HomeMy WebLinkAboutGakona Biomass Heating Systems Buster Gene Memorial Hall 09-04-2014-BIO
Feasibility Assessment for Biomass Heating Systems
Buster Gene Memorial Hall, Gakona, Alaska
800 F Street, Anchorage, AK 99501
p (907) 276-6664 f (907) 276-5042
Tony SlatonBarker, PE, and
Lee Bolling, CEA, CEM
FINAL REPORT – 9/5/2014
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. i
Contents
I. Executive Summary ............................................................................................................ 1
II. Introduction ...................................................................................................................... 2
III. Preliminary Site Investigation ........................................................................................... 3
BUILDING DESCRIPTION ................................................................................................................................................... 3
EXISTING HEATING SYSTEM .............................................................................................................................................. 3
DOMESTIC HOT WATER................................................................................................................................................... 3
BUILDING ENVELOPE ....................................................................................................................................................... 3
AVAILABLE SPACE ........................................................................................................................................................... 4
STREET ACCESS AND FUEL STORAGE ................................................................................................................................... 4
BUILDING OR SITE CONSTRAINTS ....................................................................................................................................... 4
BIOMASS SYSTEM INTEGRATION ........................................................................................................................................ 4
BIOMASS SYSTEM OPTIONS .............................................................................................................................................. 4
IV. Energy Consumption and Costs ......................................................................................... 6
WOOD ENERGY ............................................................................................................................................................. 6
ENERGY COSTS .............................................................................................................................................................. 6
EXISTING FUEL OIL CONSUMPTION .................................................................................................................................... 7
BIOMASS SYSTEM CONSUMPTION ..................................................................................................................................... 7
V. Preliminary Cost Estimating ............................................................................................... 8
VI. Economic Analysis .......................................................................................................... 10
O&M COSTS .............................................................................................................................................................. 10
DEFINITIONS................................................................................................................................................................ 10
RESULTS ..................................................................................................................................................................... 12
SENSITIVITY ANALYSIS ................................................................................................................................................... 13
VII. Forest Resource and Fuel Availability Assessments ........................................................ 14
FOREST RESOURCE ASSESSMENTS .................................................................................................................................... 14
AIR QUALITY PERMITTING .............................................................................................................................................. 14
VIII. General Biomass Technology Information ..................................................................... 15
HEATING WITH WOOD FUEL ........................................................................................................................................... 15
TYPES OF WOOD FUEL .................................................................................................................................................. 15
HIGH EFFICIENCY WOOD PELLET BOILERS ......................................................................................................................... 16
HIGH EFFICIENCY CORD WOOD BOILERS ........................................................................................................................... 16
LOW EFFICIENCY CORD WOOD BOILERS ........................................................................................................................... 17
HIGH EFFICIENCY WOOD STOVES .................................................................................................................................... 17
BULK FUEL BOILERS ...................................................................................................................................................... 17
GRANTS ..................................................................................................................................................................... 17
Appendices
Appendix A – Site Photos
Appendix B – Economic Analysis Spreadsheet
Appendix C – Site Plan
Appendix D – AWEDTG Field Data Sheet
Feasibility Assessment for Biomass Heating Systems Gakona, AK
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Abbreviations
ACF Accumulated Cash Flow
ASHRAE American Society of Heating, Refrigeration, 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 Gakona, AK
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List of Figures
Fig. 1 – Gakona, Alaska – Google Maps ........................................................................................................ 2
Fig. 2 – Buster Gene Memorial Hall – Design Drawings ................................................................................ 2
Fig. 3 – Maine Energy Systems Pellet Boiler and Polydome Silo .................................................................. 5
List of Tables
Table 1 – Economic Evaluation Summary ..................................................................................................... 1
Table 2 – Energy Comparison ....................................................................................................................... 7
Table 3 – Existing Fuel Oil Consumption ....................................................................................................... 7
Table 4 – Proposed Biomass System Fuel Consumption .............................................................................. 7
Table 5 – Option A - Estimate of Probable Cost ............................................................................................ 8
Table 6 – Option B - Estimate of Probable Cost ............................................................................................ 9
Table 7 – Inflation rates .............................................................................................................................. 10
Table 8 – Economic Definitions ................................................................................................................... 11
Table 9 – Option A - Economic Analysis Results ......................................................................................... 12
Table 10 – Option B - Economic Analysis Results ....................................................................................... 13
Table 11 – Option A Sensitivity Analysis ..................................................................................................... 13
Table 12 – Option B Sensitivity Analysis ..................................................................................................... 13
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. 1
I. Executive Summary
A preliminary feasibility assessment was completed to determine the technical and economic viability of
biomass heating systems at the Buster Gene Memorial Hall in Gakona, Alaska. The study evaluated a
wood pellet boiler system that would supply the majority of the building’s annual heating requirements.
The high price of fuel oil is the main economic driver for the use of lower cost biomass heating.
Two options were evaluated:
Option A: The wood pellet boiler would be located in a large storage room inside the existing
Memorial Hall.
Option B: The wood pellet boiler would be located in a new detached insulated building behind
the Memorial Hall.
