HomeMy WebLinkAboutWainwright Wind-Diesel Generation Project Feasibility Study - Dec 2011 - REF Grant 7030013DRAFT
Wainwright 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 Wainwright.
Contents
Executive Summary....................................................................................................................................... 1
1 Introduction.......................................................................................................................................... 3
1.1 Scope of Work............................................................................................................................... 3
1.2 Village of Wainwright.................................................................................................................... 3
1.3 Climate.......................................................................................................................................... 4
1.4 Geology......................................................................................................................................... 5
1.5 Permitting ..................................................................................................................................... 5
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
2.6 Extreme Winds.............................................................................................................................. 8
3 Wind Project Sites................................................................................................................................. 9
3.1 Site A............................................................................................................................................. 9
3.2 Site B...........................................................................................................................................10
3.3 Other Site Options ......................................................................................................................11
4 Wind-Diesel System Design and Equipment.......................................................................................12
4.1 Wind-diesel Integration Controls................................................................................................13
4.2 Energy Storage Options ...............................................................................................................13
4.2.1 Batteries..............................................................................................................................13
4.2.2 PowerStore Flywheel..........................................................................................................14
5 Wind Turbines and HOMER Modeling....................................................................................................15
5.1 Diesel Power Plant......................................................................................................................15
5.2 Wind Turbines.............................................................................................................................16
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5.2.1 Northern Power Systems Northwind 100...........................................................................16
5.2.2 Aeronautica AW29-225.......................................................................................................17
5.2.3 Wind Turbine Performance Comparison............................................................................18
5.3 Modeling.....................................................................................................................................18
5.3.1 Electric Load........................................................................................................................18
5.3.2 Thermal Load ......................................................................................................................19
5.4 Diesel Generators........................................................................................................................19
6 Economic Analysis...............................................................................................................................21
6.1 Wind Turbine Costs.....................................................................................................................21
6.2 Fuel Cost......................................................................................................................................21
6.3 HOMER Modeling Assumptions..................................................................................................22
6.4 Wind Power Scenario Cost Assumptions....................................................................................23
6.5 Site A Project Economics.............................................................................................................24
6.5.1 Medium Fuel Price Projection, 82% Turbine Availability....................................................24
6.5.2 High Fuel Price Projection, 82% Turbine Availability..........................................................25
6.5.3 Low Fuel Price Projection, 82% Turbine Availability...........................................................26
6.5.4 Medium Fuel Price Projection, 100% Turbine Availability..................................................27
6.6 Site B Project Economics.............................................................................................................28
6.6.1 Medium Fuel Price Projection, 82% Turbine Availability....................................................28
6.6.2 High Fuel Price Projection, 82% Turbine Availability..........................................................29
6.6.3 Low Fuel Price Projection, 82% Turbine Availability...........................................................30
6.6.4 Medium Fuel Price Projection, 100% Turbine Availability..................................................31
7 Conclusion and Recommendations.....................................................................................................32
Appendix A: Notice of Presumed Hazard, Site A........................................................................................33
Appendix B: Determination of No Hazard, Site B ......................................................................................34
Appendix C: Northwind 100 Wind Turbine................................................................................................35
Appendix D: Aeronautica AW29-225 Wind Turbine..................................................................................36
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Executive Summary
The measured high Class 4 to Class 5 wind resource in Wainwright, 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 6.96 m/s (15.5 mph) at 30 meters elevation. Additionally, the test location experiences
low turbulence and relatively low probability of extreme wind events, making Wainwright a superior
candidate for a wind energy project.
Two potential wind turbine sites were investigated for this study: Site A, the location of the
meteorological test tower that collected wind data for this project, is located northeast of the village
near the power plant and just beyond the protective snow fence; and site B, located two further miles to
the northeast, along the road leading to the landfill and village water source. Given the similarity of
terrain between the sites, each was considered to have equivalent wind resource potential. Site A has
an FAA-imposed height restriction which would require shorter turbine tower heights, whereas Site B
has no height restrictions. Site A requires construction of an access road but is relatively close to
existing power distribution. Site B is adjacent to good road access but requires construction of 1-1/2
miles of power distribution line for connection to the power grid. A power line to serve site B would
have other potential uses however.
