HomeMy WebLinkAboutChistochina Central Wood Heating Preliminary Economic Study - Sep 2008 - REF Grant 2195380CHEESH’NA TRIBAL COUNCIL
Community Facilities
Central Wood Heating:
Preliminary Economic Study
Prepared By:
CE2 Engineers, Inc.
Anchorage, Alaska
September 2008
Cordwood Fuel in
Wood-Fired Hydronic
Heater
Ionia, Alaska
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
September 2008 i CE2 Engineers, Inc.
TABLE OF CONTENTS
INTRODUCTION ............................................................................................................. 1
WOOD-FIRED HYDRONIC HEATER SYSTEM DESCRIPTION .................................... 1
DESIGN ASSUMPTIONS ............................................................................................... 2
ECONOMIC ANALYSIS METHODOLOGY ..................................................................... 3
RESULTS OF ECONOMIC ANALYSIS ........................................................................... 4
PRESENT VALUE OF COSTS ....................................................................................... 6
DISCUSSION AND CONCLUSIONS .............................................................................. 7
APPENDICES
A: Cost Analysis Spreadsheet For 5% Annual Oil Cost Increase
B: Cost Analysis Spreadsheet For 10% Annual Oil Cost Increase
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
September 2008 1 CE2 Engineers, Inc.
INTRODUCTION
The State of Alaska Energy Authority – Rural Energy Group (AEA/REG) requested CE2
Engineers, Inc. (CE2) to perform a simplified economic analysis for comparing the cost
of heating five Cheesh’na Tribal Council community buildings at Chistochina Village with
fuel oil versus locally obtained firewood. The five buildings are:
The proposed Washeteria/Water Plant (Construction planned in 2009)
The Library
The existing Community Hall
The existing Tribal Office
The proposed Clinic/Multi-Use Facility (construction planned in 2009)
This report will examine a scenario for using firewood to heat the facilities. Several key
assumptions were made in this analysis:
A central wood heating system was planned to meet the buildings’ heating
needs, with the existing heating oil system serving as a backup.
A cordwood-fired system was selected, which could be switched out to a bulk
biomass fuel system at a later date if the market for bulk biomass fuel develops.
WOOD-FIRED HYDRONIC HEATER SYSTEM DESCRIPTION
The wood-fired hydronic heater would be set up in a separate building, and would
consist of two Garn® Model 3200 wood-fired heaters, with a total water capacity of
6,400 gallons. This boiler is sized to provide 60% of the peak building load with a six-
hour interval between firings. The water capacity of the boiler is sized so that it would
serve as a thermal storage bank for the facility, and would require intermittent firing. In
this configuration, it is anticipated that the wood-fired boiler would meet 85% of the
buildings’ heating needs.
The boiler would be connected to the separate buildings with buried, insulated piping
and would interface with the intended heating systems through a heat exchanger. This
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
September 2008 2 CE2 Engineers, Inc.
arrangement would transfer heat with separate building and wood heating system
hydronic heating fluids, so as to prevent a catastrophic failure in the building heating
system due to a piping break inside or outside the building envelope.
DESIGN ASSUMPTIONS
Based upon existing site data, the following parameters were established for this
analysis:
Heating index was determined to be 14,000 °F Days, based upon weather data
from the Gulkana Airport.
97.5% Design Temperature: -45.7°F.
Fuel oil consumption for the existing and proposed buildings was estimated at
16,000-gallons of #1 heating oil.
Fuel oil heating value is 134,000-BTU/gallon.
Efficiency for the oil-fired boilers is set at 77%.
The cost of fuel oil is based upon delivered fuel oil to the Cheesh’na Tribal
Council, and is presently $4.57/gallon. The annual increase in fuel oil cost was
set at 5%. The price of fuel oil is difficult to predict, due to the volatility of crude
oil prices in the world market. For the purposes of this study, a 5% annual
increase in fuel oil cost was considered conservative, and would not skew the
results toward wood heat. A 10% increase scenario was also calculated and is
included in Appendix B.
The current cost of electricity paid by the Cheesh’na Tribal Council was
determined to be 68.52 cents per kilowatt-hour.
Cordwood was considered to be all spruce, 30% moisture content, by wet basis,
which is achievable by air-drying a year ahead. The net wood energy content is
8100 BTU/lb, or 16.16 million BTU/cord, wet basis.
The cost of cordwood was set at $200/cord, based upon conversations with local
woodcutters. The cost increase for cordwood was set at 3.5% per year, which is
about 1% above the present inflation rate of 2.5%.
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The wood-fired boilers would be fired to 200°F and drawn down to 150°F before
refiring.
