HomeMy WebLinkAboutFeasibility Assessment Aniak and Kalskag High schools Biomass Heating CoffmanEngineers LeeBolling FinalReport 07-28-2017-BIO
Feasibility Assessment for Biomass Heating Systems
Aniak & Kalskag High Schools
800 F Street, Anchorage, AK 99501
p (907) 276-6664 f (907) 276-5042
Lee Bolling, PE
FINAL REPORT – 7/28/2017
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. i
Contents
I. Executive Summary ............................................................................................................ 1
II. Introduction ...................................................................................................................... 2
III. Preliminary Site Investigation ........................................................................................... 3
COMMUNITY MEETING ................................................................................................................................................... 3
BUILDING DESCRIPTIONS ................................................................................................................................................. 3
EXISTING HEATING SYSTEM .............................................................................................................................................. 3
DOMESTIC HOT WATER................................................................................................................................................... 4
AIR HANDLING SYSTEM ................................................................................................................................................... 5
BUILDING ENVELOPE ....................................................................................................................................................... 5
AVAILABLE SPACE, STREET ACCESS, FUEL STORAGE AND SITE CONSTRAINTS .............................................................................. 5
BIOMASS SYSTEM OPTIONS .............................................................................................................................................. 9
BIOMASS SYSTEM INTEGRATION ........................................................................................................................................ 9
IV. Energy Consumption and Costs ....................................................................................... 10
ENERGY COSTS ............................................................................................................................................................ 10
WOOD ENERGY ........................................................................................................................................................... 10
CORDWOOD ................................................................................................................................................................ 10
WOOD PELLETS AND CHIPS ............................................................................................................................................ 11
HEATING OIL ............................................................................................................................................................... 11
ELECTRICITY ................................................................................................................................................................ 11
EXISTING FUEL OIL CONSUMPTION .................................................................................................................................. 12
BIOMASS SYSTEM CONSUMPTION ................................................................................................................................... 12
V. Preliminary Cost Estimating ............................................................................................. 13
VI. Economic Analysis .......................................................................................................... 15
O&M COSTS .............................................................................................................................................................. 15
DEFINITIONS................................................................................................................................................................ 15
RESULTS ..................................................................................................................................................................... 17
SENSITIVITY ANALYSIS ................................................................................................................................................... 18
VII. Forest Resource and Fuel Availability Assessments ........................................................ 19
FUEL AVAILABILITY ....................................................................................................................................................... 19
AIR QUALITY PERMITTING .............................................................................................................................................. 19
VIII. General Biomass Technology Information ..................................................................... 20
HEATING WITH WOOD FUEL ........................................................................................................................................... 20
TYPES OF WOOD FUEL .................................................................................................................................................. 20
HIGH EFFICIENCY WOOD PELLET BOILERS ......................................................................................................................... 21
HIGH EFFICIENCY CORDWOOD BOILERS ............................................................................................................................ 21
LOW EFFICIENCY CORDWOOD BOILERS ............................................................................................................................. 21
HIGH EFFICIENCY WOOD STOVES .................................................................................................................................... 22
BULK FUEL BOILERS ...................................................................................................................................................... 22
GRANTS ..................................................................................................................................................................... 22
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. ii
Appendices
Appendix A – Site Photos
Appendix B – Economic Analysis Spreadsheets
Appendix C – AWEDTG Field Data Sheets
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. iii
Abbreviations
ACF Accumulated Cash Flow
ASHRAE American Society of Heating, Refrigerating, and Air-Conditioning Engineers
AEA Alaska Energy Authority
AFUE Annual Fuel Utilization Efficiency
B/C Benefit / Cost Ratio
BTU British Thermal Unit
BTUH BTU per hour
CCF One Hundred Cubic Feet
CEI Coffman Engineers, Inc.
CFM Cubic Feet per Minute
Eff Efficiency
F Fahrenheit
ft Feet
GPM Gallons Per Minute
HP Horsepower
HVAC Heating, Ventilating, and Air-Conditioning
in Inch(es)
kWh Kilowatt-Hour
lb(s) Pound(s)
MBH Thousand BTUs per Hour
O&M Operations and Maintenance
MMBTU One Million BTUs
PC Project Cost
R R-Value
SF Square Feet, Supply Fan
TEMP Temperature
V Volts
W Watts
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. iv
List of Figures
Figure 1 – Aniak High School ......................................................................................................................... 2
Figure 2 – Kalskag High School ...................................................................................................................... 2
Figure 3 – Aniak High School Site Layout ...................................................................................................... 6
Figure 4 – Kalskag High School Site Layout ................................................................................................... 8
Figure 5 – Garn WHS-3200 Wood Boiler ....................................................................................................... 9
List of Tables
Table 1 – Executive Summary ....................................................................................................................... 1
Table 2 – Energy Comparison ....................................................................................................................... 1
Table 3 – Energy Comparison ..................................................................................................................... 10
Table 4 – Existing Fuel Oil Consumption ..................................................................................................... 12
Table 5 – Proposed Biomass System Fuel Consumption ............................................................................ 12
Table 6 – Estimate of Probable Cost ........................................................................................................... 14
Table 7 – Discount and Escalation rates ..................................................................................................... 15
Table 8 – Economic Definitions ................................................................................................................... 16
Table 9 – Economic Analysis Results ........................................................................................................... 17
Table 10 – Sensitivity Analysis – Aniak High School .................................................................................... 18
Table 11 – Sensitivity Analysis – Kalskag High School ................................................................................. 18
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. 1
I. Executive Summary
Coffman performed a preliminary biomass feasibility assessment for the Kuspuk School District to
determine the technical and economic viability of biomass heating systems at Aniak High School in Aniak,
Alaska and the George Morgan Sr. High School in Kalskag, Alaska. The study evaluated Garn style
cordwood boiler systems that would supply the majority of heat to the schools.
The proposed wood boilers would be located in detached modules and heating pipes would connect to a
new heat exchanger in the school’s mechanical room. The existing heating oil boiler would still
supplement heat in the schools during colder days during the heating season.
Due to the low price of heating oil at $2.60/gal, the benefit to cost ratios for each high school is less than
1.0 and therefore the cordwood boiler systems at the schools are not economically justified at this time.
However, the price of heating oil has varied greatly over the past couple of years and as heating oil prices
rise the projects can become economically viable. When heating oil reaches $3.25/gal the cordwood
boiler projects at both high schools become economically justified.
The summary of the results of the economic evaluation are shown in the table below.
Table 1 – Executive Summary
Item Aniak High School Kalskag High School
Project Capital Cost ($459,000) ($457,000)
Present Value of Project Benefits (20-year life) $762,233 $731,744
Present Value of Operating Costs (20-year life) ($411,735) ($417,549)
Benefit / Cost Ratio of Project (20-year life) 0.76 0.69
Net Present Value (20-year life) ($108,502) ($142,806)
Year Cash Flow is Net Positive First Year First Year
Payback Period (Year Accumulated Cash Flow > Project
Capital Cost) > 20 years >20 years
The energy prices in Aniak and Kalskag are shown in the following table. Wood pellets are less expensive
than heating oil and electricity on an energy basis.
