HomeMy WebLinkAboutUpper Kobuk Region Biomass Project Feasibility and Design Report - circa 2015 - REF Grants 2195397, 7040028, 7050840CONTACT:
Mr. Keith Henn, PG
(412) 921-8398
keith.henn@tetratech.com
SUBMITTED BY:
Tetra Tech
310 K St., Ste. 200
Anchorage, Alaska 99501
Northwest Arctic Borough
Project
Northwest Arctic Borough
Upper Kobuk Biomass Project
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Table of Contents
Executive Summary............................................................................................................................1
1. Wood and Waste Stream Analysis...............................................................................................1
1.1. Biomass Distribution within Upper Kobuk Region........................................................................1
1.2. Consumption and Available Biomass for Proposed Plant.............................................................7
1.3. Woody Biomass Species..............................................................................................................13
1.4. Resource Management Plan.......................................................................................................16
1.5. Waste and Refuse-Derived Fuels (RDF) ......................................................................................19
2. Biomass Energy Potential in Upper Kobuk Villages.....................................................................22
2.1. Market Conditions ......................................................................................................................22
2.2. Project Site Opportunity Analysis...............................................................................................23
2.3. Project Scenario Selection ..........................................................................................................30
3. Technology and Equipment Evaluation......................................................................................32
3.1. Biomass Boiler Technologies.......................................................................................................32
3.2. Project Scenario Technology Evaluation.....................................................................................36
3.3. Technology Vendors ...................................................................................................................41
4. Detailed Energy and Site Analysis of Selected Projects...............................................................44
4.1. Site and Energy Audit – Ambler City Hall / Washeteria..............................................................44
4.2. Site and Energy Audit – Proposed Shungnak Community Center ..............................................49
5. Boiler Facility Engineering Design..............................................................................................54
5.1. Foundation Design......................................................................................................................54
5.2. Ambler City Hall / Washeteria Biomass Boiler Engineering........................................................59
5.3. Proposed Shungnak Community Center Engineering.................................................................68
6. Economic and Financial Analysis ...............................................................................................76
6.1. Cost-Benefit Analysis: Commercial and Residential Installation................................................76
6.2. LCVA Financial Modeling Results................................................................................................80
7. Environmental, Regulatory, and Permitting...............................................................................85
7.1. Equipment Safety and Boiler Certification..................................................................................85
7.2. Permitting Requirements............................................................................................................85
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8. Conclusion and Recommendations............................................................................................88
Appendix 1: Bibliography.................................................................................................................89
Appendix 2: Upper Kobuk Public Meeting Survey..............................................................................91
Appendix A:.....................................................................................................................................93
Ambler City Hall / Washeteria Design Package..................................................................................93
Appendix B:.....................................................................................................................................94
Proposed Shungnak Community Center Design Package ...................................................................94
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Figures
Figure 1 – 10-mile Radius Study harvest Area......................................................................................2
Figure 2 – Photo of Upper Kobuk Region Forest Distribution ...............................................................3
Figure 3 – Upper Kobuk Biomass Distribution .....................................................................................4
Figure 4 – Land Management in Upper Kobuk Region..........................................................................5
Figure 5 – Ambler Target woody Biomass Distribution ........................................................................9
Figure 6 – Shungnak and Kobuk Target Woody Biomass Distribution...................................................9
Figure 7 – Photo of Representative Forested area, Upper Kobuk Region............................................13
Figure 8 – Photo of Representative Upper Kobuk Aspen Stand near Ambler ......................................16
Figure 9 – Photo of an Arctic Tundra Trail near Ambler......................................................................18
Figure 10 – Average U.S. MSW Composition .....................................................................................20
Figure 11 – Photo of Ambler IRA Boiler Room...................................................................................25
Figure 12 – Photo of Kobuk School (under construction in summer, 2013).........................................28
Figure 13 – Photo of Flood Stage in Kobuk........................................................................................29
Figure 14 – Bulk Fuel Boiler Operational Diagram..............................................................................33
