HomeMy WebLinkAboutCity of Hooper Bay Renewable Energy Resource Analysis - Jan 2012 - REF Grant 2195439
City of Hooper Bay
Water Treatment Plant
Renewable Energy
Resource Analysis
Technical Memorandum
P.O. Box 232946 Anchorage, AK 99523
January 2012
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page i
TABLE OF CONTENTS
I. INTRODUCTION ..................................................................................................................................... 1
II. ALTERNATIVES CONSIDERED ................................................................................................................ 2
A. Alternative One No-Build ............................................................................................................... 2
B. Alternative Two Wind Turbine Heat Generation at WTP/Washeteria Facility .............................. 4
C. Alternative Three Wind Turbine Electricity Generation at AVEC Wind Farm ................................ 4
III. POWER AND ECONOMICS ..................................................................................................................... 5
A. Methods Quantifying Benefit ......................................................................................................... 5
B. Wind Energy and Fuel Displacement ................................................................................................ 8
C. Cost of Fuel Displaced ....................................................................................................................... 9
D. Results Comparing Benefits ......................................................................................................... 10
E. Fuel Displacement Calculations ...................................................................................................... 11
F. Annual Cost Savings Calculations .................................................................................................... 12
G. Additional Cost Considerations ....................................................................................................... 15
IV. ADDITIONAL WIND CAPACITY ANALYSIS ............................................................................................ 16
A. HOMER Model Analysis .................................................................................................................. 16
B. HOMER Model Analysis Results ...................................................................................................... 17
C. HOMER Model Report Findings ...................................................................................................... 18
V. COMPARISON OF CE2 AND V3 ENERGY ANALYSES............................................................................. 19
A. AVEC Power Plant Fuel Displacement Estimates ............................................................................ 19
B. City of Hooper Bay WTP Fuel Displacement Estimates .................................................................. 20
C. Cost Savings Estimates .................................................................................................................... 21
VI. RECOMMENDED ALTERNATIVE .......................................................................................................... 22
List of Figures
Figure 1 Wind kWh Production Averages 2006-2010 ................................................................................ 5
Figure 2 Monthly Average Wind Production 2008-2010 ........................................................................... 6
Figure 3 2010 Wind and Diesel kWh Production ....................................................................................... 7
Figure 4 Hooper Bay Projected Monthly kWh Production, Per Turbine .................................................... 8
Figure 5 Annual Gallons Saved ................................................................................................................. 12
Figure 6 Hooper Bay Average Monthly Wind Speed ................................................................................ 17
Figure 7 Annual Savings Comparison ....................................................................................................... 20
List of Tables
Table 1 Projected WTP Fuel Consumption and Cost .................................................................................. 3
Table 2 Projected AVEC Fuel Consumption and Cost ................................................................................. 4
Table 3 AVEC Fuel Cost per Gallon ........................................................................................................... 10
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page ii
Table 4 Monthly Wind Turbine Power Production Estimates (kWh).......................................................11
Table 5 AVEC Electricity Production and Fuel Displacement ................................................................... 11
Table 6 WTP Electricity and Heat Production and Fuel Displacement ..................................................... 11
Table 7 AVEC Projected Cost Savings, Per Turbine .................................................................................. 14
Table 8 WTP Projected Cost Savings, Per Turbine ................................................................................... 14
Table 9 Projected Fuel Displacement per Turbine, as a Percentage of Facility Total Gallons ................. 15
Table 10 Percentage of Total Cost Offset ................................................................................................. 15
Table 11 HOMER Model Fuel Displacement Estimates ............................................................................ 17
Table 12 HOMER Model Annual Estimated Cost Savings for Two Wind Turbines ................................... 18
Table 13 HOMER Model Benefit/Cost Ratio for Two Wind Turbines at Either Location ......................... 18
List of Appendices
Appendix A AVEC Wind Production Data
Appendix B Monthly Average Wind Production Forecast
Appendix C Hooper Bay Electricity Production Projections
Appendix D V3 Energy Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 1
I. INTRODUCTION
The City of Hooper Bay (City) is proposing to use wind energy to reduce the costs of heating water at its
water treatment plant (WTP). The purpose of this Technical Memorandum is to examine feasible
renewable energy alternatives, specifically wind turbines, and determine the most beneficial project for
the residents of Hooper Bay.
In a proposal submitted to the Alaska Energy Authority (AEA) in 2008, the City estimated that a two-
turbine wind facility at the WTP would produce approximately 539,000 kilowatt hours (kWh) of energy
per year, the equivalent of 1.71 billion British thermal units (BTUs), which would displace approximately
16,000 gallons of heating oil at the WTP. This displacement of fuel would have saved the City an
estimated $75,000 per year. These figures are slightly higher than the new data described below.
investigation of other potential wind
turbine applications in the community before granting funds to add wind power as a dedicated source of
heat at the WTP. Expanding the existing Alaska Village Electric Cooperative (AVEC) wind turbine
installation was to be considered.
AVEC is the owner and operator of the electrical generating facility, or power plant, in Hooper Bay. In
2009, AVEC installed three Northwind 100 wind power turbines (manufactured by Northern Power
Systems, headquartered in Vermont) northeast of the Hooper Bay power plant, using wind to
thereby reducing diesel fuel consumption. This system
is very similar to the three-wind turbine systems AVEC constructed and has operated in Kasigluk and
Toksook Bay since 2006. Due to turbines
in western Alaska, and also due to the fact that wind displaces more fuel when used as a source of
electricity than when used solely as a source of heat, AEA requested the City develop a side-by-side
WTP for heat versus installing
two additional wind turbines at the existing AVEC site to produce electricity.
identify which option will be most beneficial to Hooper Bay, defined strictly in terms of
cost savings and displacement of fossil fuel, and will use the findings in this report in their decision to
award funding for two wind turbines to either the City or AVEC. AEA has indicated that fuel-savings,
rather than decreasing the customer cost for either the water or the electric utility, is the most
important criterion in its decision to fund a wind project in Hooper Bay.
In terms of financial relief, the City initiated the grant request with the goal of passing its fuel savings on
to its water and sewer utility customers. AVEC has stated that its present use of wind energy has
reduced electricity costs for Hooper Bay households. In agreeing to conduct the study, the City
understands that if the AVEC option is shown to produce a greater overall benefit, the City may not be
successful in its effort to reduce its WTP heating costs through the use of two wind turbines.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 2
II. ALTERNATIVES CONSIDERED
This report will evaluate the fuel-saving effects of three different wind-power alternatives.
Alternative 1 is the
heat energy currently produced by oil-fired boilers. Alternative 3
reduce fuel costs at the WTP, but instead describes the fuel-saving effect of adding two additional wind
turbines to the AVEC power plant.
For nearly ten years, the City of Hooper Bay has been in discussions with AEA, AVEC, and CE2 to find
ways
bills. Two possible solutions involve recovering waste heat from the AVEC power plant, and distributing
isting or future wind turbines when wind production exceeds load
requirements. Note: The waste heat recovery system for the AVEC power plant is currently moving from
the design phase to the construction funding phase.
These two possible solutions do not factor into either of the Alternatives discussed in this report.
However, implementation of any of the Alternatives discussed in this report will have a direct effect on
future discussions of waste heat recovery and dump load availability. Those potential effects are
mentioned, but not discussed at length in this report.
A. Alternative One No-Build
The WTP uses three oil-fired boilers (2,132M BTUs each) for purposes of heating treated water for use in
the washeteria, heating potable water for distribution, and warming raw groundwater to a temperature
at which it can be treated.
Presently, community water demand does not require the boilers to work at full capacity. Current boiler
fuel consumption is approximately 35,000 gallons of heating oil annually. Within a few years, as the
water distribution and wastewater system expands to directly serve individual houses, the increased
demand for heated potable water will raise fuel consumption to approximately 60,000 gallons yearly.
The cost per gallon for fuel used at the WTP has ranged from $4.30 in 2007 to $3.13 in 2010.
The price of fuel oil is projected to rise in the coming years, along with fuel consumption. Table 1 shows
the growing estimated cost of heating water at the WTP.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 3
Table 1 Projected WTP Fuel Consumption and Cost
Year Gallons Used Cost per Gallon Total Cost
2011 37,500 $3.79 142,005$
2012 40,000 $4.11 164,552$
2013 42,500 $4.44 188,736$
2014 45,000 $4.77 214,554$
2015 47,500 $5.09 242,007$
2016 50,000 $5.42 271,096$
2017 52,500 $5.75 301,819$
2018 55,000 $6.08 334,178$
2019 57,500 $6.40 368,172$
2020 60,000 $6.73 403,801$
Alternative One
source of heat to reduce the cost of supplying water to customers.
AVEC owns the local electricity generation facility powered by four diesel-fired generators and three
wind turbines. The generators at the AVEC plant consume approximately 220,000 gallons of diesel
annually and produce approximately 3,000,000 kWh per year. The efficiency of the diesel generation at
imated at 13.66 kWh per gallon (3,000,000 kWh divided by 220,000 gallons).
