HomeMy WebLinkAboutAEA Renewable Energy Fund Round VIII -Kaktovik Wind - CDRAppendix C — Conceptual Design Report
Kaktovik Wind -Diesel Analysis
November 5, 2013
Douglas Vaught, P.E.
dvaught@v3eneM.t@�3eneM.t
V3 Energy, LLC
Eagle River, Alaska
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Kaktovik Wind -Diesel Analysis
Page I
This report was prepared by V3 Energy, LLC under contract to Hattenburg, Dilley and Linnell (HDL) for
development of wind power for the village of Kaktovik, Alaska. This analysis is part of a conceptual
design project funded by the North Slope Borough.
Contents
Introduction............................................................................................................................................1
ProjectManagement...........................................................................................................................1
Kaktovik..................................................................................................................................................1
WindResource........................................................................................................................................2
WindRoses..........................................................................................................................................4
Wind Frequency Rose (measured)....................................................................................................5
TotalValue (power density) Rose......................................................................................................
5
Wind Frequency Rose (declination adjusted)...................................................................................6
Total Value (power density) Rose.....................................................................................................6
AWSTruepower and AWOS data....................................................................................
.................. 6
Cold Climate Considerations of Wind Power.........................................................................................
9
Wind -Diesel Hybrid System Overview....................................................................................................11
Wind -diesel Design Options................................................................................................................11
Low Penetration Configuration......................................................................................................11
Medium Penetration Configuration...............................................................................................12
HighPenetration Configuration ........................ _........................................................................
..12
Wind -Diesel System Components......................................................................................................14
WindTurbine(s)..........................................................................................................................14
SupervisoryControl System...........................................................................................................14
SynchronousCondenser................................................................................................................14
SecondaryLoad.............................................................................................................................15
DeferrableLoad.............................................................................................................................15
InterruptibleLoad...........................................................................................................................15
StorageOptions.............................................................................................................................16
WindTurbine Options...........................................................................................................................17
Aeronautica29-225...........................................................................................................................17
Northern Power Systems 100 (NPS 100).............................................................................................18
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VestasV27 ................................................................................................................................19
Wind -Diesel Model.................................................................................................................................19
KaktovikPowerplant...... ............ ....... ............................ I ..................... . ..........................................119
DieselGenerators........................................................................................................................20
Caterpillar 3512 Diesel Generator......................................................................... ......................
20
Caterpillar 3508 Diesel Generator..................................................................................................
21
WindTurbines.....................................................................................................................................
21
ElectricLoad......................................................................................................................................
22
ThermalLoad.....................................................................................................................................
24
Wind Turbine Configuration Options.................................................................................................
25
EconomicAnalysis.................................................................................................................................
26
FuelCost ................................................ .....................................................................................
27
ModelingAssumptions...................................................................................................................
27
WindTurbine Project Costs................................................................................................................
29
ModelingResults .......... ................................................ I....... I .............. I .... .... ..........................................29
Discussion................................................................................................................................. .........
31
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Kaktovik Wind -Diesel Analysis
Introduction
Page 11
North Slope Borough (NSB) is the electric utility for the City of Kaktovik. In October, 2012 North Slope
Borough awarded a contract to Hattenberg, Dilley, and Linnell (HDL) to complete a conceptual design
report for a possible wind -diesel project in Kaktovik. HDL subsequently subcontracted V3 Energy, LLC to
evaluate the wind resource in the community, model the Kaktovik power system with a selection of
wind turbines, and perform basic economic analyses of the proposed projects.
Project Management
The North Slope Borough has executive oversight of this project. North Slope Borough and the City of
Kaktovik are interested in the installation of wind turbines in Kaktovik primarily to reduce diesel fuel
consumption, but also to:
• Reduce long-term dependence on outside sources of energy
• Reduce exposure to fuel price volatility
• Reduce air pollution resulting from reducing fossil fuel combustion
• Reduce possibility of spills from fuel transport & storage
• Reduce overall carbon footprint and its contribution to climate change.
Kaktovik lies on the north shore of Barter Island, between the Okpilak and Jago Rivers on the Beaufort
Sea coast. It lies in the 19.6-million-acre Arctic National Wildlife Refuge, an occasional calving ground for
the porcupine caribou herd. The climate of Kaktovik is
arctic. Temperatures range from -56 to 78 OF. Precipitation is
Aftha light, averaging 5 inches, with snowfall averaging 20 inches.
Until the late nineteenth century, the island was a major
trade center for the Inupiat and was especially important as
a bartering place for Inupiat from Alaska and Inuit from
Canada. The city was incorporated in 1971. Due to Kaktovik's
isolation, the village has maintained its Inupiat Eskimo
traditions. Subsistence is highly dependent upon caribou.
A federally -recognized tribe is located in the community -- the Kaktovik Village. According to Census
2010, there were 87 housing units in the community and 72 were occupied. Its population was 88.7
percent American Indian or Alaska Native; 10 percent white; 1.3 percent of the local residents had multi-
racial backgrounds.
The North Slope Borough provides all utilities in Kaktovik. Water is derived from a surface source and is
treated and stored in a 680,000-gallon water tank. Water is delivered by truck to holding tanks; all
homes have running water in the kitchen. For the most part, the village is still on water and sewage
haul. Electricity is provided by North Slope Borough Power and Lights Systems. There is one school
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located in the community, attended by 57 students. Local hospitals or health clinics include Kaktovik
Clinic. Emergency Services have coastal and air access.
Economic opportunities in Kaktovik are limited due to the community's isolation, and unemployment is
high. Most employment is in education, the North Slope Borough, or city services. Part-time seasonal
jobs, such as construction projects, provide income.
Air travel provides the only year-round access to Kaktovik. The Barter Island Airport is owned by the Air
Force and operated by the North Slope Borough. Marine transportation provides limited seasonal
access. There are no roads leading to Kaktovik and land transportation is limited to the surrounding
area.
Topographic map of Kaktovi)
A
R B
A■ C T 1 C
N A T 1.0 K A L N I L D L I P E R E T C G. E
Wind Resource
A met tower in Kaktovik was installed at the south side of the village near the sewage treatment plant in
June, 2009. The site was not considered at the time to be a candidate for wind turbines, but was chosen
due to ease of access and land ownership considerations. However, the open tundra environment and
relatively flat topography of Kaktovik ensure that the collected wind data is representative and usable
for siting wind turbines elsewhere on Barter Island.
Kaktovik Wind -Diesel Analysis
Google Earth image of Kaktovik
Page 13
With reference to two nearby Automated Weather Observing System (AWOS) sources (Barter Island
Airport and Barter Island DEW), the wind resource in Kaktovik is outstanding (Class 5 to 6), but
verification with the met tower was fraught with difficulty, namely a lost data card, significant data loss
due to icing, and loss of both 30 meter level anemometers in early January, 2008 due to ice and wind
damage. The anemometers were not replaced until early March, resulting in more data loss. Given the
anemometer problems, collected (and filtered) anemometer data could not be used by itself to calculate
mean annual wind speed, but inserting synthesized data to the data set via a gap -fill subroutine in the
wind analysis software yielded a wind resource prediction in -line with the AWOS data sources.