Both options utilize wood pellets delivered by truck. Two new silos would be loaded by the delivery truck’s
auger boom for pellet storage.
The results of the economic evaluation are shown below. Option A is economically justified at this time,
due to the fact that the benefit to cost ratio of the option is greater than 1.0.
Economic Analysis Results Option A Option B
Project Capital Cost $84,288 $124,759
Present Value of Project Benefits (20 year life) $246,260 $246,260
Present Value of Operating Costs (20 year life) $160,306 $161,092
Benefit / Cost Ratio of Project (20 year life) 1.02 0.68
Net Present Value (20 year life) $1,666 ($39,591)
Year Accumulated Cash Flow is Net Positive First Year First Year
Year Accumulated Cash Flow > Project Capital Cost 20 years Over 20 years
Simple Payback 43.6 years 67.3 years
Table 1 – Economic Evaluation Summary
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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 Buster Gene Memorial Hall for the Native Village of Gakona in Gakona,
AK. The location of the building is shown in Figures 1 and 2.
Fig. 1 – Gakona, Alaska – Google Maps
Fig. 2 – Buster Gene Memorial Hall – Design Drawings
Feasibility Assessment for Biomass Heating Systems Gakona, AK
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III. Preliminary Site Investigation
Building Description
The Buster Gene Memorial Hall is an 8,228 SF single story building that was originally built in 2008 and
was added on to with an attached addition in 2013. The building has multiple uses and contains a health
clinic, meeting hall, commercial kitchen, and office space. There are no scheduled or planned renovations
for the building. It is used by three office staff during the work week from 8am to 5pm. It is also used for
church one day per week on Sundays and during the week for pre-school activities and for large gatherings
with up to 25 or more people. The building is typically used approximately 60 hours per week. An energy
audit was completed on the building in 2010 by Your Clean Energy, LLC. The energy audit is on file at the
Native Village of Gakona office. Please refer to Appendix D for field data sheet that contains all pertinent
information gathered during the site visit.
Existing Heating System
The building is heated by two identical Energy Kinetics oil boilers (MN: System 2000 EK-2F, 1.40 GPH Firing
Rate, 170.5 MBH Output) that were installed in 2008 during original construction. The boilers are located
in the boiler room, which has one exterior wall. The boilers serve several heating zones and an indirect
hot water heater. The building utilizes both perimeter baseboard registers and radiant floors. The boiler
system runs in a primary/secondary system, which utilizes several system pumps to transfer heated glycol
to different zones. Each boiler appears to be sized at 60% design heat load, which is typical for this type
of building. The combustion efficiency of the existing fuel oil boilers is approximately 87%. For this study,
the Annual Fuel Utilization Efficiency of the oil boiler system was estimated at 80% to account for typical
oil boiler inefficiencies, including short cycling.
There is routine maintenance of the boilers by a Gakona employee (Darin Gene). The boilers appear to
be in good shape and operating correctly. However, it was found that the boilers appear to be piped in a
non-traditional way, where the boiler supply line is piped upstream of the boiler return line. This existing
installation does not match the building’s mechanical design drawings. It is recommended that the boiler
supply/return piping is re-piped to match design drawings.
There is also an existing small wood pellet stove in the large community hall that is available for
supplemental space heating. According to building staff, the existing pellet stove is rarely used.
One 550 gal heating oil tank serves the boilers and is located to the north side of the building. The tank is
dual wall. There is no additional spill containment is present around the tank. Fuel in the tanks is used
for building heating and domestic hot water only.
Domestic Hot Water
Domestic hot water is used for hand washing, the kitchen and also for laundry. There are two commercial
washing machines in the building. Hot water is provided by a 40 gal Energy Kinetics indirect hot water
heater, which uses a loop from the boiler for heat.
Building Envelope
The building is 2x8 wood stud construction with a cold roof. Based on design drawings the walls have two
layers of 4” friction fit fiberglass batt insulation (approximately R-30). The cold roof has R-42 blown
cellulose insulation. According to the 2010 energy audit, some of the roof insulation was not installed as
Feasibility Assessment for Biomass Heating Systems Gakona, AK
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deep as called for in the design drawings and was estimated at R-33. The windows are double pane and
there are two arctic entries for the two main entrances.
Available Space
There are two options for locating a new biomass boiler system. The first option, Option A, would be to
locate the biomass boiler in the storage room (RM 108) on the east side of the community hall room. This
storage room is approximately 6 ft by 16 ft and part of this room could be converted into a code approved
mechanical room to house the biomass boiler.
The second option, Option B, would be to install the biomass boiler system inside a small, detached 8 ft
by 10 ft boiler building. The detached boiler building could be located on the north side of the building in
the vicinity of the existing shed and would be approximately 30 feet away from the existing mechanical
room.
Street Access and Fuel Storage
The building site is situated along a paved road that a bulk pellet delivery truck can easily access. The
wood pellets can be stored in two large 8.5 ton silos, which can be filled with an auger boom from the
pellet delivery truck. The client preferred location for the pellet silos is the northwest side of the building,
near the existing well. Please refer to Appendix C for the site plan. A small amount of site grading would
be required to provide delivery truck access to the silos behind the building.