Alternative One would not change the level of fuel consumption at the AVEC power plant.
In 2009, AVEC began operating three Northwind-100 wind turbines in Hooper Bay, directing
approximately 600,000 kWh of wind . With three wind
turbines in operation, the current diesel fuel consumption is reduced annually by approximately 43,700
gallons of diesel. The no-build option would not change on, while
electric power generation is estimated to continue to increase along with fuel consumption and fuel
costs.
Table 2 shows the projected increase in fuel consumption (accounting for the existing three-wind
turbine supplement) and annualized cost increases at the AVEC power plant. Explanations of the cost-
estimate projections are provided in Section III.A Methods.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 4
Table 2 Projected AVEC Fuel Consumption and Cost
Year Gallons Used Cost per Gallon Total Cost
2011 226,646 $3.69 836,325$
2012 234,634 $4.01 940,568$
2013 242,621 $4.33 1,049,902$
2014 250,608 $4.65 1,164,326$
2015 258,596 $4.96 1,283,842$
2016 266,583 $5.28 1,408,447$
2017 274,570 $5.60 1,538,144$
2018 282,558 $5.92 1,672,930$
2019 290,545 $6.24 1,812,808$
2020 298,532 $6.56 1,957,776$
B. Alternative Two Wind Turbine Heat Generation at
WTP/Washeteria Facility
Adding two wind turbines as a dedicated heat source at the WTP would reduce the amount of fuel
required to fire the boilers. Estimated fuel displacement, projected percentage fuel reduction, and
projected overall cost-savings are presented in Section III.
This alternative would retain the existing fuel use pattern at AVEC power plant, and would lower fuel
consumption in the WTP and washeteria.
C. Alternative Three Wind Turbine Electricity Generation at AVEC
Wind Farm
The third alternative would add two wind turbines to the existing three-turbine wind farm operated by
AVEC. The existing wind turbines reduce AVEC approximately 43,700 gallons per
year; this alternative would potentially annual fuel needs by an additional 29,134 gallons.
Currently, AVEC owns a control module that regulates the input of wind energy from its three
power distribution grid. New wind turbines would
be incorporated into the existing power system via this controller.
Estimated fuel displacement, projected percent displaced fuel, and projected cost-savings are presented
in Section III.
This alternative would sustain the existing pattern of fuel use in firing the boilers at the WTP, and offer
no direct decrease in the costs of operating the WTP or in the cost to Hooper Bay households for
operating the WTP.
However, if the City, in conducting this feasibility study, facilitates the funding of additional wind
turbines at the AVEC power plant, it is assumed that AVEC would compensate the City in a way that
makes operation of the WTP more affordable.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 5
III. POWER AND ECONOMICS
A. Methods Quantifying Benefit
Since 2006, AVEC has been operating three wind turbines each in the communities of Kasigluk and
Toksook Bay. The electricity produced by these wind turbines has been effective at reducing the amount
of power required of the diesel-powered electrical generators, resulting in a corresponding decrease in
diesel consumption. Figure 1 shows the monthly wind energy production for both Kasigluk and Toksook
Bay, from July 2006 to November 2010. Figure 2 shows the monthly wind production figures over 2008-
2010, and the average between the two communities.
Figure 1 Wind kWh Production Averages 2006-2010
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
K
i
l
o
w
a
t
t
H
o
u
r
s
Kasigluk Net
Wind
Toksook Net
Wind
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 6
Figure 2 Monthly Average Wind Production 2008-2010
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
K
i
l
o
w
a
t
t
H
o
u
r
s
Kasigluk
Toksook Bay
Average
AVEC has been operating three Northwind 100 wind turbines in Hooper Bay since mid-2009, but
production only reached full capacity in 2010. Once the Hooper Bay wind production reached full
capacity in 2010, the kWh figures began to parallel those in Kasigluk and Toksook Bay, as shown on the
next page in Figure 3.
The original AVEC wind production data tables are presented in Appendix A, with kWh averages and
corrections to original AVEC data in Appendix B.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 7
Figure 3 2010 Wind and Diesel kWh Production
Since there are at least three years of uninterrupted production in Kasigluk and Toksook Bay, and the
one year of Hooper Bay data appear to match those in Kasigluk and Toksook Bay, it is the average of the
Kasigluk and Toksook Bay data that were used as the basis for estimating available wind resources per
month in Hooper Bay, as illustrated on the next page in Figure 4. Tables showing wind production,
calculations, and four minor adjustments to months with very low wind production due to maintenance
issues are all contained in Appendix B.
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
JanFeb MarAprMayJunJulAugSepOctNovDecKilowatt Hours (kWh)Month
Hooper Bay
Diesel
Hooper Bay
Wind
Toksook Bay
Diesel
Toksook Bay
Wind
Kasigluk
Diesel
Kasigluk
Wind
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 8
Figure 4 Hooper Bay Projected Monthly kWh Production, Per Turbine
17,227
23,285
24,451
21,883
14,768
11,873
14,252
10,311
11,947
15,096
13,540
23,555
0
5,000
10,000
15,000
20,000
25,000
30,000
Month
AEA has stated a preference for using HOMER wind energy data when evaluating wind projects. HOMER
is a computer model developed by the National Renewable Energy Laboratory (NREL), and is used to
predict energy production based on wind measurements alone. For this study, wind energy data are
based on real turbine outputs, rather than mathematical models like HOMER. AVEC production data
from Kasigluk and Toksook Bay appear to be the most realistic estimation of what the Northwind 100
model wind turbines can produce in these Bering Sea coast communities.
It should be noted that even though the wind data comes from wind turbines owned and operated by
B. Wind Energy and Fuel Displacement
Wind energy, measured in kWh, may be used to produce either electricity or heat. In comparing the
WTP and the AVEC options, the same quantity of wind energy will displace a different amount of fuel.
Two separate equations are used to determine the gallons of fuel displaced by wind at either facility.
At the WTP, wind kWh will be used to generate heat and offset fuel use by the oil-burning boilers. The
equation requires kWh be converted into BTUs with a 95% efficiency, and then into gallons of fuel
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 9
burned in the boilers using a boiler efficiency of 80%. is set up
as follows:
BTU/kWh, multiplied by 0.95 (heat produced by
electricity)
divided by 133,800 BTU/gal, divided by 0.80
(fuel to heat conversion)
power plant, the conversion of wind kWh to gallons of fuel offset is simpler:
kWh/gal (direct fuel-to-electric conversion)
for producing electricity
Since the wind energy figures are assumed to remain constant year-to-year, the quantity of fuel
displaced will remain unchanged from year to year for both options.
roducing
electricity), results in a direct, -to- comparison of wind energy benefit.
C. Cost of Fuel Displaced
The cost of fuel changes from year to year, both for AVEC and for the City.
contained in the annual reports published by the ower Cost Equalization (PCE)
Program, which also contains energy production and cost figures. -per-gallon is known for
the years 2002-2010, and was used to infer a trend by which costs are projected to increase in the
future. Table 3, on the next page, shows the known cost-per-gallon, and the projected cost through
2020 calculated using the statistical operation called . Also included in the table is the
percent increase expected from year-to-year.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 10
Table 3 AVEC Fuel Cost per Gallon
Year Known Cost Projected Cost Percent Increase
2002 $1.24
2003 $1.14
2004 $1.31
2005 $1.66
2006 $1.83
2007 $1.88
2008 $2.58
2009 $4.18
2010 $3.05
2011 $3.69 20.98%
2012 $4.01 8.64%
2013 $4.33 7.95%
2014 $4.65 7.36%
2015 $4.96 6.86%
2016 $5.28 6.42%
2017 $5.60 6.03%
2018 $5.92 5.69%
2019 $6.24 5.38%
2020 $6.56 5.11%
The City of Hooper Bay provided the cost-per-gallon paid for fuel used at the WTP from the years 2007-
2009. These figures were incomplete, with large gaps which made them unusable for describing future
trends. Because the AVEC data offered a more reliable estimate, the
fuel costs was used to estimate growth in the cost of fuel at the WTP. The rate of increase seen in Table
3 s used to predict the cost of heating oil used at the WTP for the years 2011
through 2020. See Table 1 for projected fuel costs at the WTP based on a 2010 cost of $3.13 per gallon.
The projected cost-per-gallon of fuel was then applied to the number of gallons displaced by either the
WTP or the AVEC option. Unlike the estimated displacement of gallons, the cost savings due to
increasing fuel costs show growth over time. Cost-savings for each option are shown in detail in the
results subsection below.
D. Results Comparing Benefits
AVEC produced wind power consistently in Kasigluk and Toksook Bay for thirty-six months in 2008, 2009,
and 2010 (see Figure 2). The monthly wind production ranged from 10,331 kWh in August to 24,451
kWh in March. The average monthly kWh figures for Kasigluk and Toksook Bay were used as the proxy
production estimates for Hooper Bay, which was shown to parallel production in the other two
communities. Projected monthly averages (per turbine) range from 10,311 kWh in August to 24,451
kWh in March, as shown in Figure 4 (page 8).