Table 2 – Energy Comparison
Community Fuel Type Units Gross
BTU/unit
System
Efficiency $/unit Delivered
$/MMBTU
Aniak
Cordwood cord 17,000,000 80% $250 $18.38
Heating Oil gal 134,000 65% $2.60 $29.85
Electricity kWh 3,413 99% $0.55 $162.78
Kalskag
Cordwood cord 17,000,000 80% $250 $18.38
Heating Oil gal 134,000 70% $2.60 $27.72
Electricity kWh 3,413 99% $0.55 $162.78
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
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II. Introduction
A preliminary feasibility assessment was completed to determine the technical and economic viability of
biomass heating systems for the Aniak High School in Aniak, Alaska and the George Morgan Sr. High School
in Kalskag, Alaska. For this study, the George Morgan Sr. High School is referred to as the Kalskag High
School.
Figure 1 – Aniak High School
Figure 2 – Kalskag High School
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. 3
III. Preliminary Site Investigation
Coffman completed site visits to Aniak and Kalskag on May 16th and 17th, 2017.
Community Meeting
Coffman attended community meetings in both Aniak and Kalskag to discuss biomass heating systems
with community members. Coffman presented the different types of biomass heating systems and talked
about what opportunities are present in the communities.
Building Descriptions
Aniak
Aniak High School is a 21,400 square foot building built in the 1980’s. The school is used during the typical
school schedule and has a gym that is used by the community. Approximately 60 students attend the
school from grades 7 to 12. There have been no energy audits of the school. Most of the school has been
upgraded to T-8 lighting for energy efficiency upgrades.
Kalskag
The George Morgan Sr High School is located between the communities of Upper Kalskag and Lower
Kalskag, near the south side of the airport. The school is 19,500 square feet and was built in 2011, because
the old school burned down in 2009. The school is used during the typical school schedule and has a gym
that is used by the community. There are 55 students that attend the school in grades 7 through 12. The
school is new with a modern design. There has been no energy audit of the building.
Existing Heating System
Aniak
Aniak High School is heated by a Burnham oil fired boiler (620 MBH gross output, Model PF-504) that
serves perimeter baseboard via a glycol loop in the all the school, except the gym. A Flexaire oil fired
furnace (500 MBH gross output, Model SDF-50) provides heat for the gym. The furnace appears to be
original and the age of the boiler is unknown. Both are in adequate condition and no major maintenance
issues were reported.
Thermostats in the perimeter rooms and the gym control the heating units. There is no centralized control
system.
The boiler, furnace and central pumps are located in the boiler room, which is located on a mezzanine
room near the gym. The boiler runs in a primary arrangement, with the main pumps pumping glycol
through the baseboards and boiler. The combustion efficiency of the boiler and furnace is unknown, as
there were no combustion tests available. Due to the age and condition of the oil boiler and oil furnace
it is estimated that the Annual Fuel Utilization Efficiency is 65% to account for typical oil unit inefficiencies,
including short cycling.
A 1,000-gallon aboveground fuel tank is provided at the facility and provides oil for the emergency
generator as well. The fuel tank is filled by three 8,000 gal tanks located by the Voc Ed Building.
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
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Kalskag
Kalskag High School is heated by two Burnham oil-fired boilers (1281 MBH gross output, Model V1107).
The boilers are located in the main mechanical room located in a detached building. The shop classroom
is also in this detached building. The boilers are piped in a primary/secondary configuration and deliver
glycol to baseboard, cabinet unit heaters and air handler heating coils. The boilers were manufactured in
2010 and they are operating in adequate condition. The combustion efficiency of the oil boilers is
unknown, as there were no combustion tests available. For this study, the Annual Fuel Utilization
Efficiency is estimated at 70% to account for typical oil boiler inefficiencies, including short cycling.
A central DDC system and Heat Timer Boiler Controller control the boilers, pumps and air handling
systems. During the site visit the DDC computer could not be logged into. There were Heat Timer Boiler
Controller setpoints found that could be updated for more efficient operation. It appears that the
mechanical systems were never fully commissioned since the school was built in 2011. It is recommended
that the school be commissioned in order to ensure efficient operations.
The following items were found during the site visit that could be changed during commissioning of the
system:
1. The Heat Timer boiler controller is still in Winter Mode during the May site visit. Turning to
summer mode will reduce heating oil consumption.
2. There is currently no Outdoor Air Temp Reset on the boilers. The boilers are currently running at
185F supply water temp even when the outside air temperature is 63F. Enabling an Outdoor Air
Temp Reset will reduce heating oil consumption.
3. Consider reducing outdoor temp cutoff for the boiler (it is currently set at 70F).
4. UH-4 zone valve is broken.
5. CP-1A and 1B are constantly running in Hand mode.
6. CP-2B is constantly running in Hand mode. CP-2A is out of service for maintenance.
7. AHU-2 zone valve is disconnected, allowing hot glycol to run wild through the heating coil.
8. AHU-1 and AHU-2 are not used. It was reported that they may have never been programmed
properly.
There is one 4,000 gal and two 12,000 gal aboveground fuel tanks that provide fuel to the boilers, bus,
school trucks and teacher housing (located at a different location).
Domestic Hot Water
Aniak
Domestic hot water is provided by a Bock oil fired water heater (50 gal capacity). Hot water is used for
lavatories, kitchen, showers, and laundry. The water heater is also located in the mezzanine by the gym
with the boiler and furnace.
Kalskag
Domestic hot water is provided by a Boilermate, indirect hot water heater (119 gal) that is heated by a
loop from the boiler. The water heater is located in the same mechanical room as the boilers.
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
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Air Handling System
Aniak
Aniak High School does not have a building wide air handling system. Fresh air is supplied by operable
windows. The furnace has an outdoor air supply duct for supplying fresh air to the gym.
Kalskag
Two air handling units supply are located in a second floor mechanical near the gym. AHU-1 serves the
gym and AHU-2 serves the rest of the building. It was reported that the air handling units are typically not
used, except for during basketball games in the gym.
Building Envelope
Aniak
As-Built drawings of the school were not available and so the actual construction details of the school are
not known. The school has wood frame walls and a built-up roof. Insulation thicknesses could not be
verified during the site visit. The school has double pane windows and an artic entry at the main entry.
Kalskag
Kalskag High School is a new building that is built with a modern energy efficient building envelope. As-
built drawings of the school were not provided and so the wall and roof construction and insulation values
could not be verified. The school is on a pile foundation and the building envelope appears to be in good
condition. Windows are double pane. There are arctic entries at multiple entrances.
Available Space, Street Access, Fuel Storage and Site Constraints
Aniak
There is no available space inside the school for a new biomass boiler system. A new detached wood boiler
module is proposed. There are many site constraints around the school that limit the available space for
a new module. The south side of the school is the main entry and fields. To the east of the school is the
Voc Ed building, which was used as an old military satellite site that has environmental contamination of
the soils. There is currently an effort to remediate PCB contamination at the Voc Ed building site that is
beginning summer of 2017. The west side of the school is heavily wooded with no road access.