Storage capacity of the wood-fired boiler system was set at 6-hours at a 60% of
peak building load.
Wood-fired boiler efficiency was set at 75%, which was based upon actual testing
of Garn® boilers.
The wood heating season was set at 8 months.
Labor for stoking was figured at 2 hr/day for 5 days/week and 1 hr/day on
Saturdays and Sundays, for a total of 415-hr stoking per heating season.
Contract labor rate for stoking was set at $20/hr, which would follow the inflation
rate of 2.5% per annum.
For economic analysis, the real interest rate was set at 3%.
ECONOMIC ANALYSIS METHODOLOGY
A Microsoft Excel spreadsheet was developed to compare the cost of oil heat versus
wood heat. A copy of the spreadsheet, using a conservative 5% annual fuel cost
escalation factor, is shown in Appendix A. Steps in the analysis were as follows:
1. Based upon annual fuel oil use, heating index, boiler efficiency, and fuel cost, it
was determined that the net amount of heat needed was 1,651-million BTU/year.
2. 80% to 90% of this heat at 60% peak load would be provided by cordwood. At a
boiler efficiency of 75%, this translated to 136 cords of wood per year, or
approximately 199 green tons of cordwood.
3. This would require about 909 stokings per year for the wood-fired boilers.
4. Electricity cost for running the wood-fired boiler combustion air fans was
calculated to be $873/year.
5. O&M cost of $600/year was estimated for firebrick replacement.
6. The spreadsheet was used to compare 2008 values of costs on a 20-year
horizon.
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7. Fuel costs per million BTU were compared for fuel oil and cordwood.
8. The present value of oil heat vs. wood heat was compared over a 5-, 10-, and
20-year span.
9. Net boiler output vs. stoking intervals was analyzed to see how they varied over
heat output rates.
RESULTS OF ECONOMIC ANALYSIS
Operating costs for oil heat and wood heat are compared in Table 1, below.
Table 1 – Comparison of Operating Costs for Oil Heat and Wood Heat
Wood Heat System Oil Heat System Oil Heat Wood Heat Annual
Savings
using
Wood Heat
Labor Wood O& M Fuel Oil Fuel Oil O&M $4.57/gal $200/cord
Cost Cost Cost Cost Cost N/A Cost/Yr Cost/Yr
Year ($2008) ($2008) ($2008) ($2008) ($2008) ($2008)($2008) ($2008) ($2008)
2008 $8,304 $23,171 $1,473 $10,968 $73,120 $0 $73,120 $43,915 $29,205
2009 $8,512 $23,982 $1,509 $11,516 $76,776 $0 $76,776 $45,519 $31,257
2010 $8,724 $24,821 $1,547 $12,092 $80,615 $0 $80,615 $47,185 $33,430
2011 $8,942 $25,690 $1,586 $12,697 $84,646 $0 $84,646 $48,915 $35,731
2012 $9,166 $26,589 $1,626 $13,332 $88,878 $0 $88,878 $50,712 $38,166
2013 $9,395 $27,519 $1,666 $13,998 $93,322 $0 $93,322 $52,579 $40,743
2014 $9,630 $28,483 $1,708 $14,698 $97,988 $0 $97,988 $54,519 $43,469
2015 $9,871 $29,479 $1,751 $15,433 $102,887 $0 $102,887 $56,534 $46,353
2016 $10,118 $30,511 $1,794 $16,205 $108,032 $0 $108,032 $58,628 $49,404
2017 $10,371 $31,579 $1,839 $17,015 $113,433 $0 $113,433 $60,804 $52,629
2018 $10,630 $32,684 $1,885 $17,866 $119,105 $0 $119,105 $63,065 $56,040
2019 $10,896 $33,828 $1,932 $18,759 $125,060 $0 $125,060 $65,415 $59,645
2020 $11,168 $35,012 $1,981 $19,697 $131,313 $0 $131,313 $67,858 $63,455
2021 $11,447 $36,238 $2,030 $20,682 $137,879 $0 $137,879 $70,397 $67,482
2022 $11,733 $37,506 $2,081 $21,716 $144,773 $0 $144,773 $73,036 $71,736
2023 $12,027 $38,819 $2,133 $22,802 $152,011 $0 $152,011 $75,780 $76,231
2024 $12,327 $40,178 $2,186 $23,942 $159,612 $0 $159,612 $78,633 $80,979
2025 $12,636 $41,584 $2,241 $25,139 $167,592 $0 $167,592 $81,599 $85,993
2026 $12,951 $43,039 $2,297 $26,396 $175,972 $0 $175,972 $84,683 $91,289
2027 $13,275 $44,546 $2,354 $27,716 $184,771 $0 $184,771 $87,891 $96,880
$214,131 $657,265 $39,627 $364,675 $2,419,791 $2,419,791 $1,269,675 $1,152,124
In the first year, the cost of wood heat is approximately 60% of oil heating costs (for
2008: $43,915 wood / $73,120 oil), so the net savings is about 40% for 2008. As the
cost of oil heat climbs more rapidly than wood heat, the savings become significantly
larger. In Year 2027, the cost of wood heat is approximately 48% of the cost for oil
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
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heating (for 2027: $87,891 wood / $184,771 oil), so the net savings climbs to
approximately 52% for 2027. Note that the increase in cost for oil is very conservatively
set at 5% per year for this study, and the increase in cost for cordwood is set at 3.5%
per year.