Building or Site constraints
The site is flat with no significant site constraints. There were no wetlands or signs of historical structures
observed.
Biomass System Integration
A wood boiler system would easily be able to tie into the return line of the existing hydronic system of the
building. There appears to be sufficient room in the mechanical room to tie in to the existing piping
without major piping changes. The existing hydronic system, baseboards and radiant floors would be used
to distribute heat around the building.
Biomass System Options
The client prefers a biomass fuel that is easy to handle, utilizes automatic fuel loading, and is locally
available. Automatic fuel loading is necessary because the village does not have the personnel resources
to manually handle and load a batch burning system (such as a cord wood Garn boiler).
Based on these criteria, wood pellets are the preferred biomass fuel. Wood pellets are locally available in
Fairbanks and in Delta Junction. Cord wood was not considered as an option because it must be manually
batch loaded and fired.
There are two options for pellet boiler systems (see option A and B discussion below). Both options will
utilize two 8.5 ton silos to hold wood pellets. The pellet silos will be in the same location for each option.
Polydome silos were used as the basis for this study and are available through Superior Pellets in
Fairbanks. According to Superior Pellets, each silo can be erected on 6” concrete slabs that are
approximately 8 ft by 8 ft. For this study, it is assumed that one large 8 ft x 16 ft slab is made for both
silos to save costs.
Feasibility Assessment for Biomass Heating Systems Gakona, AK
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Transfer augers will move the pellets from the two silos to a pellet hopper integrated into the pellet boiler.
The pellet hopper is connected to the boiler and is used for daily feeding of pellets. For this study, one
Maine Energy Systems PES56 pellet boiler was used as the basis of design. This boiler is a high quality
pellet boiler with a good track record for reliability and lifespan. The PES56 has an output of 191 MBH
and can modulate down to 30% firing rate. It also has automatic ash removal systems and is easily
maintainable. There are other pellet boilers on the market that have similar characteristics that could be
used. Please refer to the Section VIII General Biomass Technology Information for a further discussion on
pellet boilers.
Fig. 3 – Maine Energy Systems Pellet Boiler and Polydome Silo
(Not to scale)
Option A: The pellet boiler will be located in the storage room on the east side of the community hall
room. Part (or all) of the storage room will be converted to a mechanical room that will contain the pellet
boiler and hopper, as well as piping and a circulation pump. The advantage of this option is that it has
much lower equipment and installation costs than locating the pellet boiler in a detached boiler building.
The disadvantage is that there will be less storage space. Insulated piping will be routed near the ceiling
to the existing mechanical room for tie-in.
Option B: For this option, the pellet boiler will be located in a detached 8 ft by 10 ft boiler building,
approximately 30 ft from the building’s existing mechanical room. The detached building will house the
pellet boiler and hopper. It is assumed that concrete slab for the new pellet silos will lengthened for use
as the detached boiler foundation for cost savings. This building can either be constructed with new
materials or it could be a retrofitted conex that is insulated and modified to meet code requirements for
mechanical, electrical, access and egress. Buried insulated piping will deliver heated glycol from the
boiler building to the existing mechanical room, where it will be tied into the existing system with a heat
exchanger. The advantage of this option is that Memorial Hall will not lose storage space. The
disadvantage is significant cost increase due to constructing the detached boiler building and buried
insulated lines. Also, the existing shed in the rear of the building will most likely need to be relocated to
make space for the detached building.
Please refer to Appendix C for a site plan of the options.
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IV. Energy Consumption and Costs
Wood Energy
The gross energy content of wood pellets varies depending on tree species, moisture content and
manufacturing. Wood pellets available in Alaska can range in moisture content from 4.5% to 6.5% and in
energy value from 8,000 to 8,250 BTU/lb, depending on manufacturer. For this study, wood pellets were
estimated to have 8,000 BTU/lb, which is equivalent to 16.0 MMBTU/ton. To determine the delivered
$/MMBTU of the biomass system, an 86% efficiency for the Maine Energy System pellet boiler was
assumed. This is based on manufacturer documentation.
Wood pellets were used as the biomass fuel for this study. However, the following is additional
information on cord wood fuel for future evaluations. 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. For this study, cord wood was estimated to have 16.0 MMBTU/cord. This is a
conservative estimate based on the fact that the community has access to both spruce and birch. To
determine the delivered $/MMBTU of the biomass system, a 75% efficiency for batch burning systems
was assumed. This is based on manufacturer documentation and typical operational issues which do not
allow firing 100% of the time.
Energy Costs
The high price of fuel oil is the main economic driver for the use of lower cost biomass heating. Fuel oil is
shipped into Gakona by truck and currently costs $3.75/gal. For this study, the energy content of fuel oil
is based on 134,000 BTU/gal, according to the UAF Cooperative Extension.
Superior Pellets out of North Pole, AK is an Alaskan source of wood pellets (contact Chad Schum acher,
General Manager at (907) 488-6055 for delivery methods and current costs). Superior Pellets
manufactures local Alaskan pellets at their North Pole factory and will deliver pellets in bulk to Gakona.