The only available area left for a wood boiler module is on the back, north side of the school. There
already exists a gravel access way on the northeast side of the school that is used to access the fuel tank
at the bank of the school. A new gravel pad is required to make space for a wood boiler module and a
wood storage shed.
It was reported that the Aniak airport will be expanded in the next three to four years, which will demolish
the Voc Ed Building.
A site layout of Aniak High School is shown in the following figure.
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. 6
Figure 3 – Aniak High School Site Layout
ANIAK
HIGHSCHOOL
VOC ED
BUILDING
TANK FARM
MAIN ENTRY
AND FIELDS
BACK UP
GENERATOR
PCB CLEAN UP AREA
PROPOSED WOOD
BOILER MODULE
PROPOSED
WOOD STORAGE
NEW GRAVEL PAD
SECOND FLOOR
MECH ROOM
ACCESS WAY TO
BACK OF SCHOOL
FUEL TANK
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. 7
Kalskag
There is no available space in Kalskag High School for a new wood boiler system. A detached wood boiler
module is proposed. The most practical location for the proposed wood boiler module and wood storage
shed is on a new gravel pad to the north of the school’s mechanical room. This will allow easy access from
the existing gravel road and have a short piping run from the module to the school’s existing boilers.
There is limited space elsewhere around the school for the module. The west side of the school has the
septic system and poor road access. The east side of the school is the main entry and parking lot. The
south side of the school is an empty lot that may be used as a playground in the future. The north west
of the school has fuel tanks, storage and the backup generator.
There is a bus barn building located to the west of the school. Heating records were not provided and the
heating system could not be accessed during the site visit. It has a below ground fuel tank and above
ground fuel tank. From the outside appears to be a typical metal warehouse type building. The bus barn
could be connected to the proposed wood boiler module with buried insulated pipe. However, the
economics of doing so are unknown at this time.
A site layout of Kalskag High School is shown in the following figure.
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. 8
Figure 4 – Kalskag High School Site Layout
GEORGE MORGAN SR
HIGHSCHOOL, KALSKAG
MAIN ENTRY AND
PARKING
SEPTIC SYSTEM
BUS BARN
MECH ROOM IN
DETACHED BUILDING
FIRE SUPRESSION
MODULES
SHOP CLASSROOM IN
DETACHED BUILDING
PROPOSED WOOD
BOILER MODULE
PROPOSED WOOD
STORAGE
NEW GRAVEL PAD
FUEL TANKS
BACK UP
GENERATOR
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. 9
Biomass System Options
Cordwood is the only biomass heating fuel that is readily available in both Aniak and Kalskag and so a
cordwood boiler system was selected as the preferred option for both schools. A Garn WHS-3200 wood
boiler selected as the basis of design.
Figure 5 – Garn WHS-3200 Wood Boiler
The Garn WHS-3200 wood boiler has a 3,200-gallon water tank and is 7’4” wide x 7’8” high x 12’ long. The
Garn boiler would be housed in an 8’ wide x 20’ long insulated module that can be fabricated offsite and
shipped to the schools for installation. The module would contain the Garn boiler, circulation pumps, heat
exchanger, piping, electrical wiring, instrumentation and control panel. The manufacture stated
combustion efficiency of the Garn boiler is 85%. For this study, the Annual Fuel Utilization Efficiency for
the Garn boiler is estimated at 80%, to account for heat loss in the system.
The Garn boiler would deliver heat to a heat exchanger inside the module, which would transfer heat to
a buried insulated piping loop system with 50% propylene glycol. This loop would deliver heat through a
direct buried, insulated arctic pipe to a new heat exchanger in the school.
Biomass System Integration
Integration for both Aniak and Kalskag High Schools will be very similar. The new heat exchanger in the
school will receive heat from the wood boiler module and connect to the return side of the existing oil
boiler heating glycol return loop. By tying into the oil boiler return line, the wood boiler will be able
minimize the firing of the oil boilers. In the event that the wood boiler cannot meet the heat demand of
the building, the existing oil boilers will fire to provide the supplemental heat required. It is recommended
that an aggressive outside temperature reset schedule on the oil boilers is used in order to maximize the
utilization of the wood boiler.
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
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IV. Energy Consumption and Costs
Energy Costs
The table below shows the energy comparison of different fuel types at the schools. The system efficiency
is used to calculate the delivered MMBTU’s of energy to the building. The delivered cost of energy to the
building, in $/MMBTU, is the most accurate way to compare costs of different energy types. As shown
below, cordwood is cheaper than fuel oil on a $/MMBTU basis in both Aniak and Kalskag.
Table 3 – Energy Comparison
Community Fuel Type Units Gross
BTU/unit
System
Efficiency $/unit Delivered
$/MMBTU
Aniak
Cordwood cord 17,000,000 80% $250 $18.38
Heating Oil gal 134,000 65% $2.60 $29.85
Electricity kWh 3,413 99% $0.55 $162.78
Kalskag
Cordwood cord 17,000,000 80% $250 $18.38
Heating Oil gal 134,000 70% $2.60 $27.72
Electricity kWh 3,413 99% $0.55 $162.78
Wood Energy
The gross energy content of a cord of wood varies depending on tree species and moisture content. Black
spruce, white spruce and birch at 20% moisture content have respective gross energy contents of 15.9
MMBTU/Cord, 18.1 MMBTU/cord and 23.6 MMBTU/cord, according to the UAF Cooperative Extension.
Wet or greenwood has higher moisture contents and require additional heat to evaporate moisture
before the wood can burn. Thus, wood with higher moisture contents will have lower energy contents.
Seasoned or dry wood will typically have 20% moisture content.
In Aniak and Kalskag, spruce is the primary wood species according to the local harvester. For this study,
cordwood was estimated to have 17.0 MMBTU/cord, which is a conservative estimate because the
moisture content of the wood may vary.
Cordwood
The primary source of cordwood is the Native Village of Napaimute, which has a timber harvest located
3 miles downriver from Lower Kalskag. It is a 400 acre, 10-year lease from the Kuskokwim Corporation
and there are approximately 7,000 to 8,000 cords on the lease. According to the timber harvest
manager, most of the wood harvested is white spruce with some minor birch when it can be found. A
mechanized harvester and firewood processer are used to harvest the wood and the operation
employees people from Kalskag and the surrounding communities. The cordwood can be either barged
on the river or shipped on the winter ice road to either Aniak or Kalskag. According to the timber
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. 11
harvest manager, Napaimute could sell cordwood to Aniak and Kalskag High School for between $250 to
$300 per cord. For this study $250/cord delivered to the schools was used.
