HomeMy WebLinkAboutAttachment 3.3 FeasibilityAssessment for Wood Heating - T.R.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood
Heating
Final Report
August 2006
Prepared by:
T. R. Miles Technical Consultants, Inc.
1470 SW Woodward Way, Portland, OR, 97225
Tel 503-292-0107 www.trmiles.com
Prepared for:
Alaska Wood Energy Development Task Group (AWEDTG)
Juneau Economic Development Council/Wood Products Development Service
204 Siginaka Way, Sitka, AK 99835
Legal Notice
This Feasibility Assessment for Wood Heating was prepared by TR Miles, Technical
Consultants, Inc. for Alaska Wood Energy Development Task Group funded by the
Juneau Economic Development Council (JEDC) and the Alaska Energy Authority
(AEA). It does not necessarily represent the views of JEDC, its employees, or the State of
Alaska. JEDC, its employees, Contractors, and subcontractors make no warranty, express
or implied, and assume no legal liability for the information in this report; nor does any
party represent that the use of this information will not infringe upon privately owned
rights. This report has not been approved or disapproved by the JEDC nor has the JEDC
passed upon the accuracy or adequacy of the information in this report.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating Table of Contents
10 August 2006 TC-1 T R Miles
Table of Contents
1.0 Executive Summary...................................................................................................1-1
1.1 Goals and Objectives...........................................................................................1-1
1.2 Evaluation Criteria, Energy Efficiency and Emissions........................................1-1
1.3 Recommended Actions for Delta–Greely Schools (Section 5)............................1-2
1.4 Recommended Actions for Thorne Bay School (Section 6)................................1-2
1.5 Recommended Actions for Craig Community Association (Section 7)..............1-3
1.6 Recommended Actions for City of Thorne Bay (Section 8)................................1-3
1.7 Recommended Actions for Venetie Village (Section 9)......................................1-3
1.8 General Recommendations for AWEDTG..........................................................1-4
2.0 Introduction................................................................................................................2-1
2.1 Background and Objectives.................................................................................2-1
2.2 Project Scope .......................................................................................................2-1
2.3 Study Organization..............................................................................................2-1
3.0 Evaluation Criteria, Energy Efficiency, Emissions ...................................................3-1
3.1 Evaluation Criteria...............................................................................................3-1
3.2 Energy Efficiency and Emissions........................................................................3-1
4.0 Fuels and Heating Systems Overview.......................................................................4-1
4.1 Wood Fuels and Recoverable Heat......................................................................4-1
4.1.1 Wood Fuel Properties .................................................................................4-1
4.1.2 Recoverable Heat and Fuel Oil Replacement.............................................4-2
4.2 Wood Heating Systems........................................................................................4-3
4.2.1 Wood Chip Systems....................................................................................4-3
4.2.2 Cordwood Boilers.......................................................................................4-6
4.2.3 Wood Heat System Capacity......................................................................4-6
4.3 Cost Estimates......................................................................................................4-9
4.3.1 Fuel Cost.....................................................................................................4-9
4.3.2 Heating System Costs: Chips....................................................................4-12
4.3.3 Heating System Costs: Cordwood............................................................4-18
4.3.4 Conclusions:..............................................................................................4-22
5.0 Delta Greely Schools.................................................................................................5-1
5.1 Overview..............................................................................................................5-1
5.2 Estimated System Costs and Benefits..................................................................5-2
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating Table of Contents
10 August 2006 TC-2 T R Miles
5.3 Recommended Actions for Delta Greely Schools...............................................5-4
6.0 Thorne Bay School ....................................................................................................6-1
6.1 Overview..............................................................................................................6-1
6.2 Wood Chip Boiler................................................................................................6-1
6.3 Cordwood Boiler..................................................................................................6-2
6.4 Estimated System Costs and Benefits..................................................................6-2
6.5 Recommended Actions for Thorne Bay School..................................................6-4
7.0 Craig Community Center...........................................................................................7-1
7.1 Overview..............................................................................................................7-1
7.2 Estimated System Costs and Benefits..................................................................7-1
7.3 Recommended Actions for Craig Community Center.........................................7-2
8.0 City of Thorne Bay....................................................................................................8-1
8.1 Overview..............................................................................................................8-1
8.2 Maintenance Shop and Duplexes.........................................................................8-1
8.3 Solid Waste Facility.............................................................................................8-4
8.4 City Hall and VPSO.............................................................................................8-4
8.5 Recommended Actions for City of Thorne Bay..................................................8-5
9.0 Venetie Airport Maintenance.....................................................................................9-1
9.1 Overview..............................................................................................................9-1
9.2 Estimated System Costs and Benefits..................................................................9-1
9.3 Recommended Actions for Venetie Village........................................................9-3
10.0 General Recommendations...................................................................................10-1
Appendices
Appendix A. List of Abbreviations and Acronyms
Appendix B. AWEDTG Evaluation Criteria
Appendix C. Wood Boiler Suppliers
Appendix D. Delta Greely
Appendix E. Thorne Bay School
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating Table of Contents
10 August 2006 TC-3 T R Miles
Appendix F. Craig Community Center
Appendix G. City of Thorne Bay
Appendix H. Venetie Airport Maintenance
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating Table of Contents
10 August 2006 TC-4 T R Miles
List of Tables
Table 3-1. Examples of Efficient Cordwood Boilers......................................................3-3
Table 3-2. Emissions from Wood Heating Appliances ..................................................3-3
Table 4-1. Wood Fuel Properties....................................................................................4-2
Table 4-2. Fuel Oil Replaced by Wood Boilers..............................................................4-3
Table 4-3. Wood Chip Boilers in Alaska........................................................................4-4
Table 4-4. Wood Chip Boilers in Montana Schools.......................................................4-5
Table 4-5. Darby Public Schools Wood Chip Boiler Costs............................................4-6
Table 4-6. Estimate of Heat Required in Coldest 24 Hr Period......................................4-8
Table 4-7. Cost Estimates for Wood Chip Boiler Systems...........................................4-12
Table 4-8. Assumptions for Economic Analysis..........................................................4-13
Table 4-9. Cost Estimates for Cordwood Systems. ......................................................4-18
Table 5-1. Estimated Wood Boiler Costs for Delta-Greely Schools..............................5-3
Table 5-2. Savings from Wood Fuel at Delta Greely Schools........................................5-4
Table 6-1. Estimated Wood Boiler Costs for Thorne Bay School..................................6-3
Table 6-2. Savings from Wood Chips at Thorne Bay School.........................................6-4
Table 6-3. Savings from Cordwood at Thorne Bay School............................................6-4
Table 7-1. Estimated Wood Boiler Costs for Craig Community Center........................7-2
Table 7-2. Savings from Wood at Craig Community Center.........................................7-2
Table 8-1. Potential Savings from Wood at City of Thorne Bay Facilities....................8-1
Table 8-2. Estimated Wood Boiler Costs for Thorne Bay Maintenance Facility...........8-3
Table 8-3. Savings from Cordwood at Thorne Bay Maintenance and Duplexes...........8-3
Table 8-4. Estimated Wood Boiler Costs for Thorne Bay Solid Waste Facility............8-4
Table 9-1. Estimated Wood Boiler Costs for Venetie Airport Maintenance Facility.....9-2
Table 9-2. Savings from Wood at Venetie Airport Maintenance Facility......................9-2
List of Figures
Figure 4-1. Effect of Wood Chip Costs on Cost of Delivered Heat.............................4-10
Figure 4-2. Effect of Cordwood Cost on Cost of Delivered Heat. ...............................4-11
Figure 4-3. Impact of Capital and Non Fuel Cost on Cost of Heat for a 4.5 MMBtuh
Boiler to replace 102,000 Gallons of Fuel Oil Per Year. Does not include
wood cost......................................................................................................4-14
Figure 4-4. Impact of Capital and Non Fuel Cost on Cost of Heat for a 1 MMBtuh Boiler
to replace 11,500 Gallons of Fuel Oil Per Year. Does not include wood cost.4-15
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating Table of Contents
10 August 2006 TC-5 T R Miles
Figure 4-5. Total Cost of Heat to Replace 102,000 Gallons at Various Wood Chip Costs
($/ton)...........................................................................................................4-16
Figure 4-6. Total Cost of Heat to Replace 11,500 Gallons At Various Wood Chip Costs
($/ton)...........................................................................................................4-17
Figure 4-7. Impact of Capital and Non Fuel Cost on Cost of Heat for a 425,000 Btuh
Cordwood Boiler to Replace 11,500 gpy Fuel Oil. Does not include wood
cost................................................................................................................4-19
Figure 4-8. Impact of Capital and Non Fuel Cost on Cost of Heat for a 425,000 Btuh
Cordwood Boiler to Replace 6,600 gpy Fuel Oil. Does not include wood cost.4-20
Figure 4-9. Total Cost of Heat to Replace 11,500 gpy Fuel Oil At Various Wood Costs
($/Cord)........................................................................................................4-21
Figure 4-10. Total Cost of Heat to replace 6,605 gal Fuel Oil at Various Wood Costs
($/Cord)........................................................................................................4-22
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 1.0 Executive Summary
10 August 2006 1-1 T R MILES
TECHNICAL CONSULTANTS INC
1.0 Executive Summary
The potential for wood heat in several Alaskan communities was evaluated for the
Alaska Wood Energy Development Task Group (AWEDTG). Organizations submitted a
Statement of Interest (SOI) to AWEDTG. TR Miles visited the village of Venetie and
Delta-Greely Schools with Dan Parrent of JEDC and Peter Crimp of the Alaskan Energy
Authority and the Prince of Wales Island with Karen Petersen of the UAF Cooperative
Extension Service in August 2005. Information was obtained for each facility.
Preliminary feasibility assessments were made and challenges were identified. Potential
wood energy systems were considered for each project using AWEDTG and AEA
objectives for energy efficiency and emissions. Recommendations are made for each site.
1.1 Goals and Objectives
• Visit sites in Venetie, Delta Junction and Prince of Wales Island.
• Assess the suitability of the sites for wood heat.
• Assess availability of wood.
• Review Statements of Interest (SOI) for wood heating systems.
• Size and estimate the capital costs of suitable systems.
• Estimate the potential economic benefits from installing a wood heating
system.
1.2 Evaluation Criteria, Energy Efficiency and Emissions
• All projects meet the AWEDTG objectives for fuel displacement, use of
forest residues for public benefit, use of local residues, sustainability of
the wood supply, project implementation and operation and maintenance.
• The large energy consumers – Delta Greely Schools (69,000-102,000
gallons of fuel oil per year), Thorne Bay School (11,500 gallons per year)
and Craig Community Association (6,605 gallons per year) have the best
potential for implementing wood energy and deserve detailed engineering
analysis.
• City of Thorne Bay Maintenance Shop and Duplexes (3,050 gpy fuel oil)
represent positive benefit but marginal savings. This site should be
considered for demonstration of an energy efficient and low emissions
system.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 1.0 Executive Summary
10 August 2006 1-2 T R MILES
TECHNICAL CONSULTANTS INC
• Systems consuming less than 2,000 gallons per year represent little or
small savings with efficient wood systems unless they can be enclosed in
an existing or low cost structure, wood is low cost and labor is free.
• Low emission energy efficient boiler systems are too expensive for most
of the small (600 gpy) applications proposed. These may be satisfied with
domestic wood appliances, such as cord wood or pellet stoves.
• Efficiency and emissions standards for Outdoor Wood Boilers (OWB) will
change beginning in October 2006 which will increase costs for small
systems.
• Economic benefits depend on low cost buildings and piping systems.
1.3 Recommended Actions for Delta–Greely Schools (Section 5)
• Delta Greely schools can benefit from a 4.5 MMBtuh wood chip heating
system at a cost of $800,000 to $1,000,000.
• At $2.50/ gallon fuel oil the district pays $173,000 or more for 69,000
gallons of fuel. New demand is estimated at a total of 102,000 gallons per
year. The district will pay $255,000 per year at $2.50gal. A wood system
represents savings of $171,175 per year.
• Conduct a detailed engineering study for a central heating plant for the
Delta Greely Schools.
• Determine fuel supply sources and costs.
