HomeMy WebLinkAboutPoint Lay Wind-Diesel Hybrid Feasibility Study - Dec 2011 - REF Grant 7030014DRAFT
Point Lay Wind-Diesel Hybrid
Feasibility Study
December 22, 2011
Douglas Vaught, P.E.
V3 Energy, LLC
Eagle River, Alaska
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This report was prepared by V3 Energy, LLC under contract to WHPacific for a North Slope Borough
project to assess the technical and economic feasibility of installing wind turbines in a wind-diesel hybrid
power system design for the villages of Point Hope, Point Lay, and Wainwright, Alaska. This report
addresses Point Lay.
Contents
Executive Summary....................................................................................................................................... 1
1 Introduction.......................................................................................................................................... 3
1.1 Scope of Work ............................................................................................................................... 3
1.2 Village of Point Lay........................................................................................................................ 3
1.3 Climate.......................................................................................................................................... 4
1.4 Geology......................................................................................................................................... 4
1.5 Permitting ..................................................................................................................................... 4
2 Wind Resource Assessment.................................................................................................................. 6
2.1 Met tower data synopsis .............................................................................................................. 6
2.2 Data Recovery............................................................................................................................... 6
2.3 Wind Speed................................................................................................................................... 6
2.4 Wind Rose..................................................................................................................................... 7
2.5 Turbulence Intensity..................................................................................................................... 7
3 Wind Project Sites................................................................................................................................. 9
3.1 Site A............................................................................................................................................. 9
3.2 Site B...........................................................................................................................................10
3.3 Other Site Options ......................................................................................................................12
4 Wind-Diesel System Design and Equipment.......................................................................................13
4.1 Wind-diesel Integration Controls................................................................................................14
4.2 Energy Storage Options ...............................................................................................................14
4.2.1 Batteries..............................................................................................................................14
4.2.2 PowerStore Flywheel..........................................................................................................15
5 Wind Turbines and HOMER Modeling....................................................................................................16
5.1 Diesel Power Plant......................................................................................................................16
5.2 Wind Turbines.............................................................................................................................17
5.2.1 Northern Power Systems Northwind 100...........................................................................17
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5.2.2 Aeronautica AW29-225.......................................................................................................18
5.2.3 Wind Turbine Performance Comparison............................................................................19
5.3 Modeling.....................................................................................................................................19
5.3.1 Electric Load........................................................................................................................19
5.3.2 Thermal Load ......................................................................................................................20
5.3.3 Diesel Generators................................................................................................................20
6 Economic Analysis...............................................................................................................................22
6.1 Wind Turbine Costs.....................................................................................................................22
6.2 Fuel Cost......................................................................................................................................22
6.3 Modeling Assumptions ...............................................................................................................23
6.4 Wind Power Site Cost Assumptions............................................................................................24
6.5 Site A Project Economics.............................................................................................................25
6.5.1 Medium Fuel Price Projection, 82% Turbine Availability....................................................25
6.5.2 High Fuel Price Projection, 82% Turbine Availability..........................................................26
6.5.3 Low Fuel Price Projection, 82% Turbine Availability...........................................................27
6.5.4 Medium Fuel Price Projection, 100% Turbine Availability..................................................28
6.6 Site B Project Economics.............................................................................................................29
6.6.1 Medium Fuel Price Projection, 82% Turbine Availability....................................................29
6.6.2 High Fuel Price Projection, 82% Turbine Availability..........................................................30
6.6.3 Low Fuel Price Projection, 82% Turbine Availability...........................................................31
6.6.4 Medium Fuel Price Projection, 82% Turbine Availability....................................................32
7 Conclusion and Recommendations.....................................................................................................33
Appendix A: Notice of Presumed Hazard, Site A........................................................................................34
Appendix B: Determination of No Hazard, Site B ......................................................................................35
Appendix C: Northwind 100 Wind Turbine................................................................................................36
Appendix D: Aeronautica AW29-225 Wind Turbine..................................................................................37
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Executive Summary
The measured high Class 4 to Class 5 wind resource in Point Lay, based on a wind classification system
with a range of 1 (poor) to 7 (superb) in terms of wind energy potential, is excellent with an average
wind velocity of 6.63 m/s (14.8 mph) at 30 meters elevation. Additionally, the test location experiences
low turbulence and relatively low probability of extreme wind events (the latter a reference to
Wainwright data), making Point Lay a superior candidate for a wind energy project.
Two potential wind turbine sites were investigated for this study: Site A, located on a fairly low but well-
exposed north-south trending hill immediately north of the village and immediately south of the mouth
of the Kokolik River; and site B, located in a well exposed area south of the village between the village
and the airport. Although Site A is higher and more exposed than Site B, for this study each site was
considered to have equivalent wind resource potential, which was collected near Site B. Site A would
require construction of an access road and distribution line extension, but has not turbine height
restrictions. Site B would require less road and distribution line construction but has an FAA-imposed
height restriction due to proximity to the airport
With an excellent wind resource and considering NSB’s goal to offset as much as possible the usage of
expensive fossil fuel to generate electricity, medium or high penetration wind-diesel power
configurations are the most suitable choice for Point Lay. There have been significant challenges to date
though with implementing high penetration wind-diesel systems in rural Alaska due to complexity, high
capital cost and operational problems. With an understanding that NSB must provide very high power
system reliability, only the medium penetration configuration was modeled in this study as it represents
a robust middle ground between insufficient fuel savings of the low penetration approach and the
expense and considerable complexity of high penetration wind. A medium penetration approach would
employ wind turbine capacity capable to approximately match peak load on windy days. In Point Lay,
this would offset 20 to 50 percent of annual diesel energy production. To maintain reliability, “spinning
reserve” (an on-line diesel generator operating between 10% and 100% rated output) would be
maintained at all times to supplement the electrical load in anticipation of fluctuating wind conditions.