Wood Pellets and Chips
There is no local wood pellet manufacturer or distributor in region, which means that wood pellets would
have to be barged into the community. Therefore, wood pellet costs would be high and not a viable
biomass source. There is also no wood chip manufacturer in the region. However, the Napaimute timber
harvest operation is considering making chips in the future. But they do not have the machinery to make
chips at this time. Due to these factors, wood pellets and wood chips were not selected as viable biomass
fuel sources.
Heating Oil
The high price of fuel oil is the main economic driver for the use of lower cost biomass heating. Fuel oil is
purchased in bulk by the school district and shipped into Aniak and Kalskag by barge. The current cost of
bulk fuel oil is $2.60/gal. For this study, the energy content of fuel oil is based on 134,000 BTU/gal,
according to “Heating Values of Fuels” by the UAF Cooperative Extension, 2009.
Electricity
Electricity for Aniak and Kalskag is provided by the Alaska Village Electric Cooperative (AVEC). According
to the utility data provided by the school district, both schools have an electricity rate of $0.55/kWh.
Heating with electricity is the most expensive energy source on a BTU basis.
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Existing Fuel Oil Consumption
An estimate of the schools’ heating oil consumption was made based on annual heating oil data provided
by the school district from 2016. Actual heating oil bills were not provided for the study.
Table 4 – Existing Fuel Oil Consumption
Building Fuel Type Annual Consumption Net MMBTU/yr Avg. Annual
Cost
Aniak High School Heating Oil #1 12,500 gal 1,088.8 $32,500
Kalskag High School Heating Oil #1 12,000 gal 1,125.6 $31,200
Biomass System Consumption
It is estimated that the proposed biomass systems will offset approximately 90% of the heating energy for
both Aniak High School and Kalskag High School. The remaining 10% of the heating energy at will be
provided by the school’s existing oil boilers. This result is based on an analysis of the school’s annual
heating oil consumption, the heat output of the Garn boiler and BIN weather data for the area. It is
assumed that the Garn WHS-3200 is loaded every 9 to 12 hours, which will produce 150,000 BTU/hr to
200,000 BTU/hr with a 125F minimum supply water temperature, per manufacturer documentation.
More frequent loading is possible, which will increase BTU output and allow additional heating oil offset
during colder times of the year. The annual energy consumption and energy savings of the projects are
shown in the following table.
Table 5 – Proposed Biomass System Fuel Consumption
Building Fuel Type % Heating
Source
Net
MMBTU/yr
Annual
Consumption
Energy
Cost
Total
Energy
Cost
Annual
Energy
Savings
Aniak
High
School
Cordwood 90% 979.9 72 cords $18,012
$21,400 $11,100 Fuel Oil 10% 108.9 1,250 gal $3,250
Additional
Electricity N/A N/A 250 kWh $138
Kalskag
High
School
Cordwood 90% 1013.0 74 cords $18,622
$21,880 $9,320 Fuel Oil 10% 112.6 1,200 gal $3,120
Additional
Electricity N/A N/A 250 kWh $138
Note – Based on wood pellets at $250/ton, heating oil at $2.60/gal and electricity at $0.55/kWh.
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
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V. Preliminary Cost Estimating
An estimate of probable costs was completed for installing the Garn boiler system at each school. The
cost estimate is based equipment quotes and from previous projects in Alaska. A 15% remote factor was
used to account for increased shipping and installation costs to the communities. Project and
Construction Management was estimated at 5%. Engineering design and permitting was estimated at
15% and a 20% contingency was used.
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
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Table 6 – Estimate of Probable Cost
Aniak Kalskag
Category Description Cost Cost
Site Work Site Grading for Module $4,500 $4,000
Gravel Fill $4,000 $3,500
Foundation (Timbers and Anchors) $5,000 $5,000
Buried Utilities $4,500 $4,500
Subtotal $18,000 $17,000
Electrical Utilities Service Entrance $4,000 $4,000
Conduit and Wiring $4,000 $4,000
Subtotal $8,000 $8,000
Wood Boiler Module Insulated Module 8 ft x 20 ft $15,000 $15,000
Garn Boiler WHS 3200 $45,000 $45,000
Heat Exchanger $7,000 $7,000
Installation, Piping & Materials $70,000 $70,000
Fire Allowance $10,000 $10,000
Controls Allowance $10,000 $10,000
Electrical Allowance $10,000
$10,000
$10,000
$10,000
Shipping $10,000
$10,000 Installing Module Onsite
Subtotal $187,000 $187,000
Wood Storage Building 3-Sided Storage Shed Allowance $30,000 $30,000
School Connection Heat Exchanger $7,000 $7,000
Insulated Piping from Module $10,000 $10,000
Boiler Room Modifications $15,000 $15,000
Subtotal $32,000 $32,000
Subtotal Material and
Installation Cost $275,000 $274,000
Remote Factor 15% $41,250 $41,100
Subtotal $316,250 $315,100
Project and Construction
Management
5%
$15,813 $15,755
Subtotal $332,063 $330,855
Design Fees and Permitting 15% $49,809 $49,628
Subtotal $381,872 $380,483
Contingency 20% $76,374 $76,097
Total Project Cost $458,246 $456,580
Total Budgetary Cost $459,000 $457,000
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc. 15
VI. Economic Analysis
The following assumptions were used to complete the economic analysis for this study.
Table 7 – Discount and Escalation rates
Real Discount Rate for Net Present Value Analysis 3%
Wood Fuel Escalation Rate 2%
Fossil Fuel Escalation Rate 5%
Electricity Escalation Rate 3%
O&M Escalation Rate 2%
The real discount rate, or minimum attractive rate of return, is 3.0% and is the current rate used for all
Life Cycle Cost Analysis by the Alaska Department of Education and Early Development. This is a typical
rate used for completing economic analysis for public entities in Alaska. The escalation rates used for the
wood, heating oil, electricity and O&M rates are based on rates used in previous Alaska Energy Authority
funded biomass pre-feasibility studies. The wood fuel escalation rate was set at 2% because it is estimated
that wood prices will rise slower than electricity prices.
A net present value analysis was completed using real dollars (constant dollars) and the real discount rate,
as required per the Alaska Department of Education and Early Development Life Cycle Cost Analysis
Handbook.
O&M Costs
Non-fuel related operations and maintenance costs (O&M) were estimated at $700 per year. The
estimate is based on annual maintenance time for the Garn boiler. For only the first two years of service,
the maintenance cost is doubled to account for maintenance staff getting used to operating the new
system. Labor costs for daily stoking of the boiler are not included, as this is typically completed by a
maintenance person who is already hired by the organization that utilizes the boiler and stoking the boiler
would become part of their daily duties.
Definitions
There are many different economic terms used in this study. A listing of all the terms with their definition
is provided below for reference.
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Table 8 – Economic Definitions
Economic Term Description
Project Capital Cost This is the opinion of probable cost for designing and constructing the
project.
Present Value of
Project Benefits
(20-year life)
The present value of all of the heating oil that would have been consumed
by the existing heating oil-fired heating system, over a 20-year period.