1.4 Recommended Actions for Thorne Bay School (Section 6)
• A 1 MMBtuh wood chip system is too expensive for Thorne Bay School
but it could benefit from a 425,000 Btuh cordwood system at an estimated
cost of $104,300, or $78,500 if it is housed in the existing covered area.
• At $2.50 per gallon and 11,501 gallons of fuel oil the school pays $28,750
per year for fuel. Wood systems represent savings of $19,940 for the wood
chip system at $30/ton and $11,705 per year for the cordwood systems at
$100/cord respectively.
• Conduct a detailed engineering study for the integration of energy
efficient, low emission cordwood boiler(s) for the Thorne Bay school and
gym.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 1.0 Executive Summary
10 August 2006 1-3 T R MILES
TECHNICAL CONSULTANTS INC
1.5 Recommended Actions for Craig Community Association
(Section 7)
• Craig Community Center can benefit from a 350,000 Btuh cordwood
system for $37,000.
• The Center pays proximately $16,513 for fuel oil at $2.50/gal. Savings
would be $7,163 per year.
• Conduct a detailed engineering study for the integration of an energy
efficient, low mission cordwood boiler for the Craig Community Center if
it does not receive heat from the City of Craig Aquatic Center project.
• Plan to install a cordwood boiler at the lower level along side the center.
1.6 Recommended Actions for City of Thorne Bay (Section 8)
• City of Thorne Bay could benefit from wood heat in the city Maintenance
Garage. The Maintenance Garage and two adjacent city owned duplexes
consume 3,050 gallons fuel oil per year at a cost of $7,625 per year.
• A $31,900 boiler could be installed at the garage to serve the garage and
duplexes for a savings of $3,125 per year.
• Conduct a detailed engineering study for the integration of energy
efficient, low emission cordwood boilers for the Maintenance garage and
City owned Duplexes. Plan to install a cordwood boiler behind the
Maintenance garage. Extend the piping to the Duplexes if feasible.
• Verify project costs for a cordwood boiler at the Solid Waste Facility
(2,000 gpy) for space heating.
• Verify the system costs for installing a small cordwood boiler to serve the
City Hall and VPSO (1250 gpy).
• The loads for the Emergency Services Building, City Shop, Water
Treatment and Wastewater Treatment facilities are too small for a wood
fired system unless a residential sized energy efficient low emission
appliance is used.
1.7 Recommended Actions for Venetie Village (Section 9)
• Venetie Airport maintenance facility is the same size as the Thorne Bay
City Hall with only slightly higher fuel consumption. Two 250,000 Btuh
heaters consume 1,688 gallons per year at a cost of $7,090 at $4.20/gallon.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 1.0 Executive Summary
10 August 2006 1-4 T R MILES
TECHNICAL CONSULTANTS INC
• Consider installing a $35,000, 350,000 Btuh boiler with heat storage for
the maintenance facility and waiting room in an external building.
• Consider an energy efficient, low emission cordwood system for heating
the facility (100,000 Btuh) if the delivered system cost is appropriate. An
$18,000 boiler could be installed at the garage and terminal building for a
savings of $3,900 per year with wood at $100/cord.
1.8 General Recommendations for AWEDTG
• Plan to install a few efficient low emission cordwood boiler systems.
• Develop and demonstrate low cost enclosures for wood boilers and low
cost heat distribution systems for hot water applications since building
costs and integration of heat distribution are the major costs for wood
burning boilers.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 2.0 Introduction
10 August 2006 2-1 T R Miles
2.0 Introduction
2.1 Background and Objectives
T. R. Miles, Technical Consultants, Inc. was retained by Juneau Economic
Development Council (JEDC) on behalf of the Alaska Wood Energy Development Task
Group (AWEDTG) to evaluate the potential for wood heat in Alaska communities. Each
organization submitted a Statement of Interest (SOI) to JEDC. TR Miles visited the
village of Venetie and the Delta-Greely Schools with Dan Parrent of JEDC and Peter
Crimp of the Alaskan Energy Authority and the Prince of Wales Island projects with
Karen Petersen of the UAF Cooperative Extension Service in August 2005. Information
was obtained for each facility and wood supply. Preliminary assessments were made and
challenges were identified. Potential wood energy systems were considered for each
project with the AWEDTG and AEA objectives for energy efficiency and emissions.
2.2 Project Scope
This report describes wood heating alternatives based on discussions with system
providers and economic analysis. After each site visit a boiler system was selected and
cost estimates were prepared. An economic model was developed to determine operating
and investment costs and potential financial benefits. Wood boiler suppliers were
consulted to refine system selection and cost assumptions. Investment estimates were
revised and the wood systems were compared with oil using a federal Life Cycle Cost
Method.
2.3 Study Organization
Following this Introduction, this report is organized into the following sections:
• Section 3 –Evaluation Criteria, Energy Efficiency and Emissions
• Section 4 – Fuels and Heating System Overview
• Section 5 – Delta Greely Schools
• Section 6 – Thorne Bay School
• Section 7 – Craig Community Association
• Section 8 – Thorne Bay City
• Section 9 – Venetie Village
Abbreviations and acronyms used in this report are listed in Appendix A.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating
3.0 Evaluation Criteria, Energy Efficiency,
Emissions
10 August 2006 3-1 T R Miles
3.0 Evaluation Criteria, Energy Efficiency, Emissions
3.1 Evaluation Criteria
The AWEDTG selected projects for evaluation based on the criteria listed in
Appendix B. All projects meet the AWEDTG criteria for fuel displacement, use of forest
residues for public benefit, use of local residues, sustainability of the wood supply,
project implementation and operation and maintenance. In all cases the wood supply
from public forest fuels or local processing residues is adequate and matches the
applications. Community support appeared to be present in most cases.
Two aspects of project implementation have been important to wood projects in
the past: clear identification of a sponsoring agency and dedication of personnel. In
situations like Venetie Village where several organizations are responsible for different
services it must be clear which organization would sponsor or implement a wood burning
project. Stoking fuel or boiler maintenance is only required for an hour once or twice a
day for most systems but dedicating personnel for operation is important to realize
savings from wood fuel. Also the cost of labor can absorb fuel costs savings. In Dot
Lake, for example, the wood system was idle for a period when an employee could not be
found to fuel and maintain the boiler. Since there are no full time personnel at the airport
at Venetie, or dedicated to the boiler at the Craig Community Center, it was not clear who
would be responsible for a wood boiler or whether there would be additional labor costs
for a wood system. All other locations assumed that the personnel would fit into the
responsibilities of existing facilities personnel.
3.2 Energy Efficiency and Emissions
An objective of the Alaska Energy Authority is to support projects that use energy
efficient and clean burning wood heating systems. Wood chip systems that are built in
schools are generally efficient and meet typical air pollution standards. Boilers convert
70% of the energy in the wood fuel to hot water when the fuel moisture is 35% MC to
45% MC (wet basis).
Outdoor Wood Boilers (OWB) for cordwood, like two that are now being used on
Prince of Wales Island, are low cost and save fuel oil but have been criticized for low
efficiency and smoky operation. The State of New York recently banned use of outdoor
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating
3.0 Evaluation Criteria, Energy Efficiency,
Emissions
10 August 2006 3-2 T R Miles
wood boilers.1 Other states have also considered regulations.2 OWB ratings are
inconsistent and misleading. Some suppliers rate their boilers on fuel input. Others rate
their boilers on hot water produced using dense, 20% MC, red oak fuel.3 Standard
procedures for evaluating wood boilers have not existed. Test data assembled by New
York showed a wide range of efficiencies and emissions among outdoor wood boilers.
Boiler efficiencies were low at 35% to 40%. Most emissions exceed acceptable standards
for residential appliances or industrial boilers.
A committee was formed under the American Society for Testing and Materials
(ASTM) to develop a standard test protocol for outdoor wood boilers.4 The rules will
include uniform testing for performance and emissions. The ASTM committee sponsored
tests of three common outdoor wood boilers using the new procedures that showed
efficiencies of 35% to 40% and emissions more than nine times the standard for industrial
boilers. The new standard will require owner training by the dealer, certification that the
owner received training, and consent by the owner that they will burn only wood fuels.
The new standard is expected to be approved and promulgated in October 2006. After
that date OWB manufacturers will have two years to test their boilers. States will use the
test results to set emission limits. Consumers will only be allowed to buy boilers that
meet state emissions limits.
Implementation of the new standard will improve air quality and boiler efficiency
but increase costs as manufacturers modify their design, fabrication and marketing to
adjust to the new standards. Some residential models, which are the scale of many of the
AWEDTG proposals, will no longer be feasible.
Table 3-1 lists examples of two boilers with high efficiency and low emissions
that are in use in Alaska. A Tarm boiler is being used to heat a 5,000 ft2 house in
Palmer.5 Tarm USA supplies boilers from 100,000 Btu/hr to 198,000 Btu/hr maximum
heat output and claims fuel to hot water efficiencies of 80%. A Garn boiler by Dectra
1 Smoke Gets in Your Lungs: Outdoor Wood Boilers in New York State, October 2005, New York State
Attorney General http://www.oag.state.ny.us/press/2005/aug/August%202005.pdf
2 Assessment of Outdoor Wood-Fired Boilers, Revised May 2006, NESCAUM, the Clean Air Association
of the Northeast States http://www.nescaum.org/documents/assessment-of-outdoor-wood-fired-boilers
3 Red Oak 20% MC 8,500 Btu/lb, 18.2 MMbtu/cord.
4 WK5982 Standard Test Method for Measurement of Particulate Emissions and Heating Efficiency of
Outdoor Wood-Fired Hydronic Heating Units, Committee E06.54 on Solid Fuel Burning Appliances
American Society of Testing and Materials. www.astm.org
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating
3.0 Evaluation Criteria, Energy Efficiency,
Emissions
10 August 2006 3-3 T R Miles
Corporation is used in Dot Lake for heating buildings to replace 7,000 gpy of fuel oil.6
Table 3-2 shows the results for a Garn WHS 1350 boiler that was tested at 157,000
Btu/hr to 173,000 Btu/hr by the State of Michigan using the new procedures compared
with EPA standards for wood stoves and boilers.7 It is also important to remember that
wood fired boilers are not always smokeless; all efficient boilers smoke for a few minutes
on startup.
Table 3-1. Examples of Efficient Cordwood Boilers.
Model MBtuh Location Supplier
Garn 900,000 Dot Lake, AK Dectra
Tarm 140,000 Palmer, AK Tarm USA
Table 3-2. Emissions from Wood Heating Appliances
Appliance Emissions
Gm/1000 Btu Delivered
EPA Certified Non Catalytic Stove 0.50
EPA Certified Catalytic Stove 0.25
EPA Industrial Boiler (many states) 0.225
GARN WHS 1350 Boiler* 0.179
Source: Intertek Testing Services, Michigan, March 2006.
Note:
*Average efficiency of 75.4% based upon the higher heating value of wood.
Garn advertises efficiencies of 70% on cordwood for the WHS series from
350,000 Btuh to 950,000 Btuh heat output and heat storage capacities of 920,000 Btu to
2,135,000 Btu (120° F - 200° F). While other suppliers may develop models with similar
performance these two units were used as a basis for the feasibility analysis.8
5 http://www.tarmusa.com/ Tarm USA Inc. P.O. Box 285 Lyme, NH 03768 This is equal to 1600 gallons
of fuel oil in the Southeast or 2500 gpy in the Interior.
6 http://www.dectra.net/garn/ Dectra Corporation, Minneapolis, Minnesota. 612-781-3585
7 Test of a Solid fuel Boiler for Emissions and Efficiency per Intertek’s Proposed Protocol for Outdoor
Boiler Efficiency and Emissions Testing. Intertek report No. 3087471 for State of Michigan, Air Quality
Department. Intertek Testing Services NA Inc. 8431 Murphy Drive, Wisconsin 53562. March 2006.
