HomeMy WebLinkAboutGrayling Biomass Pre-Feasibility 2014
Organized Village of Grayling
Biomass Heat Pre-Feasibility Study
Prepared for Interior Regional Housing Authority
October 17, 2014
Prepared by:
Energy Action, Wynne Auld
With Support from:
The Alaska Energy Authority
1231 W. Northern Lights #578
Anchorage, AK 99503
www.energyaction.info
(907) 744-1085
Page 2 of 16
Contents
Acknowledgements ....................................................................................................................................... 3
Community Contact Information .................................................................................................................. 3
Summary of Findings..................................................................................................................................... 4
Statement of Purpose ................................................................................................................................... 4
Community & Facility Information................................................................................................................ 5
Biomass Resource Availability ....................................................................................................................... 6
Site Control ................................................................................................................................................... 6
Permitting ..................................................................................................................................................... 6
Proposed Biomass System ............................................................................................................................ 7
Alternatives Considered ............................................................................................................................ 8
Heat Load & Biomass Operating Requirements ......................................................................................... 10
Opinion of Probable Cost ............................................................................................................................ 12
Financial Analysis ........................................................................................................................................ 14
Financial Summary .................................................................................................................................. 14
Benefit/ Cost Model ................................................................................................................................ 14
Sensitivity Analysis .................................................................................................................................. 16
Recommendations ...................................................................................................................................... 16
Figures
Figure 1: Biomass Project Site Map .............................................................................................................. 9
Figure 2: Fuel Energy Values ....................................................................................................................... 10
Figure 3: Current Annual Fuel Use & Cost .................................................................................................. 10
Figure 4: Projected Annual Fuel Use & Cost, Biomass Project ................................................................... 10
Figure 5: Biomass Stoking Requirements.................................................................................................... 10
Figure 6: Biomass O&M Costs (non-stoking) .............................................................................................. 10
Figure 7: Force Account Summary .............................................................................................................. 12
Figure 8: Force Account Detail .................................................................................................................... 13
Appendix
A—Biomass Technology
B – Utility Receipts
C – Site Control
D – Site Photos
Page 3 of 16
Acknowledgements
Energy Action thanks the following representatives for their assistance with this assessment:
Steven Graham, Head of Maintenance, Iditarod Area School District
Gabe Nicholi, Iditarod Area School District School Board, and Chief, Organized Village of Grayling
Rachel Freireich, Tribal Administrator, Organized Village of Grayling
Russell Snyder, Grants Coordinator, Interior Regional Housing Authority
Steven J. Stassel, P.E., Gray Stassel Engineering
Community Contact Information
Organized Village of Grayling
Contact: Gabriel Nicholi Sr., Chief
PO Box 49, Grayling, AK 99590
P. (907) 453-5116
F. (907) 453-5146
Chief, Gabriel Nicholi, gnicholi@iditarodsd.org
Tribal Administrator, Rachel Freireich, rachel.freireich@tananachiefs.org
City of Grayling
Contact: Shirley Clark, Mayor
PO Box 89, Grayling, AK 99590
P. (907) 453-5148
F. (907) 453-5223
cityofgrayling@yahoo.com
Iditarod Area School District
Contact: Steve Graham, Head of Maintenance
PO Box 90, McGrath, AK 99627
P. (907) 524-1200
F. (907) 524-3217
sgraham@iditarodsd.org
Page 4 of 16
Summary of Findings
The School Board of the Iditarod Area School District has expressed interest in assessments to
determine good candidates for biomass heat systems in District buildings.
This pre-feasibility assessment considers biomass heat at the main school building of the David Louis
Memorial School, located in the Organized Village of Grayling. The proposed biomass project would use
an estimated 86 cords per year to displace about 85% of the main School building’s fuel oil consumption,
which totals 10,000 gallons per year. The project is considered financially unfeasible at this time, largely
because the local price of cordwood does not represent sufficient savings over the purchase price of fuel
oil.
The project also faces technical challenges, since cordwood systems are not very effective when serving
building heat loads that operate in a narrow temperature range, such as 180 / 160°F.