Figure 15 – Cord-wood Gasification Boiler Operational Diagram........................................................35
Figure 16 – Range of Energy Output from Vendor Boilers..................................................................37
Figure 17 – GARN Model WHS-2000 Emissions and Efficiency Hangtag ..............................................39
Figure 18 – Tarm Froling FHG Model 20 Emissions and Efficiency Hangtag.........................................39
Figure 19 – Example Gasification Boiler Control Module....................................................................40
Figure 20 – Ambler Site Plan.............................................................................................................45
Figure 21 – Photos of Ambler City Hall Boiler Room (a) and (b)..........................................................46
Figure 22 – Shungnak Site Plan.........................................................................................................50
Figure 23 – Photo Example of Pressurized Boiler System...................................................................69
Figure 24 – Ambler Project Life-Cycle Value Analysis.........................................................................83
Figure 25 – Shungnak Project Life-Cycle Value Analysis .....................................................................83
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Upper Kobuk Biomass Project
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Tables
Table 1 – Tonnage Woody Biomass by Village @ 25-mile radius ..........................................................5
Table 2 – Kobuk Subunit Timber Allotments .......................................................................................6
Table 3 – Upper Kobuk Region Current Wood Consumption................................................................7
Table 4 – Forested Acreage and Annual Allowable Cut by Village Unit Designation ..............................8
Table 5 –Acres of Woody Biomass within 100m and 500m of Road..................................................10
Table 6 – Annual Accessible and Allowable Cut (tons) for the Upper Kobuk Region............................11
Table 7 – Annual Accessible and Allowable Cut (cords) for the Upper Kobuk Region ..........................11
Table 8 – Forest Resource Availability to Serve Heating Needs of Kobuk Communities.......................12
Table 9 – Density and Energy Value of Woody Biomass Species at 20% Moisture Content..................14
Table 10 – Waste-Derived Feedstock Potential of Upper Kobuk Villages............................................21
Table 11 – NWAB Energy Prices, December 2013 ..............................................................................22
Table 12 –Levelized cost of Fuel per MM Btu Output ..................................................................23
Table 13 – Ambler Opportunities Analysis Matrix..............................................................................25
Table 14 – Shungnak Opportunities Analysis Matrix..........................................................................27
Table 15 – Kobuk Opportunities Analysis Matrix...............................................................................29
Table 16 – Ambler Climatic Design Criteria........................................................................................44
Table 17 – Ambler City Hall Heating Demand....................................................................................46
Table 18 – Shungnak Climatic Design Criteria....................................................................................49
Table 19 – Biomass Facility Cost Benefit Analysis ..............................................................................58
Table 20 – Feedstock Storage Cost Benefit Analysis...........................................................................58
Table 21 – Ambler City Hall Boiler Construction and Installation Cost................................................63
Table 22 – Shungnak Community Center Boiler Construction and Installation Cost ............................72
Table 23 – Cost-Benefit Analysis of Municipal Cordwood-fired Boiler ................................................77
Table 24 – Cost-Benefit Analysis of Residential Cordwood-fired Boiler...............................................79
Table 25 – Summary Financial Metrics..............................................................................................82
Table 26 – Ambler Project Sensitivity Analysis ..................................................................................84
Table 27 – Shungnak Project Sensitivity Analysis...............................................................................84
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Executive Summary
Tetra Tech, Inc., and project partner DOWL HKM, completed the following Feasibility Study and initial
Engineering Design for the Northwest Arctic Borough (NWAB) under RFP #13-03: Upper Kobuk Biomass
Project. The project reviewed the viability of wood biomass heating in the Upper Kobuk region,
specifically in the villages of Ambler, Kobuk, and Shungnak. Focus of the project included woody
biomass feedstock availability and accessibility to local woodcutters to supply fuel for a biomass energy
system; site survey of viable project locations and heating demands that may be serviced by a biomass
energy system; detailed site design of biomass energy installation at selected sites; review of available
technologies and selection of optimal technology for each proposed project; engineering design of
system components and housing structures; analysis of project financial viability; and review of
permitting requirements for implementation of the project.
Overview and Problem Statement
The villages of the Upper Kobuk region see multiple opportunities to provide heat energy for village
buildings by installing one or several wood-fired boilers. The region is one of the few in the north and
west corners of Alaska to be blessed with forestland to harvest for fuel wood. Currently the majority of
the fuel wood harvest is for residential use, and the potential is apparent to combine this resource with
advancing technology in gasifying wood boilers.
The Upper Kobuk Valley region has some of the highest cost-of-living expenses in Alaska, which is the
most expensive state in the US. There are no contiguous roads connecting villages within the Upper
Kobuk Valley or outside of the borough. All resources must either be gathered from the land or flown
into each village’s airport. Use of the Kobuk River for transport is extremely limited and has only been
used once in the last 2 years.
