HomeMy WebLinkAboutShageluk Native Village Biomass Energy Action WynneAuld 10-07-2014-BIO
Shageluk Native Village
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 ................................................................................ 10
Figure 5: Biomass Stoking Requirements & Cost ........................................................................................ 10
Figure 6: Biomass O&M Costs (non-stoking) .............................................................................................. 11
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
Joyanne Hamilton, Principal/ Teacher, Innoko River School
Rebecca Wulf, Tribal Administrator, Shageluk Native Village, and Mayor, City of Shageluk
Russell Snyder, Grants Coordinator, Interior Regional Housing Authority
Steven J. Stassel, P.E., Gray Stassel Engineering
Community Contact Information
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
Iditarod Area School District
Contact: Joyanne Hamilton, Principal/ Teacher, Innoko River School
P. (907) 473-8233
F. (907) 473-8268
innoko_bird@mac.com
Shageluk Native Village Council
Contact: Rebecca Wulf, Tribal Administrator
PO Box 109, Shageluk, AK 99665
P. (907) 473-8239
F. (907) 473-8295
shageluktribe@gmail.com
City of Shageluk
Contact: Rebecca Wulf, Mayor
PO Box 110, Shageluk, AK 99665
P. (907) 473-8221
F. (907) 473-8220
shagelukcity2010@gmail.com
Page 4 of 16
Summary of Findings
The School Board of the Iditarod Area School District (IASD) has expressed interest in assessments to
determine good candidates for biomass heat systems in IASD buildings.
This pre-feasibility assessment considers biomass heat at the main School building of the Innoko River
School, located in Shageluk Native Village. The proposed biomass project would be located inside the
existing Shop building and would heat the Shop and School via a district heat loop. The project would
use an estimated 31 cords per year to displace 3,040 gallons of fuel oil (40% of the buildings’ fuel oil
consumption). 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.
Sensitivity analysis has been performed so that the IASD School Board can review price points of fuel oil
and cordwood at which the proposed project is considered financially pre-feasible.
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. School
maintenance personnel may wish to experiment with broader temperature set points to see if desired
heat output can be maintained with the existing heat system.
It is recommended that IASD 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, 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
Shageluk Native Village (population 76) is an Alaska Native village located on the east bank of the Innoko
River, approximately 20 miles east of Anvik and 34 miles northeast of Holy Cross. The Innoko River is a
tributary of the Yukon River.
Shageluk transportation facilities include cargo barge access, a seaplane base, and gravel airstrip.
Shageluk has a 3,400’ x 75’ gravel runway. Air freight goods are transported by truck, ATV, or snow
machine about four miles from the airstrip to Shageluk Native Village.
The Iditarod Area School District (IASD) owns and operates the project buildings, which comprise the
Innoko River School. Additional buildings that were considered but not evaluated for biomass are
described below.
The Innoko River 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 assessments to determine good
candidates for 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, who
attended the site visit.
Fuel is purchased by IASD in Shageluk for $3.95 per gallon (see Appendix B). Delivery is by barge.
The current going rate for drycordwood is $345 per cord, per the posting at the Shageluk Native Village
office which advertised the purchase of cordwood for elders (May 15, 2014).
Electricity is 66.10 cents per kWh, delivered from the AVEC power plant in Shageuk (see Appendix B).
Shageluk Native Village moved it its present location in 1967. Most of the new community is 20’ or more
above the Innoko River. There is no known flooding at the present townsite.
The Innoko River School is comprised of the main school building (“School”), teacher housing duplex,
Generator Building, Shop, and vocational education building. At about 13,600 ft2, the School is the main
heat load. Both the Generator Building and Shop are heated by a Toyostove.
Based on available records and discussions with maintenance personnel, the School uses an estimated
7,000 gallons of fuel oil #1 per year. The Generator Building and Shop each use an estimated 600 gallons
per year, and the teacher housing duplex uses an estimated 1,000 gallons per year. The vocational
education building uses an estimated 400 gallons per year (see Appendix B).
The School heat system includes two (2) Burnham fuel oil boilers, each with 266,000 Btu net output.
Although the boilers were installed in 2009, the model number was unreadable. The hi /lo setting is 180
/160°F, except during the coldest time of the year when the hi setting is bumped up to 200°F.
Two zones deliver heat to end uses. Zone 1 provides heat to the Kitchen, Gym, Weight Room, and High
School Wing. Zone 2 provides heat to the Boiler Room, Elementary Wing, Bathroom, Attic, Commons,
Office, Library, Pre-K, and Student Store.