It is recommended that the District consider other ways of reducing energy costs, which may include
energy management, retro-commissioning, energy efficiency upgrades, and other types of renewable
energy.
Statement of Purpose
Since 2008, the Alaska State Legislature has supported renewable electric and thermal energy projects
through the Renewable Energy Grant Recommendation Program, administered by the Alaska Energy
Authority. In Round 6 of the Program, the Interior Regional Housing Authority, which seeks
opportunities to promote community self-sufficiency through community energy projects, received
money to complete pre-feasibility studies of biomass heat in community buildings in seven villages. The
following pre-feasibility study has been funded through that grant.
Page 5 of 16
Community & Facility Information
The Organized Village of Grayling (population 188) is an Alaska Native community located in Interior
Alaska on the west bank of the Yukon River, east of the Nulato Hills. It is 18 air miles north of Anvik.
Grayling transportation facilities include cargo barge access and gravel airstrip. Grayling has a 4,000’ x
75’ gravel runway.
The Iditarod Area School District (IASD) owns and operates the David Louis Memorial School. The David
Louis Memorial School was selected for pre-feasibility assessment because it is the largest heat load in
the community, and the School Board has expressed interest in biomass heat systems.
The School District is governed by a School Board and managed by a Superintendent. The maintenance
department of led by the Head of Maintenance, Steve Graham.
Fuel is purchased by IASD in Grayling for $3.69 per gallon (See Appendix B). Delivery is by barge.
The current going rate for cordwood is $375 per cord (public meeting discussion, May 14, 2014).
Electricity is 64.38 cents per kWh, delivered from the AVEC power plant in the Organized Village of
Grayling (See Appendix B).
Grayling is located on the 100-year floodplain of the Yukon River. The recommended building elevation
is 86.57’. The top of the first step on the David Louis Memorial School is 83.56’. Meeting the
recommended building elevation for the project will require a significant elevated foundation.
The proposed project building is the main school building (“School”) at the David Louis Memorial
School. The David Louis Memorial School includes the School, a generator building, and a teacher
housing duplex. The School was built in 1984 and is about 18,500 ft2. Based on available records and
discussions with maintenance personnel, the School uses about 10,000 gallons of fuel oil #1 per year.
The boilers are turned off during summer. The generator building and teacher housing duplex are
estimated to use 450 and 1,000 gallons per year, respectively (See Appendix B).
A modular boiler room that is located about 20’ east of the School contains the School oil boilers. The
two (2) fuel oil boilers are Burnham V904A, each with 420,000 Btu net output. The hi /lo setting is 180
/160°F.
Heat emitters include baseboard with thermostatic radiator valves, unit heaters, fan convector heaters,
and air handling system (for the gymnasium). The air handling system is turned on manually when gym
activities are underway.
One 80-gallon Amtrol BoilerMate produces domestic hot water from the boilers.
Page 6 of 16
Biomass Resource Availability
This pre-feasibility study was completed simultaneous to a reconnaissance-level biomass resource
assessment by Tanana Chiefs Conference, which will be complete in fall 2014. The draft biomass
resource assessment takes account of biomass stocking by ownership, resource distance from the
Organized Village of Grayling, estimated delivered cost per dry ton, and other factors. In summary,
within a 5-mile radius of the Organized Village of Grayling, there are approximately 617,000 cords of
biomass, with nearly 94% of this material located on Hee-Yea-Lingde Corporation lands. The average
cost per cord within a 5-mile radius of Organized Village of Grayling is $87.76. This figure includes
harvest, stumpage, administration, and transport costs, but does not include the cost of processing logs
into cordwood or profit.
Site Control
The proposed project site is vested in “State of Alaska Department of Education” (Appendix C).
Permitting
Applicable project permitting is considered below:
The Alaska Department of Public Safety, Division of Fire and Life Safety must approve the project
plans before construction is started. Mechanical and electrical review is limited to that which is
necessary to confirm compliance with fire and life safety requirements.
Commercial harvests associated with the project may or may not be required to comply with the
Alaska Forest Practices and Resources Act. While most commercial operations are required to
comply, commercial operations of minor or small scale are sometimes exempted. The Act
addresses forest management along water bodies, erosion mitigation, and reforestation.