Fuel oil is currently over ten dollars per gallon, airlifted into the villages. Considering the cost of a cord of
firewood is approximately $210 (based on $70/sled load, equivalent to 1/3 cord), one million Btu’s
(MMBtu) of heat from fuel wood will cost residents of the Upper Kobuk area approximately $16.00. To
make the same energy from fuel oil costs $87.33, a savings of over $70 per MMBtu when fuel oil use is
displaced with locally-available biomass.
Right now, 2.7 million gallons of heating oil are used annually in Northwest Arctic Borough regional
communities. Only 4% (or 100,000 gallons equivalent) of heating is provided by wood. Figure ES-1
shows the fuel consumption in the borough. This indicates a large potential opportunity that has, until
the present, not been utilized in the region.
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Figure ES-1 – Estimated Annual Fuel Consumption for NANA communities
Source: NANA Region Strategic Energy Plan
Wood Supply
Woody Biomass distribution in the region surrounding Ambler, Kobuk, and Shungnak was found to be
sufficient to support a number of woody biomass energy systems.
Several woody biomass studies have already been conducted in Upper Kobuk region. These studies were
taken into account and supplemented with geospatial database research to determine quantity, quality,
and accessibility of woody biomass surrounding the villages.
The study determined that Ambler has available 181 tons of woody biomass available for harvest each
year within 328 feet (100m) of a road, and 934 tons of material within 1640 feet (500m) of a road. This
is over twice the current consumption, and can be accomplished without straying from designated road
areas. Shungnak has 486 tons available within 1640 feet (500m) of road, slightly more than the current
usage. Within 10 miles of the village there are over 7,000 tons of available biomass that can be
harvested annually. Kobuk has almost 500 tons of available annual harvestable material within 1640 feet
(500m) of a road, almost three times its current usage. Within 10 miles of the village is a massive 11,000
tons of woody biomass that can be sustainably harvested each year. It is recognized that most of the
harvesting occurs in winter months when snow machines are not restricted by roads and this was used
in determining the amount of accessible biomass.
Based on these figures, each of the three villages could heat its respective community with wood, if the
need presented itself. Local harvest techniques, primarily based on dispersed, wintertime harvest of
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Upper Kobuk Biomass Project
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trees using snow machines and sleds to haul wood back to the villages, will likely be sufficient to supply
a small, community wood boiler, but supply may be more difficult if large (over 500k Btu or 150 kilowatt
(kW) thermal output) systems are built. The scale of the proposed projects is well under that.
The proposed project scales are small-enough that their wood harvest demand would not trigger the
defined harvest structure and management guidelines in the Alaska Forest Resources and Practices Act,
but can be designed to comply with a number of the tenants of the Act. The majority of the cutting area
falls within NANA-owned lands, and collaboration with the Regional Corporation should be conducted as
early as possible in the project development phase to ensure compliance with the NANA Forest
Stewardship Plan.
Project Site Selection
The site survey determined that Ambler’s City Hall / Washeteria building, and the proposed Community
Center in Shungnak, present the best opportunities to serve the interests of the villages and also the
best logistics for biomass energy plant installation. Because a biomass boiler project is already under
development in Kobuk, it is likely best to wait until that project is constructed and wood collection
systems are developed before bringing up the possibility of another biomass boiler in that village. An
opportunity for biomass heating also exists at the Ambler IRA building, another heavily-used community
building in the village.
This study focused primarily on high-efficiency, low-emissions multi-stage boilers. For the Ambler City
Hall / Washeteria project, a design load of 199,000 Btu/hr or 56 kW (building heat only) is slightly over
the scale Tarm’s Fröling can produce, but well within the range of offerings by EKO, BioMass NextGen,
and GARN. The GARN WHS-1000 is the recommended equipment for the project. This equipment is the
optimal size for the application, meets stringent ASTM emissions and efficiency specifications that are
critical to be eligible for AEA project funding, and have an excellent track record of installations in rural
Alaska.
For the proposed Shungnak Community Center, a design load of 86,000 Btu/hr (25 kW) is well under the
production minimums of the GARN and AESI offerings, and met by Tarm, EKO, and BioMass NextGen.