Delivery is made with a 32 ft long pellet truck that can hold 15 tons of pellets. The truck has a 28 ft auger
boom for filling a large pellet storage silo (or silos) onsite. The cost for delivering bulk pellets to Gakona
is $350/ton, for a full truck load of pellets. This includes the cost of filling the pellet silos. It is proposed
that two 8.5 ton silos are used for the biomass system. This will give the building 17 tons of storage and
will allow for a full 15 ton delivery from Superior Pellets. The Superior Pellet option is used for the
economic analysis in this study because it includes all delivery costs to the pellet storage silo.
Another pellet distributor is End of the Alcan (contact Donna Supernaw at (907) 895-5321), which is
located in Delta Junction at milepost 272 on the Richardson Highway. The pellets are manufactured by
Premium Pellets in Canada and are transported to Alaska by semi-truck. Trucks carry a load of 30 tons of
pellets that can be delivered to Gakona directly. The pellets are packaged in 40 lb bags and are palletized
in one ton shipping pallets (2,000 lbs). One shipping pallet contains 50 bags of pellets. A staging area and
fork lift will be required to unload the truck and store pellets. The delivered price to the site is $332/ton.
Because this price does not include the labor and forklift required to offload the pallets or the labor to rip
open each bag of pellets to load a storage silo, this pellet source was not used for the economic analysis
in this study.
Feasibility Assessment for Biomass Heating Systems Gakona, AK
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The table below shows the energy comparison of different fuel types. 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, cord
wood and wood pellets are cheaper than fuel oil on a $/MMBTU basis.
Fuel Type Units Gross
BTU/unit
System
Efficiency $/unit Delivered
$/MMBTU
Cord Wood cords 16,000,000 75% $200 $16.67
Wood Pellets tons 16,000,000 86% $350 $25.44
Fuel Oil gal 134,000 80% $3.75 $34.98
Electricity kWh 3,413 99% $0.28 $82.87
Table 2 – Energy Comparison
Existing Fuel Oil Consumption
An estimate of the Memorial Hall’s heating oil consumption was required because the new addition of
the building has only been occupied since October 2013. An estimate was made based on heating oil bills
from 2013 and 2014, and from estimating the future consumption of the new addition. B ased on this
estimate, the Memorial Hall uses approximately 2,800 gal of fuel oil annually for space heating and
domestic hot water. The estimated annual fuel cost, based on the current price of heating oil, is $10,500.
Building Name Fuel Type
Avg. Annual
Consumption Net MMBTU/yr
Annual Fuel
Cost
Buster Gene
Memorial Hall Fuel Oil 2,800 gal 300.2 $10,500
Table 3 – Existing Fuel Oil Consumption
Biomass System Consumption
For both options it is estimated that the proposed biomass system will offset 97% of the heating energy
for the building. The remaining 3% of the heating energy be provided by the existing oil boilers. This
result is based on an analysis of outdoor temperature BIN data for the Gakona region. Based on this
analysis, even though one Maine Energy System PES56 pellet boiler will only provide 67% of the building’s
peak design load, it will provide 97% of the building’s heat on an annual basis. Both options utilize the
same pellet boiler and are expected to have the same energy costs. The two 8.5 ton silos will hold
approximately 80% of the buildings annual pellet demand, or one delivery approximately every 9 months.
Option Fuel Type % Heating
Source
Net
MMBTU/yr
Annual
Consumption
Energy
Cost
Total Energy
Cost
Option A and B
Pellets 97% 291.2 21.2 tons $7,406
$7,791 Fuel Oil 3% 9.0 84 gal $315
Additional
Electricity N/A N/A 252 kWh $71
Table 4 – Proposed Biomass System Fuel Consumption
Feasibility Assessment for Biomass Heating Systems Gakona, AK
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V. Preliminary Cost Estimating
An estimate of probable costs was completed for Option A and Option B. The cost estimate is based on a
discussions with pellet boiler manufacture’s in-house engineers, mechanical contractors, and silo
suppliers. A 5% remote factor was used to account for increased shipping and installation costs to Gakona.
Project and Construction Management was estimated at 5%. Engineering design and permitting was
estimated at 20% and a 15% contingency was used.