The 40CFR63 NESHAP Rule does not apply to the project. The Rule does not apply to a hot water
heater, which is defined in Subpart 6J as a boiler with a heat input capacity is less than 1.6
MMBtu/hr and that does not generate steam.
If State or Federal money is used to construct the project, the Alaska Department of Natural
Resources Office of History and Archaeology, State Historic Preservation Office should review
project plans to determine whether historic, prehistoric, or archaeological resources are likely to
be affected. The Office also offers suggestions to mitigate potential effects on resources.
Page 7 of 16
Proposed Biomass System
The proposed system is 975,000 Btu of cordwood boiler capacity with hydronic heat storage, to be
located in a stand-alone project building on the north side of the School. The proposed site is controlled
by the Iditarod Area School District, has sufficient space for the project, and offers good access to the
School’s boiler room module and other mechanical systems.
Cordwood systems are not very effective when serving building heat systems that operate in a narrow
temperature range, such at 180 /160°F. The project building currently operates in this range, and the
biomass boiler operating and maintenance requirements have been modeled to maintain the existing
temperature set points.
The following assumptions were made for the purpose of completing the pre-feasibility assessment, and
are not a substitute for heat load calculations and boiler sizing to be completed by the project engineer
during project development:
Annual consumption of 10,000 gallons of fuel oil per year, 95% of which serves space heat load,
5% of which serves domestic hot water
Boiler are turned off during summer, from May 20 through August 20
Three (3) 325,000 cordwood boilers with 1,830 gallons of water storage each, delta T = 40°F
Maximum 4 firings per day per boiler, with additional heat demand served by oil. Each firing
requires 20 minutes labor
Annual inflation
o Biomass O&M and scheduled repairs – 1.5%
o Cordwood – 3.0%
o Oil O&M and scheduled repairs – 1.5%
o Oil – 4.8%
Input prices, year 1
o Cordwood -- $375/cord
o Oil -- $3.69/gal
o Loaded labor rate -- $20.17/ hr
The project building cost was modeled as modified conex shipping containers bolted to wood timbers,
as detailed on the Opinion of Probable Cost below. Modifications to the conex are necessary to comply
with the Alaska Department of Public Safety, Life and Fire Safety. The cost of modification has been
included in the Opinion of Probable Cost.
At least one barge company that serves Grayling has confirmed the ability to unload the materials from
the barge and move them to the project site if the total container weight is less than 21,000 lbs.
Page 8 of 16
Alternatives Considered
The David Louis Memorial School teacher housing duplex and generator buildings were not evaluated
for biomass because of their relatively small heat loads. They are located approximately 400’ and 325’
from the School, respectively. These buildings could be economically heated with cordwood stoves.
The existing tribal office building was not evaluated for biomass energy because it has been replaced by
the new Multi-Use Facility, which is outfitted with a cordwood boiler. The new Multi-Use Facility will be
in service in July 2014. According to the Tribal Administrator, there are no plans for the Organized
Village of Grayling to continue to use the existing tribal office building.
The Water Plant was not evaluated for biomass heat because the Alaska Native Tribal Health
Consortium is working with the building owner, the City of Grayling, to develop a recovered heat project
at that site.
The City office building was not evaluated for biomass heat because the anticipated heat load is less
than 1,500 gallons per year, and because the City did not express interest to participate in this
assessment.
Page 9 of 16
Figure 1: Biomass Project Site Map
Page 10 of 16
Heat Load & Biomass Operating Requirements
Figure 2: Fuel Energy Values
Figure 3: Current Annual Fuel Use & Cost
Figure 4: Projected Annual Fuel Use & Cost, Biomass Project
Figure 5: Biomass Stoking Requirements
Gross
Btu/unit
System
efficiency
Delivered
Btu/unit
Gross
$/unit
Delivered
$/MMBtu
Oil (gal)134,500 80%107,600 $ 3.69 34.29$
Biomass, 20% MC* (cord) 16,400,000 65%10,660,000 $ 375 35.18$
*MC is Moisture Content. Moisture in biomass fuel evaporates and absorbs energy in combustion, thereby decreasing the net
energy value of the fuel.