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 Wainwright. 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 Wainwright, 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 Wainwright, 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 existing
Wainwright 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 Wainwright; the Point Lay 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 Wainwright, 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 Wainwright’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 Wainwright
In 1826 the Wainwright Lagoon was named by Capt. F.W. Beechey for his officer, Lt. John Wainwright.
An 1853 map indicates the name of the village as
"Olrona." Its Inupiat name was "Olgoonik." The
region around Wainwright was traditionally well-
populated, though the present village was not
established until 1904 when the Alaska Native
Service built a school and instituted medical and
other services. The site was reportedly chosen by
the captain of the ship delivering school
construction materials, because sea-ice conditions
were favorable for landing. A post office was
established in 1916, and a city was formed in 1962.
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Coal was mined at several nearby sites for village use; the closest was about seven miles away. Today,
though, most houses are heated by fuel oil. A U.S. Air Force Distance Early Warning (DEW) Station was
constructed nearby in the 1960’s.
A federally-recognized tribe is located in the community, the Village of Wainwright. Most Wainwright
inhabitants are Inupiat Eskimos who practice a subsistence lifestyle. Their ancestors were the
Utukamiut (people of the Utukok River) and Kukmiut (people of the Kuk River).
According to Census 2010, there were 179 housing units in the community and 147 were occupied.
Wainwright’s population of 556 people is 90 percent Alaska Native, 8 percent Caucasian, and 2 percent
Hispanic, multi-racial or other.
The North Slope Borough provides all utilities in Wainwright. Water is obtained from Merekruak Lake
three miles northeast of the community, treated and stored in tanks. Water is hauled from this point or
delivered to household tanks by truck. Hauling services are provided by the borough. The majority of
homes have running water for the kitchen. Electricity is provided by North Slope Borough. There is one
school located in the community, attended by 149 students. Local hospitals or health clinics include
Wainwright Health Clinic. Emergency Services have coastal and air access. Emergency service is
provided by 911 Telephone Service volunteers and a health aide. Auxiliary health care is provided by
Wainwright Volunteer Fire Dept. (907-763-2728).
Economic opportunities in Wainwright are influenced by its proximity to Barrow and the fact that it is
one of the older, more established villages. Most of the year-round positions are in borough services.
The sale of local Eskimo arts and crafts supplements income. Bowhead and beluga whale, seal, walrus,
caribou, polar bear, birds, and fish are harvested for subsistence.
The 2005-2009 American Community Survey (ACS) estimated 179 residents as employed. The public
sector employed 55.3% of all workers. The local unemployment rate was 29.2%. The percentage of
workers not in labor force was 29.9%. The ACS surveys established that average median household
income (in 2009 inflation-adjusted dollars) was $68,750 (MOE +/-$14,285). The per capita income (in
2009 inflation-adjusted dollars) was $20,063 (MOE +/-$4,649). About 12.7% of all residents had incomes
below the poverty level.
Note that information regarding Wainwright 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
Wainwright is located on the Chukchi Sea coast, 3 miles northeast of the Kuk River estuary. The climate
is arctic with temperatures ranging from -56° F in winter to 80 °F in summer. Precipitation is light,
averaging only five inches of water equivalent annually. The Chukchi Sea is ice-free from mid-July
through September.
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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
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 Wainwright is very good, with measured high wind power class 4 (good)
to low wind power class 5 (excellent). In addition to strong average wind speeds and wind power
density, the site experiences highly directional prevailing winds, low turbulence and calculations indicate
low extreme wind speed probability.
A 34 meter met tower, erected to 30 meters, was installed in June 2009 approximately 500 meters
(1,600 ft.) northeast of the village of Wainwright, near the Chukchi Sea shoreline. This site is relatively
near the power plant and well exposed to winter winds with no upwind obstructions. The met tower
was removed in July 2010.