A graphical view of costs of oil heat versus wood heat is seen below, using an annual
fuel oil cost increase of 5%.
Figure 1 – Annual Operating Costs for Oil Heat and Wood Heat
With a 5% Annual Oil Cost Increase
$0
$20,000
$40,000
$60,000
$80,000
$100,000
$120,000
$140,000
$160,000
$180,000
$200,000
Oil Heat vs. Wood Heat Annual Costs ($2008 dollars)
Oil Heat $4.57/gal
Wood Heat $200/cord
A scenario was also run using an annual oil cost increase of 10%. A graphical view of
costs of oil heat versus wood heat using the 10% increase is shown in Figure 2, on the
next page.
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
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Figure 2 – Annual Operating Costs for Oil Heat and Wood Heat
With a 10% Annual Oil Cost Increase
Oil Heat vs. Wood Heat Annual Costs ($2008 dollars)
$0
$50,000
$100,000
$150,000
$200,000
$250,000
$300,000
$350,000
$400,000
$450,000
$500,000
20082009201020112012201320142015201620172018201920202021202220232024202520262027Oil Heat $4.57/gal
Wood Heat $200/cord
Wood heat costs for the first year were 60% of the oil heating costs. With a 10% cost
increase in oil, the savings get dramatic. After 10 years, wood heat is 39% of oil heat
cost. After 20 years, wood heat is only 28% of the oil heat cost.
PRESENT VALUE OF COSTS
The present value of costs of oil and wood heat was compared over a 5-, 10-, and 20-
year span. Table 2, below, shows these costs.
Table 2 – Present Value of Costs for Oil and Wood-Fired Heating Systems
5% Annual Oil Cost Increase
Present value of costs
20-year 10-year 5-year
Oil Heat $1,714,908 $775,257 $369,006
Wood System $909,850 $439,096 $215,928
Wood Costs/Oil Costs 53% 57% 59%
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
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As shown in Table 2, the cost of wood heat becomes more favorable the longer the time
horizon, from 41% savings in a 5-year horizon to 47% in a 20-year horizon.
A scenario was also run on the spreadsheet using an annual increase of 10% for fuel oil
cost. The present value of costs is shown in Table 3, below.
Table 3 – Present Value of Costs for Oil and Wood-Fired Heating Systems
10% Annual Oil Cost Increase
Present value of costs
20-year 10-year 5-year
Oil Heat $2,846,304 $971,439 $406,589
Wood System $1,079,559 $468,524 $221,565
Wood Costs/Oil Costs 38% 48% 54%
As shown in Table 3, the cost of wood heat becomes more favorable the longer the time
horizon, from 46% savings in a 5-year horizon to 62% savings in a 20-year horizon. A
copy of the spreadsheet analysis using the 10% cost escalation factor is provided in
Appendix B.
DISCUSSION AND CONCLUSIONS
Using cordwood and hand stoking a wood-fired boiler system at the Cheesh’na Tribal
Council building facilities appears to be an economically viable alternative to the existing
system of oil-fired boilers and oil furnaces.
For wood heat, labor costs are approximately 19% of the wood heat costs. This is
inherent in the proposed system using a manually stoked wood-fired boiler. Some
automation could be done in the firebox loading process, which could reduce this labor
cost. More highly automated systems of loading and firing, such as automatic wood
stokers with chip systems could be considered, but choices of wood firing method then
become differences in philosophy; automation versus complexity of operation, and must
be explored separately.
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
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Capital costs have not been considered at this stage of analysis. The cost of the
heating plant will have to be considered, and this will vary by how much wood is to be
stored on-site under a roof. A heating plant with a one-month supply of wood will cost a
lot less than a heating plant with a 1-year supply of wood on site.