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 11
The production figures reflect the ongoing maintenance and idiosyncratic performance of the
Northwind 100 turbines in a real-life situation. AVEC data, for two communities over thirty-six
consecutive months from 2008-2010, shows a yearly average wind energy production output of 202,189
kWh per turbine.
Table 4 Monthly Wind Turbine Power Production Estimates (kWh)
Month One Two Three Four Five
January 17,227 34,454 51,681 68,908 86,135
February 23,285 46,571 69,856 93,141 116,426
March 24,451 48,902 73,352 97,803 122,254
April 21,883 43,767 65,650 87,534 109,417
May 14,768 29,536 44,305 59,073 73,841
June 11,873 23,746 35,619 47,492 59,365
July 14,252 28,505 42,757 57,009 71,261
August 10,311 20,622 30,934 41,245 51,556
September 11,947 23,894 35,841 47,788 59,735
October 15,096 30,191 45,287 60,383 75,478
November 13,540 27,081 40,621 54,161 67,702
December 23,555 47,110 70,665 94,220 117,775
Total Annual (kWh) 202,189 404,378 606,568 808,757 1,010,946
E. Fuel Displacement Calculations
The equations described in the Methods section (Section III) were used to produce estimated gallons of
fuel displaced by installing ONE SINGLE WIND TURBINE at both the WTP and the AVEC power plant, as
presented in Table 5 and Table 6, below.
Table 5 AVEC Electricity Production and Fuel Displacement
Annual Wind (kWh) Fuel Efficiency Fuel Offset (gal)
202,189 13.88 kWh/gal 14,567
equalsdivided by
Table 6 WTP Electricity and Heat Production and Fuel Displacement
Annual Wind (kWh) BTU/kWh Efficiency BTUs per Year
202,189 3,412 95% 655,375,425
Annual BTUs BTU/gal Efficiency Fuel Offset (gal)
655,375,425 133,800 80% 6,123
multiplied by
divided by
multiplied by
divided by
equals
equals
A bar chart illustrating the savings is shown on the next page in Figure 5.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 12
Figure 5 Annual Gallons Saved
F. Annual Cost Savings Calculations
The quantity of fuel displaced by supplementary wind energy at either option will not change
considerably from year to year, but the cost of the displaced fuel will increase.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 13
Table 7, on the next page, shows the projected cost of fuel, calculated using a trend of earlier fuel costs
described in the Methods section, as well as the total cost savings of installing one single wind turbine at
the AVEC plant. Table 8, also on the next page, shows the same projections (per turbine)
WTP.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 14
Table 7 AVEC Projected Cost Savings, Per Turbine
Year Cost per Gallon Annual Cost Savings
2011 $3.69 $53,752
2012 $4.01 $58,392
2013 $4.33 $63,036
2014 $4.65 $67,678
2015 $4.96 $72,320
2016 $5.28 $76,962
2017 $5.60 $81,604
2018 $5.92 $86,246
2019 $6.24 $90,888
2020 $6.56 $95,530
Ten-Year Total per Turbine $746,410
Table 8 WTP Projected Cost Savings, Per Turbine
Year Cost per Gallon Annual Cost Savings
2011 $3.79 $23,918
2012 $4.11 $25,983
2013 $4.44 $28,049
2014 $4.77 $30,114
2015 $5.09 $32,180
2016 $5.42 $34,245
2017 $5.75 $36,311
2018 $6.08 $38,376
2019 $6.40 $40,442
2020 $6.73 $42,507
Ten-Year Total per Turbine $332,124
Since the AVEC power plant uses more fuel than the WTP, viewing the amount of displaced fuel as a
annual fuel consumption
comparative contribution.
Table 9 shows the annual projected gallons consumed by facility, and the percent offset by a single wind
turbine. (Percent offset increases for each additional wind turbine by a factor of one.) See Appendix C
for annual PCE data (kWh), AVEC monthly data, kWh projections, and diesel consumption projections.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 15
Table 9 Projected Fuel Displacement per Turbine, as a Percentage of Facility Total Gallons
Year Gallons Required
(City)
Pct. Offset
(City)
Gallons Required
(AVEC)
Pct. Offset
(AVEC)
2011 37,500 16.8% 226,646 6.4%
2012 40,000 15.8% 234,634 6.2%
2013 42,500 14.9% 242,621 6.0%
2014 45,000 14.0% 250,608 5.8%
2015 47,500 13.3% 258,596 5.6%
2016 50,000 12.6% 266,583 5.5%
2017 52,500 12.0% 274,570 5.3%
2018 55,000 11.5% 282,558 5.2%
2019 57,500 11.0% 290,545 5.0%
2020 60,000 10.5% 298,532 4.9%
Cost savings for each facility can also be considered in terms of the total operating costs of the facility.
Both fuel- and non-fuel operating costs were obtained for the AVEC power plant (from PCE reports) and
the WTP (from City business records), and the displaced wind costs were divided by total operating
costs.
Table 10 Percentage of Total Cost Offset
Annual Fuel (gal) Fuel Cost/ Total Cost Fuel Offset (gal) Fuel Cost Offset Total Cost Offset
35,000 23.3% 6,123 17.5%4.1%
Annual Fuel (gal)* Fuel Cost/ Total Cost** Gal Fuel Offset Fuel Cost Offset* Total Cost Offset
262,589 38.8% 14,567 5.5%2.2%
City of Hooper Bay WTP (Heat)
AVEC Power Plant (Electricity)
*Projected
**PCE Data Average (2002-2010)
G. Additional Cost Considerations
In comparing the two options, it is of significance to note that AVEC already owns and operates the
control module which regulates the input of wind energy from its three Northwind 100 turbines into the
community electrical grid. The City does not own such a controller, which would be necessary in a
system where wind is directed into the WTP water heating system. AVEC reports that this type of
control module costs upwards of $1 million. Beyond that are the costs for training staff to operate and
maintain the module, costs that AVEC is already underwriting. The AVEC operator may be available to
ut the City would be required to pay AVEC for that service.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 16
IV. ADDITIONAL WIND CAPACITY ANALYSIS
As a
data from the wind turbines (in kWh) operating in nearby Kasigluk and Toksook Bay. In May 2011, CE2
and the City presented the results of this analysis to AEA, with the findings that two new wind turbines
would produce the most fuel and cost savings if used to offset electrical production at the AVEC power
plant. Precise
ut
expressed concern that the analysis was lacking because it did not use wind anemometer data modeled
by the HOMER computer software program. HOMER is the tool AEA prefers when considering the effect
of adding wind power to diesel-generated electricity systems like the AVEC plant in Hooper Bay. HOMER
uses fine-grained wind speed and community electric load data as basic input, along with other data.
The HOMER model then systematically calculates the amount of usable wind energy by subtracting the
wind ener
part of the CE2 analysis, which assumed that most if not all wind energy would be usable within the
AVEC electrical grid system.
The City of Hooper Bay contracted with V3 Energy, LLC in Eagle River, Alaska (V3 Energy) to perform the
HOMER analysis, calculate precisely the effect of integrating more wind energy at the AVEC power plant,
and compare that benefit with the benefit of integrating the same wind energy at t
Energy conducted the HOMER analysis and prepared their report in January 2012. Their report is
presented in Appendix D.
A. HOMER Model Analysis
V3 Energy obtained wind data recorded at the wind anemometer stations at three AVEC wind towers in
Hooper Bay. After reviewing the data, however, V3 recommended the data be dismissed because the
wind speeds appeared to be inaccurate
data. Instead, V3 obtained 10-minute time step power production data (in KWh) from AVEC in Hooper
Bay and converted those into wind speed data using the NW100A/20 power curve as a lookup table. The
wind speeds per 10-minute interval was the first data set input to HOMER. The average wind speed was
7.14 meters-per-second; the estimated monthly wind speeds are shown on the next page in Figure 6.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 17
Figure 6 Hooper Bay Average Monthly Wind Speed
-minute time step intervals,
for 2010. V3 calculated the load for each hour of the year, and used those data as the second input for
the HOMER model. Other data V3 used in the HOMER model include: information on the diesel
generators at AVEC, the thermal load for heating water at the WTP, the variable costs for installing wind
turbines at either of the locations, and the cost of fuel.
B. HOMER Model Analysis Results
A detailed description of the HOMER model results is presented in the V3 Energy report titled Hooper
Bay Additional Wind Capacity Analysis: Electric vs. Thermal (Appendix D).
The HOMER model calculated the amount of fuel displaced annually by one and two new windmills at
s, are
presented below in Table 11.