During higher winds and lower electrical load, surplus wind-generated electricity would be shunted to
an electric boiler to supplement thermal heat loads.
Based on the average and peak electrical loads in Point Lay, only new wind turbines between 100 and
350 kW rated power were considered in this study. Market availability for turbines in this size range is
very limited worldwide and more limited yet in the United States, so only the fully arctic-rated 100 kW
Northern Power Systems Northwind 100 and the 225 kW Aeronautica AW29-225, both manufactured in
the United States, were identified as turbines suitable for use in Wainwright. The 330 kW German
Enercon E33 would be a very good alternate choice, but this turbine is not available in the American
market. The NW100 and the AW29-225 both have a history of successful use in utility power systems
and have established support in Alaska.
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HOMER software was used to predict the performance of wind turbines if added to the planned new
Point Lay diesel power system with reference to load profile and operating costs reported to Alaska
Energy Authority for the power cost equalization (PCE) program. Based on these simulations, economic
analyses was performed to determine benefit/cost (B/C) ratios based on initial capital cost of wind
turbines and related distribution and control system upgrades, O&M cost of the diesel plant and wind
turbines, fuel cost and related avoided fuel usage. The economic analyses were tabulated using
medium, high, and low fuel cost projections (as predicted by UAA’s Institute for Social and Economic
Research) for Sites A and B with a number of different turbine configurations at each site. Even with
conservative estimates of capital costs and O&M expenses over the life of the project, the medium and
high fuel cost projections yield positive benefit-to-cost ratios for either turbine at both sites. Only the
low cost projection fails to predict positive project benefit-to-cost ratios.
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1 Introduction
The North Slope Borough (NSB) contracted with WHPacific to prepare wind power feasibility studies for
the villages of Wainwright, Point Lay, and Point Hope. WHPacific contracted with V3 Energy, LLC to
assist with the project. This report documents the feasibility study of Point Lay; the Wainwright and
Point Hope studies are contained under separate cover.
Although NSB is home to vast fields of recoverable oil and natural gas, the huge size of the borough and
the relative geographic concentration of these fossil fuel resources means that a number of NSB villages,
including the coastal village of Point Lay, cannot tap these resources in any practical manner and instead
must rely on the importation of diesel fuel for electricity generation and thermal heating. NSB desires to
reduce Point Lay’s dependency on diesel fuel by developing renewable energy sources to augment the
diesel generator and fuel oil boilers. Previous studies have determined that wind power has the most
potential of the borough’s renewable energy resources to be economically viable and hence this study
focuses only on the wind resource and wind turbines to exploit that resource.
1.1 Scope of Work
This study, which was paid for with Alaska Energy Authority funds made available through the Alaska
Renewable Energy Fund Program and with matching funds from the North Slope Borough, investigates
and evaluates wind turbine power options in Point Hope, Point Lay, and Wainwright. The scope of work
of this study includes:
Select two wind turbine locations per village
Perform geotechnical investigation at each site
Identify land and/or regulatory issues for each site
Conduct wind technology workshop with NSB
Prepare conceptual design and feasibility reports
An environmental study, which is essential in determining site feasibility, will be conducted under a
separate contract and is not included in this report.
1.2 Village of Point Lay
Point Lay is one of the more recently established Inupiaq villages on the Arctic coast and has historically
been occupied year-round by a small group of one or
two families. They were joined in 1929-30 by several
more families from Point Hope. The deeply-indented
shoreline has prevented effective bowhead whaling,
but the village participates in beluga whaling. In 1974,
the village moved from the old site on a gravel barrier
island just offshore. The old village site is now used as a
summer hunting camp. Some residents of Barrow and
Wainwright relocated to Point Lay in the mid-1970s.
Later that decade, due to seasonal flooding from the
Kokolik River, the village relocated again to a site near
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the Air Force Distance Early Warning station to the south. Homes were relocated to the new town site.
Point Lay is a traditional Inupiat Eskimo village, with a dependence upon subsistence activities. The sale
and importation of alcohol is banned in the village. According to Census 2010, there were 70 housing
units in the community and 60 were occupied. Its population of 189 people is 88 percent Alaska Native,
10 percent Caucasian, and 2 percent Hispanic, Pacific Islander, multi-racial and other.
Water is obtained from a lake near the community and is treated and stored in a tank. Households have
water delivered to home tanks, which allows running water for the kitchen. Electricity is provided by
North Slope Borough. There is one school located in the community, attended by 87 students. Local
hospitals or health clinics include Point Lay Clinic. Emergency Services have coastal and air access.
Emergency service is provided by 911 Telephone Service volunteers and a health aide. Auxiliary
healthcare is provided by Point Lay Volunteer Fire Dept. (907-833-2714). A public 4,500' long by 100'
wide gravel airstrip, owned by the U.S. Air Force, provides Point Lay's only year-round access. Marine
and land transportation provide seasonal access.