Besides mean wind speed, other parameters of importance to wind turbine operations, including
turbulence, wind shear, and directionality of winds indicate a desirable wind resource for wind power
development.
Kaktovik met tower data synopsis
Data start date
Data end date
Wind power class
Wind speed average (30 meters)
Maximum 10-min average wind speed
Maximum wind gust
IEC 61400-1 3`d ed. extreme winds
Wind power density (30 meters)
Weibull distribution parameters
Roughness Class
\'3 L� �:�._ , L L C
June 26, 2009
July 19, 2010 (13 months data)
Class 5 (excellent)
6.32 m/s
29.3 m/s
35.2 m/s (February 2010)
Class II
450 W/mz
k = 1.63, c = 7.12 m/s
0.67 (lawn grass)
Kaktovik Wind -Diesel Analysis
Power law exponent
Frequency of calms (3.5 m/s threshold)
Mean Turbulence Intensity
Wind Speed Sensor Summary, Kaktovik
Variable
Measurement height (m)
MMM wind speed (m/s)
Max 10-min avg wind speed (m/s)
Max gust wind speed (m/s)
Weibull k
Weibull c (m/s)
MMM power density (W/m2)
MMM energy content (kWh/mZ/yr)
Energy pattern factor
Frequency of calms (%)
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0.14 (moderate wind shear)
31%
0.071(IEC 61400-13`d ed. turbulence category C)
Original data set
Speed
Speed
Speed
30 A
30 B
20
30
30
20
6.26
6.03
6.07
26.4
26.2
29.3
32.7
30.2
35.2
1.75
1.75
1.62
7.04
6.79
6.78
360
324
393
3,158
2,834
3,440
2.22
2.23
2.57
31.8
33.5
35.0
Kaktovik Wind speed graph (with synthesized data)
10 Y SS wng Vftd ArOM
8-
E
Synthesized data set
Speed
Speed
Speed
30 A
30 B
20
30
30
20
6.36
6.24
6.01
1.63
1.62
1.62
7.12
6.98
6.71
450
431
384
3,943
3,774
3,361
2.56
2.59
2.60
32.4
33.2
35.6
.W Au9 Sep Od Mar Mc
Speed 30 A
Speed 30 B
- Speed 20
Wind Roses
Winds at the Kaktovik met tower test site were measured as strongly direction east-northeast and west-
southwest. The total value (or wind power density) rose indicates that the ENE and WSW Kaktovik
winds were of nearly equal power over the course of the measurement period.
Kaktovik Wind -Diesel Analysis
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Wind Frequency Rose (measured)
Yrr R�q R_
a asset
Total Value (power density) Rose
Ttlrfwr Eel [�
a
a
s
Comparison though with wind roses in the Barter Island AWOS data and with AWS Truepower modeling
(see following section) reveals a possible error in the vane offset (or zero direction) of the met tower.
The Barter Island AWOS and AWS Truewind wind roses both indicate strongly directional easterly and
westerly winds. It appears likely then that the met tower vane offset in the datalogger was set to
magnetic direction instead of true. This is significant in Kaktovik as magnetic declination is 22.7 degrees.
Kaktovik magnetic declination
L ib.w.-—
Le"kEllic: 14MW W
NNW
2013435-16 ZED E d;m kp by 0_' 3' W ms yM
Using an adjustment of 23 degrees of magnetic declination to correct the presumed datalogger vane
offset error, the adjusted wind frequency and power density roses shown indicate predominately
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Kaktovik Wind -Diesel Analysis
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easterly and westerly winds. This agrees within approximately 10 degrees of the wind roses obtained
from the Barter Island AWOS and AWS Truewind data and modeling.
Wind Frequency Rose (declination Total Value (power density) Rose
adjusted)
WOW Fmy nr T�1JKw1 E_ai f3� �1
s - r
aI '1' 3F
� T
� 9 F
9^ T
AWS Truepower and AWOS data
It is acknowledged that the wind resource measured by the met tower and nearby AWOS weather
stations has some limitations in that the met tower was operational for a relatively short period of time
and experienced significant data problems. The nearby AWOS weather stations (the airport and the
USAF Barter Island DEW) are a very longterm source of data but measurement height is only 8 meters
and the averaging method is somewhat different than that for the met tower, although with a long-term
perspective the averaging methodology converges.
To validate the met tower and AWOS wind speed data, AWS Truepower's wind site assessment
dashboard software was used to survey the wind resource in Kaktovik. The wind site assessment
dashboard is a web -based too that uses AWS Truepower's proprietary MesoMap system of mesoscale
and microscale atmospheric models. The mesoscale model simulates weather conditions for a
representative meteorological year on a horizontal grid of 2 km. Starting from an initial condition
established by regional weather data and physical equations governing the atmosphere, the model
simulates the evolution of weather conditions from the start to end of each day in the representative
year. The microscale model then refines the wind fields from the mesoscale model to capture the local
influences of the topography and surface roughness changes at a higher resolution of 200 m. For each
region, the wind maps are fine-tuned using best available surface observations.
Filtered met tower 30 meter A anemometer data indicated a mean annual wind speed of 6.26 m/s.
With inclusion of synthesized data via the Windographer gap -fill subroutine, the mean wind speed
increases to 6.36 m/s at the 30 meter level. Note below that AWS Truepower software predicts a 6.67
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m/s mean annual wind speed at the met tower site; higher than that measured by the met tower itself.
The AWS Truepower data likely is a more accurate representation of met tower site wind resource in
that it references a longer term data set than the met tower.
AWS wired assessment dashboard of met tower site, 30 m level
;P* AWSTruepower
•..
The Barter Island DEW station is located on the Beaufort Sea coast immediately northwest of Kaktovik.
Weather data has been collected at this location since 1973, although only data since 2004 was
reviewed for a comparative wind analysis. Using a wind shear power law exponent of 0.097, the 8
meter elevation Barter Island DEW mean wind speed of 5.9 m/s was extrapolated to 30 meters (below)
as further comparison. The extrapolated mean annual wind speed of 6.7 m/s is validates the AWS
Truewind prediction of 6.73 m/s at the DEW station. Overall, agreement of the three wind assessment
methods considered in this report — met tower, AWS Truepower, and Barter Island AWOS — is very good.
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Barter Island DEW Station AWOS data
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
8 m 6.8 5.9 5.7 5.2 6.0 5.2 5.3 5.2 5.8 7.0 6.9 6.2 5.9
30 m 7.7 6.7 6.5 5.9 6.8 5.9 6.0 5.9 6.6 8.0 7.8 7.0 6.7
AWS wind assessment dashboard of Barter Island DEW Station, 30 m level ss
AWS Truepowe -
e N.V woaucu w Accom[ Hop O.dmr Ar sty#
, ft—f! QW*
The prospective wind turbine site is located northwest of the fresh water lagoon water supply for
Kaktovik, which is immediately west of the village proper. AWS Truepower assessment dashboard
predicts a mean annual wind speed of 6.52 m/s at the 30 meter level and 6.89 m/s at the 40 meter level
at this site. AWS Truepower predicts a slightly lower mean annual wind speed at the prospective wind
turbine site compared to the Barter Island DEW station and the met tower sites. This can be explained
by the greater roughness of the landscape surrounding the turbine site which will slow the wind a bit
compared to the DEW station and met tower sites that have greater exposure to smooth sea ice.