Table 11 HOMER Model Fuel Displacement Estimates
AVEC Power Plant City WTP
No. Turbines Gallons No. Turbines Gallons
1 15,922 1 10,941
2 30,562 2 21,881
Next, the fuel displacement figures produced by the HOMER model were used to estimate the total
annual cost savings at either site. For the estimate, V3 used high, medium, and low per-gallon fuel costs
listed in the report titled Alaska Fuel Price Projections 2011-2035, prepared by Institute of Social and
Economic Research (ISER) in their report to the Alaska Energy Authority, dated July 7, 2011.
0
1
2
3
4
5
6
7
8
9
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average Monthly Wind Speed in Meters/Second,
Hooper Bay
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 18
The annual cost savings for adding two windmills at either site are presented below in Table 12.
Table 12 HOMER Model Annual Estimated Cost Savings for Two Wind Turbines
AVEC Power Plant City WTP
Cost Per Gallon Annual Savings Cost per Gallon Annual Savings
$2.16 $66,014 $2.16 $47,263
$4.09 $124,999 $4.09 $89,493
$6.22 $190,096 $6.22 $136,100
C. HOMER Model Report Findings
The addition of two new Northwind 100B wind turbines in Hooper Bay would create savings, whether
installed as a source of supplemental electricity at AVEC power plant, or as a dedicated heat source at
reater for the AVEC option, however.
Annually, wind power at the AVEC power plant could potentially displace 30,562 gallons of diesel at a
the potential savings at the AVEC power plant.
The V3 Energy report also used estimated start-up capital costs and post-installation operating costs to
economic parameter
and how quickly.
With the high cost of the equipment and installation, V3 Energy found that two new windmills at Hooper
: 1) the windmills are
installed at the AVEC power plant, and 2) fuel prices average in the $6 per gallon range or higher. Table
13 below shows the benefit/cost ratios calculated by V3 Energy, with 1.0 being an equity between fuel
cost savings and initial startup cost.
Table 13 HOMER Model Benefit/Cost Ratio for Two Wind Turbines at Either Location
AVEC Power Plant City WTP
Cost Per Gallon Benefit/Cost Ratio Cost per Gallon Benefit/Cost Ratio
$6.22 1.020 $6.22 0.976
$4.09 0.987 $4.09 0.967
$2.16 0.939 $2.16 0.954
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 19
V. COMPARISON OF CE2 AND V3 ENERGY ANALYSES
Both CE2 and V3 Energy arrived at the same general conclusion: integrating additional wind turbines
into the Hooper Bay electrical system via the AVEC power plant is the best option for saving fuel and
money. Alternative One
due to the fact that fossil fuels are more efficiently converted to heat in the WTP boilers, and less
efficiently converted to electricity in the power plant. By that reasoning, any amount of wind energy
would accomplish more by assisting the process that is less efficient.
CE2 and V3 Energy used different original data sets and followed different analytical steps, but arrived at
a similar conclusion. For the wind res
data from wind turbines in Kasigluk and Toksook Bay, close to Hooper Bay. Monthly wind energy
estimates were then used to determine how much energy would be displaced at both the power plant
(straight kWh transfer without conversion) and at the WTP (converting first to BTUs). Those energy
displacement figures were then used to calculate fuel displacement (See Section III.B above).
V3 Energy also used electricity production data, but of a more fine-grained nature. V3 obtained
electricity production data from AVEC, recorded in 10-minute time step intervals, and then converted
those data to wind speed measurements. These wind speed data were entered into the HOMER
software to calculate energy production and fuel displacement figures. The HOMER analysis, with its
fine-
periods, creates a more complicated picture of hybrid wind-diesel systems like the one AVEC operates in
Hooper Bay.
A. AVEC Power Plant Fuel Displacement Estimates
CE2 concluded that two wind turbines at the AVEC power plant would displace 29,134 gallons of fuel,
while V3 Energy estimated the displacement at 30,562 gallons. The figures are depicted on the next
page in Figure 7.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 20
Figure 7 Annual Savings Comparison
100A model operating in Kasigluk and Toksook Bay. V3 Energy
analysis and use the power curve for a Northwind 100B model, the newer model whose power curve
reflects better performance during periods of high wind speed. This difference in power curves is one
important factor in explaining the CE2/V3 discrepancy with regard to the AVEC power plant. See page 8
of in Appendix D for more information on their wind turbine performance
comparison.
were made using the Northwind 100B power
curve, which has better performance than the model used in the CE2 wind-power production estimates.
Additionally, the mitigating factors operating within the HOMER analytical model effectively reduce the
impact of introducing wind energy into the AVEC electrical power system. For example, the HOMER
model subtracts the amount of usable wind energy
given time entially duplicated by the
CE2 analysis, which based wind energy production estimates on wind energy production reports (see
Section III.A).
B. City of Hooper Bay WTP Fuel Displacement Estimates
46 gallons, and V3 Energy estimated a
savings of 21,881 gallons.
into heat energy (in BTUs). Then, BTUs were converted into gallons diesel.
30,562
21,881
29,134
12,246
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
AVEC Plant City WTP
Gallons Saved Annually by TwoWindmills at AVEC and City:
V3 Energy and CE2 Comparison
V3
CE2
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 21
V3 Energy stimate was calculated by the HOMER model, and their analytical steps were not explicitly
behind the large discrepancy is unclear. Some explanation may be f
in V3 Energy D.
Although it would not seem to have any impact on the total energy displaced by wind at the WTP, both
CE2 and V3 Energy took additional steps to describe the annual energy requirements of the WTP. CE2
started with fuel consumption data from the WTP itself (see Table 1). V3 Energy began their analysis
with the amount of kW required by each of the components at the WTP (see Appendix D
annual energy consumption would only become relevant when used to show the displacement figure as
a percent of the total (see Table 10).
Part of the reason for the discrepancy may lie in the fact that V3 Energy used the Northwind 100B power
s wind energy information came from Northwind 100A models
used at Kasigluk and Toksook Bay. This may also explain why V3 Energy estimated significantly higher
C. Cost Savings Estimates
In estimating the future cost of fuel, CE2 consulted the State of Alaska PCE data for Hooper Bay and
studied the upward trend in fuel prices between 2002 and 2010. Then, using the least-square statistic,
a per-gallon cost for fuel was projected for each year between 2011 and 2020 (see Tables 7 and 8). The
price-per gallon estimates track fairly closely with the estimate used by V3 Energy, with an upper-range
cost savi
displaced, as explained in the previous section.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Page 22
VI. RECOMMENDED ALTERNATIVE
The feasibility study coordinated by the City of Hooper Bay involved two separate, independent
contracts with CE2 Engineers and V3 Energy. Both informed the City of Hooper Bay that more fuel and
more money would be saved if wind energy is incorporated into the AVEC power plant, rather than the
ent analytical methods, both the CE2 and the V3 Energy
estimates put the amount of AVEC power plant fuel savings at 30,000 gallons (Figure 7). AEA should
consider both the CE2 method and the V3 Energy method as valid when considering the effect of wind
energy at the power plant.
CE2 and V3 Energy
Energy Figure 7). While the reasons
for this discrepancy are not immediately clear, both analyses show unequivocally that using wind as a
dedicated source of heat energy at the WTP is not the preferred option when compared to adding more
wind turbines at the AVEC power plant.
After consulting with two different engineering firms, and reviewing two complete feasibility studies,
the City of Hooper Bay is satisfied with the conclusion of both studies: an AEA investment in two new
100kW wind turbines for the community of Hooper Bay would be most efficient, in terms of displacing
gallons of fossil fuel and offsetting fossil fuel costs, if those wind turbines are integrated into the existing
hybrid wind-WTP would result
in significantly less displacement of fuel and fuel cost, mainly because of the difference in thermal
efficiency of the two energy systems.
Furthermore, AVEC has an advantage in already owning and operating the power controller system that
links its existing three wind turbines to the community power grid; the City would have to include a
controller for wind energy at the WTP, which would require approximately $1 million in additional
capital costs.
It is recommended that AVEC work with the City to reduce the costs of operating the WTP, by providing
waste heat and discounted electricity from wind turbine load dumping to help make treated water more
affordable to the residents of Hooper Bay.