Heat emitters include baseboard with thermostatic radiator valves, fan convector heaters, and an air
handling system (for the gymnasium). The air handling system is not operational.
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 Shageluk
Native Village, estimated delivered cost, and other factors. In summary, within a 5-mile radius of
Shageluk Native Village, there are approximately 195,000 cords of biomass, with about 91% of this
material located on Zho-Tse, Incorporated lands. The average cost within a 5-mile radius of Shageluk
Native Village is $84.59 per cord. 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 project site is vested in “SOA Department of Education,” recorded by U.S. Survey 4493. Please see
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
million Btu/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 project configuration is a 325,000 Btu cordwood boiler with hydronic heat storage located
in the existing Shop building. The project would heat the School and Shop via a district heat loop.
The proposed site is controlled by IASD, has sufficient space for the proposed projects, and reduces the
project cost by using existing building space.
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 7,600 gallons of fuel oil #1 per year, 95% of which serves space heat
load, 5% of which serves domestic hot water
One (1) 325,000 cordwood boiler with 1,830 gallons of water storage, delta T = 40°F
Boilers are turned off May 20 – August 20
Maximum 4 firings per day, 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 -- $345/cord
o Oil -- $3.95/gal
o Loaded labor rate -- $20.17/ hr
Page 8 of 16
Alternatives Considered
A stand-alone boiler building at IASD was not considered because of the additional capital cost.
Additional biomass boiler capacity, to offset 85% or more of the heat load at the School, was not
considered because the additional capital cost of a new building was not anticipated to be financially
feasible. The proposed biomass boiler can fit inside the existing Shop.
Heating the Shop and Generator building with a small biomass boiler was briefly considered. These
buildings can be efficiently and cost-effectively heated with large cordwood stoves. Weatherization is
recommended first.
With regard to community buildings outside of the Innoko River School, neither the Washateria nor the
new multi-use facility was evaluated for biomass. These buildings may be good candidates for future
assessment, but at the time of the site visit, City Mayor and Tribal Administrator Rebecca Wulf declined
to participate in the assessment. The City owns and operates the Washateria, and Shageluk Native
Village operates the multi-use facility.
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
Figure 5: Biomass Stoking Requirements & Cost
Gross
Btu/unit
System
efficiency
Delivered
Btu/unit
Gross
$/unit
Delivered
$/MMBtu
Oil (gal)134,500 80%107,600 $ 3.95 36.71$
Biomass, 20% MC* (cord) 16,400,000 65%10,660,000 $ 345 32.36$
*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 + Shop 7,600 3.95$ 30,020$
Total 30,020$
60%Oil
40%Biomass
3040 gallons displaced
Facility Fuel Type Units $ / unit Annual Fuel Cost
School + Shop Biomass, 20% MC* (cord) 30.7 345$ 10,586$
School + Shop Oil (gal)4560 3.95$ 18,012$
Total $ 28,598
Facility Total Stokings per Yr Stoking Hrs
Per Yr $ / hr Annual Stoking
Cost
School + Shop 654 218 20.17$ 4,394$
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 40$ 1 805$
Ave. Cost per Yr. 40$
Straight-Line Average Cost per Yr.583$
Electricity -- pump 420$
Total Annual Biomass O&M (non-stoking)1,003$
325,000
Biomass, 20% MC* (cord)
20.17$
0.66$
654
Page 12 of 16
Opinion of Probable Cost
Figure 7: Force Account Summary
Site & Foundation Work $0
Fire Protection $260
Biomass heat system $55,870
End-user building integration $29,155
Miscellaneous $8,700
Overhead $16,100
Freight $13,013
CONSTRUCTION SUB-TOTAL $123,097
Design & Construction Admin $11,034
Construction Management $4,414
PROJECT SUB-TOTAL $138,546