Option A – Indoor Pellet Boiler System With Exterior Silos
Category Description Cost
Site Work and Silos Site Grading $ 4,200
Concrete Slab $ 4,200
Two 8.5 Ton Silos $ 5,400
Silo Installation $ 2,100
Subtotal $ 15,900
Electrical Utilities Auger Power Connection $ 1,500
Conduit and Wiring $ 1,500
Subtotal $ 3,000
Wood Boiler and Augers Maine Energy Systems PES 56 Pellet Boiler $ 23,000
Transfer Augers $ 3,000
Subtotal $ 26,000
Interior Mechanical &
Electrical Boiler Installation, Piping & Materials $ 7,000
Fire Allowance $ 1,500
Electrical Allowance $ 2,000
Subtotal $ 10,500
Subtotal Material and
Installation Cost $ 55,400
Remote Factor 5% $ 2,770
Subtotal $ 58,170
Project and Construction
Management 5% $ 2,909
Subtotal $ 61,079
Design Fees and
Permitting 20% $ 12,216
Subtotal $ 73,294
Contingency 15% $ 10,994
Total Project Cost $ 84,288
Table 5 – Option A - Estimate of Probable Cost
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Option B – Detached Pellet Boiler Building With Exterior Silos
Category Description Cost
Site Work and Silos Site Grading $ 4,500
Concrete Slab $ 6,000
Two 8.5 Ton Silos $ 5,400
Silo Installation $ 2,100
Subtotal $ 18,000
Electrical Utilities Service Entrance $ 2,000
Conduit and Wiring $ 2,000
Subtotal $ 4,000
Wood Boiler and Augers Maine Energy Systems PES 56 Pellet Boiler $ 23,000
Transfer Augers $ 3,000
Subtotal $ 26,000
Interior Mechanical &
Electrical Boiler Installation, Piping & Materials $ 7,000
Fire Allowance $ 1,500
Electrical Allowance $ 2,000
Subtotal $ 10,500
Wood Boiler Building 8ft x 10ft Wood Boiler Building $ 20,000
Buried Utilities $ 3,500
Subtotal $ 23,500
Subtotal Material and
Installation Cost $ 82,000
Remote Factor 5% $ 4,100
Subtotal $ 86,100
Project and Construction
Management 5% $ 4,305
Subtotal $ 90,405
Design Fees and
Permitting 20% $ 18,081
Subtotal $ 108,486
Contingency 15% $ 16,273
Total Project Cost $ 124,759
Table 6 – Option B - Estimate of Probable Cost
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VI. Economic Analysis
The following assumptions were used to complete the economic analysis for this study.
Inflation Rates
Discount Rate for Net Present Value Analysis 3%
Wood Fuel Escalation Rate 3%
Fossil Fuel Escalation Rate 5%
Electricity Escalation Rate 3%
O&M Escalation Rate 2%
Table 7 – Inflation rates
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 the Alaska Energy Authority
funded 2013 biomass pre-feasibility studies. These are typical rates used for this level of evaluation and
were used so that results are consistent and comparable to the 2013 studies.
O&M Costs
Non-fuel related operations and maintenance costs (O&M) were estimated at $380 per year for Option
A. Option B was estimated at $420 per year due to additional expenses associated with a detached
building. The estimate is based on annual maintenance time for the pellet boiler. Per manufactures
recommendations the ash trays should be manually dumped for every two tons of pellets burned. This
amounts to dumping ash a little less than once per month. Dumping the ash trays takes less than 10
minutes of non-skilled labor per event. In the winter a 30 minute service is recommended to clean the
boilers heat exchanger. In the summer, a 90 minute service is recommended to clean heat exchangers
and maintain other components. According to the manufacturer the summer and winter service can be
easily completed by the Village’s existing maintenance person. 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.
Definitions
There are many different economic terms used in this study. A listing of all of the terms with their
definition is provided below for reference.
Economic Term Description
Project Capital Cost This is the opinion of probable cost for designing and constructing the
project.
Simple Payback The Simple Payback is the Project Capital Cost divided by the first year annual
energy savings. The Simple Payback does not take into account escalated
energy prices and is therefore not a good measure of project viability.
𝑅𝑖𝑖𝑖𝑖𝑎 𝑂𝑎𝑦𝑎𝑎𝑎𝑖= 𝐼𝑖𝑟𝑟𝑎𝑖𝑖𝑎𝑎 𝐵𝑖𝑟𝑟 𝑖𝑎 𝐸𝐵𝑀
𝐸𝑖𝑟𝑟𝑟 𝑌𝑎𝑎𝑟 𝐸𝑖𝑎𝑟𝑎𝑦 𝑅𝑎𝑣𝑖𝑖𝑎𝑟 𝑖𝑎 𝐸𝐵𝑀
Feasibility Assessment for Biomass Heating Systems Gakona, AK
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Economic Term Description
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 to provide 97% of the building’s
heat. It also includes the heating oil required for the existing oil-fired boilers
to provide the remaining 3% 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:
𝐵𝑎𝑖𝑎𝑎𝑖𝑟 / 𝐵𝑖𝑟𝑟 𝑅𝑎𝑟𝑖𝑖
= 𝑂𝑉(𝑂𝑟𝑖𝑖𝑎𝑎𝑟 𝐵𝑎𝑖𝑎𝑎𝑖𝑟𝑟)− 𝑂𝑉(𝑂𝑖𝑎𝑟𝑎𝑟𝑖𝑖𝑎 𝐵𝑖𝑟𝑟𝑟)
𝑂𝑟𝑖𝑖𝑎𝑎𝑟 𝐵𝑎𝑖𝑖𝑟𝑎𝑖 𝐵𝑖𝑟𝑟
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.
Year Accumulated Cash
Flow > Project Capital
Cost
This 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 is similar
to the project’s simple payback, except that it incorporates the inflation
rates. This quantity is the payback of the project including escalating energy
prices and O&M rates. This quantity is calculated as follows:
𝐼𝑖𝑟𝑟𝑎𝑖𝑖𝑎𝑎 𝐵𝑖𝑟𝑟≤∑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.