2.1 Met tower data synopsis
Data dates June 19, 2009 to July 16, 2010 (13 months)
Wind power class High 4 (good) to low 5 (excellent)
Power density mean, 30 m 413 W/m
2 (QC’d data); 392 W/m2 (with synthetic data)
Wind speed mean, 30 m 7.05 m/s (QC’d data); 6.96 m/s (with synthetic data)
Max. 10-min wind speed average 22.2 m/s
Maximum wind gust 25.8 m/s (Feb. 2010)
Weibull distribution parameters k = 2.2, c = 7.97 m/s
Wind shear power law exponent 0.137 (moderately low)
Roughness class 1.51 (crops)
IEC 61400-1, 3rd ed. classification Class III-c (lowest defined and most common)
Turbulence intensity, mean 0.072 (at 15 m/s)
Calm wind frequency 16% (<3.5 m/s)
2.2 Data Recovery
Data recovery in Wainwright was mostly acceptable, with 75 to 80 percent data recovery of the
anemometers and wind vane. Note that data recovery in December and January was particularly poor,
apparently due to hoarfrost conditions during this deep cold period of mid-winter.
2.3 Wind Speed
Wind data collected from the met tower, from the perspective of both mean wind speed and mean
power density, indicates an excellent wind resource. The cold arctic temperatures of Wainwright
contributed to the high wind power density. It is problematic, however, analyzing wind data with
significant concentrated data loss, such as occurred in Wainwright during November through January,
then again in March. To correct this problem, synthetic data was inserted in the data gaps to create a
more realistic wind speed data profile. To be sure, long segments of synthetic data introduce
uncertainty to the data set, but missing data does as well. To overcome this uncertainty, improved data
collection with heated sensors would be necessary. But, considering the robust wind resource
measured and noting the long-term airport AWOS data confirming the wind resource measured by the
met tower, continuing a wind study with heated sensors is not truly necessary in Wainwright.
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Wind speed profile
2.4 Wind Rose
Wind frequency rose data indicates highly directional winds from northeast to east-northeast. Power
density rose data (representing the power in the wind) indicates power winds are strongly directional,
from 030°T to 070°T and to a much lesser extent from 240°T. Calm frequency (percent of time that
winds at 30 meter level are less than 3.5 m/s) was 16 percent during the met tower test period.
Wind frequency rose Wind energy rose
2.5 Turbulence Intensity
Turbulence intensity at the Wainwright 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 graph
2.6 Extreme Winds
Although thirteen months of data is minimal for calculation of extreme wind probability, use of a
modified Gumbel distribution analysis, based on monthly maximum winds vice annual maximum winds,
yields reasonably good results. Extreme wind analysis indicates a highly desirable situation in
Wainwright: moderately high mean wind speeds combined with low extreme wind speed probabilities.
This may be explained by particular climactic aspects of Wainwright which include prominent coastal
exposure, offshore wind conditions, and due to the extreme northerly latitude, lack of exposure to Gulf
of Alaska storm winds.
Industry standard reference of extreme wind is the 50 year, 10-minute average probable wind speed,
referred to as Vref. For Wainwright, this calculates to 24.8 m/s, below the threshold of International
Electrotechnical Commission (IEC) 61400-1, 3rd edition criteria (of 37.5 m/s) for a Class III site. Note that
Class III extreme wind classification is the lowest defined and all wind turbines are designed for this wind
regime.
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3 Wind Project Sites
NSB requested that two wind turbine sites be identified in Wainwright. On July 6, 2011, Ross Klooster of
WHPacific and Max Ahgeak of NSB Public Works Dept. traveled to Wainwright and met with Village of
Wainwright and Olgoonik 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 Olgoonik Corporation land were chosen, identified as Site A and Site B in
the Google Earth image below.
Wainwright site options, Google Earth image
3.1 Site A
Site A is a very well exposed area immediately northeast of the village and just beyond the protective
snow fences on Wainwright’s north side. It is an expansive location with plenty of room for a multi-
turbine array, is relatively dry and hence likely to have stable permafrost for foundation construction,
and would require minimal distribution line construction to connect turbines to the power plant.