Kaktovik Wind -Diesel Analysis P a g e 19
Considering that the three sources of wind data — met tower, AWS Truepower, and DEW station AWOS —
corroborate, selection of wind data for modeling purposes was based on the data thought most
representative of annual wind fluctuations. In this regard, AWS Truewind and the AWOS data are
preferable than the met tower as their longer timeframe mitigates somewhat the significant month -to -
month variability measured by the met tower. Using the AWS Truepower dashboard information for the
preferred wind site northwest of the water supply lagoon, Windographer software was used to
synthesize hourly wind speed averages for a one year time period. This data was imported into Homer
software for modeling purposes as described later in this report.
AWS wind assessment dashboard of prospective wind wrhine site, 30 m level
AWS True ower
•�::-• Whw scNnud•� p _
Cold Climate Considerations of Wind Power
Kaktovik's harsh climate conditions is an important consideration should wind power be developed in
the community. The principal challenges with respect to turbine selection and subsequent operation is
severe cold and icing. Many wind turbines in standard configuration are designed for a lower operating
temperature limit of -4° C (-20° F), which clearly would not be suitable for Kaktovik, nor anywhere else in
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Alaska. A number of wind turbine manufacturers offer their turbine in an "arctic" configuration which
includes verification that structural and other system critical metal components are fatigue tested for
severe cold capability. In addition, arctic -rated turbines are fitted with insulation and heaters in the
nacelle and power electronics space to ensure proper operating temperatures. With an arctic rating,
the lower temperature operating limit generally extends to -40' C (-40° F). On occasion during winter
Kaktovik may experience temperatures colder than -40° C which would signal the wind turbines to stop.
Temperatures below -40° C are relatively infrequent however and when they do occur, are generally
accompanied by lighter winds.
A second aspect of concern regarding Kaktovik's arctic climate is icing conditions. Atmospheric icing is a
complex phenomenon characterized by astonishing variability and diversity of forms, density, and
tenacity of frozen precipitation, some of which is harmless to wind turbine operations and others highly
problematic. Although highly complex, with respect to wind turbines and aircraft five types of icing are
recognized: clear ice, rime ice, mixed ice, frost ice, and SLD ice (Wikipedia.org/wiki/icing_conditions).
• Clear ice is often clear and smooth. Super -cooled water droplets, or freezing rain, strike a
surface but do not freeze instantly. Forming mostly along the stagnation point on an airfoil, it
generally conforms to the shape of the airfoil.
• Rime ice is rough and opaque, formed by super -cooled drops rapidly freezing on impact. Often
"horns" or protrusions are formed and project into the airflow.
• Mixed ice is a combination of clear and rime ice.
• Frost ice is the result of water freezing on unprotected surfaces. It often forms behind deicing
boots or heated leading edges of an airfoil and has been a factor airplane crashes.
• SLD ice refers to ice formed in super -cooled large droplet (SLD) conditions. It is similar to clear
ice, but because droplet size is large, it often extends to unprotected parts of a wind turbine (or
aircraft) and forms large ice shapes faster than normal icing conditions.
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Wind -Diesel Hybrid System Overview
There are now over twenty-four wind -diesel projects in the state, making Alaska a world leader in wind -
diesel hybrid technology. There are a variety of system configurations and turbine types in operation
and accordingly there is a spectrum of success in all of these systems. As experience and statewide
industry support has increased so has overall system performance. The following figure illustrates the
locations of installed wind projects in Alaska.
Alaska wind -diesel projects
Wind -diesel Design Options
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. 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. This is a good
compromise between of displaced fuel usage and relatively minimal system complexity and is AVEC's
preferred system configuration.
Low Penetration Configiirrtinn
Low -penetration wind -diesel systems require the fewest modifications to the existing system. However,
they tend to be less economical for village installations due to the limited annual fuel savings compared
to the total wind system installation costs.
Kaktovik Wind -Diesel Analysis
Wind -Diesel System, Low Penetration"
- [Diesel generators must
run at all tunes -
• Wind power redwes
load on generators
• All wind energy goes to primary
ccmmunity electrical I«,vd
• Annual average wind
penetration urrder 20'0
• Fuel savings up to 15%
• Lower installation costs, because
system requires less complex controls
Community load
Page 1 12
Medium Penetration Configuratior
Many of the AVEC communities, Toksook Bay for example, have 24% of their energy from wind. Figure 8
indicates the configuration and key points on using a medium penetration, wind -diesel system.
Wind -Diesel System, Medium Penetration's
- Potential exists for diesel
generators to run under lower,
less efficient loads; this should be 'V a'rdd111111pokmon
considered during design
• At high wind power
production, part of wind energy
diverted for space heating or
wind generation is curtaied
• Annual average wind
Comrn unity
Wd
p netiabon 20,610 5(T'
• Fuel savings 15%to 50% L
• System controls must be Fleatirg or other uses with load mntiotf rrh
more advanced. which (for system saab knuon)
increases installation costs
High Penetration Configuration
Other communities, such as Kokhanok, are more aggressively seeking to offset diesel used for thermal
and electrical energy. They are using configurations which will allow for the generator sets to be turned
off and use a significant portion of the wind energy for various heating loads. The potential benefit of
these systems is the highest, however currently the commissioning for these system types due to the
increased complexity, can take longer. Figure 9 indicates the configuration and key points on using a
high -penetration, wind -diesel system.
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Kaktovik Wind -Diesel Analysis
Wind -Diesel System, High Penetration'
• f property configured. diesel
generators may be shun down
when wind power exceeds
electrical demand
• Auxiliary conVonents regulate
voltage and frequency
wvn needed
• Power in excess of what is
needed fur primly electrical
load can be used for space
heating or stored in batteries
• Anmal average wind
m unity
load
penetration aMb to I Yin Battery Bank L _
• fuel savings 5US to 90S with DC/A( mm let
• Hgher installation costs, because
systern requires sophisticated controls
• Operators must be highly skiled
Heating or ether use; with ksad crxxarlr-'''
(For system stklgatlon)
' Vhnd penetation rs the percentage of riee lefty supplied by wind
bEestdes teadentW a [cmrneTuO heating possibleo6m uses indode charging eleMx (ai
NotP.Th(--pmeFi-rT%*4SjCT;,mC "mrftralwimselist
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The above system descriptions can be summarized in Table 2 below. The level of instantaneous
penetration is important for power quality design considerations. The annual amount of wind energy on
the system is considered the average penetration level and helps to provide a picture of the overall
economic benefit.