Facility Fuel Oil (gal)$ / gal Annual Fuel
Cost
School 10,000 3.69$ 36,900$
Total 36,900$
15%Oil
85%Biomass
8500 gallons displaced
Facility Fuel Type Units $ / unit Annual Fuel Cost
School Biomass, 20% MC* (cord) 85.8 375$ 32,174$
School Oil (gal)1500 3.69$ 5,535$
Total $ 37,709
Facility Total Stokings per Yr Stoking Hrs
Per Yr $ / hr Annual Stoking
Cost
School 1865 622 20.17$ 12,537$
Page 11 of 16
Figure 6: Biomass O&M Costs (non-stoking)
Boiler size (Btu)
Boiler fuel
Cost of Labor
Cost of Electricity
Number of Stokings
MATERIALS
Yrs to
replacement
Cost per
Lifetime
Lower Gasket 23$ 5 92$
Motor mount 27$ 10 54$
Rear cleanout gasket kit 46$ 10 92$
Manway cover gasket 19$ 10 38$
5" cleaning brush 24$ 5 96$
Motor assembly 518$ 12 863$
3/4 HP motor 353$ 12 588$
Motor mount kit 87$ 12 145$
Motor mount ring & screws 17$ 12 28$
Misc. 250$ 5 1,000$
Anode Rod 98$ 5 392$
Chemicals 250$ 1 5,000$
Total Cost per Lifetime 8,389$
Straight-Line Average Cost per Yr.419$
LABOR Hours labor Yrs to labor
Cost per
Lifetime
Water test and replace 0.50 1 202$
Cleanout covers and heat xger 2 1 807$
Clean blower motor 0.75 0.5 605$
Clean Ash & Combustion Air Intake 0.08 0.05 614$
Check & replace gaskets 3 5 242$
Total Cost per Lifetime 2,469$
Straight-Line Average Cost per Yr.123$
ELECTRICITY Yrs. To Cost
Cost per
Lifetime
Electricity 3/4 HP fan 113$ 1 2,253$
Straight-Line Average Cost per Yr.113$
O&M Cost per Yr per Boiler 656$
No. of Boilers 2
Subtotal 1,311$
Electricity -- pump 490$
Total Annual Biomass O&M (non-stoking)1,801$
975,000
Biomass, 20% MC* (cord)
20.17$
0.65$
1865
Page 12 of 16
Opinion of Probable Cost
Figure 7: Force Account Summary
Site & Foundation Work $16,050
Biomass boiler building $62,447
Biomass heat system $133,640
End-user building integration $9,789
Miscellaneous $8,700
Overhead $24,215
Freight $37,036
CONSTRUCTION SUB-TOTAL $291,877
Design & Construction Admin $25,484
Construction Management $12,742
PROJECT SUB-TOTAL $330,103
Contingency @ 20%$66,021
Admin @ 4%$13,204
TOTAL PROJECT COST $409,328
Page 13 of 16
Figure 8: Force Account Detail
ITEM QUAN UNIT UNIT MATL UNIT LAB LAB LABOR CONTR FREIGHT TOTAL UNIT TOTAL
COST COST HRS HRS RATE COST COST COST COST WT WT(#)
SITE & FOUNDATION WORK
Site prep (layout, excavation, backfill,
compaction, grading)1 lump $5,000 $5,000 0.00 0
Wood timbers -- 8" x 8" x 8' 100 ea $63.00 $6,300 0.50 50.00 $95 $4,750 $11,050 70.00 7000
BIOMASS BOILER BUILDING $0
8 x 8 x 20 shipping container 4 ea $3,000 $12,000 0.00 0.00 $95 $0 $12,000 2500 10000
Man-door w/ hardware 1 ea $780 $780 6.0 6.00 $95 $570 $1,350 75 75
Roof, Metal -- 3' x 10' Delta rib roofing 44 ea.$175 $7,700 1.00 44.00 $95 $4,180 $11,880 96 4224
Roof frame 4 lump $900 $3,600 18.00 72.00 $95 $6,840 $10,440 400 1600
Fasteners 2 lump $250 $500 0 0.00 $95 $0 $500 100 200