The Tarm Fröling FHG-L model 30 is the recommended boiler for this application.
The residential energy scenario has a design load of 70,000 Btu/hr (20 kW), a load small enough that it is
met efficiently only by the smallest Tarm Fröling FHG-L (model 20) unit. The smallest EKO and BioMass
NextGen units, at 25kW or 85,000 Btu/hr rated output, are expect to perform reasonably well in this
environment. The BioMass Combo 25 is the same size, and with its versatility may be well-suited for the
application.
Project sites were selected, to the north of the Ambler City Hall / Washeteria and adjacent to the
northeast of the proposed Shungnak Community Center. No cultural or historical conflicts were found
for either of the selected sites; however the Shungnak project will have to be carefully sited to avoid
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crossing property boundaries into the Hall Street right-of-way. No wetland or other unexpected
geotechnical difficulties were found at either site.
Design Engineering
Design engineering was conducted for both projects. The Appendices contain the full design packages
for each facility.
Economic analyses of the project scenarios, as well as cost-benefit analysis for general wood-fired
installations in the area, were also conducted. Based on the inputs included in the financial model, both
project construction scenarios appear to be positive investments to undertake. The Ambler City Hall /
Washeteria project produces an annual cost savings averaging over $32,000, an internal rate of return
(IRR) of 8.8%, and a 20-year net present value (NPV) of $127,000. The fuel savings repays the project
capital cost in 11 years. The boiler for the proposed Shungnak Community Center produces a slim
annual average net income of just over $5,000, and project lifespan Internal Rate of Return (IRR) of
11.5% on a NPV of $29,000.
On an ongoing operations basis, the facilities are self-sustaining, saving more in fuel costs
(approximately $55,000 and $23,000 annually, for Amber and Shungnak, respectively) than their
operational costs, maintenance, and employee pay (totaling approximately $22,000 and $18,000,
respectively). Each facility is financially sound on its own merits, and additional support in the form of
grant funding to reduce the cost of capital equipment will also improve project financial metrics.
Permitting and regulatory approval for the Ambler City Hall / Washeteria Project or the proposed
Shungnak Community Center is expected to be relatively straightforward and simple. Neither boiler
system triggers federal regulatory restrictions or permit filings.
Conclusion
Based on the analysis conducted in this study, the project team recommends that NWAB and the
villages proceed with further development of biomass boiler installations in Ambler and Shungnak. The
projects appear to be technically and financially sound. Benefits to the communities include economic
development in the form of increased wood harvest revenue to woodcutters, and local labor for
construction and operation of the boilers with funds generated from fuel cost savings. As well, the
projects provide for renewable and self-reliant energy generation, and reduced imports of fuel oil
burned for heat.
Tetra Tech and DOWL HKM extend our appreciation to the Northwest Arctic Borough and Alaska Energy
Authority for the opportunity to work on this project.
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1. Wood and Waste Stream Analysis
This section reviews the woody biomass situation in the Upper Kobuk region, and the potential to
sustainably harvest biomass to fuel one or several heating installations in the region’s villages.
A number of woody biomass studies have already been conducted in Upper Kobuk region, some of them
quite recently. Three of these studies include on-site timber stand inspections to either gauge or confirm
empirical data of biomass resource volume and distribution; Forest and Land Management, Inc.’s
“Upper Kobuk Valley Wood Biomass Study”, two by Tanana Chief’s Conference Forestry program,
“Assessment of Woody Biomass Energy Resources at Villages in the Upper Kobuk Region of Northwest
Alaska: Kobuk, Shungnak, and Ambler” and “NANA Region Native Allotment Forest Inventory”. Several
other studies analyze harvesting techniques and the feasibility of biomass energy systems in the area.
NANA has produced both a “Strategic Energy Plan” and a “Forest Stewardship Plan”. Data gleaned from
these and other reports are used to develop the conclusions of biomass resource availability in the area.
1.1. Biomass Distribution within Upper Kobuk Region
Harvest Capture Radius
For the purposes of this study, the land area associated with each village has been modified slightly
compared to previous analyses. In the Tanana Chief’s Conference Upper Kobuk assessment, a 25-mile
radius was drawn around each village, and whatever land overlapped was appropriated to the closest
village. This is a very reasonable assumption, but because Shungnak lies between the other two villages,
its land base is severely restricted in that model. Since the population of Shungnak is 250% that of
Kobuk, it can be reasonably assumed that its capture area would be larger than Kobuk’s.