Present Value of
Operating Costs
(20-year life)
The present value of all of the proposed biomass systems operating costs
over a 20-year period. This includes wood fuel, additional electricity, and
O&M costs for the proposed biomass system and the heating oil required by
the existing equipment to supply the remaining amount of heat to the
building.
Benefit / Cost Ratio of
Project
(20-year life)
This is the benefit to cost ratio over the 20-year period. A project that has a
benefit to cost ratio greater than 1.0 is economically justified. It is defined
as follows:
𝐵𝑐𝑛𝑐𝑐𝑖𝑟 / 𝐵𝑛𝑟𝑟 𝑅𝑎𝑟𝑖𝑛= 𝑂𝑉(𝑂𝑟𝑛𝑖𝑐𝑐𝑟 𝐵𝑐𝑛𝑐𝑐𝑖𝑟𝑟)− 𝑂𝑉(𝑂𝑛𝑐𝑟𝑎𝑟𝑖𝑛𝑐 𝐵𝑛𝑟𝑟𝑟)
𝑂𝑟𝑛𝑖𝑐𝑐𝑟 𝐵𝑎𝑛𝑖𝑟𝑎𝑙 𝐵𝑛𝑟𝑟
Where:
PV = The present value over the 20-year period
Reference Sullivan, Wicks and Koelling, “Engineering Economy”, 14th ed.,
2009, pg. 440, Modified B-C Ratio.
Net Present Value
(20-year life)
This is the net present value of the project over a 20-year period. If the
project has a net present value greater than zero, the project is economically
justified. This quantity accounts for the project capital cost, project benefits
and operating costs.
Payback Period (Year
Accumulated Cash Flow
> Project Capital Cost)
The Payback Period is the number of years it takes for the accumulated cash
flow of the project to be greater than or equal to the project capital cost.
This quantity includes escalating energy prices and O&M rates. This quantity
is calculated as follows:
𝐼𝑛𝑟𝑟𝑎𝑙𝑙𝑐𝑐 𝐵𝑛𝑟𝑟≤∑𝑅𝑘
𝐽
𝑘=0
Where:
J = Year that the accumulated cash flow is greater than or equal to the
Project Capital Cost.
𝑅𝑘 = Project Cash flow for the kth year.
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Results
An economic analysis was completed in order to determine the simple payback, benefit to cost ratio, and
net present value of the proposed Garn cordwood boiler systems at the high schools. At each school, a
Garn boiler would be located in a detached module and heating pipes would connect to a new heat
exchanger in the school’s mechanical room. The cordwood boiler would supplement heat for the existing
oil boiler system. The cost of a cordwood storage shed at the schools was included in this analysis.
Due to the low price of heating oil, the benefit to cost ratios for each high school is less than 1.0. Any
project with a benefit to cost ratio less than 1.0 is not considered economically justified, and therefore
the cordwood boiler systems at the schools in not economically justified at this time.
However, historically the price of heating oil has varied greatly over time and as heating oil prices rise the
projects can become economically viable. When heating oil reaches $3.25/gal the cordwood boiler
projects at both Aniak and Kalskag High Schools become economically justified. This can be seen in the
sensitivity analysis on the following page. Three years ago, heating oil prices in the communities were
much higher than $3.25/gal.
A benefit of the cordwood projects is that it creates a local economy of wood use. Instead of money from
heating oil sales leaving the community, the money is used to buy cordwood that is harvested by local
labor. This creates local jobs and keeps money in the community.
The Alaska Energy Authority is now using a 25-year life span for the Garn Boiler for the Renewable Energy
Fund applications. This means that the Garn will have five years of additional benefits after the 20-year
study period.
The results are shown in the table below. Refer to Appendix B for the economic analysis spreadsheets for
greater detail. (Note: Values shown in red and parenthesis are negative numbers)
Table 9 – Economic Analysis Results
Item Aniak High School Kalskag High School
Project Capital Cost ($459,000) ($457,000)
Present Value of Project Benefits (20-year life) $762,233 $731,744
Present Value of Operating Costs (20-year life) ($411,735) ($417,549)
Benefit / Cost Ratio of Project (20-year life) 0.76 0.69
Net Present Value (20-year life) ($108,502) ($142,806)
Year Cash Flow is Net Positive First Year First Year
Payback Period (Year Accumulated Cash Flow > Project
Capital Cost) > 20 years >20 years
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Sensitivity Analysis
A sensitivity analysis was completed to show how changing heating oil costs and wood costs affect the
benefit to cost (B/C) ratios of the project. As heating oil costs increase and wood costs decrease, the
project becomes more economically viable. The B/C ratios greater than 1.0 are economically justified and
are highlighted in green. B/C ratios less than 1.0 are not economically justified and are highlighted in
orange.
For example, at a heating oil price of $3.25/gal and the current cordwood price of $250/cord, the
cordwood boiler project at both Aniak and Kalskag High Schools are economically justified.
Table 10 – Sensitivity Analysis – Aniak High School
B/C Ratios Cordwood Cost
$200/cord $225/cord $250/cord $275/cord $300/cord $325/cord
Heating
Oil Cost
$2.50/gal 0.85 0.78 0.71 0.64 0.57 0.50
$2.75/gal 0.99 0.92 0.85 0.78 0.71 0.64
$3.00/gal 1.13 1.06 0.99 0.92 0.85 0.78
$3.25/gal 1.28 1.21 1.14 1.07 1.00 0.93
$3.50/gal 1.42 1.35 1.28 1.21 1.14 1.07
$3.75/gal 1.56 1.49 1.42 1.36 1.29 1.22
$4.00/gal 1.71 1.64 1.57 1.50 1.43 1.36
$4.25/gal 1.85 1.78 1.71 1.64 1.57 1.50
$4.50/gal 1.99 1.93 1.86 1.79 1.72 1.65
$4.75/gal 2.14 2.07 2.00 1.93 1.86 1.79
$5.00/gal 2.28 2.21 2.14 2.07 2.00 1.93
$5.25/gal 2.43 2.36 2.29 2.22 2.15 2.08
Table 11 – Sensitivity Analysis – Kalskag High School
B/C Ratios Cordwood Cost
$200/cord $225/cord $250/cord $275/cord $300/cord $325/cord
Heating
Oil Cost
$2.50/gal 0.78 0.70 0.63 0.56 0.49 0.42
$2.75/gal 0.91 0.84 0.77 0.70 0.63 0.56
$3.00/gal 1.05 0.98 0.91 0.84 0.77 0.69
$3.25/gal 1.19 1.12 1.05 0.98 0.90 0.83
$3.50/gal 1.33 1.26 1.19 1.11 1.04 0.97
$3.75/gal 1.47 1.40 1.32 1.25 1.18 1.11
$4.00/gal 1.61 1.54 1.46 1.39 1.32 1.25
$4.25/gal 1.75 1.67 1.60 1.53 1.46 1.39
$4.50/gal 1.88 1.81 1.74 1.67 1.60 1.53
$4.75/gal 2.02 1.95 1.88 1.81 1.74 1.66
$5.00/gal 2.16 2.09 2.02 1.95 1.87 1.80
$5.25/gal 2.30 2.23 2.16 2.08 2.01 1.94
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VII. Forest Resource and Fuel Availability Assessments
Fuel Availability
For this study, the primary source of cordwood is the Napaimute timber harvest operation, described in
the Cordwood section of the report. According to the operations manager, there is a large burn area
across from Aniak that would be another source of cordwood. The Kuskokwim Corporation is the main
land owner in the area and all wood harvesting on their land will require permits. There is also state land
in the area, but there is limited access to it. No other Forest Resource assessments were located during
this study.