Contingency @ 20%$27,709
Admin @ 4%$5,542
TOTAL PROJECT COST $171,796
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
FIRE PROTECTION 1 lump $250 $250 0.10 0.10 $95 $10 $260 5 5
BIOMASS HEAT SYSTEM
Boiler -- GARN 2000 or equivalent 1 ea.$16,000 $16,000 16 16 $95 $1,520 $17,520 3600 3600
Pipe/Valves/Ftgs/Gauges 1 lump $5,000 $5,000 54 54 $100 $5,400 $10,400 800 800
Circ pump 1 ea.$500 $500 4 4 $100 $400 $900 60 60
Circ pump 1 ea.$1,000 $1,000 4 4 $100 $400 $1,400 120 120
Plate HXR, ( 300 MBh @ 20F)1 ea.$2,500 $2,500 2 2 $100 $200 $2,700 250 250
Misc Strut & Pipe Hangers 1 lump $1,000 $1,000 20 20 $95 $1,900 $2,900 500 500
Tank Insulation 1 lump $1,200 $1,200 3 3 $95 $285 $1,485 50 50
Stack -- 6" dia double wall UL listed +
supporting infrastructure 1 lump $1,700 $1,700 4 4 $95 $380 $2,080 3.8 4
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 $5,000 $5,000 100 100 $100 $10,000 $15,000 750 750
INTEGRATION
Arctic Pipe -- 2" PEX 408 lf $25 $10,200 0.27 110 $95 $10,465 $20,665 1 408
PEX accessories -- 408 1/ft $5 $2,040 0 0 $95 $0 $2,040 1 408
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 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 20 hr 1 20 $90 $1,800 $1,800 0
Superintendent Overhd On-Site 40 hr 1 40 $90 $3,600 $3,600 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 28 mn.dy.$60 $1,650 $1,650 0
Housing Rent 1 mo.$1,500 $1,500 $1,500 0
FREIGHT 11,908
Ground Freight 3600 lb.$1.24 $4,464
Barge 11908 lb.$0.34 $4,049
Barge Freight Tool Mob & Demob 1 lump $1,500 $1,500
Misc Small Freight & Gold Streaks 1 lump $3,000 $3,000
CONSTRUCTION SUB-TOTAL $59,790 440 $42,295 $8,000 $13,013 $123,097
Engineering (Design & CCA)10 %$11,034
Construction Management 4 %$4,414
PROJECT SUB-TOTAL $59,790 $42,295 23,448$ $13,013 $138,546
Contingency 20 %$27,709
Admin Fee 4 %$5,542
CONSTRUCTION TOTAL $171,796
Page 14 of 16
Financial Analysis
Financial Summary
The project is considered financially unfeasible at this time.
Benefit/ Cost n/a
Simple Payback Period n/a
Net present value ($182,133)
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 ($20,198)
NPV Capital Costs $161,935
B/C Ratio (0.12)
NPV Net Benefit ($182,133)
Performance Unit Value
Displaced Petroleum Fuel gallons per year 3,040
Displaced Petroleum Fuel total lifetime gallons 60,800
Avoided CO2 tonnes per year 31
Avoided CO2 total lifetime tonnes 617
Proposed System Unit Value
Capital Costs $$171,796
Project Start year 2015
Project Life years 20
Displaced Heat gallons displaced per year 3,040
Heating Capacity Btu/hr 325,000
Heating Capacity Factor %40%
Parameters Unit Value
Heating Fuel Premium $ per gallon
Discount Rate % per year 3%
Crude Oil $ per barrel
Iditarod Area School District
Shageluk School and Shop_Biomass
Shageluk
Shageluk
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 171,796$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$
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 ($3,976)($3,798)($3,603)($3,391)($3,159)($2,907)($2,634)($2,338)($2,018)($1,673)($1,301)($900)($470)($8)$488 $1,019 $1,587 $2,195 $2,845 $3,539
Transportation Savings (Costs)$ 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 ($3,976)($3,798)($3,603)($3,391)($3,159)($2,907)($2,634)($2,338)($2,018)($1,673)($1,301)($900)($470)($8)$488 $1,019 $1,587 $2,195 $2,845 $3,539
Net Benefit $ per year ($175,772)($3,798)($3,603)($3,391)($3,159)($2,907)($2,634)($2,338)($2,018)($1,673)($1,301)($900)($470)($8)$488 $1,019 $1,587 $2,195 $2,845 $3,539
Heating Units 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034
Renewable Heat gal. disp./ yr.3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040 3,040
Renewable Heat O&M (non-stoking)$ per yr.1,003$ 1,018$ 1,033$ 1,049$ 1,065$ 1,081$ 1,097$ 1,113$ 1,130$ 1,147$ 1,164$ 1,182$ 1,199$ 1,217$ 1,236$ 1,254$ 1,273$ 1,292$ 1,311$ 1,331$
Renewable Heat -- Stoking $ per yr.4,394$ 4,460$ 4,527$ 4,595$ 4,664$ 4,734$ 4,805$ 4,877$ 4,950$ 5,024$ 5,100$ 5,176$ 5,254$ 5,333$ 5,413$ 5,494$ 5,576$ 5,660$ 5,745$ 5,831$