Unfortunately though, an FAA notice of presumed hazard (refer to Appendix A) for the site limits turbine
construction to 148 ft. above ground level. With respect to the turbines options considered in this
report (refer to Section 5.2), only the Aeronautica AW 29-225 on a 30 meter tower has a sufficiently low
elevation tip height to meet FAA’s height restrictions for this site. A possible alternative is the Northern
Power Northwind 100B/21 on a 30 meter tower instead of the normal 37 meter tower (refer to Section
5.2). This possibility must be discussed with Northern Power Systems, however, as a 30 meter tower
option may not be available for the B model NW100 as it had once been for their A model NW100.
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Wainwright Site A
3.2 Site B
Site B shares the same apparent physical characteristics as Site A and hence it is a quite suitable location
for wind turbines. A key advantage of Site B over Site A is that construction height is essentially
unrestricted from an FAA perspective (refer to Appendix B). The chief disadvantage is its increased
distance from Wainwright, necessitating an additional 2.4 km (1.5 mile) distribution line construction.
But, turbines could be placed very near the access road, resulting in lower access road construction
costs than at Site A.
Wainwright Site B
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Wainwright Sites A and B comparison table
Wind Turbine Site Advantages Disadvantages
A Olgoonik Corp. land Turbines will be in view and
possible auditory range of
residents on the north side of
the village
Site is large enough to
accommodate several or more
turbines and has sufficient room
for future expansion
275 to 375 meter (900 to 1,200
ft) access road and distribution
line construction required
(depending on access direction)
Relatively dry site;likely good
geotech conditions
FAA determination of Notice of
Presumed Hazard (NPH) for
turbines exceeding 148 ft AGL
B Olgoonik Corp. land 2.4 km (1.5 miles) of new
distribution line required
Site is large enough to
accommodate several turbines
and has sufficient room for future
expansion
More expensive to develop than
Site A
Location is far from village and
unlikely to present aesthetic and
noise complaints
Relatively dry site; likely good
geotech conditions
FAA Determination of No Hazard
to Air Navigation for turbines up
to 195 ft AGL (possibly higher)
Site near existing road to landfill
3.3 Other Site Options
Other than Sites A and B, something in-between, or a minor variation of either, there are no other
realistic wind turbine site options for Wainwright. Terrain east of the village is possible, but the airport
constrains the nearer possibilities and, importantly, a road does not exist at present in that direction,
hence development costs would be extremely high. Terrain to the southwest is marginal due to its
peninsula nature between Wainwright Inlet and the Bering Sea. Plus, airport runway alignment
precludes this consideration. West of Wainwright is the Bering Sea and hence obviously unsuitable for
turbine construction.
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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 Wainwright 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 Wainwright 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 Wainwright, 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
Wainwright.
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 Wainwright, 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
Wainwright 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 Wainwright
consists of three Caterpillar 3508 diesel generators rated at 430 kW output, and two Caterpillar 3512
diesel generator rated at 950 kW output.
Wainwright powerplant diesel generators
Generator Electrical Capacity Diesel Engine Model
1 430 kW Caterpillar 3508
2 430 kW Caterpillar 3508
3 430 kW Caterpillar 3508
4 950 kW Caterpillar 3512
5 950 kW Caterpillar 3512
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Generator sets in the Wainwright power plant are controlled by Woodward 2301A load sharing and
speed control governors with protection and alarms initiated by discreet protective relays for each unit.
A user-programmable PLC controller with SCADA interface automatically parallels and dispatches the
diesel generators, based on system load and operator-programmable preferences, via a unit-based auto
synchronizer.
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 Wainwright’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 Wainwright 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 Wainwright 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.
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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 very well in the Wainwright wind regime with excellent
capacity factors and annual energy production.
Wainwright turbine capacity factor comparison
100% availability 90% availability 80% availability
Turbine
Model
Rated
Outpu
t (kW)
Hub
Height
(m)
Tip
Height
(m)*
Tip
Height
(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
308.6 34.2 277.7 30.8 246.9 27.4
AW29-225 225 30 44.5 146
598.8 30.4 538.9 27.4 479.0 24.3
225 40 54.5 179
649.0 32.9 584.1 29.6 519.2 26.3
225 50 64.5 212
689.2 35.0 620.3 31.5 551.4 28.0
*Note: assumes base of turbine tower at ground level
5.3 Modeling
Wind turbine and system performance modeling of wind-diesel configurations in Wainwright 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 Wainwright 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, 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 681 kW average load
with a 1,111 kW peak loadand approximately 380 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 Wainwright’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.