Woodcutters interviewed for this study indicated that they would travel up to 18-20 miles to harvest
wood. For the purposes of this wood supply analysis, the focus was on a 10-mile target region
surrounding each village. Use of this conservative capture area ensures that the counted wood supply is
likely to be accessible during some part of the year, and feasible to harvest and haul wood back to the
village.
Figure 1 shows the base map for woody biomass study in the Upper Kobuk. Note the significant overlap
between the harvest area for Shungnak and Kobuk. Wood product common to both villages (i.e.,
double-counted) is noted whenever possible.
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Figure 1 – 10-mile Radius Study harvest Area
Biomass Resource
The Upper Kobuk area is a mosaic of mature, well-stocked birch, aspen, and cottonwood stands
transitioning to tundra and mixed riparian stands in the lower-lying areas. Figure 2 shows an example of
the mature, mixed coniferous and deciduous forest common in the area.
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Figure 2 – Photo of Upper Kobuk Region Forest Distribution
Figure 3 shows the distribution of woody biomass within the Upper Kobuk region, delineated by
vegetation type. Wooded acreage covers 46% of the land surrounding Ambler, 49% surrounding
Shungnak, and 64% surrounding Kobuk.
As can be seen in the wood distribution map below, Shungnak has less available wood supply than the
other villages. Further upriver from Kobuk and in the surrounding mountains are the highest
concentrations of wood supply. Ambler has quality forested landmass concentration to the west and
north of it. Shungnak villagers can be expected to access wood in the mountains to the north of the
village, and possibly to the east in areas near the Bornite Mine road.
Note: Following the advice of the Tanana Chief’s Conference (TCC) Forestry Program in its “Assessment
of Woody Biomass Energy Resources at Villages in the Upper Kobuk Region of Northwest Alaska: Kobuk,
Shungnak, and Ambler,” mapping of regional biomass resources utilizes the National Land Cover
Database (NLCD) of 2001 over the Landfire database (TCC, June 2013), which has greater resolution but
mis-labels some stands in the region.
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Figure 3 – Upper Kobuk Biomass Distribution
Land Ownership
While it is difficult in practice to know which parcel of land a sled-load of wood comes from, land
ownership is important to note for inventory and estimation purposes. The designations are important
to logging rights for a larger commercial-scale operation but become less so with individual ‘one-off’
harvests by comminute members.
Land Ownership Classes
1:
BLM
USFS
State of Alaska
Alaska Native Allotment Act of 1906
Alaska Native Claims Settlement Act (ANCSA)
Figure 4 shows the land ownership distribution in the Upper Kobuk area.
1http://www.blm.gov/wo/st/en/info/history/sidebar/s/alaska/alaska_lands_transfer.html
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Figure 4 – Land Management in Upper Kobuk Region
Total regional biomass tonnage has been calculated at over 3.6 million dry tons of standing biomass, on
nearly 300,000 acres of forested land within 25-miles of the villages. Land ownership of forested areas
(based on tonnage available) is divided relatively evenly, with NANA as the largest shareholder (1.33
million tons) , followed by Federal Lands (1.19 million tons), State of Alaska lands (1.09 million tons) and
followed by Native Allotments (0.08 million tons). (TCC, June, 2013)
Table 1 quantifies the gross tonnage of biomass on that acreage by management or ownership. (Note
that this is shown as 25-mi radius). Within the 10-mile radius, the vast majority of land is owned by
NANA.
Table 1 – Tonnage Woody Biomass by Village @ 25-mile radius
Village NANA, Inc.
Native
Allotments Federal State of Alaska Total
Ambler 518,996 27,767 864,140 286,716 1,697,619
Kobuk 640,383 33,835 163,682 790,702 1,628,602
Shungnak 173,586 18,132 158,397 14,842 364,957
Total 1,332,965 79,734 1,186,219 1,092,260 3,691,178
Source: Tanana Chiefs Conference, 2013
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Native Allotments
Native allotments are interspersed within the land ownership / management categories noted above. It
is recommended that these lands be excluded from the biomass project harvest area, to the extent
possible in the management of feedstock acquisition at a biomass energy plant.