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Appendices
Appendices
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Appendix A
Appendix A
AVEC Wind Production Data
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Appendix B
Appendix B
Monthly Average Wind Production Forecast
AVERAGES BASED ON AVEC'S KASIGLUK AND TOKSOOK BAY WIND DATA
A B C D
Kasigluk Toksook Bay Average Average
Net Wind Net Wind KSB/TSB KSB/TSB
3 turbines 3 turbines 3 turbines 1 turbine
(A+B)/2 C/3
Jan-06 0 0 0 0
Feb-06 0 0 0 0
Mar-06 0 0 0 0
Apr-06 0 0 0 0
May-06 0 0 0 0
Jun-06 0 0 0 0
Jul-06 27,328 14,989 21,159 7,053
Aug-06 20,621 21,268 20,945 6,982
Sep-06 21,692 27,286 24,489 8,163
Oct-06 38,955 55,819 47,387 15,796
Nov-06 55,024 46,585 50,805 16,935
Dec-06 47,288 60,083 53,686 17,895
Jan-07 24,798 58,975 41,887 13,962
Feb-07 47,007 45,723 46,365 15,455
Mar-07 42,798 71,639 57,219 19,073
Apr-07 22,648 43,403 33,026 11,009
May-07 22,453 38,515 30,484 10,161
Jun-071 27,588 33,376 30,482 10,161
Jul-071 34,383 27,406 30,894 10,298
Aug-07 21,429 29,824 25,627 8,542
Sep-07 34,819 47,555 41,187 13,729
Oct-07 26,631 36,882 31,757 10,586
Nov-07 57,459 68,157 62,808 20,936
Dec-07 78,339 60,672 69,506 23,169
Jan-08 49,045 40,015 44,530 14,843
Feb-08 89,491 70,611 80,051 26,684
Mar-08 74,618 76,952 75,785 25,262
Apr-08 63,357 67,779 65,568 21,856
May-08 46,298 46,256 46,277 15,426
Jun-08 20,046 30,571 25,309 8,436
Jul-08 47,696 55,984 51,840 17,280
Aug-08 12,721 44,961 28,841 9,614
Sep-08 21,935 41,075 31,505 10,502
Oct-08 41,891 55,790 48,840 16,280
Nov-08 38,281 44,094 41,187 13,729
Dec-08 87,283 86,621 86,952 28,984
Jan-09 49,805 58,789 54,297 18,099
Feb-09 62,248 60,728 61,488 20,496
Mar-09 86,489 88,486 87,488 29,163
B-1
AVERAGES BASED ON AVEC'S KASIGLUK AND TOKSOOK BAY WIND DATA
A B C D
Kasigluk Toksook Bay Average Average
Net Wind Net Wind KSB/TSB KSB/TSB
3 turbines 3 turbines 3 turbines 1 turbine
(A+B)/2 C/3
Apr-09 73,488 86,536 80,012 26,671
May-09 45,156 47,593 46,375 15,458
Jun-09 35,507 49,862 42,685 14,228
Jul-09 46,919 53,679 50,299 16,766
Aug-09 41,649 32,514 37,082 12,361
Sep-09 12,113 28,929 20,521 6,840
Oct-091 55,131 20,000 37,566 12,522
Nov-091 49,304 35,000 42,152 14,051
Dec-09 63,897 55,468 59,683 19,894
Jan-10 94,702 48,536 71,619 23,873
Feb-10 47,215 41,355 44,285 14,762
Mar-10 53,063 66,354 59,709 19,903
Apr-10 34,462 49,678 42,070 14,023
May-10 27,963 46,062 37,013 12,338
Jun-10 28,800 49,766 39,283 13,094
Jul-10 22,294 23,463 22,879 7,626
Aug-10 41,751 31,463 36,607 12,202
Sep-10 55,082 69,243 62,163 20,721
Oct-10 35,495 43,828 39,662 13,221
Nov-10 43,786 41,552 42,669 14,223
Dec-10 66,758 86,935 76,847 25,616
Jan (avg)2 54,249 49,113 51,681 17,227
Feb (avg)2 82,147 57,565 69,856 23,285
Mar (avg)2 69,441 77,264 73,352 24,451
Apr (avg)2 63,303 67,998 65,650 21,883
May (avg)2 41,972 46,637 44,305 14,768
Jun (avg)2 27,839 43,400 35,619 11,873
Jul (avg)2 41,138 44,375 42,757 14,252
Aug (avg)2 25,555 36,313 30,934 10,311
Sep (avg)2 25,266 46,416 35,841 11,947
Oct (avg)2 50,701 39,873 45,287 15,096
Nov (avg)2 41,027 40,215 40,621 13,540
Dec (avg)2 64,989 76,341 70,665 23,555
Notes:
1 Months adjusted for low output due to maintenance (See Appendix A for actual output)
2 Based on average 2008, 2009, and 2010 AVEC production data
B-2
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Appendix C
Appendix C
Hooper Bay Electricity Production Projections
YearJanFebMarAprMayJunJulAugSepOctNovDecTotal2002230,455204,701224,696201,966177,975149,005158,185162,836176,260204,526211,955230,4522,333,0132003223,173198,233217,596195,584172,352144,297153,187157,691170,690198,064205,257223,1712,259,2962004227,789202,333222,096199,629175,916147,281156,355160,952174,221202,160209,502227,7862,306,0212005228,666203,113222,952200,398176,594147,849156,958161,573174,892202,939210,310228,6642,314,9072006249,643221,745243,404218,782192,794161,412171,356176,394190,935221,555229,602249,6402,527,2622007265,873236,161259,229233,005205,328171,905182,496187,862203,349235,959244,529265,8702,691,5672008274,450262,503262,231231,118208,943176,897199,535198,577205,621252,375251,535282,4222,806,2072009301,351267,961286,529258,366229,856188,658188,306201,242227,068253,800263,679290,3222,957,1382010302,299247,342308,435281,476239,851202,620214,685220,777239,602272,908293,277305,0693,128,3412011310,336271,549304,544274,645240,635201,450212,612219,541238,662274,992287,086309,7993,145,8512012321,210280,435315,515284,678249,215208,630219,999227,274247,225284,562297,400320,5733,256,7152013332,084289,320326,487294,710257,795215,811227,387235,006255,787294,131307,714331,3463,367,5802014342,958298,206337,459304,743266,375222,991234,774242,739264,350303,701318,028342,1193,478,4442015353,832307,092348,430314,776274,955230,172242,162250,471272,913313,271328,342352,8933,589,3092016364,706315,977359,402324,809283,535237,352249,549258,204281,475322,841338,656363,6663,700,1732017375,580324,863370,374334,842292,115244,533256,937265,937290,038332,411348,970374,4393,811,0382018386,454333,748381,345344,875300,695251,713264,324273,669298,601341,980359,284385,2133,921,9022019397,328342,634392,317354,908309,275258,894271,712281,402307,163351,550369,598395,9864,032,7672020408,202351,519403,289364,940317,855266,074279,099289,134315,726361,120379,912406,7594,143,631Annual kWh divided by monthly percent calculated in 2008-2010 AVEC dataMonthly data from AVECProjected trend figures using 2002-2010 dataHOOPER BAY COMMUNITY POWER REQUIREMENTS2002-2020 projected kWh by monthAppendix C
YearJanFebMarAprMayJunJulAugSepOctNovDecTotal200216,60314,74816,18814,55112,82210,73511,39711,73212,69914,73515,27116,603168,085200316,07914,28215,67714,09112,41710,39611,03711,36112,29814,27014,78816,079162,773200416,41114,57716,00114,38312,67410,61111,26511,59612,55214,56515,09416,411166,140200516,47514,63316,06314,43812,72310,65211,30811,64112,60014,62115,15216,474166,780200617,98615,97617,53615,76213,89011,62912,34612,70913,75615,96216,54217,986182,079200719,15517,01518,67616,78714,79312,38513,14813,53514,65017,00017,61719,155193,917200819,77318,91218,89316,65115,05412,74514,37614,30714,81418,18318,12220,347202,176200921,71119,30620,64318,61416,56013,59213,56714,49916,35918,28518,99720,917213,050201021,77917,82022,22220,27917,28014,59815,46715,90617,26219,66221,12921,979225,385201122,35919,56421,94119,78717,33714,51415,31815,81717,19519,81220,68322,320226,646201223,14220,20422,73220,51017,95515,03115,85016,37417,81220,50221,42723,096234,634201323,92520,84423,52221,23318,57315,54816,38216,93118,42821,19122,17023,872242,621201424,70921,48524,31321,95619,19116,06616,91517,48819,04521,88022,91324,648250,608201525,49222,12525,10322,67819,80916,58317,44718,04519,66222,57023,65625,425258,596201626,27622,76525,89423,40120,42817,10017,97918,60320,27923,25924,39926,201266,583201727,05923,40526,68424,12421,04617,61818,51119,16020,89623,94925,14226,977274,570201827,84324,04527,47424,84721,66418,13519,04419,71721,51324,63825,88527,753282,558201928,62624,68528,26525,57022,28218,65219,57620,27422,13025,32826,62828,529290,545202029,40925,32629,05526,29322,90019,17020,10820,83122,74726,01727,37129,305298,532Annual kWh divided by monthly percent calculated in 2008-2010 AVEC dataMonthly data from AVECProjected trend figures using 2002-2010 dataHOOPER BAY ELECTRICITY PRODUCTION DIESEL REQUIREMENTS(projected in gallons, no wind supplement)Appendix C
City of Hooper Bay Technical Memorandum
Water Treatment Plant Renewable Energy Resource Analysis
CE2 Engineers, Inc. Appendix D
Appendix D
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal
Hooper Bay Additional Wind Capacity
Analysis: Electric vs. Thermal
January 6, 2012
Douglas Vaught, P.E.