Table 8 – Economic Definitions
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. 12
Results
The economic analysis for Option A and Option B was completed in order to determine the simple
payback, benefit to cost ratio, and net present value of each. The results of the proposed wood pellet
boiler system are shown below.
Please refer to Appendix B for the economic analysis spreadsheets for each option.
Option A – In Option A, the pellet boiler is located in the existing building’s storage room, east of the
community hall room. Option A has a benefit to cost ratio of 1.02 over the 20 year study period, which
makes the project economically justified. Any project with a benefit to cost ratio above 1.0 is considered
economically justified. The main reason this option is viable is because of its smaller project capital cost
due to placing the pellet boiler inside the existing building’s storage room. This option does not require
building a detached boiler building or burying insulated piping, which significantly increases costs. The
disadvantage of this option is that existing storage space will be lost because it will be repurposed for the
pellet boiler. However, this may not be an issue since the items in the storage room can easily be stored
in the nearby shed behind the building.
Option A - Indoor Pellet Boiler System With Exterior Silos
Project Capital Cost $84,288
Present Value of Project Benefits (20 year life) $246,260
Present Value of Operating Costs (20 year life) $160,306
Benefit / Cost Ratio of Project (20 year life) 1.02
Net Present Value (20 year life) $1,666
Year Accumulated Cash Flow is Net Positive First Year
Year Accumulated Cash Flow > Project Capital Cost 20 years
Simple Payback 43.6 years
Table 9 – Option A - Economic Analysis Results
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. 13
Option B – In Option B the pellet boiler is installed in a detached boiler building. Option B has a benefit
to cost ratio of 0.68, making it not considered economically justified based on the cost estimate and
available heating oil offsets. The main reason this option is not viable is due to the additional costs for
building the detached building and trenching the insulated piping.
The critical project capital cost to make this option viable (with a benefit to cost ratio of 1.0) is $85,950.
If lower cost materials or labor can be found through donations, grants or in-kind support, the project
may become economically viable.
Option B - Detached Pellet Boiler Building With Exterior Silos
Project Capital Cost $124,759
Present Value of Project Benefits (20 year life) $246,260
Present Value of Operating Costs (20 year life) $161,092
Benefit / Cost Ratio of Project (20 year life) 0.68
Net Present Value (20 year life) ($39,591)
Year Accumulated Cash Flow is Net Positive First Year
Year Accumulated Cash Flow > Project Capital Cost Over 20 years
Simple Payback 67.3 years
Table 10 – Option B - Economic Analysis Results
Sensitivity Analysis
A sensitivity analysis was completed for both options to show how changing heating oil costs and wood
costs affect the benefit to cost (B/C) ratios of the projects. As heating oil costs increase and wood costs
decrease, the projects becomes more economically viable. The B/C ratios greater than 1.0 are
economically justified and are highlighted in green. B/C rations less than one are not economically
justified and are highlighted in red. As the price of heating oil goes up both options become economically
more attractive.
Option A – B/C Ratios Wood Pellet Cost ($/ton)
$300/ton $325/ton $350/ton $375/ton
Heating Oil Cost
($/gal)
$3.50/gal 1.08 0.95 0.83 0.71
$3.75/gal 1.26 1.14 1.02 0.90
$4.00/gal 1.45 1.33 1.21 1.09
$4.25/gal 1.64 1.52 1.40 1.28
Table 11 – Option A Sensitivity Analysis
Option B – B/C Ratios Wood Pellet Cost ($/ton)
$300/ton $325/ton $350/ton $375/ton
Heating Oil Cost
($/gal)
$3.50/gal 0.72 0.64 0.56 0.47
$3.75/gal 0.85 0.77 0.68 0.60
$4.00/gal 0.98 0.89 0.81 0.73
$4.25/gal 1.10 1.02 0.94 0.86
Table 12 – Option B Sensitivity Analysis
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. 14
VII. Forest Resource and Fuel Availability Assessments
Forest Resource Assessments
The Alaska Department of Natural Resources (DNR) has information on the timber and biomass resources
of the Valdez Copper River Area. Please refer to the DNR website at
http://forestry.alaska.gov/timber/vcra.htm#fiveyear for access to all their information. The DNR has
reports on timber sales, five year schedule of timber sales, maps and forest land use plans. The Copper
Area Forester is Gary Mullen, who has written the majority of the DNR documents for the Copper Area.
Contact with Mr. Mullen was attempted but unsuccessful, as he was out of the office for several weeks
during the writing of this report.
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). The recent Garn boiler system installed in Alaska of similar size and emissions output as
the proposed pellet boiler have not needed or obtained air quality permits.
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. 15
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.
Feasibility Assessment for Biomass Heating Systems Gakona, AK
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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 cord wood 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.