For wood to be a viable source of heat, it will have to be dried to about 30% moisture
content, which is a realistic level. Higher moisture content drives up the net cost of wood
heat considerably, making it less attractive as an alternative heat source to oil, as a
significant amount of the wood burned is used to drive out the moisture.
Depending upon the time horizon examined, wood heat will save 48% to 52% of the
normal operating costs of oil heat at the facility, assuming a very conservative 5%
annual increase in the cost of oil. This is a significant savings for the Cheesh’na Tribal
Council, and would greatly decrease its exposure to the uncertainties of heating oil
prices. It would also circulate money inside the community, which would provide
increased employment and revenue to citizens and local wood supply contractors.
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
September 2008 CE2 Engineers, Inc.
APPENDICES
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
September 2008 CE2 Engineers, Inc.
Appendix A
Cost Analysis Spreadsheet For 5% Annual Oil Cost Increase
CHISTOCHINA CLINIC, WASHETERIA, AND WATER TREATMENT PLANT BUILDINGSWOOD HEAT ANALYSIS USING 5% ANNUAL FUEL COST ESCALATIONWood-Fired Hydronic Heater Simple Economic AnalysisWood Heat Data:flu temp 270 FAverage MC30%amb temp70FFuel Oil Data:Cost of wood:$200/cord$/cord1 cord =100 Cubic Ft SWEApprox. Annual Fuel Cons:16,000gallons 1 Cubic Ft SWE: 30.5 OD lbsEst'd Recovered Heat Avail:0gallons Wood Energy Content: 8100 Btu/lb (OD)Net Annual Fuel Consump:16,000gallons Wood used per year: 136 cordsFuel Energy Content: 134,000Btu/gallon #1Wood used per year: 87 (BDT)Cost of Oil$4.57/gal$/gallon Btu/lb wood @ MC: 30.0%5295Btu/lbTotal Annual Cost of Heat $73,120 per yearNet Annual Cost of Oil: $73,120 per year cost of oil usedCost of wood: $27,260$/YearTotal Annual Energy Use: 2,144 MMBtu/year Annual Wood Energy Use: 2,201 MMBtu/year - Gross into BurnerNet Annual Oil Energy Use: 2,144 MMBtu/yrnet of Recvd HtWood Boiler Efficiency75%Oil Boiler Efficiency77%Wood Energy Content: 16.15 MMBtu/cord - wet basisNet Annual Oil Boiler Output: 1,651 MMBtu/year Wood Weight at MC: 30.0% 1.46 tons/green cordWood Weight at MC: 30.0% 199 green tons/yearHeating Degree Days:14000F-Days/yr97.5% Design Temp:-45.7FQ peak: (NET into water) 544 MBh Based on HDD and Approx. Annual Fuel Consumption0.6 x Q peak: (into water) 326 MBh Estimate 80% - 90% of Fuel Oil Saved at 60% of Peak LoadQ from Recvd Heat:0MBh From HRU.XLS spreadsheetWood Boiler System:326MBh Wood Boiler Peak Heat into waterMax Storage Temp:200F Assume 200F is maximum Storage water temperatureMin Storage Temp:150F Assume 150F is minimum useable heating temperatureDelta-T 50 FStorage Capacity:6HrsTime to lower Storage Capacity (gals) by50FQty of wood Req'd:0.20 cordsQty Wood to raise Storage Capacity by50F 326 outputStorage Capacity Req'd:4696GalsAt326MBh for6hrsTotal Btu's Stored:1958MBh NOTE: About .15 cords will fit into the fire box based on 0.15cords/stokeGross Btu's (Into firebox):2422MBtu fire box volume of 38 cu. ft. and cord volume of 4' x 4' x 8'Wood System Operation Burn Time (hr) 2 HrNumber of Boilers:2GARNsWood Burner Output:908MBh - into waterBoiler InputBoiler OutputAnnual Wood Energy Use: 2,201 MMBtu/year (into Burner)Fuel Oil 34.10$ $/MMBtu $44.29 $/MMBtu Boiler energy input/stoking: 2.4 MMBtu/stoking into burner/GARNWood 12.38$ $/MMBtu $16.51 $/MMBtu # Stokings/year 909 # Stokings/year (total) Months/year8approx. Manhours/stoking: 0.18hrs/stokingPER GARN (not used directly) Manhours/year:415(see stoking labor section below)Present value of costs Cost of labor ($/hr)1.17OH Rate (Not used) 20-year10-year5-year Cost of labor ($/hr)$20.00(contract labor) Oil Heat $1,714,908 $775,257 $369,006 Cost/yr contract worker $8,304Wood System $909,850 $439,096 $215,928 Electric Blower Energy:0.75HP /GARN Wood Costs/Oil Costs 53% 57% 59%Page 1 of 3 9/26/2008