8 Keunzel, New Horizon and Alternate Heating Systems are sometimes recommended for high efficiency
boilers; however they are not yet used in Alaska and no efficiency or emissions data was available for this
study. www.newhorizoncorp.com/ www.kuenzel.de/English/indexE.htm
www.alternateheatingsystems.com/Multi-Fuel_boilers.htm
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating
3.0 Evaluation Criteria, Energy Efficiency,
Emissions
10 August 2006 3-4 T R Miles
In these analyses a non-pressurized cord wood boiler would supplement, not
replace, an oil fired system. Glycol from the existing oil-fired boiler would be circulated
through a heat exchanger at the wood boiler ahead of an existing oil boiler or a heat
exchanger. The existing oil fired systems would be available for peak demand or backup
in the event of a failure in the wood system. In wood chip systems the boiler would be
integrated with the existing oil fired system.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-1 T R Miles
4.0 Fuels and Heating Systems Overview
The projects reviewed for AWEDTG fall into three sizes: small institutions,
schools and residential scale heating systems. Wood fuels and fuel oil replacement for
typical systems are discussed below.
4.1 Wood Fuels and Recoverable Heat
Wood fuels on Prince of Wales Island and in Delta Junction are likely to be chips,
sawdust or hogged fuel from larger sawmills and whole tree chipping operations or
cordwood from forest cleanup and small sawmills. Sawdust and shavings are used at Icy
Straits Milling in Hoonah and Regal Enterprises in Copper Center. Three boilers on
Prince of Wales Island use cordwood: two from mill residues such as slabs, edgings, butt
cuts and buck-outs and the other with purchased cordwood.
4.1.1 Wood Fuel Properties
Heating values for Alaskan woods are listed in Table 4-1. Oven dry (od) heating
values are similar for most species on a weight basis. Cordwood is considered to be air
dried to 20% moisture content (MC20), wet basis. Heating value of the cordwood as fired
is 6,650-6,896 Btu/lb at 20% MC. Density varies from Western Red Cedar to Hemlock.
Sitka Spruce has an intermediate density and is used here. The as-fired heating value of
Sitka Spruce cordwood at MC20 is about 13.4 Million Btu (MMBTU) per cord (80 ft3).
Many wood boilers are rated on northern Red Oak which contains 18.2 MMBtu per cord
(1.4 tons per cord) at MC20. More cordwood will be required for the Alaskan wood
compared with the northern and eastern hardwoods.
Wood chips are typically 45% to 50% moisture content, wet basis (MC50) and are
sold either by weight (per ton) or volume (per Unit of 200 ft3). Since there are no pulp
mills on Prince of Wales Island or near Delta Junction it is likely that the chips will be
sold by weight. Sitka Spruce has a Gross Heating Value (GHV) of 4,100 Btu/lb at MC50.
Wet fuel may be a problem for wood chip boilers on Prince of Wales Island. Most
small boilers operate well when wood chips are 35% to 45% MC and very poorly above
that. Wood chips that are stored outside can absorb rainwater and reach moistures as high
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-2 T R Miles
as 60% to 65%.9 Schools in the Northeast using wood chips select suppliers carefully and
often pay extra for clean chips below 40% MC.10
Table 4-1. Wood Fuel Properties.
Species HHV
Btu/lb od
a
GHV
Btu/lb
MC20 a
Lb/Cord
b, c
Ton/Cord
b, c
MMBtu/
cord c
GHV
Btu/lb
MC50 a
Western Red Cedar 8,620 6,896 1,860 0.93 12.8 4,310
Hemlock 8,338 6,670 2,512 1.26 13.9 4,169
Sitka Spruce 8,200 6,650 2,040 1.02 13.4 4,100
White (Englemann) Spruce 8,401 6,721 2,040 1.02 13.7 4,201
Source: Juneau Economic Development Council
Notes:
a Higher Heating Value (HHV) and Gross Heating Value (GHV) from JEDC.
GHV = HHV (1-MCwb/100)
b Specific Gravity: Cedar 0.31, Hemlock 0.42, Spruce 0.34
c 80 ft 3 per cord
4.1.2 Recoverable Heat and Fuel Oil Replacement
Wood boilers are more expensive to install, own and operate than oil boilers. Fuel
savings must pay for these higher costs. The amount of fuel oil replaced depends on the
heating value of the fuel and the efficiency of the wood boiler. Table 4-2 shows the
amount of fuel oil displaced at typical efficiencies by wood with the heating values in
Table 4-1. Boiler conversion efficiency (CE) can be expected to vary from 35% to 70%
of the energy in the fuel. Recovered heat is calculated using the equation Recovered
Heating Value (RHV) = Gross Heating Value (GHV) x % Conversion Efficiency (CE).11
Fuel oil replacement based on Sitka Spruce is calculated at 49 gallons for a ton of green
wood chips at 70% conversion efficiency. Fuel oil replacement for an efficient cordwood
boiler at 66 gallons of fuel oil saves twice as much as an inefficient boiler at 33 gallons
per cord.
9 Wood with moisture greater than about 63% MC will not support combustion.
10 Interviews with schools in Massachusetts and Vermont. 2005.
11 Briggs, David, 1994. Forest Products Measurements and Conversion factors: with Special Emphasis on
the U.S. Pacific Northwest, University of Washington Institute of Forest Resources, AR-10, Seattle,
Washington 98195 Chapter 8.
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Table 4-2. Fuel Oil Replaced by Wood Boilers
Fuel, boiler Conversion
Efficiency
CE
Energy in
Fuel
HHV
Btu
Delivered
RHV
Gal Fuel
Oil
Fuel Oil, Btu/gal 85% 138,500 117,300 1
a Wood chip boiler, 50% MC,
MMBtu/ton, gal/ton
70% 8.2 5.8 49
b Efficient Cordwood Boiler
20% MC, MMBtu/cd, gal/cord
70% 11.1 7.8 66
c Low efficiency wood boiler,
20% MC, MMBtu/cd, gal/cord
35% 11.1 3.9 33
Notes:
a Typical conversion efficiency 70%. Recovered Heating Value (RHV) = Gross
Heating Value (GHV) x % Conversion Efficiency (CE).
b Based on references cited in Section 3.0
c Typical efficiency 35% to 40%
4.2 Wood Heating Systems
The Delta Greely Schools are suited to a chipped wood boiler. Most other systems
are better suited for cordwood. The sources and supply of wood must be verified. On
Prince of Wales Island both wood chips and cordwood are available. In the Interior
cordwood is probably more available now but chips will be available if there is a demand.
4.2.1 Wood Chip Systems
Wood chip boilers are generally used for commercial, institutional or light
industrial applications. The larger energy consumers, like Delta Greely Schools (69,000-
102,000 gallons of fuel oil per year) have the best potential for installing wood chip
boilers and deserve detailed engineering analysis. Chip handling systems are generally
too expensive for small boilers.
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Wood chips are delivered in self-unloading trailers that hold about 24 tons of
green chips. A school replacing 60,000 gallons of oil might use 35 tons per week or about
1 1/2 trailers.12
There are at least three wood chip boilers in Alaska. Table 4-3. The most recent
was installed in Hoonah in 2006. A 4 MMBtuh chip boiler will be installed at the Craig
Aquatic Center to replace 36,000 gals of fuel oil per year. It is similar in size to boilers
recently installed in Montana schools as shown in Table 4-4.
Table 4-3. Wood Chip Boilers in Alaska.
Location Boiler
Horsepower
MMBtuh Heating
Degree Days
Supplier
Craig Aquatic Center,
Craig, AK
120 4 7,487 Chiptek
Icy Straits Lumber &
Milling, Hoonah, AK
72 2.4 8,217 Decton
Regal Enterprises,
Copper Center, AK
N/A N/A 13,797 Messersmith
(Fuel bin only)
Notes:
* Heat delivered as hot water or steam. 1 Boiler Horsepower = 33,475 Btuh or 34.5
pounds of water at a temperature of 100°C (212°F) into steam at 212°F
The cost of these systems ranges from $0.5 to $2 million with about $350,000 to
$900,000 in equipment. Fuel handling and boiler equipment for an 8 MMBtuh (300 BHP)
system was recently quoted to a school in the Northeast for $900,000. Boiler and fuel
handling equipment for the 3 to 4 MMBtuh systems is about $350-$500,000. A 2.4
MMBtuh system in Hoonah was installed at a saw mill for $250,000. Fuel and boiler
equipment for a 1 MMBtuh system is estimated at $250,000 to $280,000. At Hoonah an
existing building was used and there were economies in fuel preparation and handling.
Several schools in New England have been able to use existing buildings or boiler rooms.
The Montana projects are all in new buildings. Schools in Montana and New England
save about half the total cost of fuel oil consumed at 60,000 gallons per year.
12 Athol Royalston High School, Massachusetts, a 3 MMBtuh boiler replaces 60,000 gpy fuel oil, installed
1998.
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Table 4-4. Wood Chip Boilers in Montana Schools.
Table Header Phillipsburg
Public Schools
Darby Public
Schools
Thompson
Falls Public
Schools
Victor
Public
Schools
Location Phillipsburg,
MT
Darby, MT Thompson
Falls, MT
Victor, MT
Heating Degree Days*** 8,734 7,041 6,496 7,494
Project Cost * $650,000 $650,000 $455,000 $628,991
Square Footage ** 99,000 82,000 60,474 47,000
Peak Output Btu/hr 3.87 million 3 million 1.6 million 4.9 million
Annual wood fuel Use 400 tons 750 tons 400 tons 500 tons
Fuel Replaced Natural Gas Fuel Oil Fuel Oil Natural Gas
Estimated Fuel Use NA 50,000 gal 24,000 gal NA
Estimated Annual fuel
Savings
$67,558
($11 dkt)
$100,000
($2.50/gal)
$60,000
($2.50/gal)
$31,898
($13.82/MM
Btu)
Supplier*** N/A Messersmith Chiptek Messersmith
Date Operational 01/05 11/03 10/05 09/04
Source: Montana Department of Natural Resource Conservation, http://dnrc.mt.gov
Notes:
* Darby cost excludes $268,000 in repairs to existing heat distribution system.
** Victor boiler sized to heat an additional 16,000 sq. ft. in future.
*** Additional data not supplied by Montana DNRC
Table 4-5 shows costs from the Darby project at $1,001,000 including
$268,000 for repairs to the existing system. Integration to any school will require repairs
and rework that must be included in the wood system cost. Adding the indirect costs of
engineering, permits, etc. to the equipment cost puts the total cost at Darby between
$716,000 and $766,000 for the 3 million Btuh system to replace 47,000 gallons of fuel oil
per year. Since the boiler was installed at Darby building and equipment costs have
increased from as low as 10-15% to as high as 25%. A new budget price for the Darby
system might be $800,000 without repairs to the existing system. The Craig Aquatic
Center project has been estimated at $1 million to replace propane and fuel oil equal to
36,000 gallons of fuel oil. Building and system integration costs for the pool and two
schools increased the project costs.
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Table 4-5. Darby Public Schools Wood Chip Boiler Costs.
Boiler Capacity 3 MMBtuh
Fuel Oil Displaced 47,000
Heating Degree Days 7,186
System Costs
Building, Fuel Handling $ 230,500
Boiler and Stack $ 285,500
Boiler system $ 516,000
Piping, integration $ 95,000
Other repairs, improvements $ 268,000
Total direct Costs $ 885,000
Engineering, permits, indirect $ 116,000
Total Cost $1,001,000
Source: Biomass Energy Resource Center, 2005.
4.2.2 Cordwood Boilers
Cordwood boilers best suit applications from 100,000 Btuh to 900,000 Btuh.
There are a few examples of the high efficiency, low emission boilers in Alaska. Two are
listed in Table 3-1. At Dot Lake the $66,000 project replaces 7,000 gpy of fuel oil for a
fuel savings of $16,000 per year.
Fuel quality has a large impact on the performance of cordwood boilers. It is
assumed for this study that cordwood has been seasoned and dried to 20% MC.
4.2.3 Wood Heat System Capacity
Wood boilers are often sized to displace only a portion of the heating load since
the oil system will remain in place for peak demand. Fuel oil consumption for each site
was compared with heating demand based on heating degree days to determine the boiler
capacity required for heating only on the coldest 24 hour day. Table 4-6. This method
matches well with woodchip boilers installed in schools across the country. While there
are many reasons for sizing heating systems it is clear that in all cases in this study a
wood system of reduced size could replace a substantial quantity of fuel oil.
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The calculation shows that installed oil capacity at most sites is three to four times
the demand for the coldest day. Excess capacity may be necessary in the interior. Wood
boilers with hot water tanks for thermal storage can also supply heat at higher than their
rated capacity for short periods. The 4,000 gallon tank at Dot Lake, for example, can
store more than 2 million Btu which would be enough to heat the Thorne Bay School on
the coldest day for five hours.