Categories of wind -diesel penetration levels
Penetration
Wind Penetration
Level
Instantaneous
Average
Category
Operating Characteristics and System Requirements _
<60%
<8%
Very Low
• Diesel generator(s) runs full time
• Wind power reduces net load on diesel
• All wind energy serves primary load
60 to 120%
• No supervisory control system
• Diesel generator(s) runs full time
Low
8 to 20%
• At high wind power levels, secondary loads are
dispatched to insure sufficient diesel loading, or wind
generation is curtailed
_
• Re[atively simple control system
• Diesel generator(s) runs full time
Medium
120 to 300%
20 to 50%
• At medium to high wind power levels, secondary
loads are dispatched to insure sufficient diesel
loading
• At high wind power levels, complex secondary load
control system is needed to ensure heat loads do not
become saturated
sophisticated control system
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Kaktovik Wind -Diesel Analysis
Penetration Wind Penetration Level
Category Instantaneous Average
High 300+% 50 to 150%
(Diesels -off
Capable)
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Operating_ Characteristics and System Requirements
• At high wind power levels, diesel generator(s) may be
shut down for diesels -off capability
• Auxiliary components required to regulate voltage
and frequency
■ Sophisticated control system
Wind -Diesel System Components
Listed below are the main components of a medium to high -penetration wind -diesel system:
• Wind turbine(s), plus tower and foundation
• Supervisory control system
• Synchronous condenser
• Secondary load
• Deferrable load
• Interruptible load
• Storage
Wind Turbine(s)
Village -scale wind turbines are generally considered to be 50 kW to 250 kW rated output capacity. This
turbine size once dominated with worldwide wind power industry but has been left behind in favor of
much larger 1,000 kW plus capacity turbines. Conversely, many turbines are manufactured for home or
farm application, but generally these are 10 kW capacity or less. Consequently, few new village size -
class turbines are on the market, although a large supply of used and/or remanufactured turbines are
available. The latter typically result from repowering older wind farms with new, larger wind turbines.
Medium- and high -penetration wind -diesel systems require fast -acting real and reactive power
management to compensate for rapid variation in village load and wind turbine power output. A wind -
diesel system master controller, also called a supervisory controller, would be installed inside the
Kaktovik power plant or in a new module adjacent to it. The supervisory controller would select the
optimum system configuration based on village load demand and available wind power.
Synchronous Condenser
A synchronous condenser, sometimes called a synchronous compensator, is a specialized synchronous
electric motor with an output shaft that spins freely. Its excitation field is controlled by a voltage
regulator to either generate or absorb reactive power as needed to support the grid voltage or to
maintain the grid power factor at a specified level. Grid power factor and voltage support is essential
for a wind -diesel system's reliability.
For the Kaktovik power system, a synchronous condenser may be an economical option for voltage and
reactive power support.
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Kaktovik Wind -Diesel Analysis
Synch rorrorr.s condenser at the Kakhonak, AK powerplanI
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Secondary Load
A secondary or "dump" load during periods of high wind is required for a wind -diesel hybrid power
system to operate reliably and economically. The secondary load converts excess wind power into
thermal power for use in space and water heating through the extremely rapid (sub -cycle) switching of
heating elements, such as an electric boiler imbedded in the diesel generator jacket water heat recovery
loop. As seen in Figure 16, a secondary load controller serves to stabilize system frequency by providing
a fast responding load when gusting wind creates system instability.
An electric boiler is a common secondary load device used in wind -diesel power systems. An electric
boiler (or boilers), coupled with a boiler grid interface control system, could be installed in Kaktovik to
absorb excess instantaneous energy (generated wind energy plus minimum diesel output exceeds
electric load demand). The grid interface monitors and maintains the temperature of the electric hot
water tank and establishes a power setpoint. The wind -diesel system master controller assigns the
setpoint based on the amount of unused wind power available in the system. Frequency stabilization is
another advantage that can be controlled with an electric boiler load. The boiler grid interface will
automatically adjust the amount of power it is drawing to maintain system frequency within acceptable
limits.
Defer-rable (Load
A deferrable load is electric load that must be met within some time period, but exact timing is not
important. Loads are normally classified as deferrable because they have some storage associated with
them. Water pumping is a common example - there is some flexibility as to when the pump actually
operates, provided the water tank does not run dry. Other examples include ice making and battery
charging. A deferrable load operates second in priority to the primary load and has priority over
charging batteries, should the system employ batteries as a storage option.
Interruptible Load
Electric heating either in the form of electric space heaters or electric water boilers could be explored as
a means of displacing stove oil with wind -generated electricity. It must be emphasized that electric
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Kaktovik Wind -Diesel Analysis
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heating is only economically viable with excess electricity generated by a renewable energy source such
as wind and not from diesel -generated power. It is typically assumed that 40 kWh of electric heat is
equivalent to one gallon of heating fuel oil.
Storage Options
Electrical energy storage provides a means of storing wind generated power during periods of high
winds and then releasing the power as winds subside. Energy storage has a similar function to a
secondary load but the stored, excess wind energy can be converted back to electric power at a later
time. There is an efficiency loss with the conversion of power to storage and out of storage. The
descriptions below are informative but are not currently part of the overall system design.
Flywheels
A flywheel energy system has the capability of short-term energy storage to further smooth out short-
term variability of wind power, and has the additional advantage of frequency regulation. The smallest
capacity flywheel available from Powercorp (now ABB), however, is 500 kW capacity, so it is only
suitable for large village power generation systems.
Battery storage is a generally well -proven technology and has been used in Alaskan power systems
including Fairbanks (Golden Valley Electric Association), Wales and Kokhanok, but with mixed results in
the smaller communities. 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 5 to 15 minutes long. Storage for several hours or days is also possible with
batteries, but this requires higher capacity and cost. In general, the disadvantages of batteries for utility -
scale energy storage, even for small utility systems, are high capital and maintenance costs and limited
lifetime. Of particular concern to rural Alaska communities is that batteries are heavy and expensive ship
and most contain hazardous substances that require special removal from the village at end of service
life and disposal in specially -equipped recycling centers.
There are a wide variety of battery types with different operating characteristics. Advanced lead acid
and zinc -bromide flow batteries were identified as "technologically simple" energy storage options
appropriate for rural Alaska in an Alaska Center for Energy and Power (ACEP) July, 2009 report on
energy storage. Nickel -cadmium (NiCad) batteries have been used in rural Alaska applications such as
the Wales wind -diesel system. Advantages of NiCad batteries compared to lead -acid batteries include a
deeper discharge capability, lighter weight, higher energy density, a constant output voltage, and much
better performance during cold temperatures. However, NiCads are considerably more expensive than
lead -acid batteries and one must note that the Wales wind -diesel system had a poor operational history
and has not been functional for over ten years.