CHISTOCHINA CLINIC, WASHETERIA, AND WATER TREATMENT PLANT BUILDINGSWOOD HEAT ANALYSIS USING 5% ANNUAL FUEL COST ESCALATION Fan Runtime:2.5hrs/firing assume 30 minutes longer than wood takes to burn Energy Consumption: 1.4 kWh/firing/GARN Cost of Electricity:$0.686per kWhOil Heat Wood HeatLabor Wood O& M Fuel Oil Fuel Oil O&M$4.57/gal $200/cord Fan Energy Cost: $873Total all units Cost Cost Cost Cost Cost N/ACost/Yr Cost/YrWood Sys Maintenance Year($2008)($2008)($2008)($2008)($2008)($2008)($2008)($2008)($2008) Fire brick cost$6002008 $8,304 $23,171 $1,473 $10,968 $73,120 $0 $73,120 $43,915 $29,205Total O&M Cost: $1,4732009 $8,512 $23,982 $1,509 $11,516 $76,776 $0 $76,776 $45,519 $31,2572010 $8,724 $24,821 $1,547 $12,092 $80,615 $0 $80,615 $47,185 $33,430Wood Equipment Cost$02011 $8,942 $25,690 $1,586 $12,697 $84,646 $0 $84,646 $48,915 $35,731Heat Load met by GARN85%2012 $9,166 $26,589 $1,626 $13,332 $88,878 $0 $88,878 $50,712 $38,1662013 $9,395 $27,519 $1,666 $13,998 $93,322 $0 $93,322 $52,579 $40,743Oil system O&M cost /yr*$02014 $9,630 $28,483 $1,708 $14,698 $97,988 $0 $97,988 $54,519 $43,469* Note: Sunk cost, not included in comparison 2015 $9,871 $29,479 $1,751 $15,433 $102,887 $0 $102,887 $56,534 $46,353Real Interest rate:3.00%2016 $10,118 $30,511 $1,794 $16,205 $108,032 $0 $108,032 $58,628 $49,4042017 $10,371 $31,579 $1,839 $17,015 $113,433 $0 $113,433 $60,804 $52,629Real Fuel Oil Price Increase:5.00%2018 $10,630 $32,684 $1,885 $17,866 $119,105 $0 $119,105 $63,065 $56,040Real Wood Price Increase:3.50%2019 $10,896 $33,828 $1,932 $18,759 $125,060 $0 $125,060 $65,415 $59,645Rate of Inflation:2.50%2020 $11,168 $35,012 $1,981 $19,697 $131,313 $0 $131,313 $67,858 $63,4552021 $11,447 $36,238 $2,030 $20,682 $137,879 $0 $137,879 $70,397 $67,4822022 $11,733 $37,506 $2,081 $21,716 $144,773 $0 $144,773 $73,036 $71,7362023 $12,027 $38,819 $2,133 $22,802 $152,011 $0 $152,011 $75,780 $76,2312024 $12,327 $40,178 $2,186 $23,942 $159,612 $0 $159,612 $78,633 $80,9792025 $12,636 $41,584 $2,241 $25,139 $167,592 $0 $167,592 $81,599 $85,9932026 $12,951 $43,039 $2,297 $26,396 $175,972 $0 $175,972 $84,683 $91,2892027 $13,275 $44,546 $2,354 $27,716 $184,771 $0 $184,771 $87,891 $96,880GIVEN: $214,131 $657,265 $39,627 $364,675 $2,419,791 $2,419,791 $1,269,675 $1,152,124Number of Boilers: 2 EAGARN Model No.: 3200 6,400 Gallons total boiler volumeMax Boiler Temp 200 FMin Boiler Temp 150 FBuilding Heat Required (MBh) 326MBh - into waterGross Wood Btu's/Stoking (MBtu):4,845 MBtu - Gross wood energyGross Wood Btu's/hr (MBH):2,422 MBh - GrossTime to burn out one Stoking (Hr): 2.0 Hr - burn time check, compare to cell B33Net Wood Burner ouput/hr (MBH):1,816.8MBh - into waterPeak+200M btu/hrPeak + 100 M btu/hrPeak btu/hrPeak-100M btu/hrPeak-200Mbtu/hrNET Boiler Output (MBh)744 644 544 444 344BOILER FIRING INTERVALTime to Heat (Hr)2.5 2.3 2.1 1.9 1.8Stokings Req'd (Firings)1.2 1.1 1.0 1.0 0.9Time to Cool (Hr)3.6 4.1 4.9 6.0 7.8Time to Heat + Cool (Hr)6.1 6.4 7.0 8.0 9.6Avg Stoking Interval (Hr)4.9 5.6 6.7 8.2 10.6Wood Heat System Oil Heat SystemAnnual Savings using Wood HeatPage 2 of 3 9/26/2008