A study of Native Allotments and their land cover distribution was commissioned by Maniilaq
Association in 2012. This report is useful also because it subdivides the forest plots by tree size.
Assuming the plots are well distributed within the region, the percentage distribution of tree sizes can
be extrapolated to the publicly-owned, extractable areas of the region. The data captured is based on
both field analysis and stand inventory, as well as desktop analysis, and can give detail of tree type
distribution previously unavailable in the Upper Kobuk region. The Kobuk Subunit stretches from Kiana
to the west to Kobuk to the east, and within this area 291 Native Allotment parcels were covered by
aerial and included in the analysis (TCC, January 2013).
Table 2 describes the timber distribution withinthe Native Allotments of the Kobuk Subunit.
Table 2 – Kobuk Subunit Timber Allotments
In this designation, ‘Sawtimber’ stands contain tress of greater than or equal to 9.0 inches diameter at
breast height (DBH). ‘Poletimber’ stands contain trees in the range of 4.5 – 8.9 inches. Dwarf or
reproduction stands are primarily less than 25 feet tall, and less than 4.5 inches DBH. Stands with mixed
forest types are given the classification of the dominant species.
In the Kobuk Subunit, forested area accounts for 58.8% of the acres.
Of the forested regions, poletimber dominates sawtimber (38% to 6.9%). Poletimber also represents
twice the total timber volume of sawtimber stands. Also noted that while dwarf and reproduction
stands (and to a lesser degree, shrub lands) are not counted as containing harvestable timber in a
NANAKobukSubunit 1
CubicFeet
Region Acres % CubicFeet % Peracre
Sawtimber 1,932 6.9% 2,677,604 36.1% 1,386
Poletimber 10,598 38.0% 4,736,008 63.9% 447
Dwarf / Repro 3,789 13.6% - 0.0% -
Shrubland 6,464 23.2% - 0.0% -
Wetland 3,697 13.3% - 0.0% -
RiversandLakes 1,117 4.0% - 0.0% -
Barren and Cultural 172 0.6% - 0.0% -
Unknown 88 0.3% - 0.0% -
Total 27,857 100% 7,413,612 100% -
TimberVolumeAcreage
1 - Refers to Native Alottments within Subunit stretching from Kiana to Kobuk along Kobuk River
Source: NANA Region Native Allotment Forest Inventory, Tanana Chiefs Conference, ForestryProgram
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traditional sense, chip-wood biomass plants can process the small-diameter stunted tress and scrub
species such as willow and alder.
1.2. Consumption and Available Biomass for Proposed Plant
This section quantifies the sustainably harvestable biomass within a 10-mile radius of each village that
can be used to supply a biomass energy project.
Current Usage
Quantified data regarding the annual wood usage for heating in the Upper Kobuk area is not available.
Other indirect datasets were compiled to gauge an approximation of the current wood usage.
Households in the Northwest Arctic Borough spend an average of $137 per month on wood for heat,
according to a survey conducted by NANA in support of its Regional Energy Strategic Plan (NANA, 2009).
Assuming a sled-load of wood will cost $70, each household consumes on average two sled-loads per
month on the winter season, or approximately 0.75-1 ton of wood per month, at an estimated 850-1000
lbs per sled-load and an 8-month heating season. Based on lower estimate of these figures, the current
wood usage is 856 cords amongst all villages. The breakdown of wood consumption for home in each
village heating is shown below in Table 3.
Table 3 – Upper Kobuk Region Current Wood Consumption
Annual
Wood Use
Ambler Kobuk Shungnak
(tons)480 180 462
(cords) 369 138 355
TCC came to a similar conclusion in their analysis for the Kobuk Harvest Plan (TCC DRAFT Nov. 2013).
Assuming a use of 5 cords per household per year, the study concluded community residential wood
consumption at 100-150 cords per year in that village.
Available and Accessible Biomass for Harvest
Within a 25-mile radius of the three villages, an annual harvest of over 67,500 tons would be sustainable
for the area ecosystems.