The two groups of buildings at the Delta Greely schools each have an installed
capacity of about twice the estimated demand of 3.988 MMBtuh. This suggests that a 4.5
MMBtuh boiler could replace all the oil used at the schools. The two centers are more
than 1000 feet apart which increases piping costs but since they are at the same elevation
it is feasible to distribute to them from a single boiler. The smaller buildings at Delta
Greely - VoTech center, Career Advancement and Cyber Center - were each estimated at
approximately 400,000 Btuh.
According to this calculation the Thorne Bay school could supply 100% of its
heating needs of 347,000 Btuh with a 425,000 Btuh wood fired boiler. The Craig
Community Center could use a 350,000 Btuh system to meet its demand of 207,000
Btuh. All of the other buildings evaluated require capacities less than 100,000 Btuh.
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Table 4-6. Estimate of Heat Required in Coldest 24 Hr Period.
Facility Fuel Oil
Used
gal/year a
Heating
Degree
Days b
Btu/DD c Design
Temp b
F
Capacity
MMBtuh c
Installed
MMBtuh a
Delta-Greely Schools
(Estimated)
102,000 13,549 866,261 -43 3.988 ~10.000
2004 Fuel Oil 69,000 13,549 599,529 2.698 4.200
High School and
Admin(former
elementary)
33,000 d 286,731 1.290 4.200
VoTec, Career
Advancement and
Cyber Center, (est ea)
9,300 d 80,806 0.363 ~.500
New Elementary 33,000 d 286,731 1.290 4.500
Thorne Bay School 11,501 7,802 173,540 17 0.347 1.800
Craig Community Assn 6,605 7,487 103,857 17 0.207 0.704
City of Thorne Bay
Maintenance Garage
and Duplexes
3,050 7,802 46,022 17 0.092
Maintenance Garage 1,800 18,861 17 0.054 0.140
City Duplexes 1,250
Solid Waste Building 2,000 30,178 0.060 0.080
City Hall, VPSO 1,250 18,861 0.038 0.190
Emergency Services,
Water Treatment
600 9,053 0.018 0.080
Wastewater Treatment 600 9,053 0.018 0.120
Venetie Airport
Maintenance
1,688 16,465 12,069 -57 0.061 0.500
Notes:
a From SOI and site visits
b Alaska Housing Manual, 4th Edition Appendix D: Climate Data for Alaska Cities,
Research and Rural Development Division, Alaska Housing Finance Corporation,
4300 Boniface Parkway, Anchorage, AK 99504, January 2000.
c Btu/DD= Btu/year x oil furnace Efficiency (0.85) /Degree Days; Boiler capacity
Required for the coldest Day, Btu/hr= Btu/DD x (65 F-Design Temp=DD)/24 hrs
d Estimated from total fuel oil consumption and building area.
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4.3 Cost Estimates
The selection of a wood heating system has an impact on fuel economy. Wood
system costs include the fuel cost and the cost of owning the heating system. After each
site visit a boiler system was selected and cost estimates were prepared. An economic
model was developed to determine the operating and investment costs and potential
financial benefits for the system. The breakeven for each system was determined which
became a target cost. Wood system suppliers were consulted to refine system selection
and cost assumptions. Investment estimates were revised and the wood systems were
compared with oil using a Life Cycle Cost Method to calculate savings compared with
the existing oil systems. The general results of these assessments are discussed below.
4.3.1 Fuel Cost
The major advantage of wood compared with fuel oil is the cost of the fuel. Wood
burning boilers are usually first installed where chips, pallets or cordwood are free. Two
wood boilers on Prince of Wales Island use cordwood that is essentially free. At Thorne
Bay Wood Products [in Thorne Bay] and W.R. Jones & Son Lumber Co. [in Craig],
slabs, edgings, butt cuts and buck-outs are burned in cordwood boilers to heat a process
building and dry kilns. Planer shavings and sawdust are used at Icy Straits Lumber in
Hoonah and at Logging and Milling Associates at Dry Creek in the Interior. Chips and
cordwood can also be free at the mill site. Hog fuel, composed of unscreened bark and
sawdust, can be available from Viking Mill in Klawock for slightly more than the cost of
delivery, or about $10-15/ton ($20-$30/odt). For comparison typical delivered chip costs
at schools in New England are $30-$40/ton at 40% MC ($58/odt) which is equal to
$30/ton at 50% MC.
The price of chipped wood usually has a low impact on the cost of heat. Figure 4-
1. The chart assumes that the wood chip boiler converts 70% of the energy in the chips to
useful heat and that oil is converted to heat at 85% efficiency. Fuel at $30/ton is equal to
$5/MMBtu compared with fuel oil ($2.50/gallon) at $21.31/MMBtu. Chip prices of
$15/ton and $30/ton were used for Thorne Bay and Delta-Greely. When fuel supplies are
identified for Delta-Greely chips may cost $30/ton or more.
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0
5
10
15
20
25
0 5 10 15 20 25 30 35
Cost of Wood Chips ($/ton)Hot Water ($/MMBtuOil $2.50/gal
70% Efficiency
Figure 4-1. Effect of Wood Chip Costs on Cost of Delivered Heat.
Figure 4-2 shows that the price of cordwood can have a large impact on the cost
of heat. If cordwood at 20% MC, like the slabs and edging used on POW, could be
delivered to a low efficiency boiler for $25/cord the cost of heat would be $5/MMBtu,
which is equal to $30/ton of green chips. Figure 4-1 Cordwood prices in southeast Alaska
vary from $75 to $160 per cord, with $100 to $125 per cord being typical on Prince of
Wales Island. Figure 4-2 shows that at 35% efficiency heat from wood at $100/cord is
equal to the cost of oil at $2.50/gallon, before considering the cost of the boiler, however,
at high (70%) efficiency, heat from wood at $200/cord is equal to the cost of oil at $2.50
per gallon, before considering the cost of the boiler. Given fuel oil at $2.50 per gallon,
most low efficiency boiler projects would not be feasible with cordwood prices at or
above $100 per cord. At 70% efficiency and $100/cord a boiler will deliver heat at half
the cost of fuel oil. Figure 4-2 shows that at a given efficiency project savings increase
significantly with decreases in the delivered price of cord wood.
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0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
25 50 75 100 125 150 175 200
Cost of Wood ($/cord)Cost of HotWaterer($/MMBtu35% Efficiency
70% Efficiency
Oil $4.00/gal
Oil $3.50/gal
Oil $3.00/gal
Oil $2.50/gal
Figure 4-2. Effect of Cordwood Cost on Cost of Delivered Heat.
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4.3.2 Heating System Costs: Chips
Wood heating systems include the cost of the fuel delivery and storage, boiler
equipment, piping, heat exchangers, electrical service to integrate with existing
distribution systems, installation, and for larger and institutional projects: allowance for
engineering and contingency. Table 4-7 summarizes cost estimates for two wood chip
boiler systems. The total system cost is two to three times the cost of the boiler. Building
and piping cost are the most significant costs besides the boiler. Building costs deserve
more site specific investigation to reduce system costs.
Table 4-7. Cost Estimates for Wood Chip Boiler Systems.
Facility Delta Greely Schools* Thorne Bay School**
Capacity, Btuh 4,500,000 1,000,000
Fuel Oil Replaced, gallons per
year
102,000*** 11,501
Estimated costs
Buildings $ 228,000 $ 158,000
Boilers, Fuel System, Stack $ 397,000 $ 280,000
Piping, Integration $ 231,000 $ 52,500
Other Installation $ 80,000 $ 48,100
Total Direct Costs $ 936,000 $ 538,600
Engineering, permits $ 120,000 $ 70,000
Contingency 15% $ 158,000 $ 91,000
Total $ 1,214,000 $ 699,000
Notes:
* Section 5 Table 5-1
** Section 6 Table 6-1
*** 69,000 gpy at old school plus estimated 33,000 gpy at new elementary= 102,000
gpy
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Assumptions in Table 4-9 were used for economic analysis to assess the
feasibility of the wood fired systems.
Table 4-8. Assumptions for Economic Analysis.
Component Factor Units
Cost of Power $0.17, $0.25 /kWh
Cost of Fuel Oil $ 2.50 /gal
Cost of Chips, MC50 $15, $30 /ton
Cost of Cordwood $60-$100 /cord
Operating and Maintenance as
% of Capital
3%
2%
Chips
Cordwood
Loan Interest or Capital
Recovery
6% Interest rate
Loan Term 20, 10, 5 Years
Discount rate (for constant
dollar PV calculation)
3%
Inflation 3%
Power price escalator 3%
Tax rate None
Grant financing None
Debt None
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Figure 4-3 illustrates the effect of capital and non-fuel costs on the cost of heat for
a 4,500,000 Btuh wood chip system to replace 102,000 gallons of fuel oil per year. At
this annual fuel consumption the 70% efficient system would be used at a full load
equivalent of 2,660 hours per year or about 30.4% capacity factor (2,660 hours/8760
hours at 45 MMBtuh). The cost to recover a $1.2 million investment would be about
$11/MMBtu for 10 years, or $6.24/MMBtu for 20 years.
0.00
5.00
10.00
15.00
20.00
25.00
30.00
800000 900000 1000000 1100000 1200000 1300000 1400000 1500000
Capital Cost ($/4.5 MMBtuh)Cost Hot Water($/MMBtu)20 years 10 years
5 years Oil 2.50/gal
Figure 4-3. Impact of Capital and Non Fuel Cost on Cost of Heat for a 4.5 MMBtuh
Boiler to replace 102,000 Gallons of Fuel Oil Per Year. Does not include wood cost.
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Figure 4-4 illustrates the effect of capital and non-fuel costs on the cost of heat for
a 1,000,000 Btuh wood chip system to replace 11,500 gallons of fuel oil per year. At this
annual fuel consumption the 70% efficient system would be used at a full load equivalent
of 1,349 hours per year or about 15.4% capacity factor (1,349 hours/8760 hours at 1
MMBtuh). The cost to recover a $699,000 investment would be about $50.34/MMBtu
for 10 years, or $32.30/MMBtu for 20 years. Figure 4-4 suggests that when fuel oil costs
$2.50/gallon a chip system to replace 11,500 gallons should cost less than $300,000.
0.00
20.00
40.00
60.00
80.00
100.00
120.00
200000 300000 400000 500000 600000 700000 800000 900000
Capital Cost ($/1 MMBtuh)Cost Hot Water($/MMBtu)20 years 10 years
5 years Oil 2.50/gal
Figure 4-4. Impact of Capital and Non Fuel Cost on Cost of Heat for a 1 MMBtuh Boiler
to replace 11,500 Gallons of Fuel Oil Per Year. Does not include wood cost.
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Figure 4-5 shows the total cost of heat for a 4.5 MMBtuh system saving 102,000
gallons of fuel oil per year at 20 year cost recovery with an interest rate of 6% and an
annual maintenance cost of 2%). Operating and maintenance costs include labor since
fuel handling would be included in the normal duties of maintenance personnel. From
this calculation for an investment of $1.2 million fuel chips at $30/ton would generate
heat at a total cost of $11.53/MMBtu compared with fuel oil at $21.21/MMBtu
($2.50/gallon). This is the sum of fuel costs (Figure 4-1) of $5.23/MMBtu at $30/ton and
non-fuel costs (Figure 4-3) of approximately $6.30/MMBtu.
5.00
7.00
9.00
11.00
13.00
15.00
17.00
19.00
21.00
23.00
800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800
Capital Cost ($1,000/4.5 MMBtuh HW)Cost of Hot Water ($/MMBtuOil $2.50 $15.00 $20.00
$30.00 $40.00
20 Year CR 6%
Figure 4-5. Total Cost of Heat to Replace 102,000 Gallons at Various Wood Chip Costs
($/ton).
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Figure 4-6 shows the total cost of heat for a 1 MMBtuh system saving 11,500
gallons of fuel oil per year at 20 year cost recovery with an interest rate of 6% and an
annual maintenance cost of 3%. Operating and maintenance costs include labor since
fuel handling would be included in the normal duties of maintenance personnel. From
this calculation for an investment of $699,000 with fuel chips at $30/ton would generate
heat at a total cost of $37.84/MMBtu compared with fuel oil at $21.21/MMBtu
($2.50/gallon). This is the sum of fuel costs (Figure 4-1) of $5.23/MMBtu at $30/ton and
non-fuel costs (Figure 4-3) of approximately $32.30/MMBtu.