CHISTOCHINA CLINIC, WASHETERIA, AND WATER TREATMENT PLANT BUILDINGSWOOD HEAT ANALYSIS USING 5% ANNUAL FUEL COST ESCALATIONSTOKING LABORHeating season 8 mo x 4.33 wk/mo = 34.6 weeksWeekday stoking labor 2 hr/d x 5 d/wk x 34.6 wk =346.0 hr/heating seasonSaturday stoking labor 1 hr/d x 1 d/wk x 34.6 wk =34.6 hr/heating seasonSunday stoking labor 1 hr/d x 1 d/wk x 34.6 wk =34.6hr/heating seasonTotal Stoking Labor Time 415.2 hr/heating seasonASSUMPTIONSNOTES4. Firing rates are based upon using 2 each Garn 3200 boiler (6400 gal water capacity).1. Labor time can be significantly reduced by use of equipment, such as a skid steer loader to help position pallets or skids of firewood for stoking.7. Wood fuel cost is expected to rise at a lower rate than that of fuel oil. In this case, it has been fixed at 1% above the rate of inflation, or 3.5% per annum in this analysis.8. Wood fuel is assumed to replace 85% of the oil consumption at the facility.2. There should be a year's worth of wood on hand to ensure the 30% moisture content. The moisture content of wood fuel up to 40% can drive up the equivalent cost of wood significantly.5. Firewood is assumed to be all local spruce, dried to 30% moisture content.6. Firewood is assumed to be 100 cu ft per cord, which includes cordwood bark.3. Labor rate is based upon an estimated rate of $20/hour, with 2 hr/day stoking on weekdays, 1 hr/day on Saturdays, and 1 hr/day on Sundays.2. Wood price estimate is from discussions with local consumers. Going rate is estimated at $200/cord. The village can get cordwood from Ahtna, Inc. land holdings.1. Fuel oil cost is based upon September 2008 price of #1 heating oil that the community received from Fisher's Fuel, Inc.Oil Heat vs. Wood Heat Annual Costs ($2008 dollars)$0$20,000$40,000$60,000$80,000$100,000$120,000$140,000$160,000$180,000$200,00020082009201020112012201320142015201620172018201920202021202220232024202520262027Oil Heat $4.57/galWood Heat $200/cordPage 3 of 3 9/26/2008
Cheesh’na Tribal Council Central Wood Heating Preliminary Economic Study
September 2008 CE2 Engineers, Inc.
Appendix B
Cost Analysis Spreadsheet With 10% Annual Oil Cost Increase
CHISTOCHINA CLINIC, WASHETERIA, AND WATER TREATMENT PLANT BUILDINGSWOOD HEAT ANALYSIS USING 10% ANNUAL FUEL COST ESCALATIONWood-Fired Hydronic Heater Simple Economic AnalysisWood Heat Data:flu temp 270 FAverage MC30%amb temp70FFuel Oil Data:Cost of wood:$200/cord$/cord1 cord =100 Cubic Ft SWEApprox. Annual Fuel Cons:16,000gallons 1 Cubic Ft SWE: 30.5 OD lbsEst'd Recovered Heat Avail:0gallons Wood Energy Content: 8100 Btu/lb (OD)Net Annual Fuel Consump:16,000gallons Wood used per year: 136 cordsFuel Energy Content: 134,000Btu/gallon #1Wood used per year: 87 (BDT)Cost of Oil$4.57/gal$/gallon Btu/lb wood @ MC: 30.0%5295Btu/lbTotal Annual Cost of Heat $73,120 per yearNet Annual Cost of Oil: $73,120 per year cost of oil usedCost of wood: $27,260$/YearTotal Annual Energy Use: 2,144 MMBtu/year Annual Wood Energy Use: 2,201 MMBtu/year - Gross into BurnerNet Annual Oil Energy Use: 2,144 MMBtu/yrnet of Recvd HtWood Boiler Efficiency75%Oil Boiler Efficiency77%Wood Energy Content: 16.15 MMBtu/cord - wet basisNet Annual Oil Boiler Output: 1,651 MMBtu/year Wood Weight at MC: 30.0% 1.46 tons/green