V3 Energy, LLC
Eagle River, Alaska
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | i
This report was prepared by V3 Energy, LLC under contract to City of Hooper Bay, via CE2 Engineers of
Anchorage, for a City of Hooper Bay project to assess the technical and economic feasibility of installing
two new Northwind 100 B model wind turbines in the existing three-turbine wind-diesel hybrid power
system in Hooper Bay. The intent of this analysis is to identify the most efficient and cost effective
configuration option, specifically whether the new turbines should be integrated into the existing
electrical system or operate stand-alone to service thermal loads.
Contents
Executive Summary.......................................................................................................................................1
Introduction..................................................................................................................................................2
Scope of Work...........................................................................................................................................2
Village of Hooper Bay................................................................................................................................2
Wind Resource Assessment..........................................................................................................................3
Hooper Bay Wind Resource......................................................................................................................3
Hooper Bay Wind Turbine Anemometers.............................................................................................3
Wind Turbine Power Output-derived Wind Speed...............................................................................4
Wind Direction..........................................................................................................................................5
Wind-Diesel System Design and Equipment.................................................................................................6
HOMER Modeling...........................................................................................................................................7
Diesel Power Plant....................................................................................................................................7
Wind Turbines...........................................................................................................................................7
Wind Turbine Performance Comparison..............................................................................................8
Electric Load..............................................................................................................................................8
Thermal Load ........................................................................................................................................9
Diesel Generators ...................................................................................................................................10
Economic Analysis.......................................................................................................................................11
Wind Turbine Costs.................................................................................................................................11
Fuel Cost..................................................................................................................................................11
HOMER Modeling Assumptions..............................................................................................................12
Wind Power Scenario Cost Assumptions................................................................................................13
Measured Electrical Load (7.32 MWh/d); Hooper Bay turbine output-derived wind (7.14 m/s average)
................................................................................................................................................................14
Medium Fuel Price Projection ($4.09/gal average)............................................................................14
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | ii
High Fuel Price Projection ($6.22/gal average)...................................................................................14
Low Fuel Price Projection ($2.16/gal average)...................................................................................15
2010 Fuel Price ($3.05/gal).................................................................................................................15
PCE (2010)-reported Electrical Load (8.43 MWh/d); measured wind in Chevak (7.38 m/s average)....16
Medium Fuel Price Projection ($4.09/gal average)............................................................................16
High Fuel Price Projection ($6.22/gal average)...................................................................................16
Low Fuel Price Projection ($2.16/gal average)...................................................................................17
2010 Fuel Price ($3.05/gal).................................................................................................................17
Conclusion and Recommendations ............................................................................................................18
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 1
Executive Summary
Hooper Bay has an outstanding Class 6 wind resource as evidenced by wind data collected in the nearby
village of Chevak and analysis of power output of the three existing Northwind 100 A model wind
turbines operating in the village. Given the robust wind resource and the relatively high electrical and
thermal loads in Hooper Bay, it was proposed to install two additional wind turbines (the upgraded
Northwind 100 B model) in one of two configurations: serving the electrical load in parallel operation
with the diesel generators and existing wind turbines with secondary service of thermal loads, or in a
stand-alone configuration serving only the thermal load.
Analysis suggests that although both configuration options are feasible, it is more economical over the
estimated twenty year life of the project for new wind turbines to primarily serve the electrical load vice
primarily serving thermal loads, but not significantly so. This can be understood by recognizing that
generation of electricity with diesel-powered generators is an inherently less efficient use of fuel than
burning the fuel in boilers to create heat. Hence, displacing use of the less efficient method of energy
conversion – operation of diesel generators to generate electricity – is preferable to displacing use of
fuel for the more efficient fuel oil boiler.
Given Hooper Bay’s coastal and relatively accessible location for fuel delivery, fuel prices in the
community are predicated to be moderately low compared to villages in the interior or further north, as
documented by University of Alaska Anchorage’s Institute of Social and Economic Research (ISER). For
this reason, fuel prices must be slightly higher than ISER’s medium fuel price projection for the more
efficient configuration of new wind turbines primarily serving the electrical load to return a benefit-to-
cost ratio greater than 1.0. Prices must be marginally higher yet for a configuration of new wind
turbines primarily serving thermal loads to return a benefit-to-cost ratio greater than 1.0.
Although not within the scope of this study, evaluation of new wind turbines in Hooper Bay could be
broadened to other models that are of similar output capacity as the Northwind 100 but lower cost,
such as the remanufactured asynchronous Vestas models. If so, improved project benefit-to-cost ratios
would result. Regardless of wind turbine, however, it will remain economically more advantageous to
primarily serve an electrical load, presuming sufficient load demand, and secondarily serve a thermal
load in lieu of primarily serving a thermal load only, all things being equal.
Project goals and client needs, however, may dictate equipment configurations that are not absolutely
optimal from a purely economic standpoint, such as the thermal load-only service configuration. In that
event, with fuel prices and other assumptions noted in this report, wind turbines with lower installed
costs could demonstrate improved economic benefits than modeled in this report.
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 2
Introduction
Alaska Village Electric Cooperative (AVEC) is the electric utility for the City of Hooper Bay. A few years
ago AVEC installed three Northwind 100 A model turbines with 20 meter diameter rotor blades.
Recently the City of Hooper Bay received a grant from the Alaska Energy Authority (AEA) to evaluate the
cost/benefit potential of installing two more Northwind 100 wind turbines (although the new turbines
would be B model with 21 meter rotors) in the community.
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 City of Hooper Bay, investigates and
evaluates options for installing two additional Northwind 100 wind turbines in Hooper Bay.
Configuration options are:
Connect the new wind turbines to the existing electrical system and operate in parallel with
the diesel generators and existing NW100A/20 turbines. Excess energy would service the
thermal loads.
Dedicate the new wind turbines to stand-alone use to service only thermal loads.
Village of Hooper Bay
Hooper Bay is located twenty miles south of Cape Romanzof and twenty-five miles south of Scammon
Bay in the Yukon-Kuskokwim Delta. The city is separated into two sections: a heavily built-up town site
located on gently rolling hills and a newer section in the lowlands. Hooper Bay is located 500 miles west
of Anchorage.
A federally-recognized tribe is located in the community – the Native Village of Hooper Bay. Hooper Bay
is a large traditional Yup'ik Eskimo community. Commercial fishing and subsistence activities are the
primary means of support. Members of the Village of Paimiut also live in Hooper Bay. The sale and
importation of alcohol is banned in the village by local option. A Youth and Elder Cultural Center was
completed during the summer of 2006.
The center provides an area for teaching
crafts, marketing, gatherings, and
language.
According to Census 2010, there are 283
housing units in the community and 256
are occupied. Hooper Bay’s population of
1,093 persons (2010 U.S. census) is 95
percent Alaska Native, 2 percent
Caucasian, and 3 percent multi-racial or
other.
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 3
Wind Resource Assessment
The wind resource in Hooper Bay is known to be very, very good for wind power development, as
evidenced by the successful operation of the three existing wind turbines in the village, but a wind
resource assessment with a meteorological test tower in Hooper Bay was never conducted. The existing
wind turbine project in Hooper Bay was designed and installed with reference to the measured wind
resource in Chevak, 22 miles to the east. Chevak has an outstanding (Class 6) wind resource and was
summarized as follows in the 2007 Chevak wind resource report:
Chevak met tower data synopsis
Wind power class Class 6 –Outstanding
Average wind speed (30 meters) 7.38 m/s
Maximum wind speed (10 min. average)30.3 m/s
Mean wind power density (50 meters) 661 W/m
2
Mean wind power density (30 meters)546 W/m2
Roughness Class 1.02 (fallow field)
Power law exponent 0.15 (low to moderate wind shear)
Data start date December 10, 2004
Most recent data date March 27, 2007
Hooper Bay Wind Resource
Because the Hooper Bay wind turbine site was never characterized with a proper wind resource analysis,
AEA requested that the wind resource at the site be evaluated with data collected from the existing
Hooper Bay wind turbines.
Hooper Bay Wind Turbine Anemometers
The initial effort had been to calculate mean annual wind speed with data collected from the turbine
control anemometers installed on each existing NW100 A model turbine. The anemometers are NRG
IceFree (heated) models and are mounted on the top aft portion of the turbine nacelles. Although
analysis of the data was very straightforward as no filtering was required, annual wind speeds at the
sensors were calculated at 8.7 m/s at wind turbine generator (WTG) 1 to over 9.0 m/s at WTG 3.
Through discussion with AEA representatives, these averages were thought unrealistically high and if
true, would indicate a Class 7 wind resource.
The likely reason for the speed error is that the NRG IceFree anemometers are sensitive to off-axis
airflow, which is likely with the sensors mounted on the back of the turbine nacelle. Air must flow
through the rotor disc and then up and over the rotor hub and front of the nacelle before impacting the
sensor. A second possible source of error is that for use in wind resource assessment, IceFree
anemometer transfer functions must be adjusted in order to read accurately. This requires reference to
a standard, non-heated anemometer, which was not available. For turbine operations, the inherent
errors of the IceFree anemometers are of little concern, but are significant if used uncorrected for wind
resource assessment.