Two of the best quality pellet boilers in the U.S. market are the Maine Energy Systems PES boilers and the
Froling P4 boilers. These boilers have high end controls, automatic ash removal and have a good
reputation for quality. The Maxim Pellet Boiler is a less costly option and can be used directly outdoors if
needed. According to Chad Shumacher, General Manager of Superior Pellets, his Maxim boiler
automation does not operate as well as the Maine Energy Systems units, but they are less than half the
price. The working lifespan of the Maxim boilers also may be less than the higher quality units.
High Efficiency Cord Wood 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, infloor 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 fo r
extra hot water circulating capacity. Most facilities using cordwood boilers keep existing oil-fired systems
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. 17
operational to provide heating backup during biomass boiler downtimes and to provide additional heat
for peak heating demand periods.
Low Efficiency Cord Wood 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
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 twenty five (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 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 many grant opportunities for biomass work state, federal, and local for feasibility studies, design
and construction. If a project is pursued, a thorough search of websites and discussions with the AEA
Biomass group would be recommended to make sure no possible funding opportunities are
missed. Below are some funding opportunities and existing past grants that have been awarded.
Currently, there is a funding opportunity for tribal communities that develop clean and renewable energy
resources through the U.S. Department of Energy. On April 30, 2013, the Department of Energy
announced up to $7 million was available to deploy clean energy projects in tribal communities to reduce
reliance on fossil fuel and promote economic development on tribal lands. The Energy Department’s Tribal
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. 18
Energy Program, in cooperation with the Office of Indian Energy, will help Native American communities,
tribal energy resource development organizations, and tribal consortia to install community or facility
scale clean energy projects.
http://apps1.eere.energy.gov/tribalenergy/
The Department of Energy (DOE), Alaska Native programs, focus on energy efficiency and add ocean
energy into the mix. In addition the communities are eligible for up to $250,000 in energy-efficiency aid.
The Native village of Kongiganak will get help strengthening its wind-energy infrastructure, increasing
energy efficiency and developing “smart grid technology”. Koyukuk will get help upgrading its energy
infrastructure, improving energy efficiency and exploring biomass options. The village of Minto will
explore all the above options as well as look for solar-energy ideas. Shishmaref, an Alaska Native village
faced climate-change-induced relocation, will receive help with increasing energy sustainability and
building capacity as it relocates. And the Yakutat T’lingit Tribe will also study efficiency, biomass and ocean
energy. This DOE program would be a viable avenue for biomass funding.
http://energy.gov/articles/alaska-native-communities-receive-technical-assistance-local-clean-energy-
development
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
http://www.usda.gov/wps/portal/usda/usdahome?contentid=2009/08/0403.xml
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/re-fund-6/4_Program_Update/FinalREFStatusAppendix2013.pdf
http://www.akenergyauthority.org/PDF%20files/PFS-BiomassProgramFactSheet.pdf
http://www.akenergyauthority.org/RenewableEnergyFund/RFA_Project_Locations_20Oct08.pdf
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 washeteria system.
http://www.akenergyauthority.org/biomasswoodenergygrants.html
http://www.akenergyauthority.org/BiomassWoodEnergy/Aleknagik%20Final%20Report.pdf
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
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc. 19
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/EETFundGrantProgram.html
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc.
Appendix A
Site Photos
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc.
1. South elevation of building. 2. West elevation of building.
3. North elevation of building. 4. East elevation of building.
5. Site entrance. 6. Approximate location of new biomass
building and pellet storage.
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc.
7. Fuel tank and boiler room access door. 8. Boiler room.
9. Boiler room. 10. Boiler Close Up
11. Community Hall Room. 12. Large kitchen.
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc.
Appendix B
Economic Analysis Spreadsheet