Because batteries operate on direct current (DC), a converter is required to charge or discharge when
connected to an alternating current (AC) system. A typical battery storage system would include a bank
of batteries and a power conversion device. The batteries would be wired for a nominal voltage of
roughly 300 volts. Individual battery voltages on a large scale system are typically 1.2 volts DC. Recent
V3 ENFRGY LL
Kaktovik Wind -Diesel Analysis P age 117
advances in power electronics have made solid state inverter/converter systems cost effective and
preferable a power conversion device. The Kokhanok wind -diesel system is designed with a 300 volts DC
battery bank coupled to a grid -forming power converter for production of utility -grade real and reactive
power. Following some design and commissioning delays, the solid state converter system in Kokhanok
should be operational by late 2013 and will be monitored closely for reliability and effectiveness.
Wind Turbine Options
The most significant factor with respect to choice of wind turbines for Kaktovik is the height limitation
dictated by the proximity of the prospective wind turbine site to the new airport. This height limitation
eliminates consideration of larger wind turbines that would potentially be suitable, such as the 900 kW
Emergya Wind Technologies DW 52-900 wind turbine presently operational in Kotzebue or the 500 kW
Vestas V39 wind turbine operational in Sandpoint.
Turbine choice therefore was oriented turbines that are large enough to match well with the Kaktovik
load but not so large to exceed FAA height restrictions with respect to the new airport. Turbines that
meet these criteria are generally in the 100 to 250 kW size range. The wind power industry, however,
does not provide many options as village wind power is a small market worldwide compared to utility
grid -connected projects where wind turbines are 1,000 kW and larger capacity, or home and farm
applications where wind turbines are generally 10 kW or less capacity. For this project, three wind
turbines are considered:
1. Aeronautica AW 29-225: 225 kW rated output; new
2. Northern Power Systems 100-21, 100 kW rated output; new
3. Vestas V27: 225 kW rated output; remanufactured
The choice of selecting new or remanufactured wind turbines is an important consideration and one
which North Slope Borough will want to consider carefully. There are advantages and potential
disadvantages of each, including cost, support and parts availability. Note however that the three wind
turbines presented in this report have solid track records and very good support capacity within Alaska.
Aeronautica 29-225
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 httpJlaeronauticawind.com/awlindex.htmi.
V3 ENFRG) LLC
Kaktovik Wind -Diesel Analysis
Aeronautica AW 29-225 wind turbine
Page 118
Northern Power Systems 100 (NPS 100)
The Northern Power System NPS 100 wind turbine is manufactured by Northern Power Systems in
Barre, Vermont. The NPS 100 turbine is rated at 100 kW, is stall -regulated and operates upwind with
active yaw control, has a direct -drive permanent magnet synchronous generator, comes equipped with
a 21 meter or 24 meter diameter rotor, and is available on 30 and 37 meter tubular steel monopole
towers, or on a 48 meter four -leg lattice tower.
The NPS 100-21 is available as fully arctic -climate certified to -40' C and is the most represented village -
scale wind turbine in Alaska with a significant number of installations in the Yukon-Kuskokwim Delta
region of the state, but also five turbines in Gambell and Savoonga on St. Lawrence Island. More
information can be found at: http://www.nor-thernpgwet.LOM/.
Design class of the NPS 100-21 (21 meter rotor) is IEC (International Electrotechnical Commission) Class
II -A (air density 1.225 kg/m3, average wind speed below 8.5 m/s, and 50-year peak gust below S9.5 m/s).
Northern Power Systems 100 wind turbines, Toksook Buy, Alaska
V FNFRGY LFC.
Kaktovik Wind -Diesel Analysis
Vestas V27
Page 119
The Vestas V27 was originally manufactured by Vestas Wind Systems A/S in Denmark and is no longer in
production in Europe, although the turbine reported is presently manufactured under license in India.
For many years the V27 was Vestas' workhorse wind turbine and many are still in operation worldwide.
Present availability of the V27 in Alaska is as a remanufactured unit from Halus Power Systems in San
Leandro, California. Marsh Creek, LLC of Anchorage is the distributor in Alaska for Halus Power Systems.
The V27 is pitch -regulated, has a synchronous (induction) double -wound generator, active yaw control,
a 27 meter diameter rotor, is rated at 225 kW power output, and is available with 30, 40, or 50 meter
tubular steel towers.
Vestas V27 wind turbines, Saint Paul Island, Alaska
Wind -Diesel Model
HOMER renewable energy modeling software was used to analyze the potential for wind turbines to
augment the existing Kaktovik diesel generator power plant. HOMER is designed to analyze hybrid
power systems that contain a mix of conventional and renewable energy sources such as diesel
generators, wind turbines, solar panels, batteries, etc. and is widely used to aid development of Alaska
village wind power projects. It is a static energy balance model, however, and is not designed to model
the dynamic stability of a wind -diesel power system. It will, however, warn of system design with
sufficient renewable energy input to potentially result in instability. For proposed high penetration
configurations, it is advisable to model dynamic system stability with appropriate software during the
design phase of the project. The intent of this modeling exercise is to highlight the potential benefit of
wind turbines in Kaktovik.
Kaktovik Powerplan[
Electric power (comprised of the diesel power plant and the electric power distribution system) in
Kaktovik is provided by North Slope Borough. The power plant being is comprised of four diesel
generators: two 910 kW Caterpillar 3512 diesel generators and two 450 kW Caterpillar 3508 diesel
generators. Kaktovik's diesel generators will automatically parallel to meet load demand during periods
V3 ENFRGY LLC
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Kaktovik Wind -Diesel Analysis
Page 120
of high power usage. Via a review of the powerplant operational records, a typical operational
configuration is one Cat 3512 and one Cat 3508 on-line.
Diesel Generators
For purposes of modeling, the Kaktovik diesel generators are assigned bays (or positions) 1 through 4 in
the power house, although note that position of generators in the actual power house may be different.
Bays 1 and 2 are for the two 910 kW Caterpillar 3512 marine diesels and bays 3 and 4 are the smaller
450 kW Caterpillar 3508C marine diesels.
New powerplant diesel generators in Hamer model
Generator Diesel Engine Model
Generator
Electrical Rating
Heat Recovery
1 Caterpillar 3512
Leroy -Sommer SR4
910 kW
Jacket water
2 Caterpillar 3512
Leroy -Sommer SR4
910 kW
Jacket water
3 Caterpillar 3508
Leroy -Sommer SR4
450 kW
Jacket water
4 Caterpillar 3508
Leroy -Sommer SR4
450 kW
Jacket water
Diesel generator HOMER modeling inform aIion
Diesel generator
Cat 3512
Cat 3508
Power output (kW)
910
450
Intercept coeff. (L/hr/kW rated)
0.02029
0.02184
Slope (L/hr/kW output)
0.2328
0.2378
Minimum electric
15.0%
15.0%
load (%)
(135 kW)
(67 kW)
Heat recovery ratio (% of generator
40
40
waste heat energy available to serve
the thermal load; when modeled)
Notes: Intercept coefficient — the no-load fuel
consumption of the generator
divided by its capacity
Slope — the marginal fuel consumption of the
generator
Caterpillar 3512 Diesel Generator
The graphs below illustrate fuel usage and consequent electrical and thermal efficiency of the Cat 3512
diesel generator used in Homer modeling. Note that NSB did not report a seasonal or other specific
scheduling plan, hence Homer software was programmed to select the most efficient diesel for any time
period. Also note that Homer was programmed to allow parallel diesel generator operation, although
this was not specifically verified.