Most year-round employment opportunities are with the borough government. Subsistence activities
provide food sources. Seals, walrus, beluga, caribou, and fish are staples of the diet.
The 2005 to 2009 American Community Survey estimated 59 (MOE +/-25) residents as employed. The
ACS surveys established that average median household income (in 2009 inflation-adjusted dollars) was
$46,875 (MOE +/-$36,041). The per capita income (in 2009 inflation-adjusted dollars) was $14,067 (MOE
+/-$4,832). About 16.8% (MOE +/-19.2%) of all residents had incomes below the poverty level.
Note that information regarding Point Lay is drawn from the Alaska Community Database Community
Information Summaries (CIS) which can be found at http://www.dced.state.ak.us/dca/commdb/CIS.cfm.
Regarding the American Community Survey information, MOE refers to margin of error.
1.3 Climate
Point Lay is located just south of the mouth of the Kokolik River, about 300 miles southwest of Barrow.
The climate is arctic. Temperatures range from -55 F in winter to 78 °F in summer. Precipitation is light,
averaging seven inches annually with 21 inches of snow. The Chukchi Sea is ice-free from late June until
September.
1.4 Geology
Geotechnical study was accomplished at Sites A and B by Golder and Associates of Anchorage. Their
report of findings may be found under separate cover.
1.5 Permitting
The permits that are typically required to erect wind turbines and construct supporting access roads and
power distribution lines are:
Federal Aviation Administration (FAA) obstruction notification
State of Alaska land use, if constructing on State land
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Local land use, if constructing on Borough land
Alaska Fish and Game fish habitat, if access road crosses stream(s)
U.S. Army Corps of Engineers (USACE) wetlands, if constructing on identified wetlands; may
require concurrence with:
o National Historic Preservation Act
o Endangered Species Act, if endangered species potentially impacted
o Consideration of essential fish habitat, if access road crosses stream(s)
o Migratory Bird Act, U.S. Fish and Wildlife Service
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2 Wind Resource Assessment
The wind resource measured in Point Lay is very good, measured at high wind power class 4 (good) to
low wind power class 5 (excellent). In addition to strong average wind speed and wind power density,
the site experiences highly directional prevailing winds and low turbulence.
A thirty meter NRG met tower was supplied to the Point Lay’s Cully Corporation in 2006 by the National
Renewable Energy Laboratory’s (NREL) under their anemometer loan program. A number of details of
the project are not known, including the rationale for choosing the test site, but the location of the
tower is desirable for a wind resource assessment as it is well away from obstructions such as buildings
and well exposed to winds from all directions. Although data collection in 2006 and 2007 was slightly
short of twelve months, the met tower was returned to operational status in June 2011, enabling
additional data collection to strengthen the earlier data set.
2.1 Met tower data synopsis
Data dates October 5, 2006 to September 11, 2007
Wind power class High 4 (good) to low 5 (excellent)
Power density mean, 30 meters 403 W/m
2
Wind speed mean, 30 meters 6.63 m/s
Weibull distribution parameters k = 1.74, c = 7.44 m/s
Wind shear power law exponent 0.142 (moderate), June to September data only
Roughness class 0.54 (snow surface), June to September only
IEC 61400-1, 3rd ed. classification Class III-c (likely, based on nearby Wainwright data)
Turbulence intensity, mean 0.072 (at 15 m/s)
Calm wind frequency 23% (less than 3.5 m/s)
2.2 Data Recovery
Specific sensor data recovery problems typical of Alaska met tower operations, such as freezing rain,
hoarfrost, and rime icing, likely occurred to some extent during the nearly one year met tower study in
Point Lay, but original data was not available, other than in an Excel file with data from June 7 through
September 11, 2007. Although this three month data set could be reviewed for data loss typically due
to atmospheric icing conditions, such weather does not occur during the months of June, July, August
and (early) September. All met tower data (including that not included in the Excel file download of
original data) is summarized in several WindPRO software reports prepared by the National Renewable
Energy Laboratory.
2.3 Wind Speed
Wind data collected from the met tower and summarized in the NREL WindPRO reports, from the
perspective of both mean wind speed and mean power density, indicates an excellent wind resource.
Note that temperature data was not included in the analysis of power density. Given the extremely cold
temperatures, and hence high air densities, of Point Lay, true wind power density will be higher yet,
categorizing Point Lay more solidly as wind power class 5. For purposes of analysis, wind data monthly
wind speed summaries contained in the 30 meter WindPRO report, along with other statistical data
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gleaned from the three-month Excel data, was used to synthesize a virtual data set. This enabled certain
mathematic and graphical analyses not contained in the WindPRO reports.
Wind speed profile (30 meter height)
2.4 Wind Rose
Wind frequency rose data (from NREL’s WindPRO report) indicates highly directional winds from
northeast to east-northeast. Although the NREL report did not show a power density rose, Wainwright
data confirms the Point Lay directional frequency and indicates that power winds are nearly exclusively
northeast to east-northeast, which presumably is representative of Point Lay.