Air Quality Permitting
Currently, air quality permitting is regulated according to the Alaska Department of Environmental
Conservation Section 18 AAC 50 Air Quality Control regulations. Per these regulations, a minor air quality
permit is required if a new wood boiler or wood stove produces one of the following conditions per
Section 18 AAC 50.502 (C)(1): 40 tons per year (TPY) of carbon dioxide (CO2), 15 TPY of particulate matter
greater than 10 microns (PM-10), 40 TPY of sulfur dioxide, 0.6 TPY of lead, 100 TPY of carbon monoxide
within 10 kilometers of a carbon monoxide nonattainment area, or 10 TPY of direct PM -2.5 emissions.
These regulations assume that the device will operate 24 hours per day, 365 days per year and that no
fuel burning equipment is used. If a new wood boiler or wood stove is installed in addition to a fuel
burning heating device, the increase in air pollutants cannot exceed the following per AAC 50.502 (C)(3):
10 TPY of PM-10, 10 TPY of sulfur dioxide, 10 TPY of nitrogen oxides, 100 TPY of carbon monoxide within
10 kilometers of a carbon monoxide nonattainment area, or 10 TPY of direct PM-2.5 emissions. Per the
Wood-fired Heating Device Visible Emission Standards (Section 18 AAC 50.075), a person may not operate
a wood-fired heating device in a manner that causes black smoke or visible emissions that exceed 50
percent opacity for more than 15 minutes in any hour in an area where an air quality advisory is in effect.
From Coffman’s discussions with Patrick Dunn at the Alaska Department of Environmental Conservation,
these regulations are focused on permitting industrial applications of wood burning equipment. In his
opinion, it would be unlikely that an individual wood boiler would require an air quality permit unless
several boilers were to be installed and operated at the same site. If several boilers were installed and
operated together, the emissions produced could be greater than 40 tons of CO2 per year. This would
require permitting per AAC 50.502 (C)(1) or (C)(3). Permitting would not be required on the residential
wood fired stoves unless they violated the Wood-fired Heating Device Visible Emission Standards (Section
18 AAC 50.075). Recent similarly sized Garn wood fired boiler systems installed in Alaska have not
required air quality permits.
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VIII. General Biomass Technology Information
Heating with Wood Fuel
Wood fuels are among the most cost-effective and reliable sources of heating fuel for communities
adjacent to forestland when the wood fuels are processed, handled, and combusted appropriately.
Compared to other heating energy fuels, such as oil and propane, wood fuels typically have lower energy
density and higher associated transportation and handling costs. Due to this low bulk density, wood fuels
have a shorter viable haul distance when compared to fossil fuels. This short haul distance also creates an
advantage for local communities to utilize locally-sourced wood fuels, while simultaneously retaining local
energy dollars.
Most communities in rural Alaska are particularly vulnerable to high energy prices due to the large number
of heating degree days and expensive shipping costs. For many communities, wood-fueled heating can
lower fuel costs. For example, cordwood sourced at $250 per cord is just 25% of the cost per MMBTU as
#1 fuel oil sourced at $7 per gallon. In addition to the financial savings, the local communities also benefit
from the multiplier effect of circulating energy dollars within the community longer, more stable energy
prices, job creation, and more active forest management.
The local cordwood market is influenced by land ownership, existing forest management and ecological
conditions, local demand and supply, and the State of Alaska Energy Assistance program.
Types of Wood Fuel
Wood fuels are specified by energy density, moisture content, ash content, and granulometry. Each of
these characteristics affects the wood fuel’s handling characteristics, storage requirements, and
combustion process. Higher quality fuels have lower moisture, ash, dirt, and rock contents, consistent
granulometry, and higher energy density. Different types of fuel quality can be used in wood heating
projects as long as the infrastructure specifications match the fuel content characteristics. Typically, lower
quality fuel will be the lowest cost fuel, but it will require more expensive storage, handling, and
combustion infrastructure, as well as additional maintenance.
Projects in rural Alaska must be designed around the availability of wood fuels. Some fuels can be
harvested and manufactured on site, such as cordwood, woodchips, and briquettes. Wood pellets can
also be used, but typically require a larger scale pellet manufacturer to make them. The economic
feasibility of manufacturing on site is determined by a financial assessment of the project. Typically, larger
projects offer more flexibility in terms of owning and operating the wood harvesting and manufacturing
equipment, such as a wood chipper, splitter, or equipment to haul wood out of forest, than smaller
projects.
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High Efficiency Wood Pellet Boilers
High efficiency pellet boilers are designed to burn wood pellets cleanly and efficiently. These boilers utilize
pellet storage bins or silos that hold a large percentage of the building’s annual pellet supply. Augers or
vacuums transfer pellets from the silos to a pellet hopper adjacent to the pellet boiler, where pellets can
be fed into the boiler for burning. Pellets are automatically loaded into the pellet boiler and do not require
manual loading such as in a Garn cordwood boiler. The pellet boilers typically have a 3 to 1 turn down
ratio, which allows the firing rate to modulate from 100% down to 33% fire. This allows the boiler to
properly match building heat demand, increasing boiler efficiency. The efficiencies of these boilers can
range from 85% to 92% efficiency depending on firing rate.
High Efficiency Cordwood Boilers
High Efficiency Low Emission (HELE) cordwood boilers are designed to burn cordwood fuel cleanly and
efficiently. The boilers use cordwood that is typically seasoned to 25% moisture content (MC) or less and
meet the dimensions required for loading and firing. The amount of cordwood burned by the boiler will
depend on the heat load profile of the building and the utilization of the fuel oil system as back up. Two
HELE cordwood boiler suppliers include Garn (www.garn.com) and TarmUSA (www.woodboilers.com).
Both of these suppliers have units operating in Alaska. TarmUSA has a number of residential units
operating in Alaska and has models that range between 100,000 to 300,000 BTU/hr. Garn boilers,
manufactured by Dectra Corporation, are used in Tanana, Kasilof, Dot Lake, Thorne Bay, Coffman Cove
and other locations to heat homes, washaterias, schools, and community buildings.
The Garn boiler has a unique construction, which is basically a wood boiler housed in a large water tank.