Cat 3512 fuel curve
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Cat 3512 electrical energy efficiency curve
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Kaktovik Wind -Diesel Analysis
Cat 3512 electrical and thermal energy efficiency curve
014"rt R4
— Be= — TWmrMl — Taft
Page 121
Caterpillar 3508 Diesel Generator
The graphs below illustrate fuel usage and consequent electrical and thermal efficiency of the Cat 3508
diesel generator used in Homer modeling. Note again that NSB did not report a seasonal or other
specific scheduling plan, hence Homer software was programmed to select the most efficient diesel for
any time period.
Cat 3508 ravel curve Cat 3508 electrical enemy efciencv curve
vT5O
0
it
E TOO
M
e
O 50
7
a
7
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3 4-
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Cut 3508 electrical and thermal energy efficiency curve
000s*M
— 0M. I — pall -
L7~ 0"
Wind Turbines
Wind turbine options for Kaktovik are discussed previously in this report. For Homer modeling, standard
temperature and pressure (STP) power curves were used. This is quite conservative in that actual
turbine power production in Kaktovik will typically be higher than predicted by the STIR power curves
due to the cold temperature climate and consequent high air density of the area.
V3 LNFRn LLC
Kaktovik Wind -Diesel Analysis
Aeronautica AW 29-225 power curve
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Vestas V27 power curve
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Page 122
Electric Load
For modeling purposes with Homer software, the Kaktovik electric load was derived from calendar year
2012 powerplant data forwarded to HDL and V3 Energy, LLC by North Slope Borough in an Excel
spreadsheet entitled 2012 Kaktovik PPOR. The spreadsheet tabulates average power per hour for each
diesel engine on-line. If two diesel engines are operating in parallel, individual generator power output
is summed to equal total hour (average) load. Hours are organized into days and days into months. For
each day, generator output is summed to yield kWh produced per turbine and aggregate. Below is an
example of daily generator output/load data.
V3 ENFRGY LLC
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Kaktovik Wind -Diesel Analysis
Page 123
Kaktovik Power Plant
lanuary 3, 2012
Hour
0:00
Engine 1
Caterpillar 3512
Serial # 67ZO1838
Total Load
345
Engine 2
Caterpillar 3512
Serial # 67ZO1839
Engine 3
Caterpillar 3508
Serial # 70ZO1055
Total Load
Engine 4
Caterpillar 3508
Serial # 70ZO1054
Total Hourly
Load
587
632
Peak Load
of the Day
689
Total Load
Total Load
242
245
1:00
387
2:00
385
246
631
■ & ■ i ■ f : s
3:00
388
250
638
' _'om+'as■' ■
am
4:00
389
245
634
* . + . o : o m
5:00
408
245
653
' r ' r
6:00
400
245
645
: o r m mai m
7:00
410
247
657
' ■' ■ r ■' ■
8:00
440
242
682
w : s : m . ;
9:00
446
243
689
e■m■m■■■
w ■ ■
10:00
385
245
630
:' .' .' : ■
. ■ ■ ■
11:00
383
246
629
; ■ : + : ■ _ ■
r
1mi
2:00
416
250
666
''''''''
13:00
393
245
638
■' ■' moss,
■ ■ ■ ■•
14:00
385
244
629
moisimom
15:00
371
242
613
;■:■:■;■
16:00
383
245
628
a w a a r a i
17:00
372
235
607
' '
aa0aaaaa
18:00
343
244
587
■ o ■ s ■ a ■ m
19:00
327
241
568
' •' ■'mu r ' •
�
20:00
326
242
568
a■';.' �■ • :■'
21:00
326
240
566
'. r ' '
.' +.'.'
22:00
330
241
571
■ ' ' '
23:00
351
244
595
Total
9,089 0
0
5,854
147943
';':'.'.
For Homer input, load data is organized into 8,760 lines, representing 24 hours per day for 365 days per
year. In a number of instances diesel generator power (load) data was missing from the data set. In
these cases, missing data was filled by interpolating from before and after the blank sections. The
graphs below show a summary of the Kaktovik load from the powerplant data.
Kaktovik electric Iona
±
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Kaktovik Wind -Diesel Analysis
24
Thermal Load
a
Page 124
The Kaktovik powerplant is equipped with a heat recovery system to extract jacket water waste heat
from the diesel generators and supply it to the following village thermal (heat) loads: powerplant,
washeteria, school, USDW, water plant, fire station, VMS, clinic. Referencing a February, 2010 draft RSA
Engineering, Inc. report to North Slope Borough entitled North Slope Borough Village Heat Recovery
Project Analysis Report, CIP No. 13-222, the combined design day heat load of the above -referenced
structures is 3.29 MMBTU/hr. Also noted in the RSA Engineering, Inc. report is the possibility of adding
PSO and the vacuum station to the heat recovery loop, which would increase the design data heat load
by 0.13 MMBTU/hr. Data from the RSA Engineering report details on a monthly basis existing waste heat
(from the powerplant heat recovery system) consumption and the estimated contribution of waste heat
to the actual heat load. This data can be used to derive estimated actual thermal or heat demand, which
is different than the design day heat load.
RSA Engineering thermal load dre[n. PSO and vacuum station not included
Heat
Heat Demand
Heat
Unused
Available
Consumed
% heat
Heat
Month
(BTU/hr)
(BTU/hr)
(kW)
(BTU/hr)
load
(BTU/hr)
1
1,372,830
137,283,000
40,197.9
1,372,830
100%
2
1,434,300
143,430,000
41,997.8
1,434,300
100%
3
1,272,429
127,242,900
37,258.0
1,272,429
100%
4
1,139,244
113,924,400
33,358.2
1,139,244
100%
5
1,026,549
102,654,900
30,058.4
1,026,549
100%
6
963,030
96,303,000
28,198.5
963,030
100%
-
7
942,540
94,254,000
27,598.6
929,063
99%
13,477
8
1,040,892
104,089,200
30,478.4
829,640
80%
211,252
9
1,047,039
104,703,900
30,658.4
1,034,744
99%
12,295
10
1,104,411
110,441,100
32,338.3
1,104,411
100%
-
11
1,133,097
113,309,700
33,178.3
1,133,097
100%
12
1,202,763
120,276,300
35,218.2
1,202,763
100%
Data from the above table was converted from BTU/hr to kW (heat) load for use in Homer software to
create the following thermal load profile for modeling purposes:
V3 ENERGY LLC
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Kaktovik Wind -Diesel Analysis
lfnktovik Cher mai load
t_
Page 125
a
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Wind Turbine Configiiration Options
ariin
Discussions between HDL and North Slope Borough have indicated that the borough's goals with a wind -
diesel system in Kaktovik is to offset a significant percentage of fuel used in the powerplant, but not
create a highly complex system with significant thermal offset and/or electrical storage capability. This
philosophy dictates a medium penetration design approach (see previous section of this report) where
wind power supplies 20 to 50 percent of the electric load, but at least one diesel generator is always on-
line to provide spinning reserve and control grid frequency. Medium penetration design does, though,
mean that instantaneous wind power will at times be well over 100 percent of the load. This can result
in unstable grid frequency, which can occur when electrical power generated exceeds the load demand.