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Table 4 – Forested Acreage and Annual Allowable Cut by Village Unit Designation
Village
Forested
Acreage
Forested % by
Project area
Biomass
(dry tons)
AAC
(dry tons/yr)
Ambler 136,701 14%1,697,619 31,606
Kobuk 126,514 17%1,628,602 29,452
Shungnak 33,319 7%364,957 6,572
Total 296,534 38.0%3,691,178 67,630
Source: Tanana Chiefs Conference, 2013
However, the calculated AAC figure represents the maximum sustainable harvest in the harvestable
region (25-mile radius around each village). The numbers are built around what the forests are capable
of bearing, and do not take into account accessibility and manpower of the villages to physically harvest
those amounts on an annual basis. This is obviously much more than can conceivably be accessed and
harvested by the villagers.
Annual Allowable Cut, calculated through the ‘Hanzlik formula’, is defined as:
“AAC is deemed to be the maximum level of annual harvest that is possible in perpetuity without
diminishment of the level of harvest or the amount and quality of the resource.
“TCC’s inventory data indicates total biomass tons of well stocked cottonwood, birch, or aspen
stands to be in a somewhat lower range (~20-50 tons/acre), with lower stand ages to be
expected to produce those volumes (~50-80 years). In the Kobuk region, TCC Forestry’s inventory
data suggests a substantially lower mean annual increment. Based on this, a value of 0.3 green
tons/acre/year and 0.25 dry tons/acre/year is assumed as optimum mean annual growth rates.”
(TCC, June, 2013)
Accessible Annual Allowable Cut
A method to further break down the forest and woody biomass resource that is reasonably accessible to
the local villagers is part of a woody biomass project, and more accurately anticipates the capture
potential by local woodcutters. It can be inferred that the easiest and most accessible biomass would be
that which is just off the roads and trails. Though a somewhat simplistic analysis and not representative
of the actual day-to-day harvest methods in the Upper Kobuk villages, Table 5 shows the woody biomass
potential within 100 meters and 500 meters of a road or trail documented by publicly-available
databases. This is naturally conservative as many well-established trails in the area will not show up on
the very limited map sets for the area. Data were gathered by Tetra Tech with the assistance of NANA’s
land management group, BIA, TCC, the University of Alaska-Fairbanks Geographic Information Network
of Alaska (GINA) system, and several local contractor firms.
Figure 5 and 6 show the woody biomass distribution and documented roads and trials in the areas of
each village.
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Figure 5 – Ambler Target woody Biomass Distribution
Figure 6 – Shungnak and Kobuk Target Woody Biomass Distribution
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Within 100m of documented roads in the region, each village has a limited number of available wooded
acreage, between 600 acres (Ambler) and 1,300 acres (Kobuk). While Shungnak has less wooded
acreage than the other villages, its road and trial system better intersects the forest than the other
villages, with nearly 1,250 acres of available forestland.
Within 500m of documented roads, the evergreen forest acreage near Ambler jumps significantly, to
2,850 acres. In other areas, the forested acreage up to 500m from roads is not appreciably better than
near the roads, indicating the dispersed nature of forested areas in the region.
Note that the NLCD designation ‘woody wetlands’ is omitted from the calculation, as this designation is
by definition only 20-25% populated with harvestable tree stands.
Table 5 –Acres of Woody Biomass within 100m and 500m of Road
Acreage CalculatedbyGIS
Analysis
100m from
Roaded area
500m from
Roaded area
10-mile radius
from Village
Deciduous Forest 4.7 16.5 483.9
Evergreen Forest 547.2 2,849.6 25,692.4
Mixed Forest 51.6 248.7 3,000.3
WoodyWetlands 655.4 2,929.1 34,865.7
Total (w/out WW) 603.5 3,114.8 29,176.5
Deciduous Forest 522.7 120.4 2,299.0
Evergreen Forest 681.2 1,334.3 18,838.1
Mixed Forest 37.9 165.9 2,706.7
WoodyWetlands 4,117.4 835.4 24,629.5
Total (w/out WW) 1,241.8 1,620.5 23,843.8
Deciduous Forest 522.7 120.7 2,984.0
Evergreen Forest 767.6 1,780.0 29,718.7
Mixed Forest 10.1 279.7 4,504.1
WoodyWetlands 4,117.4 681.3 21,145.9
Total (w/out WW) 1,300.4 2,180.4 37,206.9
Deciduous Forest 1,326.4
Evergreen Forest 14,752.6
Mixed Forest 1,799.9
WoodyWetlands 14,281.9
Total (w/out WW) - - 17,878.8
Kobuk-Shungnak Overlap
Ambler
Shungnak
Kobuk
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Upper Kobuk Biomass Project
Page | 11
Using TCC guidelines for calculation of Annual Allowable Cut (AAC) noted above, and including the
documented road and trail network in the region indicated the accessibility of the woody biomass
resource for harvest.