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 4
Wind Turbine Power Output-derived Wind Speed
With use of the wind turbine anemometers to directly measure wind speed in Hooper Bay abandoned, it
was decided that it might be possible to instead derive wind speed from wind turbine power output
data. The theory is that power output from a turbine can be converted to wind speed at hub height by
correlating turbine output to wind speed with the turbine power curve. This was ultimately
accomplished by converting ten-minute time step power delivered data (in kWh) for each turbine to kW
output to obtain actual turbine power in the time step. By use of the NW100A/20 power curve as a
lookup table (in 0.5 m/s speed increments) in Microsoft Excel software, wind speed was derived.
Because the wind turbines are occasionally inoperative, out of service for maintenance, in start-up or
shut-down phase, or otherwise not generating power expected for the given wind speed, the turbine
power output-derived wind speed was filtered by comparing it to data from the turbine control
anemometer on WTG 1. If the values were within 2.5 m/s of each other, the turbine was considered to
be operating properly and the data was retained. Further filtering was accomplished to remove wind
speed data for time steps where all three turbines were non-operational. If at least one turbine was
operational in the time step, the derived wind speed average was retained. If two or three turbines
were operational, the data was retained and the values averaged.
A pivot table was employed to generate monthly wind speed averages from the combined turbine wind
speeds and compared to the WTG anemometer data and the Chevak met tower data as a method check.
With wind turbine output-derived wind speed data comparable to anemometer data from the Chevak
met tower, as indicated below, this method was deemed usable for this project.
It is entirely possible, however, that although reasonably accurate as a method to determine wind
speed, aspects of the methodology such as use of a lookup table to translate power to wind speed in 0.5
m/s increments resulted in a cumulative low bias. A low bias is conservative, which is desirable, in that
it under-predicts rather than over-predicts performance of new wind turbines and their economic
viability, but the bias is acknowledged nonetheless.
Wind speed table (comparison to Chevak met tower data)
Month
Hooper Bay
WTG 1
anemometer,
m/s
Hooper Bay
WTG 1, 2, 3-
pwr output
derived speed,
30 m hub ht.,
m/s
Chevak, 30 m A
anem., m/s
1 10.93 8.46 9.09
2 9.82 7.67 9.25
3 8.78 7.60 8.61
4 9.12 6.68 8.52
5 7.70 6.86 6.56
6 8.04 6.75 5.85
7 7.62 6.37 5.49
8 8.02 6.58 5.87
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 5
9 9.08 6.85 6.94
10 7.92 6.75 6.31
11 8.18 7.07 7.35
12 9.56 8.05 8.77
Annual 8.73 7.14 7.38
Hooper Bay wind speed profile from WTG data
Wind Direction
Although not absolutely relevant at this stage of the project, Chevak wind frequency rose data indicates
prevailing winds from north to northeast with easterly, southeasterly and westerly winds to a lesser
extent. The power density rose (representing the power in the wind) indicates power winds are
primarily north-northeasterly and southeasterly with some easterly winds.
Wind frequency rose Total energy (power density) rose
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 6
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. 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. At present,
Hooper Bay operates at medium wind power penetration. This is a good compromise between of
displaced fuel usage and relatively minimal system complexity and is AVEC’s preferred system
configuration. Installation of two additional Northwind 100 wind turbines would maintain the medium
penetration level.
Categoriesofwind-dieselpenetrationlevels
Penetration PenetrationLevel Operatingcharacteristics and system requirements
Instantaneous Average
Low 0% to 50% Less than
20%
Diesel generator(s)run full time at greater than minimum
loading level. Requiresminimalchangesto existingdiesel
controlsystem. All wind energy generatedsupplies 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 electricboiler
augmenting a generator heat recovery loop. At high wind
power levels, secondary (thermal) loads are dispatchedto
absorb energynot 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 sophisticatednew
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.
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 7
HOMER Modeling
HOMER energy modeling software was used to analyze the Hooper Bay 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.
Diesel Power Plant
Electric power (comprised of the diesel power plant and the electric power distribution system) in
Hooper Bay is provided by AVEC. The existing power plant in Hooper Bay consists of two Caterpillar
diesel generators, a model 3412 rated at 350 kW output and a model 3456 rated at 505 kW output, and
two Cummins diesel generators, a model KTA 2300 rated at 557 kW output and a model KTA 38 rated at
824 kW output.
Hooper Bay powerplantdiesel generators
Generator Electrical Capacity Diesel Engine Model
1 350 kW Caterpillar 3412
2 505 kW Caterpillar 3456
3 557 kW Cummins KTA 2300
4 824 kW Cummins KTA 38
Wind Turbines
At present, three Northwind 100 A model wind turbines equipped with 20 meter diameter rotors (19
meter rotor design with blade extenders) are operational in Hooper Bay. The proposal is to install two
more Northwind turbines, although the new ones would be B model which are equipped with 21 meter
blades. Besides the larger rotor size, which is reflected in an improved power curve with the B model
turbine, another difference is hub height. The existing turbines are at a 30 meter hub height while the B
model turbines are installed with a standard 37 meter hub height.
The Northwind 100 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 (B model), is rated at 100 kW power output, and is available on a
37 meter tubular steel tower. The NW100B/21 is fully arctic-climate certified to -40° C.
The NW100 A and B model wind turbines are the most widely represented village-scale wind turbines 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/. Power curves
are shown below.
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 8
NW100A/20 power curve NW100B/21 power curve
Wind Turbine Performance Comparison
The following table presents an analysis of turbine output and capacity factor performance of the
NW100A/20 and NW100B/21 wind turbines, with comparisons at 100%, 95% and 85% turbine
availability (percent of time that the turbine is on-line and available for energy production). Both
turbine models perform very well in the Hooper Bay wind regime with excellent capacity factors and
annual energy production.
Hooper Bay turbine capacity factor comparison
100% availability 95% availability 85% availability
Turbine Model
Rated
Output
(kW)
Hub
Height
(m)
Annual
Energy
(MWh)
Capacity
Factor
(%)
Annual
Energy
(MWh)
Capacity
Factor
(%)
Annual
Energy
(MWh)
Capacity
Factor
(%)
NW 100A/20 100 30 262.3 29.1 249.2 27.6 223.0 24.7
NW 100B/21 100 37 328.5 37.5 312.1 35.6 279.2 31.9
Electric Load
Hooper Bay 2010 load data, collected from December 26, 2009 to December 29, 2010, was received
from Mr. Bill Thompson of AVEC. These data are in 15 minute increments and represent total electric
load demand during each time step. The data were processed by adjusting the date/time stamps nine
hours from GMT to Yukon/Alaska time, multiplying each value by four to translate kWh to kW (similar to
processing of the wind turbine data), and creating a January 1 to December 31 hourly list for export to
HOMER software. The resulting load is shown graphically below. Average load is 305 kW with a 584 kW
peak load and an average daily load demand of 7,321 kWh. Interestingly, however, AVEC reported to
the Alaska RCA an average daily total load demand of 8,434 kWh for the 2010 power cost equalization
program with an average 7,530 kWh sold on a daily basis (representing 89 percent of energy generated).
This latter value compares closely with the AVEC load data received from Mr. Thompson. Although not
investigated, it is possible that the AVEC load collection data represents only electricity sold, with non-
sellable station and other load not included. For the HOMER model, the 7,321 kWh/day result is
evaluated, but the load was scaled to 8,434 kWh/day as documented in the 2010 PCE report and is also
considered.
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 9
Thermal Load
The thermal load demand in Hooper Bay is not well quantified, but reportedly varies between 50 kW to
880 kW. Thermal demand is comprised of three loads in separate locations, with priority in the
following order:
1. Washeteria hydronic system for dryers and sauna, with glycol temperature of 200° F
2. Water plant hydronic system with glycol temperatures of 180° F
3. Water storage tank(s)
The thermal load is a primary focus of this paper’s analysis as the option with the planned two new
NW100B/21 wind turbines is to serve the electrical load first and divert excess power to thermal loads,
or configure the new wind turbines to serve the thermal load only. For either configuration scenario, it
is not especially important in this analysis to accurately quantify each thermal load individually. Rather,
they can be evaluated as a group with a presumption that the power system controls will divert excess
power to whichever thermal load demands it. For the water storage tank(s), thermal demand can be
considered essentially limitless, although a question arises regarding at what point continued energy
input to the storage tank(s) is superfluous and no longer necessary to maintain minimum water
temperature.
Because the thermal loads are not quantified individually or in aggregate, a constant 400 kW load was
assumed at all times. It is recognized that this assumption is not accurate, but it is a reasonable average
of the identified thermal load range in Hooper Bay and reflective of the nearly infinite thermal sink of
the water storage tank(s), at least with respect to the potential energy input of the existing and planned
new wind turbine capacity.