Wall insulation 35 ea $170 $5,950 1.5 52.50 $95 $4,988 $10,938 20 700
Roof insulation -- 8 - 12" batt 4 lump $195 $780 5.00 20.00 $95 $1,900 $2,680 96 384
Fire extinguisher 1 lump $250 $250 0.10 0.10 $95 $10 $260 5 5
Conex reinforcement 4 ea $1,200 $4,800 20.00 80.00 $95 $7,600 $12,400 3300 13200
BIOMASS HEAT SYSTEM
Boiler -- GARN 2000 or equivalent 3 ea.$16,000 $48,000 16 48 $95 $4,560 $52,560 3600 10800
Pipe/Valves/Ftgs/Gauges 3 lump $5,000 $15,000 54 162 $100 $16,200 $31,200 800 2400
Circ pump 4 ea.$500 $2,000 4 16 $100 $1,600 $3,600 60 240
Plate HXR, ( 300 MBh @ 20F)2 ea.$2,500 $5,000 2 4 $100 $400 $5,400 250 500
Misc Strut & Pipe Hangers 3 lump $1,000 $3,000 20 60 $95 $5,700 $8,700 500 1500
Tank Insulation 3 lump $1,200 $3,600 3 9 $95 $855 $4,455 50 150
Stack -- 6" dia double wall UL listed +
supporting infrastructure 3 lump $1,700 $5,100 4 12 $95 $1,140 $6,240 3.8 11
Ventilation & Combustion Air Intake 1 lump $1,200 $1,200 3 3 $95 $285 $1,485 50 50
BTU meter 0 ea.$2,500 $0 18 0 $95 $0 $0 0 0
Electrical 1 lump $10,000 $10,000 100 100 $100 $10,000 $20,000 750 750
$0
INTEGRATION $0
Arctic Pipe -- 2" PEX 60 lf $25 $1,500 0.27 16 $95 $1,539 $3,039 1 60
PEX accessories -- 60 1/ft $5 $300 0 0 $95 $0 $300 1 60
Pipe penetration exclosure 2 lump $750 $1,500 5 10 $95 $950 $2,450 200 400
Temp controls 1 lump $750 $750 8 8 $100 $800 $1,550 200 200
Electrical work 1 lump $1,250 $1,250 12 12 $100 $1,200 $2,450 200 200
MISCELLANEOUS
Misc Hardware 1 lump $2,500 $2,500 0 0 $95 $0 $2,500 500 500
Misc Tools & Safety Gear 1 lump $1,500 $1,500 0 0 $95 $0 $1,500 1446 1446
Consumables, Gases, Etc.1 lump $2,000 $2,000 0 0 $95 $0 $2,000 1500 1500
Wood splitter 1 ea $2,700 $2,700 0 0 $95 $0 $2,700 657 657
OVERHEAD
ROW Legal Work 0 lump $0 0
Rent Heavy Equip 1 lump $1,500 $1,500 0
Misc Tool Rent 1 lump $1,250 $1,250 0
Commission System & Training 20 hr 1 20 $90 $1,800 $1,800 0
Superintendent Overhd Off-Site 40 hr 1 40 $90 $3,600 $3,600 0
Superintendent Overhd On-Site 80 hr 1 80 $90 $7,200 $7,200 0
Crew Travel Time 10 hr 1 10 $90 $900 $900 0
Crew Airfares 2 trips $1,050 $2,100 $2,100 0
Crew Per Diem 48 mn.dy.$60 $2,865 $2,865 0
Housing Rent 2 mo.$1,500 $3,000 $3,000 0
FREIGHT 58,812
Ground Freight 10800 lb.$1.24 $13,392
Barge 58812 lb.$0.30 $17,644
Barge Freight Tool Mob & Demob 2 lump $1,500 $3,000
Misc Small Freight & Gold Streaks 1 lump $3,000 $3,000
CONSTRUCTION SUB-TOTAL $149,560 935 $89,566 $15,715 $37,036 $291,877
Engineering (Design & CCA)10 %$25,484
Construction Management 5 %$12,742
PROJECT SUB-TOTAL $149,560 $89,566 53,941$ $37,036 $330,103
Contingency 20 %$66,021
Admin Fee 4 %$13,204
CONSTRUCTION TOTAL $409,328
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Financial Analysis
Financial Summary
The project is considered financially unfeasible at this time.