In a wind -diesel power system without electrical storage, there are two options to prevent this
possibility:
1. Curtail one or more wind turbines to prevent instantaneous wind penetration from exceeding
100 percent (one must also account for minimum loading of the diesel generator).
2. Install a secondary load controller with a resistive heater. The secondary load controller is the
fast -acting switching mechanism commanding heating elements to turn on and off to order to
maintain stable frequency. The resistive heater can be as simple as a heater ejecting energy to
the atmosphere or an interior air space or, more desirably, a boiler serving one or more thermal
loads. The boiler can be installed in the powerplant heat recovery loop and operated in parallel
with fuel oil boilers.
In either case, system frequency control features are necessary in medium penetration design as,
generally speaking, the diesel generator paralleled with the wind turbines during periods of high wind
energy input may not have sufficient inertia to control frequency by itself. This design philosophy is
typical of most wind -diesel systems presently operational in Alaska and provides a solid compromise
0 V3 ENFRMI, LLC
1 'k � 1 ,il �:,.,-
Kaktovik Wind -Diesel Analysis
Page 126
between the minimal benefit of low penetration wind systems and the cost and complexity of high
penetration wind systems.
Many utilities prefer to install more than one wind turbine in a village wind power project to provide
redundancy and continued renewable energy generation should one turbine be out -of -service for
maintenance or other reasons. With this guideline in mind, and referencing the medium wind power
penetration design philosophy discussed above, modeled wind turbine configuration options considered
in this report are as follows:
• Aeronautica AW 29-225, three turbines (675 kW capacity)
• Northern Power NPS 100-21, seven turbines (400 kW to 700 kW capacity)
• Vestas 27, three turbines (675 kW capacity)
Turbine types are not mixed, however, as it is assumed that North Slope Borough will select only one
type of wind turbine. A typical configuration for this project is show below. Note that turbine type can
be switched from the AW 29-225 (shown) to the NPS 100-21 or V27.
Wind -diesel configtirrat on fnr Knktovih-
Aerana fna 29-z..
J
Pmwiry Load 1
W2. Erg 1
13 MWhld
769 kW peak
VtEag2
3= Erg 3
U ump Load
36U3. Enp 4
AC
TbmwiLeadl
Boiar
Resaerces -
06M --
r VM Remuce
Emovics
J. Diesel Q2.14UC ...
system CarAml
JDindM.134K---
Eaisdans
Cori*aiis
Economic Analvsi
Installation of wind turbines in medium penetration mode is evaluated in this report to demonstrate the
economic impact of these turbines with the following configuration philosophy: turbines•are connected
to the electrical distribution system to serve the electrical load. Although system configuration will
require a secondary load controller and an electric heater or boiler to divert excess electrical power, the
offset of thermal load(s) via a secondary load controller is not modeled in this report. This is due to the
relatively small amount of excess energy produced by the wind turbine configurations described in the
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Kaktovik Wind -Diesel Analysis
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previous section and the complications of cost modeling thermal loads together with electrical loads in
Homer software. Additionally, it is not certain that an electric boiler is the best choice to dissipate
excess energy as it is possible that space heating may prove simpler and less expensive to construct and
operate.
Fuel Cost
A fuel price of $5.27/gallon ($1.39/Liter) was chosen for the initial HOMER analysis by reference to
Alaska Fuel Price Projections 2013-2035, prepared for Alaska Energy Authority by the Institute for Social
and Economic Research (ISER), dated June 30, 2103 and the 2013 06 R7Prototype—final 07012013
Excel spreadsheet, also written by ISER. The $5.27/gallon price reflects the average value of all fuel
prices between the 2015 (the assumed project start year) fuel price of $4.50/gallon and the 2034 (20
year project end year) fuel price of $6.19/gallon using the medium price projection analysis with an
average social cost of carbon (SCC) of $0.58/gallon included.
By comparison, the fuel price for Kaktovik (without social cost of carbon) reported to Regulatory
Commission of Alaska for the 2012 PCE report is $4.28/gallon ($1.13/Liter), without inclusion of the SCC.
Assuming an SCC of $0.40/gallon (ISER Prototype spreadsheet, 2013 value), the 2012 Kaktovik fuel price
was $4.68/gallon ($1.24/Liter).
Heating fuel displacement by excess energy diverted to thermal loads is valued at $6.32/gallon
($1.67/Liter) as an average price for the 20 year project period. This price was determined by reference
to the 2013 06 R7Prototype final 07012013 Excel spreadsheet where heating oil is valued at the cost
of diesel fuel (with SCC) plus $1.05/gallon, assuming heating oil displacement between 1,000 and 25,000
gallons per year.
rel cost table, SCC included
ISER med.
projection
2015 (/gal)
Diesel Fuel
$4.50
Heating Oil
$5.55
Average Average
2034 (/gal) (/gallon) (/Liter)
$6.19 $5.27 $1.39
$7.24 $6.32 $1.67
Mocieling Assumptions
HOMER energy modeling software was used to analyze the Kaktovik power System. HOMER was
designed to analyze hybrid power systems that contain a mix of conventional and renewable energy
sources, such as diesel generators, wind turbines, solar panels, batteries, etc. and is widely used to aid
development of Alaska village wind power projects.
Modeling assumptions are detailed in the table below. Many assumptions, such as project life, discount
rate, operations and maintenance (O&M) costs, etc. are AEA default values. Other assumptions, such as
diesel overhaul cost and time between overhaul are based on general rural Alaska power generation
experience. The base or comparison scenario is the Kaktovik powerplant with its present configuration
of diesel generators and the existing thermal loads connected to the heat recovery loop.
V3 ENFRM, LLC
Kaktovik Wind -Diesel Analysis
Page 128
Modeling assumes that wind turbines constructed in Kaktovik would operate in parallel with the diesel
generators. Although excess energy could serve thermal loads via a secondary load controller and
electric boiler that would augment the existing jacket water heat recovery system, it is not modeled as
such. Installation cost of this turbine project assumes three-phase upgrade of the distribution system to
the wind turbine site.