Garn boilers come in several sizes and are appropriate for facilities using 100,000 to 1,000,000 BTUs per
hour. The jacket of water surrounding the fire box absorbs heat and is piped into buildings via a heat
exchanger, and then transferred to an existing building heating system, in-floor radiant tubing, unit
heaters, or baseboard heaters. In installations where the Garn boiler is in a detached building, there are
additional heat exchangers, pumps and a glycol circulation loop that are necessary to transfer heat to the
building while allowing for freeze protection. Radiant floor heating is the most efficient heating method
when using wood boilers such as Garns, because they can operate using lower supply water temperatures
compared to baseboards.
Garn boilers are approximately 87% efficient and store a large quantity of water. For example, the Garn
WHS-2000 holds approximately 1,825 gallons of heated water. Garns also produce virtually no smoke
when at full burn, because of a primary and secondary gasification (2,000 ºF) burning process. Garns are
manually stocked with cordwood and can be loaded multiple times a day during periods of high heating
demand. Garns are simple to operate with only three moving parts: a handle, door and blower. Garns
produce very little ash and require minimal maintenance. Removing ash and inspecting fans are typical
maintenance requirements. Fans are used to produce a draft that increases combustion temperatures
and boiler efficiency. In cold climates, Garns can be equipped with exterior insulated storage tanks for
extra hot water circulating capacity. Most facilities using cordwood boilers keep existing oil-fired systems
operational to provide heating backup during biomass boiler downtimes and to provide additional heat
for peak heating demand periods.
Low Efficiency Cordwood Boilers
Outdoor boilers are categorized as low-efficiency, high emission (LEHE) systems. These boiler systems are
not recommended as they produce significant emission issues and do not combust wood fuels efficiently
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or completely, resulting in significant energy waste and pollution. These systems require significantly
more wood to be purchased, handled and combusted to heat a facility as compared to a HELE system.
Additionally, several states have placed a moratorium on installing LEHE boilers because of air quality
issues (Washington). These LEHE systems can have combustion efficiencies as low as 25% percent and
produce more than nine times the emission rate of standard industrial boilers. In comparison, HELEs can
operate around 87% efficiency.
High Efficiency Wood Stoves
Newer high efficiency wood stoves are available on the market that produce minimal smoke, minimal ash
and require less firewood. New EPA-certified wood stoves produce significantly less smoke than older
uncertified wood stoves. High efficiency wood stoves are easy to operate with minimal maintenance
compared to other biomass systems. The Blaze King Classic high efficiency wood stove
(www.blazeking.com) is a recommended model, due to its built-in thermostats that monitor the heat
output of the stove. This stove automatically adjusts the air required for combustion. This unique
technology, combined with the efficiencies of a catalytic combustor with a built-in thermostat, provides
the longest burn times of any wood stove. The Blaze King stove allows for optimal combustion and less
frequent loading and firing times.
Bulk Fuel Boilers
Bulk fuel boilers usually burn wood chips, sawdust, bark or pellets and are designed around the wood
resources that are available from the local forests or local industry. Several large facilities in Tok, Craig,
and Delta Junction (Delta Greely High School) are using bulk fuel biomass systems. Tok uses a commercial
grinder to process woodchips. The chips are then dumped into a bin and are carried by a conveyor belt
to the boiler. The wood fuel comes from timber scraps, local sawmills and forest thinning projects. The
Delta Greely High School has a woodchip bulk fuel boiler that heats the 77,000 square foot facility. The
Delta Greely system, designed by Coffman engineers, includes a completely separate boiler building which
includes a chip storage bunker and space for storage of tractor trailers full of chips (so handling of frozen
chips could be avoided). Woodchips are stored in the concrete bunker and augers move the material on
a conveyor belt to the boilers.
Grants
There are state, federal, and local grant opportunities for biomass work for feasibility studies, design and
construction. If a project is pursued, a thorough search of websites and discussions with the AEA Biomass
group is recommended to make sure no possible funding opportunities are missed. Below are some
funding opportunities and existing past grants that have been awarded.
The U.S. Department of Agriculture Rural Development has over fifty financial assistance programs for a
variety of rural applications. This includes energy efficiency and renewable energy programs.
http://www.rd.usda.gov/programs-services
The city of Nulato was awarded a $40,420 grant for engineering services for a wood energy project by the
United States Department of Agriculture (USDA) and the United States Forest Service. Links regarding the
award of the Woody Biomass Utilization Project recipients are shown below:
http://www.fs.fed.us/news/2012/releases/07/renewablewoods.shtml
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Delta Junction was awarded a grant for engineering from the Alaska Energy Authority from the Renewable
Energy Fund for $831,203. This fund provides assistance to utilities, independent power producers, local
governments, and tribal governments for feasibility studies, reconnaissance studies, energy resource
monitoring, and work related to the design and construction of eligible facilities.
http://www.akenergyauthority.org/Programs/RenewableEnergyFund
The Alaska Wood Energy Development Task Group (AWEDTG) consists of a coalition of federal and state
agencies and not-for-profit organizations that have signed a Memorandum of Understanding (MOU) to
explore opportunities to increase the utilization of wood for energy and biofuels production in Alaska. A
pre-feasibility study for Aleknagik was conducted in 2012 for the AWEDTG. The preliminary costs for the
biomass system(s) are $346,257 for the city hall and health center system and $439,096 for the city hall,
health center, and future washateria system.
http://www.akenergyauthority.org/Programs/AEEE/Biomass
The Emerging Energy Technology Fund grand program provides funds to eligible applicants for
demonstrations projects of technologies that have a reasonable expectation to be commercially viable
within five years and that are designed to: test emerging energy technologies or methods of conserving
energy, improve an existing energy technology, or deploy an existing technology that has not previously
been demonstrated in Alaska.
http://www.akenergyauthority.org/Programs/EETF1
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Appendix A
Site Photos
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Aniak High School
1. South Elevation of Building 2. South West Elevation of Building
3. North Elevation of Building 4. Proposed area for cordwood boiler module
on North side of building. Fuel tank in the
background.