B/C: n/a
Simple Payback Period: n/a
Net present value: ($527,801)
Benefit/ Cost Model
The following model was designed by University of Alaska Anchorage Institute of Social and Economic
Research, for use by the Alaska Energy Authority. The model has been adapted to the project and
completed according to the aforementioned assumptions.
AEA B/C Model (adapted)
Project Description
Community
Nearest Fuel Community
Region
RE Technology
Project ID
Applicant Name
Project Title
Category
Results
NPV Benefits ($141,971)
NPV Capital Costs $385,830
B/C Ratio (0.37)
NPV Net Benefit ($527,801)
Performance Unit Value
Displaced Petroleum Fuel gallons per year 8,500
Displaced Petroleum Fuel total lifetime gallons 170,000
Avoided CO2 tonnes per year 86
Avoided CO2 total lifetime tonnes 1,726
Proposed System Unit Value
Capital Costs $$409,328
Project Start year 2015
Project Life years 20
Displaced Heat gallons displaced per year 8,500
Heating Capacity Btu/hr 975,000
Heating Capacity Factor %85%
Parameters Unit Value
Heating Fuel Premium $ per gallon
Discount Rate % per year 3%
Crude Oil $ per barrel
Iditarod Area School District
Grayling school_biomass
Grayling
Grayling
Rural
Biomass
Page 15 of 16
Annual Savings (Costs)Units 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034
Project Capital Cost $ per year 409,328$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$
Electric Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Heating Saving (Costs)$ per year ($15,148)($14,822)($14,457)($14,049)($13,596)($13,094)($12,542)($11,935)($11,270)($10,545)($9,754)($8,895)($7,963)($6,954)($5,863)($4,685)($3,416)($2,051)($582)$994
Transportation Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Total Savings (Costs)$ per year ($15,148)($14,822)($14,457)($14,049)($13,596)($13,094)($12,542)($11,935)($11,270)($10,545)($9,754)($8,895)($7,963)($6,954)($5,863)($4,685)($3,416)($2,051)($582)$994
Net Benefit $ per year ($424,475)($14,822)($14,457)($14,049)($13,596)($13,094)($12,542)($11,935)($11,270)($10,545)($9,754)($8,895)($7,963)($6,954)($5,863)($4,685)($3,416)($2,051)($582)$994
Heating Units 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034
Renewable Heat gal. disp./ yr.8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500 8,500
Renewable Heat O&M (non-stoking)$ per yr.1,801$ 1,828$ 1,856$ 1,883$ 1,912$ 1,940$ 1,969$ 1,999$ 2,029$ 2,059$ 2,090$ 2,122$ 2,153$ 2,186$ 2,219$ 2,252$ 2,286$ 2,320$ 2,355$ 2,390$
Renewable Heat -- Stoking $ per yr.12,537$ 12,726$ 12,916$ 13,110$ 13,307$ 13,506$ 13,709$ 13,915$ 14,123$ 14,335$ 14,550$ 14,768$ 14,990$ 15,215$ 15,443$ 15,675$ 15,910$ 16,149$ 16,391$ 16,637$
Renewable Fuel Use Qty (biomass)cords 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8 85.8
Renewable Fuel Cost $ per unit 375$ 386$ 398$ 410$ 422$ 435$ 448$ 461$ 475$ 489$ 504$ 519$ 535$ 551$ 567$ 584$ 602$ 620$ 638$ 658$
Total Renewable Fuel Cost $ per yr.32,174$ 33,139$ 34,133$ 35,157$ 36,212$ 37,299$ 38,417$ 39,570$ 40,757$ 41,980$ 43,239$ 44,536$ 45,872$ 47,249$ 48,666$ 50,126$ 51,630$ 53,179$ 54,774$ 56,417$
Supplemental Fuel Qty (Oil)gal.1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500 1500
Fuel Cost $ per gal.3.69$ 3.87$ 4.05$ 4.25$ 4.45$ 4.66$ 4.89$ 5.12$ 5.37$ 5.63$ 5.90$ 6.18$ 6.48$ 6.79$ 7.11$ 7.45$ 7.81$ 8.19$ 8.58$ 8.99$