Renewable Fuel Use Qty (biomass)cords 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7 30.7
Renewable Fuel Cost $ per unit 345$ 355$ 366$ 377$ 388$ 400$ 412$ 424$ 437$ 450$ 464$ 478$ 492$ 507$ 522$ 537$ 554$ 570$ 587$ 605$
Total Renewable Fuel Cost $ per yr.10,586$ 10,904$ 11,231$ 11,568$ 11,915$ 12,273$ 12,641$ 13,020$ 13,411$ 13,813$ 14,227$ 14,654$ 15,094$ 15,546$ 16,013$ 16,493$ 16,988$ 17,498$ 18,023$ 18,563$
Supplemental Fuel Qty (Oil)gal.4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560 4560
Fuel Cost $ per gal.3.95$ 4.14$ 4.34$ 4.55$ 4.76$ 4.99$ 5.23$ 5.48$ 5.75$ 6.02$ 6.31$ 6.62$ 6.93$ 7.27$ 7.61$ 7.98$ 8.36$ 8.76$ 9.19$ 9.63$
Supplemental Fuel Cost $ per yr.18,012$ 18,877$ 19,783$ 20,732$ 21,727$ 22,770$ 23,863$ 25,009$ 26,209$ 27,467$ 28,786$ 30,167$ 31,615$ 33,133$ 34,723$ 36,390$ 38,137$ 39,967$ 41,886$ 43,896$
Proposed Heat Cost $ per yr.33,996$ 35,259$ 36,574$ 37,944$ 39,371$ 40,857$ 42,406$ 44,019$ 45,700$ 47,451$ 49,277$ 51,179$ 53,162$ 55,229$ 57,384$ 59,631$ 61,974$ 64,417$ 66,964$ 69,622$
Fuel Use gal. per yr.7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600 7,600
Fuel Cost $ per gal. 3.95$ 4.14$ 4.34$ 4.55$ 4.76$ 4.99$ 5.23$ 5.48$ 5.75$ 6.02$ 6.31$ 6.62$ 6.93$ 7.27$ 7.61$ 7.98$ 8.36$ 8.76$ 9.19$ 9.63$
Fuel Cost $ per yr.30,020$ 31,461$ 32,971$ 34,554$ 36,212$ 37,950$ 39,772$ 41,681$ 43,682$ 45,779$ 47,976$ 50,279$ 52,692$ 55,221$ 57,872$ 60,650$ 63,561$ 66,612$ 69,809$ 73,160$
Base Heating Cost $ per yr.30,020$ 31,461$ 32,971$ 34,554$ 36,212$ 37,950$ 39,772$ 41,681$ 43,682$ 45,779$ 47,976$ 50,279$ 52,692$ 55,221$ 57,872$ 60,650$ 63,561$ 66,612$ 69,809$ 73,160$
Proposed
Base
Page 16 of 16
Sensitivity Analysis
Sensitivity analysis was also performed. All other variables remaining equal, the following variable
results in an economically feasible project.
Sensitivity analysis was also performed for the price of cordwood. If the project owner can source fuel at
$125 per cord, as the Tanana Chiefs Conference reconnaissance-level biomass resource assessment
suggests, the following variable fuel oil price results in an economically feasible project.
Recommendations
Biomass heat at the Innoko River School “School” and Shop building 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.
If the price of fuel oil reaches $7.22 per gallon, the project may be considered financially pre-feasible, all
other variables remaining equal.
If the project owner can source cordwood at $125 per cord per year or less, as the Tanana Chiefs
Conference reconnaissance-level biomass resource assessment suggests, the project may be considered
financially pre-feasible if the price of fuel oil reaches $5.35 per gallon or more.
The project also has challenges with technical feasibility, because the existing heat system operates in a
narrow temperature range, 180 /160°F. Cordwood systems are not very effective when serving building
heat systems that operate in a narrow temperature range. The School maintenance personnel may wish
to experiment with broader temperature set points to see if desired heat output can be maintained with
the existing heat system. The operations and economics of the project will improve if the system can
operate in a broader temperature range.
It is recommended that the IASD consider other ways of reducing energy costs, which may include
energy management, retro-commissioning, energy efficiency upgrades, and other types of renewable
energy.
Appendix
A—Biomass Technology
B – Utility Receipts
C – Site Control
D – Site Photos
Fuel Oil Price per Gal, Yr. 1 7.22$
Benefit / Cost 1.25
NPV Net Benefit $39,901
Variable
Results
Cordwood, $ / cord, Yr. 1 125$
Fuel Oil Price per Gal, Yr. 1 5.35$
Benefit / Cost 1.25
NPV Net Benefit $40,192Results
Variable
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.
A-2
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
A-3
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.
B-1
B – Utility Receipts
C-1
C – Site Control
D-1
Appendix D
D-2
D-3
D-4
D-5
D-6
D-7
D-8
D-9