Buster Gene Memorial Hall - Option AGakona, AlaskaProject Capital Cost($84,288)Present Value of Project Benefits (20 year life)$246,260Present Value of Operating Costs (20 year life)($160,306)Benefit / Cost Ratio of Project (20 year life)1.02Net Present Value (20 year life)$1,666Year Accumulated Cash Flow is Net PositiveFirst YearYear Accumulated Cash Flow > Project Capital Cost20 yearsSimple Payback = Total Project Cost / First Year Cost Savings43.6 yearsDiscount Rate for Net Present Value Analysis3%Wood Fuel Escalation Rate3%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$3.752,800gal$10,500$11,025$11,576$12,155$12,763$13,401$14,071$14,775$15,513$16,289$17,103$17,959$18,856$19,799$20,789$21,829$22,920$24,066$25,270$26,533Biomass System Operating CostsWood Pellet Fuel (Delivered to site)$350.0097%21.2tons($7,420)($7,643)($7,872)($8,108)($8,351)($8,602)($8,860)($9,126)($9,399)($9,681)($9,972)($10,271)($10,579)($10,897)($11,223)($11,560)($11,907)($12,264)($12,632)($13,011)Fossil Fuel$3.753%84gal($315)($331)($347)($365)($383)($402)($422)($443)($465)($489)($513)($539)($566)($594)($624)($655)($688)($722)($758)($796)Additional Electricity$0.28252kWh($71)($73)($75)($77)($79)($82)($84)($87)($89)($92)($95)($98)($101)($104)($107)($110)($113)($117)($120)($124)Operation and Maintenance Costs($380)($388)($395)($403)($411)($420)($428)($437)($445)($454)($463)($472)($482)($492)($501)($511)($522)($532)($543)($554)Additional Operation and Maintenance Costs for first 2 years($380)($388)$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0Total Operating Costs($8,566)($8,821)($8,689)($8,953)($9,225)($9,505)($9,794)($10,092)($10,399)($10,716)($11,043)($11,380)($11,727)($12,086)($12,455)($12,836)($13,229)($13,635)($14,053)($14,484)Annual Operating Cost Savings$1,934 $2,204 $2,887 $3,202 $3,538 $3,896 $4,277 $4,682 $5,114 $5,573 $6,060 $6,579 $7,129 $7,714 $8,334 $8,992 $9,691 $10,431 $11,217 $12,049Accumulated Cash Flow$1,934 $4,138 $7,025 $10,227 $13,765 $17,661 $21,938 $26,620 $31,734 $37,306 $43,367 $49,945 $57,075 $64,788 $73,122 $82,115 $91,805 $102,237 $113,453 $125,502Net Present Value($82,410) ($80,333) ($77,691) ($74,846) ($71,794) ($68,531) ($65,054) ($61,358) ($57,438) ($53,292) ($48,913) ($44,299) ($39,445) ($34,345) ($28,996) ($23,392) ($17,529) ($11,402) ($5,005)$1,666Energy UnitsHeating Source ProportionEconomic Analysis ResultsInflation RatesDescription Unit CostAnnual Energy Units
Buster Gene Memorial Hall - Option BGakona, AlaskaProject Capital Cost($124,759)Present Value of Project Benefits (20 year life)$246,260Present Value of Operating Costs (20 year life)($161,092)Benefit / Cost Ratio of Project (20 year life)0.68Net Present Value (20 year life)($39,591)Year Accumulated Cash Flow is Net PositiveFirst YearYear Accumulated Cash Flow > Project Capital CostOver 20 yearsSimple Payback = Total Project Cost / First Year Cost Savings67.3 yearsDiscount Rate for Net Present Value Analysis3%Wood Fuel Escalation Rate3%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$3.752,800gal$10,500$11,025$11,576$12,155$12,763$13,401$14,071$14,775$15,513$16,289$17,103$17,959$18,856$19,799$20,789$21,829$22,920$24,066$25,270$26,533Biomass System Operating CostsWood Pellet Fuel (Delivered to site)$350.0097%21.2tons($7,420)($7,643)($7,872)($8,108)($8,351)($8,602)($8,860)($9,126)($9,399)($9,681)($9,972)($10,271)($10,579)($10,897)($11,223)($11,560)($11,907)($12,264)($12,632)($13,011)Fossil Fuel$3.753%84gal($315)($331)($347)($365)($383)($402)($422)($443)($465)($489)($513)($539)($566)($594)($624)($655)($688)($722)($758)($796)Additional Electricity$0.28252kWh($71)($73)($75)($77)($79)($82)($84)($87)($89)($92)($95)($98)($101)($104)($107)($110)($113)($117)($120)($124)Operation and Maintenance Costs($420)($428)($437)($446)($455)($464)($473)($482)($492)($502)($512)($522)($533)($543)($554)($565)($577)($588)($600)($612)Additional Operation and Maintenance Costs for first 2 years($420)($428)$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0$0Total Operating Costs($8,646)($8,903)($8,731)($8,995)($9,268)($9,549)($9,839)($10,138)($10,446)($10,764)($11,092)($11,430)($11,778)($12,137)($12,508)($12,890)($13,284)($13,691)($14,110)($14,543)Annual Operating Cost Savings$1,854 $2,122 $2,845 $3,160 $3,495 $3,852 $4,232 $4,636 $5,067 $5,525 $6,012 $6,529 $7,078 $7,662 $8,281 $8,939 $9,636 $10,375 $11,159 $11,990Accumulated Cash Flow$1,854 $3,977 $6,822 $9,981 $13,476 $17,328 $21,559 $26,196 $31,263 $36,788 $42,799 $49,328 $56,407 $64,068 $72,350 $81,288 $90,924 $101,300 $112,459 $124,449Net Present Value($122,959) ($120,958) ($118,354) ($115,547) ($112,533) ($109,307) ($105,866) ($102,206) ($98,323) ($94,212) ($89,869) ($85,290) ($80,470) ($75,404) ($70,089) ($64,518) ($58,689) ($52,594) ($46,230) ($39,591)Energy UnitsEconomic Analysis ResultsInflation RatesDescription Unit CostHeating Source ProportionAnnual Energy Units
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc.
Appendix C
Site Plan
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc.
Site Plan of Buster Gene Memorial Hall
Existing
Mechanical Room Existing Storage
Rm for Option A
Detached Pellet
Boiler Building for
Option B
Two 8.5 Ton Silos
for Pellet Storage
Site Grading
necessary
for pellet
truck access
to silos.
Feasibility Assessment for Biomass Heating Systems Gakona, AK
Coffman Engineers, Inc.
Appendix D
AWEDTG Field Data Sheet