2, 2012
WHPacific 11 113-95757
Atmautluak Wind Turbine
If standing water or flooding is expected at the tower sites, we should be notified in order to assist the
project civil engineer with the design of an appropriate insulation anchoring system to control insulation
movement due to buoyancy.
8.6 Construction Considerations
For the recommendations above, we have assumed that construction will occur during the winter months
when the tundra surface is fully frozen and protected from surface damage from construction activities. If
construction activities are planned at other times of the year, specifically summer and fall conditions when
standing water may be present at ground surface, access roadways and construction pads may be
required to protect the tundra surface.
If access roads and construction pads are required, they may be constructed out of non-structural mineral
soil fill over a woven or non-woven geotextile separation fabric. The roadways and pads should be
designed by the project civil engineer to accommodate the expected construction and
operation/maintenance needs for the project. If locally available fine-grained or potentially wind or water
erodible materials are used for embankment construction, additional fill protection measures may be
needed. We can coordinate with the project civil engineer once access pad and roadway requirements
are determined.
It is essential that construction planning for the pile foundations include adequate time after installation to
allow for freezeback of the slurry backfill. If installation schedules do not allow for adequate cooling prior
to foundation loading, differential foundation movements may occur.
The contractor should be prepared to advance the pile borehole to the design embedment depth. If
conditions restrict the installation depth of any pile to less than recommended design embedment, Golder
should be notified and allowed to verify the allowable axial capacity of the pile in question. Any pile that is
installed to a depth less than the design minimum embedment may need colder ground temperatures to
develop adequate axial and lateral resistance for the final design loads.
9.0 USE OF THIS REPORT
For preliminary design purposes, we have assumed a Northwind 100 wind turbine and a monopole tower
system will be the preferred option for this village. While site-specific tower base reactions have not been
developed for this system, we have based on preliminary geotechnical engineering analysis and
recommendations on tower base reactions developed for a similar wind turbine system recently installed
in Quinhagak, Alaska. All parties must acknowledge and accept that the tower base reactions developed
for the Quinhagak wind turbine project may not be suitable or appropriate for the wind turbine project(s)
proposed for Atmautluak.
Until the final, site-specific wind turbine tower geometry and base reactions are provided to us and we
conduct our review of the design data, the geotechnical recommendations presented in this submittal
should not be used for final design or construction. Once tower base reactions are provided to us, we will
review our preliminary geotechnical recommendations presented in this submittal and provide written
modifications in our final report for owner and design team consideration.
This report has been prepared exclusively for the use of WHPacific for site planning and preliminary
design of the proposed wind turbines in Atmautluak, Alaska. If there are significant changes in the nature,
design, or location of the facilities, we should be notified so that we may review our conclusions and
recommendations in light of the proposed changes and provide a written modification or verification of the
changes.
There are possible variations in subsurface conditions between explorations and also with time.
Therefore, inspection and testing by a qualified geotechnical engineer or technician should be included
during construction to provide corrective recommendations adapted to the conditions revealed during the
design of the proposed wind turbines in Atmautluak, Alaska. If there are significant changes in the nature, design of the proposed wind turbines in Atmautluak, Alaska. If there are significant changes in the nature,
design, or location of the facilities, we should be notified so that we may review our conclusions and design, or location of the facilities, we should be notified so that we may review our conclusions and
recommendations in light of the proposed changes and provide a written modification or verification of the recommendations in light of the proposed changes and provide a written modification or verification of the
There are possible variations in subsurface conditions between explorations and also with time. There are possible variations in subsurface conditions between explorations and also with time.
Therefore, inspection and testing by a qualified geotechnical engineer or technician should be included Therefore, inspection and testing by a qualified geotechnical engineer or technician should be included
during construction to provide corrective recommendations adapted to the conditions revealed during the during construction to provide corrective recommendations adapted to the conditions revealed during the
Mr. Dennis Sharp July 2, 2012
WHPacific 12 113-95757
Atmautluak Wind Turbine
work. In addition, a contingency for unanticipated conditions should be included in the construction
budget and schedule.
The work program followed the standard of care expected of professionals undertaking similar work in the
State of Alaska under similar conditions. No warranty expressed or implied is made.
10.0 CLOSING
Please contact myself or Richard Mitchells with any questions or concerns.
GOLDER ASSOCIATES INC.
DRAFT, No Signatures
Heather M. Brooks, PE Richard A. Mitchells, PE
Project Geotechnical Engineer Associate and Senior Geotechnical Engineer
Attachments: Figure 1 Vicinity Map
Figure 2 Site Plan
Appendix A Borehole Logs
Appendix B Laboratory Results
Appendix C Ground Temperatures
HMB/RAM/mlp
FIGURES
SCALE01 1MILEWHPACIFICATMAUTLUAK WIND TURBINESATMAUTLUAK, ALASKATITLEPROJECTSCALEDESIGNPROJECT No. FILE No.CADDCHECKREVIEWAS SHOWN113-95757 Vicinity_Map_USAK83__2012---- ----APG 6/27/12HMB 6/27/12---- ----D R A F T1.) MAP CREATED USING USGS 1:63360 SCALETOPO MAPS AS PROVIDED BY THE STATEWIDEDIGITAL MAPPING INITIATIVE (SDMI)PROJECT LOCATIONPROJECT LOCATIONATMAUTLUAK WIND TURBINESATMAUTLUAK WIND TURBINESATMAUTLUAK, ALASKAATMAUTLUAK, ALASKADESIGNDESIGNPROJECT No.PROJECT No.CADDCADDCHECKCHECKREVIEWREVIEW113-95757 Vicinity_Map_USAK83__2012---- -------- ----APG 6/27/12APG 6/27/12HMB 6/27/12HMB 6/27/12
ATT-01
ATT-02
ATT-03
SITE PLAN
WHPACIFIC
ATMAUTLUAK WIND TURBINES
ATMAUTLUAK, ALASKA
FIGURE 2
TITLE
PROJECT
SCALEDESIGN
PROJECT No. FILE No.
CADD
CHECK
REVIEW
AS SHOWN
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D R A F T
REFERENCE
LEGEND
SCALE
0
FEET
500 500
ATT-03
BOREHOLE LOCATION AND
DESIGNATOR
1.) AERIAL IMAGERY PROVIDED BY ALASKA
DEPARTMENT OF COMMERCE, COMMUNITY, AND
ECONOMIC DEVELOPMENT (DCCED). IMAGERY DATED
BETWEEN 9/7/2007 AND 10/11/2007.
SITE PLANSITE PLAN
ATMAUTLUAK WIND TURBINESATMAUTLUAK WIND TURBINES
ATMAUTLUAK, ALASKAATMAUTLUAK, ALASKA
DESIGNDESIGN
PROJECT No.PROJECT No.
CADDCADD
CHECKCHECK
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D R A F T
APPENDIX A
BOREHOLE LOGS
APPENDIX B
LABORATORY RESULTS
APPENDIX C
GROUND TEMPERATURES
Wind-Diesel Power System