Supplemental Fuel Cost $ per yr.5,535$ 5,801$ 6,079$ 6,371$ 6,677$ 6,997$ 7,333$ 7,685$ 8,054$ 8,441$ 8,846$ 9,270$ 9,715$ 10,182$ 10,670$ 11,182$ 11,719$ 12,282$ 12,871$ 13,489$
Proposed Heat Cost $ per yr.52,048$ 53,494$ 54,984$ 56,522$ 58,107$ 59,742$ 61,429$ 63,169$ 64,963$ 66,815$ 68,725$ 70,697$ 72,731$ 74,831$ 76,998$ 79,235$ 81,545$ 83,929$ 86,391$ 88,933$
Fuel Use gal. per yr.10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000
Fuel Cost $ per gal. 3.69$ 3.87$ 4.05$ 4.25$ 4.45$ 4.66$ 4.89$ 5.12$ 5.37$ 5.63$ 5.90$ 6.18$ 6.48$ 6.79$ 7.11$ 7.45$ 7.81$ 8.19$ 8.58$ 8.99$
Fuel Cost $ per yr.36,900$ 38,671$ 40,527$ 42,473$ 44,511$ 46,648$ 48,887$ 51,234$ 53,693$ 56,270$ 58,971$ 61,802$ 64,768$ 67,877$ 71,135$ 74,550$ 78,128$ 81,878$ 85,808$ 89,927$
Base Heating Cost $ per yr.36,900$ 38,671$ 40,527$ 42,473$ 44,511$ 46,648$ 48,887$ 51,234$ 53,693$ 56,270$ 58,971$ 61,802$ 64,768$ 67,877$ 71,135$ 74,550$ 78,128$ 81,878$ 85,808$ 89,927$
Proposed
Base
Page 16 of 16
Sensitivity Analysis
Sensitivity analysis was also performed. All other variables remaining equal, the following fuel variables
results in an economically pre-feasible project.
Recommendations
Biomass heat at the David Louis Memorial School “School” building is considered financially unfeasible
at this time, largely due to the relatively low price of fuel oil that the District is able to negotiate.
Additionally, the U.S. Army Corp of Engineers Recommended Building Elevation in Grayling adds
significant expense to the estimated cost of the building structure.
The project also had challenges with technical feasibility, because the existing heat system operates in a
narrow temperature range, 180 / 160°F. Cordwood systems are not very effective when serving building
heat systems that operate in a narrow temperature range.
It is recommended that the District consider other ways of reducing energy costs, which may include
energy management, retro-commissioning, energy efficiency upgrades, and other types of renewable
energy.
Appendix
A—Biomass Technology
B – Utility Receipts
C – Site Control
D – Site Photos
Fuel Oil Price per Gal, Yr. 1 6.97$
Benefit / Cost 1.25
NPV Net Benefit $94,917
Variable
Results
A-1
Appendix A – Biomass Technology
Although humans have used wood for heat for millennia, modern high-efficiency biomass boilers have
only been in use for a few decades. Biomass boilers may use wood fuels such as cordwood, wood chips,
or wood pellets, to heat commercial buildings. Biomass boiler projects depend on sustainable forest
management, quality biomass fuel sourcing, processing, and storage, and reliable fuel handling. Biomass
boilers frequently integrate with conventional hydronic heat systems, which use water to move heat
from where it is produced to where it is needed. Small-scale biomass systems often incorporate a hot
water storage tank, which promotes efficient combustion and improves the availability of biomass heat.
To provide reliable heat, the biomass boiler, building heat distribution system, controls, and heat
emitters must be properly matched.
Sustainable
Forest
Management
Wood fuel
Processing &
Storage
Handling Combustion Thermal
Storage
Heat
Distribution
The Nature of Wood Fuels
Composition
All wood is made primarily of cellulose, hemi-cellulose, and
lignin. It is about 50% Carbon, 44% Oxygen, and 6% Hydrogen.