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
200 300 400 500 600 700 800
Capital Cost ($1,000/1 MMBtuh HW)Cost of Hot Water ($/MMBtuOil $2.50 $15.00 $20.00
$30.00 $40.00
20 Year CR 6%
11,500 gpy Fuel Oil
Figure 4-6. Total Cost of Heat to Replace 11,500 Gallons At Various Wood Chip Costs
($/ton).
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4.3.3 Heating System Costs: Cordwood
Table 4-9 summarizes cost estimates for four cordwood systems. The total cost is
often two to three times the cost of the boiler.
Table 4-9. Cost Estimates for Cordwood Systems.
Facility Thorne Bay
School
Craig
Community
Center
Thorne Bay
Shop +
Duplexes
Thorne Bay
Solid
Waste
Fuel Oil, gallons per year 11,501 6,605 3,050 2,000
Calculated required capacity* 347,000 207,000 90,000 60,000
Wood Boiler, Btuh 425,000 350,000 350,000 100,000
Building and Equipment Costs
Building $ 21,600 $ 14,500 $ 6,500 $ 1,900
Boilers $ 19,500 $ 15,540 $ 15,540 $ 9,200
Piping $ 38,300 $ 3,500 $ 8,000 $ 3,200
Installation $ 3,500 $ 1,200 $ 1,300 $ 2,100
Total Direct Costs $ 81,700 $ 34,700 $ 31,340 $ 16,400
Engineering +Contingency** $ 22,000 $ 2,000 $ 560 $ 600
Total $ 104,300 $ 37,000 $ 31,900 $ 17,000
Notes:
* Table 4-6 Estimate of heat required in Coldest 24 Hr period.
** This larger project may require more allowance for indirect costs such as
engineering, approvals, etc.
Building and piping are the most significant costs besides the boiler. Building
costs deserve more site specific investigation. A variety of prefabricated buildings were
considered to enclose the boiler and wood supply. A quote was obtained from one
supplier to deliver a pre-assembled boiler in a shipping container. Since the boiler
enclosure had to meet special codes the cost of a containerized boiler was higher than in a
separate building.
Piping from the wood-fired boiler is another area of potential cost saving. The
impact of piping costs can be seen in the costs estimates for Craig Community Center
compared with the Thorne Bay school. Long piping runs and additional heat exchanger
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substantially increase project costs. The hard pipe normally used in Alaska costs
$70/foot. If plastic or PEX piping is used the cost is reduced to about $40/foot.
Allowance for indirect costs such as engineering and contingency are most
important for larger systems that involve extensive permitting and budget approval by
public agencies. This can increase the cost of a project by 25% to 50%.
Figure 4-7 illustrates the effect of capital and non-fuel costs on the cost of heat for
a 425,000 Btuh cordwood system to replace 11,500 gallons of fuel oil per year at
different terms of cost recovery. This is the reported use at the Thorne Bay School. A
70% efficient boiler system would be used at a full load equivalent of 3,175 hours per
year or about 36% capacity. The cost to recover a $104,300 investment would be about
$13.23/MMBtu for 5 years, $7.57/MMBtu for 10 years or $4.86 for 20 years. Boilers in
this example have been in use for more than 20 years. No labor is included in this
calculation since most sites indicated that stoking the wood boilers would be included in
responsibilities of existing personnel.
0.00
5.00
10.00
15.00
20.00
25.00
20000 40000 60000 80000 100000 120000
Capital Cost ($/425 kBtuh)Cost Hot Water($/MMBtu)20 years 10 years
5 years Oil 2.50/gal
Figure 4-7. Impact of Capital and Non Fuel Cost on Cost of Heat for a 425,000 Btuh
Cordwood Boiler to Replace 11,500 gpy Fuel Oil. Does not include wood cost.
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Figure 4-8 illustrates the effect of capital and non-fuel costs on the cost of heat for
a 425,000 Btuh cordwood system to replace 6,605 gallons of fuel oil per year at different
terms of cost recovery. This is the reported use at the Craig Community Center. A 70%
efficient boiler system would be used at a full load equivalent of 1,823 hours per year or
about 21% capacity. The cost to recover a $40,000 investment would be about
$8.84/MMBtu for 5 years, $5.06/MMBtu for 10 years or $3.25 for 20 years. Boilers in
this example have been in use for more than 20 years. No labor is included in this
calculation since most sites indicated that stoking the wood boilers would be included in
responsibilities of existing personnel.
0.00
5.00
10.00
15.00
20.00
25.00
30.00
20000 40000 60000 80000 100000 120000
Capital Cost ($/425 kBtuh)Cost Hot Water($/MMBtu)20 years 10 years
5 years Oil 2.50/gal
Figure 4-8. Impact of Capital and Non Fuel Cost on Cost of Heat for a 425,000 Btuh
Cordwood Boiler to Replace 6,600 gpy Fuel Oil. Does not include wood cost.
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Figure 4-9 shows the total cost of heat including the wood and capital cost for a
425,000 Btuh system saving 11,501 gallons of fuel oil per year at 20 year capital cost
recovery with an interest rate of 6% and an annual maintenance cost of 3% ($1,200).
Operating and maintenance costs do not include labor since each institution indicated that
fuel handling would be included in the normal duties of maintenance personnel. From
this figure $160/cord would be the maximum price for fuel when fuel oil is $2.50/gallon
($21.31/MMBtu). This example would fit a single boiler at Thorne Bay school to recover
all of the fuel oil consumed.
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
40000 50000 60000 70000 80000 90000 100000 110000
Capital Cost ($/425 kBtuh HW)Cost of Hot Water ($/MMBtuOil $4.00 $75.00 $100.00 $125.00 $150.00 $175.00
Oil $3.50 Oil $3.00 Oil $2.50
20 Year CR 6%
Figure 4-9. Total Cost of Heat to Replace 11,500 gpy Fuel Oil At Various Wood Costs
($/Cord).
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-22 T R Miles
Figure 4-10 shows the total cost of heat including the wood and capital cost for a
425,000 Btuh system saving 6,605 gallons of fuel oil per year at 20 year capital cost
recovery with an interest rate of 6% and an annual maintenance cost of 3%. Operating
and maintenance costs do not include labor since each institution indicated that fuel
handling would be included in the normal duties of maintenance personnel. From this
figure $160/cord would be the maximum price for fuel when fuel oil is $2.50/gallon
($21.31/MMBtu). This example would fit the Craig Community Center. If the $66,000
Dot Lake system were built again today it could afford to pay about $140/cord to be
equal to oil at $2.50/gal.
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
20000 30000 40000 50000 60000 70000 80000
Capital Cost ($/425 kBtuh HW)Cost of Hot Water ($/MMBtuOil $4.00 $75.00 $100.00 $125.00 $150.00 $175.00 Oil $3.50 Oil $3.00 Oil $2.50
20 Year CR 6%
Figure 4-10. Total Cost of Heat to replace 6,605 gal Fuel Oil at Various Wood Costs
($/Cord).
4.3.4 Conclusions:
• This analysis suggests that a chip system would be feasible at Delta Greely
Schools but a low cost system ($300,000) would be necessary for the
Thorne Bay School.
• Cordwood systems may be appropriate at Thorne Bay School and Craig
Community Center or similar applications saving 6,600 to 11,500 gpy fuel
oil.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-23 T R Miles
• Chip fuel cost has a low impact on wood boiler systems at a high level of
oil replacement (102,000 gpy).
• Capital costs have a high impact at low levels of oil replacement (11,500
gpy).
• Cordwood fuel costs have a high impact on small and large systems.
• Capital costs have a high impact at low levels of oil replacement.
• Building and piping or integration costs must be kept low for wood boilers
to be feasible.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 5.0 Delta Greely Schools
10 August 2006 5-1 T R Miles
5.0 Delta Greely Schools
5.1 Overview
Delta Greely Schools consumed 69,000 gallons of fuel oil in 2004.13 Fuel oil
consumption at the new school was estimated 33,000 gallons based on the area of the
facility. Total consumption for both complexes was estimated at 102,000 gallons per
year. Installed capacity for the combined schools and auxiliary buildings is about 10
MMBtuh. (Table 4-6) The system is divided into two complexes with capacities of 4.5
MMBtuh for the new elementary and about 5.5 MMBtuh for the old campus. The total
capacity required for the coldest day for both complexes is calculated to be 4 MMBtuh
(Table 4-6). This is a typical size for chip-fired boilers in schools.
School officials want to reduce fuel costs. They recognize that the boilers in the
older school building will eventually need replacement. And they would like to take
advantage of wood available from land clearing, forest cleanup and community recycling.
In this assessment a single boiler is sized for 4.5 MMBtuh which would cover
100% of the current demand at both complexes. Detailed engineering will be required to
determine if the calculation of capacity required for the coldest day (Table 4-6) is
accurate or if a larger boiler is needed.
Fuel would be delivered as chips in self unloading trailers to a fuel storage bin
where it would be automatically metered to the boiler on demand. At peak demand (4
MMBtuh) the boiler would consume 19 ton per day or 133 tons per week. This is equal to
about 5.5 trailers per week. The boiler would normally consume an average of 50 tons
per week or about two trailer loads. New systems of this size are normally supplied with
storage for 80 tons or about three trailer loads.
The amount of fuel available from local sawmills or clearing operations has not
been determined. Chipped or milled pallets and urban wood waste may be available from
the solid waste facility. Whole tree chips from forest salvage must also be identified.
Supply sources will determine feasibility. For this analysis we have used $15-$30/green
ton for chipped wood delivered to the school compared with oil at $2.50/gallon.
13 60,000 gallons per year has been considered to be the minimum fuel oil consumption for considering
wood fuel in New England. At this consumption a wood system can save about half of what is spent on oil.
Biomass Energy Resource Center, 2005.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 5.0 Delta Greely Schools
10 August 2006 5-2 T R Miles
The fuel handling and boiler system is large enough that it could be supplied by
several companies. Each supplier has a slightly different approach to receiving and
burning wood. In most cases they buy components from other suppliers and install an
integrated system at the site. The boiler building would house the fuel receiving and
metering bin, boiler, water treatment and pumps, and cyclones for gas cleanup. A stack
for a boiler of this size may be integrated within the building or built as a separate stack.
In this case we have assumed that the stack would be separate.
Integration with the existing heating systems will be a significant cost. Delta-
Greely has two centers of operation: the old campus containing the main high school, old
elementary (now administration), Vocational Technology Center, Career Advancement
Center, Cyber Center and several modular classrooms which consume 69,000 gpy fuel
oil; and a new elementary. The old campus is an appropriate location for a central heating
plant. The plant must be sited so that stack exhaust does not create fog on a busy local
access road. Pipe routing must be designed between the buildings. The boiler would
connect to the new elementary building which is 1,000 feet from the old campus. Since
they are at the same elevation the two clusters can be serviced by a single boiler house.14
5.2 Estimated System Costs and Benefits
Capital costs and savings for two alternatives are shown in tables 5-1 and 5-2. In
the first case (A) a 4.5 MMBtuh system is sized just for the old campus that has been
consuming 69,000 gallons of fuel oil per year. In this case the boiler house would be
located to serve the existing buildings. Total estimated cost is $1,034,000. The calculated
Present Value (PV) of the savings from wood compared with oil at $2.50/gal is positive
so the wood chip boiler project is viable at fuel prices of $15/ton and $30/ton.15
In the second case (B) the same boiler would supply heat to both the old campus
and the new elementary school to displace 102,000 gallons per year of fuel oil.
Additional capital costs are included for piping and integration of the new school. The
14 Messersmith. 2006.
15 Present Value (PV) of the savings from wood compared with oil is used to assess the financial viability
of a project. A project is viable when the present value of the savings is greater than zero for a given
discount rate. The capital investment for the wood heating system is estimated. Then the net annual cash
flow is estimated for each year up to the end of the useful life of the system. A heating system has no direct
annual revenues. Cash requirements are reduced by savings from using wood instead of fuel oil. BLCC5.3-
6, Building Life Cycle Cost, from the USDOE Federal Energy Management Program was used to calculate
savings from the wood fuel alternatives. Assumptions are listed in table 4-9.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 5.0 Delta Greely Schools
10 August 2006 5-3 T R Miles
total estimated cost is $1,214,000. Present Value (PV) of the savings from wood
compared with oil is positive so the wood chip boiler project is viable at fuel prices of
$15/ton and $30/ton. Estimated savings after fuel, electricity and labor are $171,175 per
year which would imply a simple payback of about 7 years.