2.5 Turbulence Intensity
From the NREL report, turbulence intensity at the Point Lay test site is well within acceptable standards
with an IEC 61400-1, 3rd edition (2005), classification of turbulence category C, which is the lowest
defined. Mean turbulence intensity at 15 m/s is 0.072
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Turbulence graphs
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3 Wind Project Sites
NSB requested that two wind turbine sites be identified in Point Lay. On June 24, 2011, Ross Klooster of
WHPacific, Doug Vaught of V3 Energy LLC, and Max Ahgeak of NSB Public Works Dept. traveled to Point
Lay and met with City of Point Lay and Cully Corporation representatives to discuss the wind power
project and to identify the two sites. This was accomplished by reviewing maps and ownership records
and then driving and walking to a number of locations near the village to assess suitability for
construction and operation of wind turbines. Two sites on Cully Corporation land were chosen,
identified as Site A and Site B in the Google Earth image below. The Cully Corporation controls much of
the land surrounding Point Lay and has championed wind power in Point Lay for a number of years,
including working with NREL in 2006 for the met tower that measured the local wind resource. With
this in mind, locating wind turbines on Cully Corporation land is highly desirable.
Point Lay site options, Google Earth image
3.1 Site A
Site A is located on a fairly low but well-exposed north-south trending hill immediately north of the
village and immediately south of the mouth of the Kokolik River. Site A presents a number of positive
features for a wind power site including a large enough area for several wind turbines, clear exposure in
all directions, relative proximity to existing three-phase power distribution, and dry tundra.
Additionally, and very importantly, the Federal Aviation Administration (FAA) made a determination of
no hazard for wind turbines up to 195 ft. (60 meters) above ground level, which enables significant
flexibility with turbine selection (refer to Appendix A). Less positive features of Site A include its
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proximity to Point Lay residences and the possible preclusion of future residential development along
this ridge, which is the natural direction of future housing expansion for the village.
Point Lay Site A
3.2 Site B
Site B is located in a well exposed area south of the village between the village and the airport. Positive
features of Site B for wind power development is that it is on the “industrial” side of Point Lay, has good
wind exposure in all directions, is very near existing three-phase power distribution, and would require
minimal access improvements. Adversely, however, an FAA determination of notice of presumed
hazard for wind turbines at Site B indicated that turbines would be restricted to 162 ft. AGL, limiting
turbine options to the Northwind 100B/21 or the Aeronautica AW29-225 to a 30 meter tower (refer to
Appendix B). The Site B area also is a bit constrained, which may restrict the option of future wind
power expansion at this site.
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Point Lay Site B
Point Lay Sites A and B comparison table
Wind Turbine Site Advantages Disadvantages
A Cully Corp. land Possible area of village expansion
Site large enough to accommodate
several turbines
Turbines will be in view and
possible auditory range of village
residents
Relatively dry site;likely good geotech
conditions
Possible avian conflicts with near
proximity to mouth of the Kokolik
River
FAA Determination of No Hazard
(DNH) for turbines up to 195 ft (59.5
meters) AGL
Somewhat limited space for future
expansion
Short road and distribution line
required
B Cully Corp. land FAA determination of Notice of
Presumed Hazard (NPH) for
turbines exceeding 162 ft AGL
Short road and distribution line
required
Somewhat limited space for future
expansion
Location is on the “industrial” side of
the village with less viewshed and
possible noise issues
Relatively dry site; likely good geotech
conditions
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3.3 Other Site Options
Other than Sites A and B, the only other realistic area for wind turbines in Point Lay is the terrain east of
the village. Although expansive and easily large enough to contain many wind turbines, it is
characterized by very marshy and wet conditions which would require considerable fill material for
construction. Additionally, with prevailing northeasterly to easterly winds, turbines east of the village
would have to be located reasonably distant to avoid noise and downwind ice throw problems. Also,
the absence of electric power distribution east of the village presents a further disadvantage and would
increase development costs.
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4 Wind-Diesel System Design and Equipment
Wind-diesel power systems are categorized based on their average penetration levels, or the overall
proportion of wind-generated electricity compared to the total amount of electrical energy generated.
Commonly used categories of wind-diesel penetration levels are low penetration, medium penetration,
and high penetration, as summarized below. The wind penetration level is roughly equivalent to the
amount of diesel fuel displaced by wind power. Note however that the higher the level of wind
penetration, the more complex and expensive a control system and demand-management strategy is
required.
Categories of wind-diesel penetration levels
Penetration PenetrationLevel Operating characteristics and system requirements
Instantaneous Average
Low 0% to 50% Less than
20%
Diesel generator(s) run full time at greater than minimum
loading level. Requires minimal changes to existing diesel
control system. All wind energy generated supplies the
village electric load; wind turbines function as “negative
load” with respect to diesel generator governor response.
Medium 0%to 100+%20%to
50%
Diesel generator(s)run full time at greater than minimum
loading level. Requirescontrol system capable of
automatic generator start, stop and paralleling. To control
system frequency during periods of high wind power input,
system requires fast acting secondary load controller
matched to a secondary load such as an electric boiler
augmenting a generator heat recovery loop. At high wind
power levels, secondary (thermal) loads are dispatched to
absorb energy not used by the primary (electric) load.
Without secondary loads, wind turbines must be curtailed
to control frequency.
High
(Diesels-off
Capable)
0% to 150+% Greater
than 50%
Diesel generator(s) can be turned off during periods of
high wind power levels. Requires sophisticated new
control system, significant wind turbine capacity, secondary
(thermal)load,energy storage such as batteries or a flywheel,
and possibly additional components such as demand-
manageddevices.