Basic modeling assumptions
Economic Assumptions
Project life
20 years (2014 to 2033)
Discount rate for net present value
3%
calculations
System fixed capital cost (plant
Included in turbine project cost
upgrades required to accommodate
wind turbines)
Operating Reserves
Load in current time step
10%
Wind power output
100% (forces diesels to always operate)
Fuel Properties (no. 2 diesel for
powerplant)
Heating value
46.8 MJ/kg (140,000 BTU/gal)
Density
830 kg/m3 (6.93 lb./gal)
Price (20 year average; ISER 2013,
$5.27/gal ($1.39/Liter)
medium projection plus social cost of
carbon)
Fuel Properties (no. 1 diesel to serve
thermal loads)
Heating value
44.8 MJ/kg (134,000 BTU/gal)
Density
830 kg/m3 (6.93 lb./gal)
Price (20 year average; ISER 2013,
$6.32/gal ($1.67/Liter)
medium projection plus social cost of
carbon)
Diesel Generators
Generator capital cost
$0 (already installed)
O&M cost
$0.02/kWh
Overhaul cost
$50,000 for Cat 3512; $30,000 for Cat 3508
Minimum load
15%
Schedule
Optimized
Wind Turbines
Availability
80% (adjusted by reducing mean wind speed in Homer)
Turbine hub height
30 meters (all turbines)
O&M cost
$0.049/kWh
Wind speed
6.52 m/s at 30 m level at prospective wind turbine site; wind
speed scaled to 5.85 m/s for 80% turbine availability and
6.18 m/s for 90% availability
Density adjustment
Measured Kaktovik density of 1.286 kg/m3 is 5.0% higher
than standard air density of 1.225 kg/m3. Density
compensation by setting elevation at -530 m in Homer.
V') E .vR(-N LO_
Kaktovik Wind -Diesel Analysis P a g e 129
Energy Loads
Electric 13,124 kWh/day mean annual electrical load
Thermal 12,110 kWh/day mean annual available via recovered heat
loop
Fuel oil boiler efficiency 85%
Electric boiler efficiency 100%
Wind Turbine Project Costs
Construction cost for wind turbine installation and integration with the diesel power plant would be
determined with high degree of accuracy during the design phase of the project. Note that costs listed
below are estimates.
Nina i uroine c.osrs
No.
Turbine Turbines
Aeronautica
HDL's Cost per Tower
Estimated Installed kW Height
Project Cost kW Capacity Tower Type (meters)
AW29-225 3 $7,815,795 675 $11,579 Monopole 30
Northern Power
NPS100-21 7 $11,312,500 700 $16,161 Monopole 30
Vestas V27 3 $7,122,795 675 $10,552 Monopole 30
Modeling Results
The following modeling information assumes the existing thermal loads without addition of the PSO and
vacuum station. Economic benefit -to -cost is shown by the ISER method which does not account for heat
loss from the diesel engines with respect to heating oil offset. ISER cost modeling assumptions are
noted above or are discussed in the 201306 R7Prototype_ inal 07012013 Excel spreadsheet.
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Kaktovik Wind -Diesel Analysis
Discussion
Page 131
Installing wind turbines and creating a wind -diesel power system in a small village is a demanding
challenge. At first glance, the benefits of wind power are manifest: the fuel is free and it is simply a
manner of capturing it. The reality of course is more complicated. Wind turbines are complex machines
and integrating them into the diesel power system of a small community is complicated. With wind -
diesel, a trade-off exists between fuel savings and complexity. A system that is simple and inexpensive
to install and operate will displace relatively little diesel fuel, while a wind -diesel system of considerable
complexity and sophistication can achieve very significant fuel savings.
The ideal balance of fuel savings and complexity is not the same for every community and requires
careful consideration. Not only do the wind resource, electric and thermal load profiles, and
powerhouse suitability vary between villages, so does technical capacity and community willingness to
accept the opportunities and challenges of wind power. A very good wind -diesel solution for one village
may not work as well in another village, for reasons that go beyond design and configuration questions.
Ultimately, the electric utility and village residents must consider their capacity, desire for change and
growth, and long-term goals when deciding the best solution to meets their needs.
The purpose of this Wind -Diesel Analysis report is to introduce and discuss the viability of wind power in
Kaktovik. As discussed, many options are possible, ranging from a very simple low penetration system
to a highly complex, diesels -off configuration theoretically capable of displacing 75 percent or more of
fuel usage in the community. It's possible that North Slope Borough and Kaktovik residents will
ultimately prefer a very simple or very complex option, but from past discussions and work it has been
determined and possibly also assumed that a moderate approach to wind power in Kaktovik is
preferred, at least initially.
With a moderately complex project design framework in mind, a configuration of relatively high wind
turbine capacity but without electrical storage and without diesels -off capability was chosen. This
provides sufficient wind capacity to make a substantive impact on fuel usage but does not require an
abrupt transition from low to high complexity. Although conceptually elegant, there is a trade-off to
consider with this approach. Installing a large amount of wind power capacity (approximately 700 kW
are recommended) is expensive, but without electrical or thermal storage some of the benefits of this
wind power capacity cannot be captured and will be lost.
The thermodynamics of energy creation and use dictates that wind power is more valuable when used
to offset fuel used by diesel generators to generate electricity than fuel used in fuel oil boilers to serve
thermal loads. Referring to the energy production summaries for the three turbine configurations under
Modeling Results, one can see that the wind turbines are expected to produce minimal excess
electricity, even at 90 percent turbine availability. This excess electricity, although minimal, must be
shunted via a secondary load controller to the diesel generator heat recovery loop or simple radiation
heaters to avoid curtailing wind turbines during periods of high wind and relatively light electrical load.
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Kaktovik Wind -Diesel Analysis P a g e 132
Although perhaps not readily apparent in the report, this compromise of wind capacity versus
complexity is contained within the economic benefit -to -cost tables. Because excess wind energy is not
modeled as serving the thermal load nor stored in batteries, it is not valued in the net present value
calculations. So, a compromise, which is common with wind -diesel designs, is that capital costs are high,
but usage of energy generated is imperfect, from an efficiency point of view. The most efficient usage
of energy from a technical point of view, however, may be too expensive from a cost -benefit
perspective.
It is important to not focus strictly on benefit -to -cost ratio of a particular configuration design or
particular turbine option, but also consider a wider view of the proposed wind project for Kaktovik.
Installing approximately 700 kW capacity of wind power has considerable short-term benefit with
reduction of diesel fuel usage, but more importantly it would provide a platform of sustainable
renewable energy growth in Kaktovik for many years to come. This could include enhancements such as
thermal load offset, battery storage to enable diesels -off capability, creation of deferred heat loads such
as water heating, and installation of distributed electrical home heat units (Steffis heaters or similar)
controlled by smart metering. The latter, presently operational to a limited extent in the villages of
Kongiganak, Kwigillingok, Tuntutuliak, has enormous potential in rural Alaska to not only reduce the very
high fuel oil expenses borne by village residents, but also to improve the efficiency and cost benefit of
installed and future wind power projects. These opportunities and benefits are tangible and achievable,
but their cost benefit was not modeled in this report.
Lastly, it must be acknowledged that a wind power project in Kaktovik will provide benefits that are not
easily captured by the economic modeling contained in this report. These are the externalities of
economics that are widely recognized as valuable, but often discounted because they are soft values
compared to the hard numbers of capital cost, fuel quantity displaced, etc. These include ideals such as
long-term sustainability of Kaktovik, independence of Kaktovik from foreign -sourced fuel, reduction of
Kaktovik's carbon footprint, and opportunities for education and training of Kaktovik residents, among
others.
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