Table 5-1. Estimated Wood Boiler Costs for Delta-Greely Schools.
Facility A
4.5 MM Btuh
Old School
B*
4.5 MMBtuh
New+ Old
Difference
Fuel Oil Replaced, gallons per year 69,000 102,000 33,000
Building, 50 x 40 $ 228,000 $ 228,000
Boilers, Fuel System $ 397,000 $ 397,000
Piping, Integration $ 106,000 $ 231,000 $ 125,000
Other Installation $ 66,000 $ 80,000 $ 14,000
Total Direct Costs $ 797,000 $ 936,000 $ 139,000
Indirect Costs: Engineering, Permits $ 102,000 $ 120,000 $ 18,000
Contingency, unlisted items 15% $ 135,000 $ 158,000 $ 23,000
Total $1,034,000 $ 1,214,000 $ 180,000
Savings Compared With Fuel Oil**
PV Wood at $15/ton $ 580,000 $ 1,236,800
PV Wood at $30/ton $ 265,000 $ 770,400
Notes:
* Wood system sized to supply actual consumption from schools. Table 4-6.
** Present Value Life Cycle Cost, 20 Year, 3% discount rate, constant dollars
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 5.0 Delta Greely Schools
10 August 2006 5-4 T R Miles
Table 5-2. Savings from Wood Fuel at Delta Greely Schools
Table Header Cost Quantity $ Total
Fuel Oil Used, gallons $2.50/gal 102,000 $ 255,000
Wood chips used, tons green* $30/ton 2,084 $ 62,520
Electricity, kWh $0.17/kWh 66,500 $ 11,305
Labor, hr $20/hr 500 $ 10,000
$ 83,825
Gross Savings from Wood** $ 171,175
Notes:
* 66 gallons of fuel oil per tons of wood chips Table 4-2
** Does not include maintenance, financing or other costs not listed above
Building, piping and integration costs are the largest areas of uncertainty in these
estimates. A detailed engineering study will be required to estimate these more accurately
and to reduce piping and integration costs.
Heating the main schools at Delta Greely should prove feasible, especially since
most of the heating equipment is old and some probably due for replacement.
Replacement costs were not considered in this preliminary analysis.
5.3 Recommended Actions for Delta Greely Schools
• Conduct a detailed engineering study for a central heating plant for the
Delta Greely Schools.
Several alternatives must be considered to supply all or part of the Delta
Greely Schools with wood heat. This must be done in a more detailed
engineering analysis which can evaluate the condition of the existing oil
boilers and furnaces and the costs of integrating them with a central wood heat
system or systems.
• Determine fuel supply sources and costs.
There is still uncertainty about the sources and cost of 2,084 tons of wood
chips required to supply the Delta-Greely schools. There is no existing
infrastructure for delivering wood chips as fuel. It is not likely that it would all
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 5.0 Delta Greely Schools
10 August 2006 5-5 T R Miles
be supplied from a single sawmill like Logging and Milling Associates at Dry
Creek. Substantial savings could be made if mill residues were available at
$15/ton but it is more likely that there will be a variety of fuel sources at
higher costs. Whole tree chips from forest fuel reduction or land clearing may
cost $30/ton or more.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 6.0 Thorne Bay School
10 August 2006 6-1 T R Miles
6.0 Thorne Bay School
6.1 Overview
Fuel oil consumption at Thorne Bay School is 11,500 gallons per year. There are
two boiler rooms in the school: one for the upper school and one for the lower building
including the gymnasium. The installed fuel oil heating capacity is 1.8 MMBtuh for the
two buildings. The calculated demand from Table 4-6 is only 347,000 Btuh so that a
wood system producing 425,000 Btuh could replace all of the fuel oil now used. Both
chip and cordwood systems are considered below.
Thorne Bay School is interested in reducing fuel costs and providing educational
opportunities with a wood system for their students.
6.2 Wood Chip Boiler
A wood chip boiler would consist of a receiving bin, boiler, cyclone and separate
stack. The bin would be 50 x 18 ft x 8 ft tall which would hold approximately 60 tons or
two truckloads of woodchips. The bin would be filled by self unloading trailers. At the
rate of use the bin would be filled about once every two to four weeks. There is not much
room for an automated chip system near the school. The smallest chip system would be
about 1 MMBtuh. It would require a 50 ft x 30 ft building.
Chips are available at the Viking mill in Klawock or a chipper could be installed
at one of the mills at the Goose Creek industrial park.
The components and estimated costs of a chip system are listed in Table 6-1.
Chips would be metered on demand into a boiler burning fuel directly on a grate
(Messersmith, Decton) or to a separate gasifier (Chiptek). Hot gas exhausting from the
boiler would be cleaned in a cyclone and exit from a separate stack. The separate stack is
a significant cost but may be necessary for emissions control at this location.
Hot water from the boiler would be integrated directly into the existing heating
system. The two systems in the Thorne Bay school are separated by about 600 feet. A
significant cost may be for the plumbing to supply both buildings
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 6.0 Thorne Bay School
10 August 2006 6-2 T R Miles
6.3 Cordwood Boiler
A single cordwood boiler burning 147 cords per year could replace all of the fuel
oil used. A cordwood boiler was based on a preassembled Garn WHS 2000 (425,000
Btuh) boiler with integral heat exchangers and a small horizontal stack. It has minimal
installation and power requirements. A building could be built with one boiler installed to
supply the upper building which is a short piping run from the boiler, or both the upper
and lower buildings. A second boiler and piping could be installed later if it was found
that the first boiler has excess capacity and if piping to the lower building can be
completed economically. A 20 ft x 30 ft, building could house up to two 425,000 Btuh
cordwood boilers which could supply 850,000 Btuh. Cordwood would be stored in the
building or under cover adjacent to the boiler. The boiler would be filled approximately
twice a day for a 2 hour burn. Operation during the daytime would also fill thermal
storage incorporated into each boiler that is equal to 1,300,000 Btu. This may be
sufficient to handle large heat demands for short periods. School personnel would stoke
the boilers at no extra labor cost. An alternative arrangement would be to install a boiler
under the existing cover which would avoid building a separate building. This would
reduce the project cost.
The boiler could burn dry pallet waste or seasoned cordwood. Cordwood is
available from small lumber processors in the Goose Creek Industrial area or in bulk
from the small log processor at Viking lumber. For the purposes of this study cordwood
has been priced at $60/cord and $100/cord.
6.4 Estimated System Costs and Benefits
Costs for the chip and cordwood systems are estimated in Table 6-1. The base
price of the chip boiler includes a separate stack which is 10%-15% of the total cost. The
total direct costs estimated here for the chip system are similar to other projects. Savings
for the wood chip system of $19,940 result in a payback of 35 years. The present value of
the chip savings compared with oil is negative at both $30/ton and $15/ton. This
illustrates that a small wood chip system must displace a much higher oil consumption
than the 11,500 gallons per year currently used at the school. With fuel at $15/ton a boiler
system would have to cost $250,000. With fuel at $30/ton a boiler would have to cost
$135,000 or less to be feasible. Adjacent buildings such as the city maintenance shop do
not add much to the load. It has also been suggested that the Ranger station and school
combine as a co-op but the ranger station must have a significantly higher demand to
justify a combined system.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 6.0 Thorne Bay School
10 August 2006 6-3 T R Miles
A similar size but lower cost chip system was recently installed at a mill in
Hoonah but the equipment used may not be acceptable in a school environment.
Table 4-6 showed that one 425,000 Btuh boiler could offset the fuel oil consumed
by the school. The capital costs are estimated here at $104,300. Savings of $14,150
would result in a simple payback of 8 years. Tables 6-1, 6-3. The project is feasible with
one boiler as shown by the positive present value of savings from wood in Table 6-1
when cordwood is available for $60/cord or $100/cord.
Capital costs could be reduced if a boiler can be placed under the existing covered
area near the utility entrance to the school. Savings from the wood boiler are positive at
both $60/cord and $100/cord and the project is viable.
Annual savings would be $11,705 on an investment of $104,300 for a nine year
payback using wood at $100/cord. Payback would be seven years without a building.
Table 6-1. Estimated Wood Boiler Costs for Thorne Bay School.
Facility Wood Chips Cordwood
(1) boiler*
Cordwood
(1) boiler**
Capacity, Btuh 1,000,000 425,000 425,000
Fuel Oil, gallons per year 11,500 11,500 11,500
Buildings, 1500 ft2; 600 ft2 $ 158,000 $ 21,600 **
Boilers, Fuel System, Stack $ 280,000 $ 19,500 $ 19,500
Pumps, Piping, Integration $ 52,500 $ 38,300 $ 38,300
Other Installation, Electrical $ 48,100 $ 2,300 $ 3,500
Total Direct Costs $ 538,600 $ 81,700 $ 61,260
Engineering +Contingency $ 161,000 $ 22,600 $ 17,20
Total $ 699,000 $ 104,300 $ 78,500
NPV $ 15/ton, $60/cord ($455,000) $ 93,700 $ 119,500
NPV $30/ton, $100/cord ($510,400) $ 6,000 $ 31,800
Notes:
* Building sufficient for two boilers. Install one (Garn WHS 2000) since estimated
load is less than 425,000 Btuh. Table 4-6.
* * Install boiler under existing building cover.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 6.0 Thorne Bay School
10 August 2006 6-4 T R Miles
Table 6-2. Savings from Wood Chips at Thorne Bay School.
Table Header Cost Quantity $ Total
Fuel Oil Used, gallons a $2.50/gal 11,500 $ 28,750
Wood chips used, tons green b $30/ton 236 $ 7,080
Electricity $0.17/kWh 10,170 $ 1,730
Labor Inc Inc -
$ 8,810
Gross Savings from Wood $ 19,940
Notes:
a 2004 11,500 gal at $2.00/gal
b 49 gallons of fuel oil/ton wood chips, Table 4-2.
Table 6-3. Savings from Cordwood at Thorne Bay School.
Table Header Cost Quantity $ Total
Fuel Oil Used, gallons a $2.50/gal 11,500 $ 28,750
Cordwood b c $100/cord 147 $ 14,700
Electricity $0.17/kWh 13794 $ 2,345
Labord Inc. Inc
$ 17,045
Annual Savings from Wood $ 11,705
Notes:
a 2004 11,500 gal at $2.00/gal
b 66 gallons fuel oil per cord at 70% efficiency, Table 4-2.
c Slabs and edgings available from Goose Creek or Klawock
d Labor by school personnel
6.5 Recommended Actions for Thorne Bay School
Thorne Bay School provides a good opportunity for an efficient, low emission
cordwood system. There is interest and enthusiasm for the project. Capital costs should
be kept to less than $104,300. Integration and piping costs may be greater than expected.
Conduct a detailed engineering study for the integration of energy efficient, low
mission cordwood boilers for the Throne Bay School and gym.
Plan to demonstrate wood heat with one boiler for half the load and a second in
the future if feasible.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 7.0 Craig Community Center
10 August 2006 7-1 T R Miles
7.0 Craig Community Center
7.1 Overview
Community Center consumes 6,605 gallons of fuel oil per year. They are
concerned about fuel cost increases. They expect fuel use to increase as the new Tribal
Hall and Tech Center are used more. They would need to hire personnel to supply wood
or maintain a wood boiler. A boiler can not be located in their 200 vehicle parking which
is already at capacity for special functions.
Fuel use at the center could be replaced by approximately 52 cords of wood. A
two hour burn during the day should supply the center’s needs. The boiler could burn dry
pallet waste or seasoned cordwood. Cordwood is available from sawmills in the Craig
vicinity as slabs and edgings or off cuts from small log processing.