Choosing the ideal wind penetration for Point Lay depends on a number of factors, including load profile
of the community, wind resource, construction cost and challenges, fuel price and also technical
capability and experience of the utility with wind power and energy storage systems. There is no one
“right” answer and the most optimal wind-diesel system for Point Lay may not be the one that displaces
the most fuel, nor even one that has the highest estimated benefit-to-cost ratio. It is presumed for the
purposes of this feasibility study that North Slope Borough’s interest will be with a medium penetration
option as that provides significant enough fuel savings to justify the high construction costs of a wind
turbine project yet avoids the significant design complexity and operational challenges of high
penetration.
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4.1 Wind-diesel Integration Controls
Medium to 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, typically referred to as a supervisory control and data acquisition
(SCADA) system, is installed to select theoptimum system component configuration based on village
load demand and available wind power. Regardless of the supplier, a SCADA system is capable of
controlling individual components and allowing those components to communicate status to the
system. A typical SCADA will consist of the following:
Station Controller: schedules and dispatches diesel generators, wind turbines and other
components units, performs remote control functions, and stores collected component and
system data
Generation Controller: monitors and controls individual diesel generators
Wind Turbine Controller: monitors and controls individual wind turbine and dispatches wind
turbines
Feeder Monitor: monitors vital statistics of an individual distribution feeder, including
ground fault information
Demand Controller: monitors, controls, and schedules demand-managed devices
4.2 Energy Storage Options
Although high penetration wind power is not proposed in this feasibility study, as reference for future
development, electrical energy storage provides a means of storing wind generated power during
periods of high winds and releasing that power to the electrical distribution system as winds subside.
4.2.1 Batteries
Batteries are most appropriate for providing medium-term energy storage to allow a transition, or
bridge, between the variable output of wind turbines, and diesel generation. This bridging period is
typically between five and fifteen minutes. Storage for several hours or days is also possible with
batteries, but requires more capacity and higher cost. In general, the disadvantages of batteries for
energy storage, even for a small utility system, are high capital and maintenance costs and limited
lifetime. Of particular concern to rural Alaska communities is that batteries are heavy and expensive to
transport to the site, and many contain toxic material that requires disposal as hazardous waste at the
end of a battery’s useful life.
Because batteries operate on direct current (DC), a converter is required when connected to an
alternating current (AC) system. A typical battery storage system includes a bank of batteries and a
power conversion device. Recent advances in power electronics have made solid state converter
(inverter/rectifier) systems cost effective and hence the preferred power conversion device.
Despite some drawbacks, electric power storage with batteries is a proven technology, but it has seen
limited use in rural Alaska wind-diesel projects to date. Wales is equipped with a high penetration wind
system with battery storage that is functional, but its operational history has been very disappointing
and given the design age, it is not considered a reproducible system. Kokhanok has a recently-installed
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high-penetration wind-diesel system with lead-acid type battery storage, designed and constructed by
Marsh Creek LLC of Anchorage, although it is not yet operational. Of interest is a 250 kW flow battery
that Kotzebue Electric Association plans to install in 2012 in Kotzebue to support their planned
installation of two 900 kW EWT wind turbines.
4.2.2 PowerStore Flywheel
Built by Powercorp Pty of Darwin, Australia, the PowerStore is a very fast-acting energy source and sink
system based on a modern flywheel and bi-directional converter. During normal operation, energy is
supplied to the PowerStore as a steady 12 kW load to maintain rotational energy. When necessary to
control power system frequency, energy is delivered to or drawn from the flywheel. The PowerStore
can absorb or deliver 300 or 1000 kW (depending on the inverter) of power in 5 milliseconds. The
PowerStore has been used in rural wind-diesel and mining applications in a number of locations
worldwide, including Antarctica and remote regions of Australia.
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5 Wind Turbines and HOMER Modeling
Considering NSB’s goal of displacing as much diesel fuel for electrical generation as possible and yet
recognizing the present limitations of high penetration wind power in Alaska and NSB’s desire to
operate a highly stable and reliable electrical utility in Point Lay, only the medium penetration wind-
diesel configuration scenario was modeled with HOMER software. Note that low penetration wind was
not modeled as this would involve use of smaller farm-scale turbines that are not designed for severe
cold climates, and low penetration would not meet NSB’s goal of significantly displacing fuel usage in
Point Lay.
As previously noted, a medium penetration wind-diesel configuration is a compromise between the
simplicity of a low penetration wind power and the significant complexity and sophistication of the high
penetration wind. With medium penetration, instantaneous wind input is sufficiently high (at 100 plus
percent of the village electrical load) to require a secondary or diversion load to absorb excess wind
power, or alternatively, to require curtailment of wind turbine output during periods of high wind/low
electric loads. For Point Lay, appropriate wind turbines for medium wind penetration are generally in
the 100 to 300 kW range with more numbers of turbines required for lower output machines compared
to larger output models.
There are a number of comparative medium penetration village wind-diesel power systems presently in
operation in Alaska. These include the AVEC villages of Toksook Bay, Chevak, Savoonga, Kasigluk,
Hooper Bay, among others. All are characterized by wind turbines directly connected to the AC
distribution system. AC bus frequency control during periods of high wind penetration, when diesel
governor control would be insufficient, is managed by the sub-cycle, high resolution, and fast-switching
capability of the secondary load controller (SLC). Ideally, the SLC is connected to an electric boiler
serving a thermal load as this will enhance overall system efficiency by augmenting the operation of the
fuel oil boiler(s) serving the thermal load.