5. East Elevation 6. Voc Ed Building
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7. Water Heater 8. Boiler
9. Hydronic Pumps 10. Well Water Tanks
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11. Furnace 12. Boiler and Water Heater in Mech Room
13. Diesel Day Tank 14. Electrical Panels
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Kalskag High School
15. East Elevation 16. East Elevation of School and Detached Shop
and Mechanical Building
17. West Elevation 18. South Elevation
19. North Elevation 20. Bus Barn North Elevation
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21. Fuel Tanks 22. Detached Shop and Mechanical Room
Building
23. Fuel Transfer Pump Control Panel 24. Shop Service Disconnect
25. Boiler B-1 26. Boiler Circ Pump
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27. Expansion Tank 28. Well Tanks and Hot Water Heater
29. Main Hydronic Circ Pumps 30. Electrical Panels
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31. Air Handling Units 32. Gym
34. Building Layout 35. Classroom Thermostat
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Appendix B
Economic Analysis Spreadsheets
Aniak High SchoolAniak, AlaskaProject Capital Cost($459,000)Present Value of Project Benefits (20-year life)$762,233Present Value of Operating Costs (20-year life)($411,735)Benefit / Cost Ratio of Project (20-year life)0.76Net Present Value (20-year life)($108,502)Year Accumulated Cash Flow is Net PositiveFirst YearPayback Period (Year Accumulated Cash Flow > Project Capital Cost)> 20 yearsDiscount Rate for Net Present Value Analysis3%Wood Fuel Escalation Rate2%Fossil Fuel Escalation Rate5%Electricity Escalation Rate3%O&M Escalation Rate2%YearYearYearYearYearYearYearYearYearYearYearYearYearYearYearYearYearYearYearYear1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Existing Heating System Operating CostsExisting Heating Oil Consumption$2.6012,500gal$32,500$34,125$35,831$37,623$39,504$41,479$43,553$45,731$48,017$50,418$52,939$55,586$58,365$61,284$64,348$67,565$70,943$74,491$78,215$82,126Biomass System Operating CostsCord Wood (Delivered to site)$250.0090%72.0cords($18,000)($18,360)($18,727)($19,102)($19,484)($19,873)($20,271)($20,676)($21,090)($21,512)($21,942)($22,381)($22,828)($23,285)($23,751)($24,226)($24,710)($25,204)($25,708)($26,223)Fossil Fuel$2.6010%1,250gal($3,250)($3,413)($3,583)($3,762)($3,950)($4,148)($4,355)($4,573)($4,802)($5,042)($5,294)($5,559)($5,837)($6,128)($6,435)($6,757)($7,094)($7,449)($7,822)($8,213)Additional Electricity$0.55250kWh($138)($142)($146)($150)($155)($159)($164)($169)($174)($179)($185)($190)($196)($202)($208)($214)($221)($227)($234)($241)Operation and Maintenance Costs($700)($714)($728)($743)($758)($773)($788)($804)($820)($837)($853)($870)($888)($906)($924)($942)($961)($980)($1,000)($1,020)Additional Operation and Maintenance Costs for first 2 years($700)($714)$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0Total Operating Costs($22,788)($23,342)($23,184)($23,757)($24,347)($24,954)($25,579)($26,223)($26,886)($27,569)($28,274)($29,000)($29,749)($30,521)($31,317)($32,138)($32,986)($33,861)($34,764)($35,696)Annual Operating Cost Savings$9,713 $10,783 $12,647 $13,866 $15,157 $16,526 $17,974 $19,508 $21,131 $22,849 $24,665 $26,586 $28,617 $30,763 $33,031 $35,427 $37,957 $40,630 $43,451 $46,430Accumulated Cash Flow$9,713 $20,495 $33,142 $47,008 $62,165 $78,691 $96,665 $116,173 $137,305 $160,153 $184,818 $211,404 $240,021 $270,784 $303,815 $339,241 $377,199 $417,829 $461,280 $507,710Net Present Value($449,570) ($439,406) ($427,833) ($415,513) ($402,439) ($388,599) ($373,984) ($358,584) ($342,389) ($325,387) ($307,568) ($288,921) ($269,435) ($249,097) ($227,896) ($205,819) ($182,854) ($158,989) ($134,209) ($108,502)Economic Analysis ResultsInflation RatesDescription Unit CostHeating Source ProportionAnnual Energy UnitsEnergy Units
George Morgan Sr High SchoolKalskag, AlaskaProject Capital Cost($457,000)Present Value of Project Benefits (20-year life)$731,744Present Value of Operating Costs (20-year life)($417,549)Benefit / Cost Ratio of Project (20-year life)0.69Net Present Value (20-year life)($142,806)Year Accumulated Cash Flow is Net PositiveFirst YearPayback Period (Year Accumulated Cash Flow > Project Capital Cost) >20 yearsDiscount Rate for Net Present Value Analysis3%Wood Fuel Escalation Rate2%Fossil Fuel Escalation Rate5%Electricity Escalation Rate3%O&M Escalation Rate2%Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Existing Heating System Operating CostsExisting Heating Oil Consumption$2.60 12,000gal$31,200 $32,760 $34,398 $36,118 $37,924 $39,820 $41,811 $43,902 $46,097 $48,401 $50,822 $53,363 $56,031 $58,832 $61,774 $64,863 $68,106 $71,511 $75,087 $78,841Biomass System Operating CostsCord Wood (Delivered to site)$250.00 90% 74.0cords($18,500) ($18,870) ($19,247) ($19,632) ($20,025) ($20,425) ($20,834) ($21,251) ($21,676) ($22,109) ($22,551) ($23,002) ($23,462) ($23,932) ($24,410) ($24,899) ($25,397) ($25,904) ($26,423) ($26,951)Fossil Fuel$2.60 10%1,200gal($3,120) ($3,276) ($3,440) ($3,612) ($3,792) ($3,982) ($4,181) ($4,390) ($4,610) ($4,840) ($5,082) ($5,336) ($5,603) ($5,883) ($6,177) ($6,486) ($6,811) ($7,151) ($7,509) ($7,884)Additional Electricity$0.55 250kWh($138) ($142) ($146) ($150) ($155) ($159) ($164) ($169) ($174) ($179) ($185) ($190) ($196) ($202) ($208) ($214) ($221) ($227) ($234) ($241)Operation and Maintenance Costs($700) ($714) ($728) ($743) ($758) ($773) ($788) ($804) ($820) ($837) ($853) ($870) ($888) ($906) ($924) ($942) ($961) ($980) ($1,000) ($1,020)Additional Operation and Maintenance Costs for first 2 years($700) ($714)$0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0Total Operating Costs($23,158) ($23,716) ($23,561) ($24,137) ($24,730) ($25,340) ($25,968) ($26,614) ($27,280) ($27,965) ($28,672) ($29,399) ($30,149) ($30,922) ($31,719) ($32,541) ($33,389) ($34,263) ($35,165) ($36,096)Annual Operating Cost Savings$8,043 $9,044 $10,837 $11,981 $13,194 $14,480 $15,843 $17,288 $18,817 $20,436 $22,150 $23,963 $25,881 $27,910 $30,055 $32,321 $34,717 $37,248 $39,921 $42,745Accumulated Cash Flow$8,043 $17,087 $27,924 $39,904 $53,098 $67,578 $83,422 $100,709 $119,526 $139,962 $162,112 $186,075 $211,957 $239,867 $269,921 $302,243 $336,960 $374,207 $414,129 $456,874Net Present Value($449,191.75) ($440,666.56) ($430,749.49) ($420,104.82) ($408,723.60) ($396,596.63) ($383,715) ($370,068) ($355,646) ($340,440) ($324,438) ($307,631) ($290,007) ($271,555) ($252,264) ($232,123) ($211,118) ($189,239) ($166,472) ($142,806)Economic Analysis ResultsInflation RatesDescription Unit CostHeating Source ProportionAnnual Energy UnitsEnergy Units
Feasibility Assessment for Biomass Heating Systems Aniak & Kalskag High Schools
Coffman Engineers, Inc.
Appendix C
AWEDTG Field Data Sheets