cordWood Weight at MC: 30.0% 199 green tons/yearHeating Degree Days:14000F-Days/yr97.5% Design Temp:-45.7FQ peak: (NET into water) 544 MBh Based on HDD and Approx. Annual Fuel Consumption0.6 x Q peak: (into water) 326 MBh Estimate 80% - 90% of Fuel Oil Saved at 60% of Peak LoadQ from Recvd Heat:0MBh From HRU.XLS spreadsheetWood Boiler System:326MBh Wood Boiler Peak Heat into waterMax Storage Temp:200F Assume 200F is maximum Storage water temperatureMin Storage Temp:150F Assume 150F is minimum useable heating temperatureDelta-T 50 FStorage Capacity:6HrsTime to lower Storage Capacity (gals) by50FQty of wood Req'd:0.20 cordsQty Wood to raise Storage Capacity by50F 326 outputStorage Capacity Req'd:4696GalsAt326MBh for6hrsTotal Btu's Stored:1958MBh NOTE: About .15 cords will fit into the fire box based on 0.15cords/stokeGross Btu's (Into firebox):2422MBtu fire box volume of 38 cu. ft. and cord volume of 4' x 4' x 8'Wood System Operation Burn Time (hr) 2 HrNumber of Boilers:2GARNsWood Burner Output:908MBh - into waterBoiler InputBoiler OutputAnnual Wood Energy Use: 2,201 MMBtu/year (into Burner)Fuel Oil 34.10$ $/MMBtu $44.29 $/MMBtu Boiler energy input/stoking: 2.4 MMBtu/stoking into burner/GARNWood 12.38$ $/MMBtu $16.51 $/MMBtu # Stokings/year 909 # Stokings/year (total) Months/year8approx. Manhours/stoking: 0.18hrs/stokingPER GARN (not used directly) Manhours/year:415(see stoking labor section below)Present value of costs Cost of labor ($/hr)1.17OH Rate (Not used) 20-year10-year5-year Cost of labor ($/hr)$20.00(contract labor) Oil Heat $2,846,304 $971,439 $406,589 Cost/yr contract worker $8,304Wood System $1,079,559 $468,524 $221,565 Electric Blower Energy:0.75HP /GARN Wood Costs/Oil Costs 38% 48% 54%Page 1 of 3 9/26/2008
CHISTOCHINA CLINIC, WASHETERIA, AND WATER TREATMENT PLANT BUILDINGSWOOD HEAT ANALYSIS USING 10% ANNUAL FUEL COST ESCALATION Fan Runtime:2.5hrs/firing assume 30 minutes longer than wood takes to burn Energy Consumption: 1.4 kWh/firing/GARN Cost of Electricity:$0.686per kWhOil Heat Wood HeatLabor Wood O& M Fuel Oil Fuel Oil O&M$4.57/gal $200/cord Fan Energy Cost: $873Total all units Cost Cost Cost Cost Cost N/ACost/Yr Cost/YrWood Sys Maintenance Year($2008)($2008)($2008)($2008)($2008)($2008)($2008)($2008)($2008) Fire brick cost$6002008 $8,304 $23,171 $1,473 $10,968 $73,120 $0 $73,120 $43,915 $29,205Total O&M Cost: $1,4732009 $8,512 $23,982 $1,509 $12,065 $80,432 $0 $80,432 $46,067 $34,3652010 $8,724 $24,821 $1,547 $13,271 $88,475 $0 $88,475 $48,364 $40,111Wood Equipment Cost$02011 $8,942 $25,690 $1,586 $14,598 $97,323 $0 $97,323 $50,816 $46,506Heat Load met by GARN85%2012 $9,166 $26,589 $1,626 $16,058 $107,055 $0 $107,055 $53,439 $53,6162013 $9,395 $27,519 $1,666 $17,664 $117,760 $0 $117,760 $56,245 $61,516Oil system O&M cost /yr*$02014 $9,630 $28,483 $1,708 $19,430 $129,537 $0 $129,537 $59,251 $70,286* Note: Sunk cost, not included in comparison 2015 $9,871 $29,479 $1,751 $21,374 $142,490 $0 $142,490 $62,474 $80,016Real Interest rate:3.00%2016 $10,118 $30,511 $1,794 $23,511 $156,739 $0 $156,739 $65,934 $90,8052017 $10,371 $31,579 $1,839 $25,862 $172,413 $0 $172,413 $69,651 $102,762Real Fuel Oil Price Increase:10.00%2018 $10,630 $32,684 $1,885 $28,448 $189,654 $0 $189,654 $73,648 $116,007Real Wood Price Increase:3.50%2019 $10,896 $33,828 $1,932 $31,293 $208,620 $0 $208,620 $77,949 $130,671Rate of Inflation:2.50%2020 $11,168 $35,012 $1,981 $34,422 $229,482 $0 $229,482 $82,583 $146,8992021 $11,447 $36,238 $2,030 $37,865 $252,430 $0 $252,430 $87,580 $164,8502022 $11,733 $37,506 $2,081 $41,651 $277,673 $0 $277,673 $92,971 $184,7022023 $12,027 $38,819 $2,133 $45,816 $305,440 $0 $305,440 $98,794 $206,6462024 $12,327 $40,178 $2,186 $50,398 $335,984 $0 $335,984 $105,089 $230,8962025 $12,636 $41,584 $2,241 $55,437 $369,583 $0 $369,583 $111,898 $257,6852026 $12,951 $43,039 $2,297 $60,981 $406,541 $0 $406,541 $119,269 $287,2732027 $13,275 $44,546 $2,354 $67,079 $447,195 $0 $447,195 $127,254 $319,941GIVEN: $214,131 $657,265 $39,627 $630,200 $4,189,956 $4,189,956 $1,535,199 $2,656,765Number of Boilers: 2 EAGARN Model No.: 3200 6,400 Gallons total boiler volumeMax Boiler Temp 200 FMin Boiler Temp 150 FBuilding Heat Required (MBh) 326MBh - into waterGross Wood Btu's/Stoking (MBtu):4,845 MBtu - Gross wood energyGross Wood Btu's/hr (MBH):2,422 MBh - GrossTime to burn out one Stoking (Hr): 2.0 Hr - burn time check, compare to cell B33Net Wood Burner ouput/hr (MBH):1,816.8MBh - into waterPeak+200M btu/hrPeak + 100 M btu/hrPeak btu/hrPeak-100M btu/hrPeak-200Mbtu/hrNET Boiler Output (MBh)744 644 544 444 344BOILER FIRING INTERVALTime to Heat (Hr)2.5 2.3 2.1 1.9 1.8Stokings Req'd (Firings)1.2 1.1 1.0 1.0 0.9Time to Cool (Hr)3.6 4.1 4.9 6.0 7.8Time to Heat + Cool (Hr)6.1 6.4 7.0 8.0 9.6Avg Stoking Interval (Hr)4.9 5.6 6.7 8.2 10.6Wood Heat System Oil Heat SystemAnnual Savings using Wood HeatPage 2 of 3 9/26/2008
CHISTOCHINA CLINIC, WASHETERIA, AND WATER TREATMENT PLANT BUILDINGSWOOD HEAT ANALYSIS USING 10% ANNUAL FUEL COST ESCALATIONSTOKING LABORHeating season 8 mo x 4.33 wk/mo = 34.6 weeksWeekday stoking labor 2 hr/d x 5 d/wk x 34.6 wk =346.0 hr/heating seasonSaturday stoking labor 1 hr/d x 1 d/wk x 34.6 wk =34.6 hr/heating seasonSunday stoking labor 1 hr/d x 1 d/wk x 34.6 wk =34.6hr/heating seasonTotal Stoking Labor Time 415.2 hr/heating seasonASSUMPTIONSNOTES1. Fuel oil cost is based upon September 2008 price of #1 heating oil that the community received from Fisher's Fuel, Inc.2. Wood price estimate is from discussions with local consumers. Going rate is estimated at $200/cord. The village can get cordwood from Ahtna, Inc. land holdings.3. Labor rate is based upon an estimated rate of $20/hour, with 2 hr/day stoking on weekdays, 1 hr/day on Saturdays, and 1 hr/day on Sundays.2. There should be a year's worth of wood on hand to ensure the 30% moisture content. The moisture content of wood fuel up to 40% can drive up the equivalent cost of wood significantly.4. Firing rates are based upon using 2 each Garn 3200 boiler (6400 gal water capacity).5. Firewood is assumed to be all local spruce, dried to 30% moisture content.6. Firewood is assumed to be 100 cu ft per cord, which includes cordwood bark.7. Wood fuel cost is expected to rise at a lower rate than that of fuel oil. In this case, it has been fixed at 1% above the rate of inflation, or 3.5% per annum in this analysis.8. Wood fuel is assumed to replace 85% of the oil consumption at the facility.1. Labor time can be significantly reduced by use of equipment, such as a skid steer loader to help position pallets or skids of firewood for stoking.Oil Heat vs. Wood Heat Annual Costs ($2008 dollars)$0$50,000$100,000$150,000$200,000$250,000$300,000$350,000$400,000$450,000$500,00020082009201020112012201320142015201620172018201920202021202220232024202520262027Oil Heat $4.57/galWood Heat $200/cordPage 3 of 3 9/26/2008