5.1 Diesel Power Plant
Electric power (comprised of the diesel power plant and the electric power distribution system) in Point
Lay is provided by North Slope Borough Public Works Department, the utility for all communities on the
North Slope, with the exception of Deadhorse and Barrow. The existing power plant in Point Lay consists
of five Caterpillar 3406B diesel generators and one Caterpillar 3412 diesel generator, all rated at 330
kW. This power plant is due to be replaced in 2013, however, with four Caterpillar 3508C diesel
generators, all rated at 600 kW. Because the power plant will be upgraded soon, wind-diesel system
modeling for this report is based on the configuration of the new plant.
Point Lay powerplant diesel generators (planned, 2013)
Generator Electrical Capacity Diesel Engine Model
1 600 kW Caterpillar 3508C
2 600 kW Caterpillar 3508C
3 600 kW Caterpillar 3508C
4 600 kW Caterpillar 3508C
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The control system for the new power plant will consist of Woodward EasyGen 3200P2 generator
controller/protective relay package for each of the four new Cat 3508C generators, General Electric
Multiline 350 feeder protection package for each of the two feeders, and an Allen Bradley 1769 PLC for
automated system control.
5.2 Wind Turbines
For this study, the wind turbines considered are restricted to rated outputs of 100 to 350 kW as this size
range well matches Point Lay’s electric load. This eliminates the battery-charging turbines and small
grid-connect home and farm-scale turbines that are insufficient for village power needs and the very
large utility-scale turbines that would overwhelm the Point Lay power system. Unfortunately though,
the world wind turbine market offers very few turbines in this mid or village-scale size range. Of new
turbines, two American-made options are the 100 kW Northwind 100 and the 225 kW Aeronautica 29-
225. The 330 kW German-made Enercon E33 would be an excellent option, but it remains unavailable
to the U.S. market due to a past patent dispute between Enercon and General Electric. Remanufactured
wind turbines are a possible option for NSB to consider, with the 225 kW Danish-made Vestas V27
available through Halus Power Systems of San Leandro, California.
Whether new or remanufactured, the primary criteria for wind turbines suitable for Point Lay are:
Alternating current (AC) generator; synchronous or asynchronous are acceptable
Cold-climate capable (rated to -40° C) with appropriate use of materials, lubricants and heaters
IEC Class II rated
A “known” turbine with an existing track record of installed operation
Suitable for marine environments
Established North American support capability, preferably with an Alaska presence
5.2.1 Northern Power Systems Northwind 100
The Northwind 100 (the NW100B/21 model) wind turbine is manufactured by Northern Power Systems
in Barre, Vermont. The NW100 turbine is stall-regulated, has a direct-drive permanent magnet
synchronous generator, active yaw control, a 21 meter diameter rotor, is rated at 100 kW power output,
and is available only on a 37 meter tubular steel tower. The NW100B/21 is fully arctic-climate certified
to -40° C and is the most represented village-scale wind turbine in Alaska at present with a significant
number of installations in the Yukon-Kuskokwim Delta and on St. Lawrence Island. More information
can be found at: http://www.northernpower.com/and in Appendix C of this report.
Point Lay Wind-Diesel Hybrid Feasibility Study P a g e | 18
NW100 wind turbine NW100B/21 power curve
5.2.2 Aeronautica AW29-225
The Aeronautica AW29-225 wind turbine is manufactured new by Aeronautica in Durham, New
Hampshire. This turbine was originally designed by the Danish-manufacturer Norwin in the 1980’s and
had a long and successful history in the wind industry before being replaced by larger capacity turbines
for utility-scale grid-connect installations. The AW29-225 turbine is stall-regulated, has a synchronous
(induction) generator, active yaw control, a 29 meter diameter rotor, is rated at 225 kW power output,
and is available with 30, 40, or 50 meter tubular steel towers. The AW29-225 is fully arctic-climate
certified to -40° C and is new to the Alaska market with no in-state installations at present. More
information can be found at http://aeronauticawind.com/aw/index.html and in Appendix D of this
report.
Aeronautica AW29-225 AW29-225 power curve
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5.2.3 Wind Turbine Performance Comparison
In the table below is an analysis of turbine output and capacity factor performance of the turbines
profiled above, with comparisons of manufacturer rated output power at 100%, 90% and 80% turbine
availability (percent of time that the turbine is on-line and available for energy production). Both the
NW100B/21 and the AW29-225 perform well in the wind regime of Point Lay with excellent capacity
factors and annual energy production.
Turbine capacity factor comparison
100% availability 90% availability 80% availability
Turbine
Model
Rated
Output
(kW)
Hub
Height
(m)
Tip
Heigh
t (m)*
Tip
Heigh
t (ft.)*
Annual
Energy
(MWh)
Capacit
y Factor
(%)
Annual
Energy
(MWh)
Capacit
y Factor
(%)
Annual
Energy
(MWh)
Capacit
y Factor
(%)
NW100B/21 100 37 47.5 156 282.5 31.3 254.3 28.2 226.0 25.0
AW29-225 225 30 44.5 146 552.4 28.0 497.2 25.2 441.9 22.4
225 40 54.5 179 594.3 30.2 534.9 27.2 475.4 24.2
225 50 64.5 212 627.2 31.8 564.5 28.6 501.8 25.4
*Note: assumes base of turbine tower at ground level
5.3 Modeling
Wind turbine and system performance modeling of wind-diesel configurations in Point Lay was
accomplished with HOMER software. This software enables static modeling of a power system to
demonstrate energy balances and fuel displacement with introduction of wind power. A limitation of
the software is that it is not suitable for dynamic modeling. In other words, it cannot model voltage and
frequency perturbations and power system dynamics, although it will provide a warning for systems that
are potentially unstable.