Theoretically, complete combustion (100% efficient) would
result in only two products: carbon dioxide and water. In
practice, biomass boilers range from about 77 -- 83% efficient.
Wood that is not completely burned become carbon monoxide
and hydrocarbons, often in the form of smoke and ash.1
Combustion
Biomass fuel undergoes fascinating changes as it burns.
Pyrolysis occurs at 500 – 600°F, in which organic gasses leave
behind charcoal solids. Primary combustion is burning of
charcoal solids.2 Secondary combustion is burning of organic
gasses. Because about 60% of the heating value is contained in
gasses, secondary combustion is essential to high efficiency
wood burning.
1 Rick Curkeet, PE, Wood Combustion Basics, EPA Burnwise Workshop 2011,
http://www.epa.gov/burnwise/workshop2011/WoodCombustion-Curkeet.pdf (June 19, 2014).
2 Curkeet, Rick.
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Emissions
In wood burning, the primary emissions concern is particulate matter 2.5 microns or less in size (“PM
2.5”), which is hazardous to human health. Additionally, unburned wood signifies lost heat and potential
creosote formation. Creosote formation results in higher fuel costs, shortens the life of the boiler, and
increases other maintenance costs. Boiler manufacturers have certified emissions tests conducted
according to the ASTM E2618-13 standard that document boiler efficiency. High efficiency wood boilers
emit about 0.07 – 0.3 lbs of PM 10 per million BTU in test conditions.
Boiler manufacturers specify operating conditions for the field. One important condition is wood fuel
specifications, which include moisture content and fuel dimensions. Other important conditions for
efficient operation include proper fuel storage, routine operations and maintenance, and system design
(such as proper boiler sizing and incorporating a hot water storage tank).
One valuable source of information for seasoning cordwood in Interior Alaska is available at the Cold
Climate Housing Research Center’s (CCHRC) website.3 “Properly prepared and stored” cordwood can be
dry enough to burn safely within six weeks during the summer. In regions other than the Interior, similar
storage principles would apply, but recommended storage durations may be different. Below is a
summary of how to properly prepare and store cordwood:
Cut to stove length (two feet or shorter)
Split the wood at least once
Stack in a pile with air space between the pieces
Store wood in a shed or cover only the top of the pile with a large piece of plywood or some
waterproof tarp
Allow sun and air to reach the sides of the wood pile to help dry the wood
Season at least six weeks during the summer months
If beginning after August 1st, wait to burn until the next summer
When properly stored, more time is always better
Figure 1: Excerpt from CCHRC's Cordwood Handling Brochure
3 http://www.cchrc.org/docs/best_practices/Cordwood_Handling_Brochure.pdf
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Wood Fueled Heating Systems
Below are the characteristics of cordwood, wood chip, and wood pellet boiler systems.
Advantages Disadvantages
Cordwood Local wood resource
Small size (less than 1 MMBTU)
Simple to operate
Higher labor costs, including hand-
feeding the boiler, manual ash
removal, and manual grate
cleaning
Labor is needed intermittently, so
someone must be available “on
site”
Typically non-pressurized, which
may require more frequent boiler
chemical additions
Pellets Can operate unattended, and
automatically match heat load
Scalable from small to large sizes
(generally 100,000 btu – 1
MMBTU)
Relatively small footprint
Typically the most efficient
biomass combustion
Pellet fuel is typically not locally
produced, and therefore depends
on “imports”
Shipping pellets is very costly; even
a freight rate of $0.05 per lb.
results in an additional cost of
$100 per ton.
Relatively expensive wood fuel
Ash removal and grate cleaning
may be automated or manual
Chips Can operate unattended, and
automatically match heat load
Wood chips may be the lowest
cost fuel
Local wood resource may be
available or produced
Large projects achieve economies
of scale
Creates jobs in the woods and at
the boiler plant
Large systems are expensive
Typically large sizes > 1,000,000
MMBTU
Wood chip fuel can be diverse,
which can make it difficult to meet
fuel specifications. Screens and
other devices can improve fuel
quality.
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B – Utility Receipts
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C – Site Control
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Appendix D
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