There is a location behind the center that would be suitable for a 14 x 20 building
and fuel storage for a Garn WHS 1500 (350,000 Btuh 920,000 Btu storage). An internal
glycol heat exchanger in the Garn would heat glycol circulated from the existing heating
loop to the existing boiler. Dectra can supply a pre-engineered package which will
require just attaching pipes to the heat exchanger on the Garn. The system would require
two low power circuits.
If Craig Community Center participates in the Craig Aquatic Center boiler project
hot water would be piped across the street to the center.
7.2 Estimated System Costs and Benefits
Cordwood system costs are estimated in Table 7.1. The principal cost is the
boiler. Piping from the existing system would be connected to a heat exchanger built into
the cordwood boiler. At a capital cost of $37,000 the savings at current fuel use is $7,163
for a payback of about 5 years. Present value savings from wood are positive at $60/cord
and $100/cord.
Labor is an important consideration at the Community Center since there is no
one currently available to stoke a wood boiler. Labor costs are included in the facilities
maintenance personnel. However this may be a cost that needs to be added. If 500 hours
per year (1 hour per day) is added at $20/hour then any savings from wood is offset by
the labor cost.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 7.0 Craig Community Center
10 August 2006 7-2 T R Miles
Table 7-1. Estimated Wood Boiler Costs for Craig Community Center.
Facility Cordwood
Capacity, Btuh 350,000
Fuel Oil, gallons per year 6,605
Buildings, 20ft x 14ft, 280 ft2 $ 14,500
Boilers, Fuel System, Stack Garn WHS 1500 $ 15,500
Pumps, Piping, Integration $ 3,500
Other Installation, Electrical $ 1,200
Total Direct Costs $ 34,700
Engineering +Contingency $ 2,300
Total $ 37,000
Present Value Savings compared with Fuel Oil, 20 year
Wood $60/cord $ 90,800
Wood $100/cord $ 40,400
Table 7-2. Savings from Wood at Craig Community Center.
Table Header Cost Quantity $ Total
Fuel Oil Used, gallons a $2.50/gal 6,605 $16,513
Wood chips used, tons green b $100/cord 89 $8,900
Electricity $0.17/kWh 2,347 $ 450
Labor Inc Inc -
$ 9,350
Gross Savings from Wood $ 7,163
Notes:
a 2004 6,605 gal at $2.45/gal, 10,000 ft2 in use
b 66 gallons of fuel oil/cord, Table 4-2.
7.3 Recommended Actions for Craig Community Center
Conduct a detailed engineering study for the integration of energy efficient, low
emission cordwood boilers for the Craig Community Center. The wood system can be
easily located at the ground floor alongside the building accessible from the rear. Detailed
specifications for the piping and civil work and cost estimates should be obtained so that
a true cost of the project can be determined.
Identify who will operate the boiler and supply the fuel.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 8.0 City of Thorne Bay
10 August 2006 8-1 T R Miles
8.0 City of Thorne Bay
8.1 Overview
City of Thorne Bay facilities are listed in Table 8-1 with the fuel oil consumption
and potential savings from wood. All of the facilities are small. Oil consumption is
significantly less than installed capacity, as shown in Table 4-6. The buildings are
dispersed and there are few opportunities for combining loads. The City Hall, VPSO and
Emergency Services which are in the same location are too small and too far apart to
make use of combined loads. The City Maintenance facility may be large enough to
support a cordwood boiler, especially if the load is combined with the adjacent duplexes.
Fuel consumption at the solid waste building is similar.
Table 8-1. Potential Savings from Wood at City of Thorne Bay Facilities.
Facility Oil
Gal/yr a
Wood
Cord/yr b
Oil
$/yr c
Wood
$/yr d
Potential
Savings
$/yr
City Shop and Duplexes 3,050 46 $ 7,625 $ 4,600 $ 3,025
City shop 1,800 27 $ 4,500 $ 2,700 $ 1,800
City Owned Duplexes 1,250 19 $ 3,125 $ 1,900 $ 1,225
Solid Waste Building 2,000 30 $ 5,000 $ 3,000 $ 2,000
City Hall + VPSO 600 9 $ 1,500 900 $ 600
Emergency Services 600 9 $ 1,500 900 $ 600
Water Treatment 600 9 $ 1,500 900 $ 600
Wastewater Treatment 600 9 $ 1,500 900 $ 600
Notes:
a 2004 use from SOI
b 66 gallons per cord Table 4-2
c $2.50/gal
d $100/cord
8.2 Maintenance Shop and Duplexes
City of Thorne Bay Maintenance Shop consumes 1,800 gpy of fuel oil. Adjacent
to the shop are two city owned duplexes that consume 1250 gpy. Together they consume
3,050 gallons per year. The duplexes would add load without adding significant cost.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 8.0 City of Thorne Bay
10 August 2006 8-2 T R Miles
The City of Thorne Bay Maintenance Shop and Bus Garage is the former high
school gym. It is heated primarily by oil fired furnaces that consume 1800 gpy. There is a
location behind the center that would be suitable for a 14 x 20 building and fuel storage
for a Garn WHS 1500 (350,000 Btuh. 920,000 Btu storage). This would provide heat at
approximately the same rate as the installed fuel oil capacity. An internal glycol heat
exchanger in the Garn would heat glycol circulated from the existing heating loop to the
existing boiler. The cost of this system is estimated in Table 8-2 at $31,900. Savings from
wood are approximately $3,125/year which would result in a payback of 10 years. The
present values (PV) of the savings from wood are positive at $60/cord and negative at
$100/cord.
Demand on the coldest day for both the maintenance facility and duplexes was
estimated in Table 4-6 at less than 100,000 Btuh. Costs for a boiler of this size based on
TarmUSA and Alternative Heating systems are shown in Table 8-2. In this case payback
at $3,125 per year would be six years. The Present Values of the savings of wood
compared with fuel oil for this arrangement are positive for wood at both $60/cord and
$100/cord. If the same boiler is used for just the duplexes or for the City Hall and VPSO
then savings are positive at $60/cord but negative at $100/cord. The costs shown in Table
8-2 are the lowest obtained for boilers in this size.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 8.0 City of Thorne Bay
10 August 2006 8-3 T R Miles
Table 8-2. Estimated Wood Boiler Costs for Thorne Bay Maintenance Facility.
Facility Full
Capacity
Smaller
Boiler
Duplex, or
City Hall
and VPSO
Capacity, Btuh 350,000 100,000 100,000
Fuel Oil, gallons per year 3,050 3,050 1,250
Buildings, 20ft x 14ft, 160 ft2 $ 6,500 $ 1,900 $ 1,900
Boilers, Fuel System, Stack $15,500 $ 9,200 $ 9,200
Pumps, Piping, Integration $8,000 $ 3,200 $ 3,200
Other Installation, Electrical $1,300 $ 2,100 $ 1,100
Total Direct Costs $31,300 $16,400 $15,400
Engineering +Contingency $600 $ 600 $ 600
Total $31,900 $17,000 $16,000
Present Value of Savings from Wood
compared with Fuel Oil, 20 year
Wood $60/cord $21,000 $ 40,800 $ 6,400
Wood $100/cord ($ 2,300) $ 17,500 ( $ 3,200)
Notes:
* Garn WHS 1500 350,00 Btuh
** Alternate Heating Systems or Tarm 100,000 Btuh
Table 8-3. Savings from Cordwood at Thorne Bay Maintenance and Duplexes.
Table Header Cost Quantity $ Total
Fuel Oil Used, gallons a $2.50/gal 3,050 $ 7,625
Cordwood b $100/cord 46 $ 4,600
Electricity $0.17/kWh 3,520 600
Labor c Incl. Incl.
$ 4,500
Annual Savings from Wood $ 3,125
Notes:
a 2004 Maintenance 1800 gal, Duplexes, 1250 gal at $2.00/gal
b 66 gallons fuel oil per cord at 70% efficiency, Table 4-2.
c Labor by school personnel
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 8.0 City of Thorne Bay
10 August 2006 8-4 T R Miles
8.3 Solid Waste Facility
City of Thorne Bay Solid Waste Facility bales municipal refuse. It is heated with
an oil fired air heater that consumes 2,000 gpy of fuel oil. The building is inefficient since
the garage doors are often open during operation. Consumption was estimated at 60,000
Btuh in Table 4-2. A 100,000 Btuh boiler could be installed as shown in Table 8-4 at a
cost of $17,000. Potential savings are $2,000/year at $100 cord. Present values of the
savings from wood compared with oil are positive at $60/cord and $100/cord.
Table 8-4. Estimated Wood Boiler Costs for Thorne Bay Solid Waste Facility
Facility Solid Waste Facility
Capacity, Btuh 100,000
Fuel Oil, gallons per year 2,000
Buildings, 50 ft2 $ 1,900
Boiler $ 9,200
Pumps, Piping, Integration $ 3,200
Other Installation, Electrical $ 2,100
Total Direct Costs $16,400
Engineering +Contingency $ 600
Total $17,000
Present Value Savings compared with Fuel Oil, 20 year
Wood $60/cord $ 19,600
Wood $100/cord $ 4,300
8.4 City Hall and VPSO
Evaluation of other systems include the Thorne Bay City Hall and VPSO (1250
gpy). These systems represent a $3000 to $4,000/year fuel savings on investments of
$16,000 to $18,000. They represent a positive net savings with a longer payback.
Thorne Bay City Hall and VPSO is central to the community and a good visible
demonstration site. It is located at the end of a cluster of buildings that include the City
Hall, VPSO, emergency services and in future will include a new City Hall and other
public buildings. The site was evaluated for a central heating system with hot water
distributed to the small buildings. However piping the hot water to the adjacent buildings
is too costly for such low loads of about 600 gpy each. A Tarm residential system was
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 8.0 City of Thorne Bay
10 August 2006 8-5 T R Miles
evaluate for the City Hall and VPSO and shows savings of $3100 per year on an
investment of $16,000 for a six year payback and net positive savings.
Low emission energy efficient boiler systems are too expensive for most small
(600 gpy) applications proposed. These may be satisfied with domestic wood appliances.
Small buildings at Thorne Bay are heated with small efficient oil heaters supplied
by Monitor or Toyo. These 40,000 Btuh units are efficient and difficult to replace with
anything but a small wood appliance.
8.5 Recommended Actions for City of Thorne Bay
Conduct a detailed engineering study for the integration of energy efficiency, low
emission cordwood boilers for the City of Thorne Bay Maintenance garage with the
addition of the duplexes.
Installation at the Maintenance garage would replace old furnaces by putting a
heat exchanger in the ducting. Those requirements and costs must be determined.
Plan to install a cordwood boiler behind the Maintenance garage. Extend the
piping to the Duplexes if feasible.
By locating a boiler behind the garage glycol from a heat exchanger can be
pumped to the city owned duplexes. Piping and heat exchangers must be specified and
costs estimated to determine if this is feasible.
Verify project costs to duplicate the cordwood boiler for sites like the
Maintenance garage or the Solid Waste Facility (2000 gpy) for space heating.
As discussed above, the Solid waste facility may be a difficult place to heat or to
save money with wood heat. The Garn WHS 1500 could be used to heat the facility as a
duplicate to the Maintenance garage.
Verify the system costs for installing a small cordwood boiler to serve the City
Hall and VPSO (1250 gpy).
Installation costs for a Tarm boiler have not thoroughly been investigated here.
The City Hall application is similar to a wood boiler in a residence. The boiler would be
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 8.0 City of Thorne Bay
10 August 2006 8-6 T R Miles
located a short distance from the City Hall or on the end of the City Hall building. Glycol
from the boiler system would be piped through a heat exchanger on the wood boiler.
The loads for the Emergency Services Building, City Shop, Water Treatment and
Wastewater Treatment facilities are too small for a wood fired system unless a residential
sized energy efficient low emission appliance is used.
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Feasibility Assessment for Wood Heating 9.0 Venetie Airport Maintenance
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9.0 Venetie Airport Maintenance
9.1 Overview
Venetie Village presented several proposals for wood heating. Most were for
future buildings that were not yet in the planning or design phase. The airport at the
village has a maintenance garage and waiting area. The maintenance garage is heated
with two oil-fired unit heaters and with waste heat from a diesel generator. The principal
concerns at the village are: 1) the high cost of fuel, since all the fuel must be flown in; 2)
availability of fuel when there is no winter delivery or failure of the engine, which
occurred in 2004-2005; 3) keeping the snow removal equipment in the maintenance
garage warm; and 4) heating the waiting room (16 x 24 ft).