5.4 Diesel Generators
The HOMER model was constructed with all five Wainwright generators, although clearly there is
redundant capacity in the system. For cost modeling purposes, AEA assumes a generator O&M cost of
$0.020/kWh. This was converted to $13.60/operating hour for each diesel generator for use in the
HOMER software model (based on Wainwright’s modeled average electrical load of 681 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.
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Diesel generator HOMER modeling information
Diesel generator Caterpillar
3508
Caterpillar
3508
Caterpillar
3508
Caterpillar
3512
Caterpillar
3512
HOMER model
identification
Cat 1 Cat 2 Cat 3 Cat 4 Cat 5
Power output (kW)430 430 430 950 950
Intercept coeff.
(L/hr/kW rated)
0.02368 0.02368 0.02368 0.01937 0.01937
Slope (L/hr/kW
output)
0.2377 0.2377 0.2377 0.2325 0.2325
Minimum electric
load (%)
12% (50 kW) 12% (50 kW) 12% (50 kW) 10 10
Heat recovery ratio (%
of waste heat that can
serve the thermal
load)
18 18 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 Caterpillar 3512 fuel efficiency curve
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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.
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 $5.85/gallon ($1.55/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 $5.85/gallon price reflects the average value of
all fuel prices between the 2013 (assumed project start year) fuel price of $4.80/gallon and the 2032 (20
year project end year) fuel price of $6.64/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
moving average price is $9.06/gallon ($2.39/Liter). For the low price projection, the average 2013 to
2032 three-year moving average price is $2.97/gallon ($0.79/Liter). Note also that heating fuel in
HOMER is priced the same as diesel fuel.
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Fuel cost table
Cost
Scenario 2013 (/gal) 2032 (/gal)
Average
(/gallon)
Average
(/Liter)
Medium $4.80 $6.64 $5.85 $1.549
High $5.95 $10.61 $9.06 $2.397
Low $3.84 $2.71 $2.97 $0.785
ISER, MA3 cost projections
6.3 HOMER Modeling Assumptions
In the HOMER modeling simulations, the annual average wind speed was reduced to 6.30 m/s (from a
measured 6.96 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 $534,000/year (2010 PCE Report)
Operating Reserves
Load in current time step 10%
Wind power output 50%
Fuel Properties (both types)
Heating value 42.5 MJ/kg
Density 820 kg/m3
Diesel Generators
Generator capital cost $0 (already exist)
O&M cost $13.60/hour ($0.02/kWh)
Time between overhauls 20,000 hours
Overhaul cost (Cat 3508)$75,000
Overhaul cost (Cat 3512) $100,000
Minimum load ratio 10%or 50 kW; based on AVEC’s
operational experience of 50 kW
minimum diesel loading with their
wind-diesel systems
Schedule Optimized
Wind Turbines
Availability 82%
Scaled annual average wind
speed
6.30 m/s (6.96 m/s non-scaled,
from met tower data)
O&M cost $0.0469/kWh (translated to $/year
based on 26% turbine CF)
NW100B/21 $10,700/yr/turbine
AW 29-225 $24,000/yr/turbine
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6.4 Wind Power Scenario Cost Assumptions
The base or comparison scenario, which does not include wind turbines, is the existing Wainwright
powerplant with its present configuration of diesel generators.
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 existing 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 $425,000 for Site A and
$848,000 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 upgrade, SLC, boiler $150,000 $150,000
$100,000 $608,000
Road extension $125,000 $40,000
Permitting $50,000 $50,000
$0 $425,000 $848,000
Distribution distance (miles) 0.25 1.52
Road distance (miles) 0.25 0.08
Notes:
Distribution line, $400K/mi
Road, $500K/mi
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7 Conclusion and Recommendations
The prospect of wind power in Wainwright 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 Wainwright power system.
It is highly recommended and strongly urged that NSB pursue a conceptual design for a wind-diesel
power system for Wainwright. 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.
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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