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 10
Diesel Generators
The HOMER model was constructed with all four Hooper Bay generators. For cost modeling purposes,
AEA assumes a generator O&M cost of $0.020/kWh. For HOMER modeling purposes, this was converted
to $7.00/operating hour for each diesel generator (based on Hooper Bay’s modeled average electrical
load of 305 kW).
It was desired in the HOMER model to use manufacturer fuel curves for the diesel generators, but this
proved especially difficult given the age of the generators and non-availability of accurate fuel curves for
each engine. Instead, generic fuel curves were derived such that HOMER, with the existing equipment
configuration scenario of the diesel generators and three NW100A/20 wind turbines, modeled fuel
usage and efficiency that matched AVEC-reported fuel use and efficiency in AEA’s 2010 Statistical Report
of the Power Cost Equalization Program (at the higher load of 8,434 Kwh/day as reported in the PCE
Report).
Diesel generator HOMER modeling information
Diesel generator Caterpillar
3412
Caterpillar
3456
Cummins
KTA 2300
Cummins
KTA 38
Power output (kW)350 505 557 824
Intercept coeff.
(L/hr/kW rated)
0.030 0.030 0.030 0.030
Slope (L/hr/kW
output)
0.240 0.240 0.240 0.240
Minimum electric
load (%)
14.2%
(50 kW)
9.9%
(50 kW)
9.0%
(50 kW)
6.0%
(50 kW)
Heat recovery ratio (%
of waste heat that can
serve the thermal
load)
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
Fuel efficiency curve
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 11
Economic Analysis
Installation of up to two Northwind 100B/21 wind turbines in medium penetration mode are evaluated
in this report to demonstrate the economic impact of these turbines in two configuration modes:
1. Connected to the electrical distribution system with first priority to serve the electrical load, and
second priority to serve the thermal load via the existing secondary load controller and electric
boiler (an SLC and boiler were installed previously to support the existing three NW100A/20
turbines)
2. Dedicated to thermal loads only with electric boiler(s)
Wind Turbine Costs
Capital and installation costs of wind turbines are difficult to estimate without detailed consideration of
shipping fees, foundation design, cost efficiencies with installation of multiple turbines, identification of
constructor, mobilization fees, etc. Because this information is not yet known or estimated, an installed
cost of $1.0 million for new NW100B/21 turbine and $1.9 million for two NW100B/21 turbines is
assumed. This cost is in-line with other rural Alaska wind projects of the past few years where NW100
wind turbines have been installed. It is assumed that turbine construction would occur in 2013 with
operational start in 2014.
Fuel Cost
A fuel price of $4.09/gallon ($1.08/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 $4.09/gallon price reflects the average value of
all fuel prices between the 2014 (assumed project start year) fuel price of $3.46/gallon and the 2033 (20
year project end year) fuel price of $4.54/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 2014 to 2033 three-year
moving average price is $6.22/gallon ($1.64/Liter). For the low price projection, the average 2014 to
2033 three-year moving average price is $2.16/gallon ($0.57/Liter). Note also that heating fuel in
HOMER is priced the same as diesel fuel.
For comparison, the 2010 fuel price reported to AEA for the 2010 PCE report is $3.05/gallon
($0.81/Liter).
Fuel cost table
Cost Scenario
2014
(/gal)
2033
(/gal)
Average
(/gallon)
Average
(/Liter)
Low $2.48 $2.03 $2.16 $0.57
Medium $3.46 $4.54 $4.09 $1.08
High $4.71 $7.09 $6.22 $1.64
2010 fuel price $3.05 $0.81
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 12
HOMER Modeling Assumptions
HOMER 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 defaults. Other assumptions, such
as diesel overhaul cost and time between overhaul are based on general rural Alaska power generation
experience.
Basic modeling assumptions
Economic Assumptions
Project life 20 years
Discount rate 3%
System fixed O&M cost $600,000/year
Operating Reserves
Load in current time step 10%
Wind power output 50%
Fuel Properties (both types)
Heating value 42.5 MJ/kg (18,300 BTU/lb.)
Density 820 kg/m3 (6.85 lb./gal)
Diesel Generators
Generator capital cost $0 (gensets already exist)
O&M cost $7.00/hour (at $0.02/kWh)
Time between overhauls 15,000 hours (run time)
Overhaul cost (all diesel gensets
except Cummins KTA 38)
$75,000
Overhaul cost (Cummins KTA 38) $100,000
Minimum load 50 kW; based on AVEC’s
operational experience of 50 kW
minimum diesel loading with their
wind-diesel systems
Schedule Optimized
Wind Turbines
Availability 100%
O&M cost per NW100A and B
model turbine
$0.0469/kWh (translated to
$10,700/year based on 26%
turbine CF)
Wind speed 7.14 m/s (calculated from Hooper
Bay turbine output; also 7.38 m/s
(measured in nearby Chevak)
Energy Loads
Electric 7.32 MWh/day measured in
Hooper Bay; also scaled to 8.43
MWh/day (in 2010 PCE report)
Thermal 400 kW constant
Boiler Efficiencies
Electric 0.98
Fuel oil 0.80
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 13
Wind Power Scenario Cost Assumptions
The base or comparison scenario is the existing Hooper Bay powerplant with its present configuration of
diesel generators and three NW100A/20 wind turbines operating in parallel with the diesels. Also
assumed in the base or comparison scenario is that excess wind turbine energy supplements the
thermal load via a secondary load controller and electric boiler connected to the diesel generator heat
recovery loop.
As stated previously, two new turbine configurations are considered: NW100B/21 turbines connected
to the electrical distribution system primarily serving the electric load and serving the thermal load in a
secondary capacity, and the new turbines serving only the thermal loads. The economic analysis is
presented as a benefit-to-cost (B/C) ratio with the base or comparison scenario defined as B/C equals
unity (or 1.0).
For the economic evaluations, two (of four possible) major divisions of modeled information are
presented: directly measured electric load and NW100A/20 wind turbine output-derived wind speed
(most conservative), and electric load reported to AEA per the 2010 PCE report and the slightly higher
wind resource measured in Chevak (least conservative). Within these two divisions, four fuel cost
options are presented: ISER’s medium, high, and low projected fuel costs averaged over a 20 year time
period from 2014 to 2033, plus the 2010 fuel cost AVEC reported to AEA and listed in the 2010 PCE
report.
Note that economic performance of new wind turbines dedicated to only the thermal load was
evaluated partially outside of the HOMER model. This is because HOMER is not designed to consider
wind turbines operating independently of an electrical load. For this configuration, NW100B/21 wind
turbine output in kWh/year calculated by HOMER software was converted to fuel oil equivalent by unit
conversion and assumptions of 80 percent fuel oil boiler efficiency and 98 percent electric boiler
efficiency. The resulting conversion ratio is 0.0333 gallons fuel oil per kWh wind turbine energy supplied
to an electric boiler serving only a thermal load.
Hooper Bay Additional Wind Capacity Analysis: Electric vs. Thermal P a g e | 18
Conclusion and Recommendations
For all cost options in the preceding tables, whether considering one or two new NW100B/21 turbines,
it is more economically advantageous to configure the turbines to primarily serve the electrical load,
with secondary service of the thermal load. In brief, this can be understood as a consequence of the
superior efficiency of transferring energy directly from a wind turbine to a thermal load versus burning
fossil fuel to create electrical energy in a diesel generator. Because wind turbines connected to the
electrical grid will offset fuel burned in the diesel generators before directly serving the thermal load, it
is preferable to avoid duel usage in the diesel generators as a first priority.
Also one should note that a project benefit-to-cost ratio greater than 1.0, with modeling assumptions
noted in this report, occurs only with NW100B/21 wind turbines connected to the electrical grid at
ISER’s high fuel price projection, although at ISER’s medium fuel price projection the benefit-to-cost
ratios very nearly match the base or existing configuration option. Another way to understand this is
shown below. For a primary load of 7.32 MWh/day and essentially independent of wind speed or wind
turbine availability (the y-axis of the graph), an average fuel price of $1.22/Liter ($4.62/gallon) or higher
over the 20 year period of 2014 to 2033 is required for one new NW100B/21 wind turbine to be more
economical than the existing power system configuration of diesel engines and three NW100A wind
turbines, and a fuel price of $1.50/Liter ($5.68/gallon) or higher is required for two NW100B/21 wind
turbines to be more economical than the existing power system configuration. Although not shown, this
evaluation is essentially unchanged if one considers a higher electrical load of 8.43 MWh/day.
It should be noted that the economic evaluation of this project, for either scenario, would improve if
wind turbine capital costs were lower. The assumption of $1.0 million for installation of one new
NW100B/21 wind turbine and $1.9 million for two NW100B/21 wind turbines may seem high, but in
reality it is perhaps somewhat optimistic. Other wind turbines with lower capital costs could be
considered in order to improve benefit-to-cost ratios.