Heat is supplied to the maintenance facility by two 250,000 Btuh oil-fired unit
heaters. This total capacity of 500,000 Btuh may be necessary to heat the facility in the
severe cold; however actual consumption suggests that the heat required on the coldest
day is less than 100,000 Btuh. Table 4-6. Two wood systems were considered: a 350,000
Btuh boiler with 920,000 Btuh storage capacity located in an adjacent building; and a
smaller 100,000 Btuh boiler that might be located in the maintenance facility itself. Table
9-1.
9.2 Estimated System Costs and Benefits
Table 9-1 shows that the savings from the wood system could be installed for
$35,000 for the 350,00 Btuh system or $18,000 for the 100,000 Btuh system. Table 9-2
shows that Venetie Village could save approximately $3,900/year from wood at
$100/cord compared with fuel oil at $4.20/gallon. Payback would be nine years on a
350,000 Btuh boiler or five years on a 100,000 Btuh boiler. The present values for
savings from wood are positive in both cases.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 9.0 Venetie Airport Maintenance
10 August 2006 9-2 T R Miles
Table 9-1. Estimated Wood Boiler Costs for Venetie Airport Maintenance Facility.
Facility Excess
Capacity
Small Boiler
Capacity, Btuh 350,000 100,000
Fuel Oil, gallons per year 1,688 1,688
Buildings, 20ft x 14ft, 160 ft2 $ 10,100
Boilers, Fuel System, Stack $14,000 $ 9,200
Pumps, Piping, Integration $4,000 $ 2,300
Other Installation, Electrical, Freight $6,300 $ 4,200
Total Direct Costs $34,400 $15,700
Engineering +Contingency $600 $ 2,300
Total $35,000 $18,000
Present Value of Savings from Wood compared with
Fuel Oil, 20 year
Wood $60/cord $ 26,800 $ 46,700
Wood $100/cord $ 13,900 $ 33,800
Notes:
* Garn WHS 1500 350,000 Btuh
** Alternate Heating Systems or Tarm 100,000 Btuh
Table 9-2. Savings from Wood at Venetie Airport Maintenance Facility
Table Header Cost Quantity $ Total
Fuel Oil Used, gallons a $4.20/gal 1,688 $ 7,090
Wood chips used, tons green b $100/cord 26 $2,600
Electricity $0.25/kWh 2,347 $ 590
Labor Inc Inc -
$ 3,190
Gross Savings from Wood $ 3,900
Notes:
a 2004 1688 gal at $4.20/gal
b 66 gallons of fuel oil/cord, Table 4-2.
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Feasibility Assessment for Wood Heating 9.0 Venetie Airport Maintenance
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9.3 Recommended Actions for Venetie Village
Venetie Airport Maintenance Facility is the same size as the Thorne Bay City
Hall with only slightly higher fuel consumption. Consider an energy efficient, low
emission cordwood system for heating the facility if the delivered system cost is
appropriate. Select the higher capacity system with the built-in heat storage capacity and
the potential for heating the waiting room and other buildings as appropriate.
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Feasibility Assessment for Wood Heating 10.0 General Recommendations
10 August 2006 10-1 T R Miles
10.0 General Recommendations
Plan to install five or six energy efficient low emission cordwood boiler systems.
There may be several cordwood systems which can be selected for demonstration.
Transportation costs can be improved if several boilers from the same supplier are
delivered on the same load.
Develop and demonstrate low cost buildings and heat distribution systems for hot
water applications.
Assessments of energy system were initially made using the steel pipe
construction common in Alaska. Lower cost systems using the PEX piping should be
evaluated. These are being used effectively in the OWB applications in Alaska and have
been used for many years in the Northern US.
Alaska Wood Energy Development Task
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Feasibility Assessment for Wood Heating
Appendix A. List of Abbreviations and
Acronyms
10 August 2006 A-1 T.R. Miles
Appendix A. List of Abbreviations and Acronyms
AEA Alaska Energy Authority
AWEDTG Alaska Wood Energy Development Task Group
BDT Bone Dry Ton
BTU British Thermal Unit (MBtu, thousand Btu ; MMBtu, million Btu)
CE Conversion Efficiency (fuel to heat)
CHP Combined Heat and Power
CO Carbon Monoxide
Cord 80 ft3 of solid wood
CR Cost Recovery; years to recover investment at indicated interest rate
DB Dry Basis (wet weight –dry weight/dry weight)
DD Degree Days (Heating Degree Days)
EPA U.S. Environmental Protection Agency
GHV Gross Heating Value (also Higher Heating Value)
Gm Gram
Gpy Gallons per year
HHV Higher Heating Value
JEDC Juneau Economic Development Council
KBtu Thousand Btu
KWe Kilowatts, electric
KWt Kilowatts, thermal
MC Moisture Content (e.g. MC20 20 % moisture)
MBtu Thousand Btu (also kBtu)
MMBtu Million Btu
NHV Net Heating Value
NPV Net Present Value
OD Oven Dry (weight)
ODT Oven Dry Ton
O&M Operating and Maintenance
OWB Outdoor Wood Boiler
POW Prince of Wales Island
PV Present Value
RHV Recovered Heating Value
Unit A shipping volume of 200 ft3
WB Wet basis (wet weight-dry weight/wet weight)
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Appendix B. AWEDTG Evaluation Criteria
The following criteria were used to evaluate and recommend projects for
feasibility assessments:
1. The opportunity for displacing fuel oil, natural gas, propane or diesel-generated
electricity used by targeted facilities for heating needs (i.e., current fuel type, gallons of
fuel per year, annual cost per year);
2. Local presence of high-hazard forest fuels and potential for utilizing these fuels
for heating schools, other public facilities, and buildings owned and operated by not-for-
profit organizations;
3. Availability of local wood processing residues (e.g., sawdust, planer shavings,
and slabs);
4. Project cost versus yearly savings (cost-effectiveness);
5. Sustainability of the wood fuel supply;
6. Community support and project advocacy;
7. Ability to implement the project;
8. Ability to operate and maintain the project.
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Appendix C. Wood Boiler Suppliers
Wood boiler suppliers contacted in this study.
Alternative Heating Systems, Inc.
Chiptek
Dectra/Garn
Decton Inc.
Messersmith
Precision Energy Systems
TarmUSA
1. Tarm USA, House in Palmer, AK 2. Alternate Heating Systems 100,000 Btuh -230,000
Btuh
3. Garn 350,000 Btuh WHS 1500 Ready to Ship 4. Dectra, Garn WHS 3200 Dot Lake,AK
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1. 3 MMBtuh Boiler with Gasifier, MA 2. 3 MMBtuh Chiptek Gasifier, Athol, MA
3. 4.9 MMBtuh Boiler Building Victor, MT 4. Fuel Bin With Chip Reclaim Auger, Victor MT
5. Fuel Bin, Chip Reclaim and Boiler, Victor, MT 6. Low Fire, Victor MT
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Appendix D. Delta Greely
Project: Delta Greely Schools
Location: Delta Junction, Fairbanks 64.035 N 145.725 W
1.Delta Elementary School, Now Admin 2. Delta Junction School
3. Delta Junction School 4. Delta High School
5. Shop Area of High School 6. Existing Stacks and Vents
Alaska Wood Energy Development Task
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Feasibility Assessment for Wood Heating Appendix D. Delta Greely
10 August 2006 D-6 T.R. Miles
7. Typical Oil Boiler 8. Typical Hot Water Air Heater
9. Hot Water Heater 10. Oil fired Air Heater
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11. Boiler at High School 12. Boiler at High School
13. Vocational Tech and Buildings 14. Separately Heated Votech Building
15. Modular Classrooms 16. Front of New Elementary
Alaska Wood Energy Development Task
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Feasibility Assessment for Wood Heating Appendix D. Delta Greely
10 August 2006 D-8 T.R. Miles
17. View New Elementary to Old Campus 18. Front Entry New Elementary
19. Side of New Elementary 20. New Elementary Fuel Tank
21. New Elementary Boiler Room 22. 4 MMBtuh (3 Boilers)+ Hot Water
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Feasibility Assessment for Wood Heating Appendix E. Thorne Bay School
10 August 2006 E-9 T.R. Miles
Appendix E. Thorne Bay School
Project: Thorne Bay School, Southeast Island School District
Location: Thorne Bay, Prince of Wales Island 55.67 N 132.49 W
.
1.Thorne Bay High School Entry approach 2. TB School Upper and Lower Buildings
3. TB School Upper Entry 4. TB School Utility Entry
5. Possible Location for Wood Boiler 6. Back Wall to Upper Boiler Room
Alaska Wood Energy Development Task
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Feasibility Assessment for Wood Heating Appendix E. Thorne Bay School
10 August 2006 E-10 T.R. Miles
7. Boilers in Upper Building 8. Water Heater Upper Building
9. Upper and Lower Building 10. Boiler Room Lower Building
11. Road Past Lower Building 12. Lower Building Water Heater and Boilers
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Feasibility Assessment for Wood Heating Appendix E. Thorne Bay School
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13. Duct Heat Exchanger 14. Duct Exchanger and Unit Heater
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Feasibility Assessment for Wood Heating Appendix F. Craig Community Center
10 August 2006 F-12 T.R. Miles
Appendix F. Craig Community Center
Project: Craig Community Association
Location: Craig, Prince of Wales Island 55.48 N 133.14 W
1. Craig Community Center Parking Area 2. Upper Level Meeting Hall
3. Lower Side-road Access Left 4. Upper Parking Above Boiler
5. Rear Used For Playground 6. Road Access Possible Boiler Location
Alaska Wood Energy Development Task
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Feasibility Assessment for Wood Heating Appendix F. Craig Community Center
10 August 2006 F-13 T.R. Miles
7. Bridge Entry. Fuel Oil Tank Near Boiler 8. West Side Fence Line
9. Boiler 10. Hot Water
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Feasibility Assessment for Wood Heating Appendix G. City of Thorne Bay
10 August 2006 G-14 T.R. Miles
Appendix G. City of Thorne Bay
Project: City of Thorne Bay
Location: Thorne Bay, Prince of Wales Island 55.68 N 132.52 W
1. Thorne Bay City Hall 2. Boiler Room and Fuel Tank
3. City Hall Boiler 4. VPSO and Emergency Service Buildings
5. VPSO Heater Fuel Tank 6. Emergency Services Building
Alaska Wood Energy Development Task
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Feasibility Assessment for Wood Heating Appendix G. City of Thorne Bay
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7. Fuel and Exhaust Emergency Services 8. Air Heater Exhaust Emergency Services
9. City Garage (Former Gym) 10. Air Heated Garage
11. Adjacent City Duplexes for Teachers 12. Access to Garage Air heater
Alaska Wood Energy Development Task
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Feasibility Assessment for Wood Heating Appendix G. City of Thorne Bay
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13. Fuel Oil Tank Near Heater 14. Air Heater
15. Maintenance Shop 16. Water Treatment
17. Water Treatment South Heater 18. Typical Heater
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19. Sanitary Plant 20. Sanitary Boiler
21. Air Heater in Sanitary Plant 22. Municipal Waste Building
23. Fuel Tank Municipal Waste 24. Waste Baler and Office
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Appendix H. Venetie Airport Maintenance
Project: Venetie Village
Location: Venetie, Yukon-Koyukuk 67.01895 N 146.40012 W
1.Venetie Village, School Washeria to Left 2. Lance Whitell and Council President
3. Hauling Firewood 4. Airport Garage and Waiting Room
5. Unit Heater Stack, Rear Side 6. Diesel Fuel and Engine Exhaust
Alaska Wood Energy Development Task
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7. Diesel storage, Engine Exhaust 8. Heat Vent and Engine Exhaust
9. Oil Unit Heater (45,000 Btuh) 10. Heater and Stack (1 of 2)
11. Heated Equipment Room 12. Generator Room
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10 August 2006 H-20 T.R. Miles
13. Engine Exhaust, Radiator and Vent 14. Waiting Room
15. Waiting Room 16. Washeteria
17. Washing Machines 18. Showers
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19. Dryers 20. Hot Water From Generator Exhaust
21. Fuel Oil, Hot Water, Water Supply 22. Shop: Converted Water Tank
23. Community School 24. Community School