5.3.1 Electric Load
The Point Lay electric load was synthesized with the Alaska Electric Load Calculator Excel program
written in 2006 by Mia Devine of the Alaska Energy Authority. This spreadsheet allows one to create a
“virtual” village load in one hour increments, suitable for import into HOMER software. For this
feasibility study, 2009 and 2010 PCE data of reported gross kWh generated, average power, fuel usage,
and powerplant efficiency was used with the Alaska Load Calculator to synthesize a 402 kW average load
with a 632 kW peak load and approximately 230 kW minimum load. Graphical representations of the
electric load are shown below.
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5.3.2 Thermal Load
The thermal load available to the diesel generator heat recovery system was estimated based on better-
documented thermal loads in other villages, the size of Point Lay’s electrical load, and village meter log
information. Typically very difficult to quantify as accurately as the electric load, the thermal load serves
as an energy “dump” in medium and high penetration wind-diesel configurations, or, more precisely, as
the secondary load available to absorb excess electrical energy generated by wind turbines during
periods of relatively high wind turbine output and low electric load demand.
5.3.3 Diesel Generators
The Point Lay power plant is scheduled for replacement in 2013 at a new location and with four new
diesel generators and switchgear. Because the new diesel generators will be redundant in capacity, the
HOMER model was constructed with three (of the four new) 600 kW Caterpillar 3508C diesel generators.
For cost modeling purposes, AEA in their Renewable Energy Fund grant program assumes a generator
O&M cost of $0.020/kWh. This was converted to $8.00/operating hour for each diesel generator for use
in the HOMER software model (based on Point Lay’s modeled average electrical load of 402 kW).
Manufacturer fuel curves for the diesel generators, provided by David Lockard of AEA in an Excel file
entitled Cat C9M C18M 3508 3512 3456 Mar 20081, were used in the HOMER models. In addition, the
diesel engines in the modeling runs were set to “optimize”, which HOMER interprets as use of the most
efficient diesel generator whenever possible.
Point Lay Wind-Diesel Hybrid Feasibility Study P a g e | 21
Diesel generator HOMER modeling information
Diesel generator Caterpillar
3508C
Caterpillar
3508C
Caterpillar
3508C
HOMER model
identification
Cat 1 Cat 2 Cat 3
Power output (kW)600 600 600
Intercept coefficient
(L/hr/kW rated)
0.02368 0.02368 0.02368
Slope (L/hr/kW output)0.2377 0.2377 0.2377
Minimum electric
load (%)
10 10 10
Heat recovery ratio
(percent of waste heat
that can serve the
thermal load)
18 18 18
Intercept coefficient – the no-load fuel consumption of the generator divided by its capacity
Slope – the marginal fuel consumption of the generator
Caterpillar 3508C fuel efficiency curve
Point Lay Wind-Diesel Hybrid Feasibility Study P a g e | 22
6 Economic Analysis
Selected wind turbines in medium penetration mode are modeled in this report to demonstrate the
economic viability of various configurations and fuel price points. Basic economic modeling assumptions
of this feasibility study that are default assumptions of Alaska Energy Authority in their Renewable
Energy Fund grant program are a 20 year project life and a three percent discount or interest rate (the
cost of money). Based on Point Lay’s 2009 and 2010 PCE data, an annual utility fixed operations and
maintenance (O&M) cost of $500,000 is assumed.
6.1 Wind Turbine Costs
Capital and installation costs of wind turbines are somewhat difficult to estimate without detailed
consideration of shipping fees, foundation design, cost efficiencies with installation of multiple turbines,
identification of constructor, mobilization fees, etc. Although the cost assumptions detailed below
should be considered tentative, they are generally in-line with other rural Alaska wind projects of the
past few years. Note that for modeling purposes, an AW29-225 on a 30 meter tower is assumed to cost
1.5 percent less than noted below.
Wind turbine cost assumptions
Single Turbine
450-500 kW installed
turbine capacity
NW100B
(100 kW)
AW29-225
(225 kW)
NW100B
(100 kW)
AW29-225
(225 kW)
Total turbine output (kW) 100 225 500 450
No. of turbines 1 1 5 2
Price/turbine $348,000 $580,000 $348,000 $580,000
Engineering, VAR support n/a $35,000 n/a $35,000
Capacitors cost/turb, VAR support n/a $40,000 n/a $80,000
Turbine cost $348,000 $655,000 $1,740,000 $1,355,000
Turbine capital cost/kW $3,480 $2,756 $3,480 $2,933
Construction cost (estimated) $696,000 $1,160,000 $2,923,200 $2,088,000
Total installed cost $1,047,480 $1,817,756 $4,666,680 $3,445,933
Total installed cost/kW $10,475 $8,079 $9,333 $7,658
Note: AW29-225 price with 40 meter tower
6.2 Fuel Cost
A fuel price of $6.79/gallon ($1.80/Liter) was chosen for the initial HOMER analysis by reference to
Alaska Fuel Price Projections 2011-2035, prepared for Alaska Energy Authority by the Institute for Social
and Economic Research (ISER), dated July 7, 2011. The $6.79/gallon price reflects the average value of
all fuel prices between the 2013 (assumed project start year) fuel price of $5.50/gallon and the 2032
(the 20 year project end year) fuel price of $7.75/gallon using the medium price projection three-year
moving average (MA3) analysis.
Additional analyses with ISER’s low price projection MA3 and high price projection MA3 are included in
the economic analysis of this report. For the high price projection, the median 2013 to 2032 three-year
Point Lay Wind-Diesel Hybrid Feasibility Study P a g e | 23
moving average price is $10.73/gallon ($2.84/Liter). For the low price projection, the average 2013 to
2032 three-year moving average price is $3.24/gallon ($0.86/Liter). Note also that heating fuel in
HOMER is priced the same as diesel fuel.
Fuel cost table
Cost Scenario 2013 (/gal) 2032 (/gal)
Average
(/gallon)
Average
(/Liter)
Medium $5.50 $7.75 $6.79 $1.80
High $6.91 $12.64 $10.73 $2.84
Low $4.32 $2.92 $3.24 $0.86
ISER, MA3 cost projections
6.3 Modeling Assumptions
In the HOMER modeling simulations, the annual average wind speed was reduced to 6.00 m/s (from a
measured 6.63 m/s) to yield an approximate turbine availability of 82 percent. This is in-line with AEA
assumptions of turbine availability in their economic models. HOMER modeling assumptions are listed
in the table below.
Basic modeling assumptions
Economic Assumptions
Project life 20 years
Discount rate 3%
System fixed O&M cost $500,000/year (average of 2009
and 2010 PCE Reports)
Operating Reserves
Load in current time step 10%
Wind power output 50%
Fuel Properties (both types)
Heating value 42.5 MJ/kg (126,000 Btu/gal)
Density 820 kg/m3 (6.84 lbs./gal)
Diesel Generators
Generator capital cost $150,000
O&M cost $8.00/hour ($0.02/kWh)
Time between overhauls 20,000 hours
Overhaul cost $75,000
Minimum load ratio 10% or 60 kW; based on AVEC’s
operational experience of 50 kW
minimum diesel loading with their
wind-diesel systems
Schedule Optimized
Wind Turbines
Availability Approx. 82%
Scaled annual average wind
speed
6.00 m/s (6.63 m/s non-scaled,
from met tower data)
O&M cost $0.0469/kWh (translated to $/year
based on 26% turbine CF)
Point Lay Wind-Diesel Hybrid Feasibility Study P a g e | 24
NW100B/21 $10,700/yr/turbine
AW 29-225 $24,000/yr/turbine
6.4 Wind Power Site Cost Assumptions
The base or comparison scenario, which does not include wind turbines, is construction of the new
power plant with four Caterpillar 3508C generators valued at $150,000 each. Additionally, a capital cost
of $150,000 is assumed for the new SCADA system. The cost of the power plant itself is not modeled as
it is a necessary expense in any scenario.
Wind turbines in a medium penetration system configuration may be constructed at Site A or Site B.
Development costs between the sites will be different because of varying distances of access roads and
new power distribution lines. For both sites, $150,000 is assumed both for SCADA improvements to
accommodate the inclusion of wind power into the new diesel power plant operating system and a
secondary load controller and electric boiler to allow excess wind turbine power to serve the thermal
load. Additionally for both sites, $50,000 is assumed for basic permitting and project management. As
noted in the table below, these fixed costs plus the varying road access and power distribution
extension development costs for each site result in total development costs of $524,000 for Site A and
$309,000 for Site B. Typically, geotechnical studies are also included as part of the site development
process to support the design of turbine foundations, but these efforts have already been accomplished.
Wind project cost assumptions
Base Site A Site B
SCADA system for new diesel
generators $150,000
SCADA upgrade, SLC, boiler $150,000 $150,000
extension $144,000 $64,000
Road extension $180,000 $45,000
Permitting and project mgmt. $50,000 $50,000
$150,000 $524,000 $309,000
Distribution line distance (miles) 0.36 0.16
Road distance (miles) 0.36 0.09
Notes:
Distribution line, $400K/mi
Road, $500K/mi
Point Lay Wind-Diesel Hybrid Feasibility Study P a g e | 33
7 Conclusion and Recommendations
The prospect of wind power in Point Lay is excellent due to the relatively high average wind speed, high
wind power density, highly directional winds, and lack of extreme wind events. In anticipation of
medium to high fuel price projections over a 20-year project period and even with the conservative
nature of the cost and performance assumptions, the economic analyses contained in this report show
positive benefit-to-cost ratios for incorporation of wind power into the Point Lay power system.
It is highly recommended and strongly urged that NSB pursue a conceptual design for a wind-diesel
power system for Point Lay. Although the prospects of a high penetration wind-diesel system, based on
present experience in Alaska with current technology, do not seem favorable at this time, upgrade to
high penetration will be a strong consideration in the near future and is the natural evolution of the
recommended medium penetration configuration option modeled in this study.
Point Lay Wind-Diesel Hybrid Feasibility Study P a g e | 34
Appendix A: Notice of Presumed Hazard, Site A
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Appendix B: Determination of No Hazard, Site B
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Appendix C: Northwind 100 Wind Turbine
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Appendix D: Aeronautica AW29-225 Wind Turbine