The study determined that Ambler has available 181 tons of woody biomass available for harvest each
year within 100m of a road, and 934 tons of material within 500m of roaded areas. This is over twice
the current consumption, and can be accomplished without straying from designated road areas.
Shungnak has 486 tons available within 500m of a road, slightly more than the current usage. Within 10
miles of the village there is over 7,000 tons of available biomass that can be harvested annually.
Kobuk has almost 500 tons of available annual harvestable material within 500m of road, almost three
times its current usage. Within 10 miles of the village are 11,000 tons of woody biomass that can be
sustainable harvested each year.
The study was not able to allot areas of forestland between Shungnak and Kobuk to either community,
therefore the ‘overlap’ of capture areas is included. Local wood gatherers are only parties that know
where wood is sourced, and do not divulge their wood sources. Attempt was made to account for
overlap so that wood supply was not double-counted.
Table 6 shows the AAC in tons for the region, while Table 7 converts the AAC to cords, a more common
measurement in the region.
Table 6 – Annual Accessible and Allowable Cut (tons) for the Upper Kobuk Region
Table 7 – Annual Accessible and Allowable Cut (cords) for the Upper Kobuk Region
Annual Allowable Cut (AAC)
Tons @ 0.3 tons/acre/yr
100m from
Roaded area
500m from
Roaded area
10-mile radius
from Village
Amber 181 934 8,753
Shungnak 373 486 7,153
Kobuk 390 654 11,162
Kobuk-Shungnak Overlap - - 5,364
Annual Allowable Cut (AAC)
Cords @ 0.3 tons/acre/yr
100m from
Roaded area
500m from
Roaded area
10-mile radius
from Village
Amber 138 713 6,682
Shungnak 284 371 5,460
Kobuk 298 499 8,521
Kobuk-Shungnak Overlap
- - 4,094
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Upper Kobuk Biomass Project
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Wood Biomass Resource Ability to Provide for all Regional Heating Demand
A hypothetical question was raised whether the local forests could sustainably fulfil the heating demand
for all of the buildings in the villages.
In Ambler, the volume of wood required to heat every building in town is estimated to be approximately
1,070 cords per year. In Shungnak, the fuel need is slightly less at 954 cords per year. Kobuk, being the
smallest village, would hypothetically have the least total fuel need at 406 cords per year.
The estimated AAC, or, as mentioned above, total volume of wood that could sustainably be harvested
each year, is many times greater that the demand of the villages. Ambler’s total demand would only
take 16% of the total AAC to be fully supplied, Shungnak 17%, and Kobuk 5%, due to its small size and
ample forested acreage within a 10-mile radius. A 2x or 3x ratio of available resource, compared to the
need, is usually considered a positive sign for forest health. Here that number is 6 times to 20 times,
indicating ample wood product.
Table 8 – Forest ResourceAvailability to Serve Heating Needs of Kobuk Communities
Supply
Annual Allowable Cut (AAC)
Cords @ 0.3 tons/acre/yr Amber Shungnak Kobuk
Kobuk-
Shungnak
Overlap
100m from Roaded area 138 284 298 -
500m from Roaded area 713 371 499 -
10-mile radius from Village 6,682 5,460 8,521 4,094
Demand
100% Wood Demand (Hypothetical)
Residential 585 563 219
Commercial 220 170 100
Schools 266 221 87
Total 1,070 954 406
% of AAC 16%17%5%
This is not to recommend that the villages heat entirely with forest wood, at least not as one large
project. It is instead a hypothetical exercise to gauge the level of fuel supply in the area, and whether
multiple municipal wood heating projects could be undertaken over time.
It must be noted the larger-scale harvest practices requires significant investment in equipment for
harvest, as well as a change in harvest practices, including summertime harvest, mechanical felling /
bunching, or river transport of harvested feedstock.
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Upper Kobuk Biomass Project
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Figure 7 – Photo of Representative Forested area, Upper Kobuk Region
1.3. Woody Biomass Species
Softwoods / Evergreen
White Spruce and Black Spruce (Picea genus)
- 100-yr rotation (slow)
- Most-used firewood species – high resin (sap) content which allows for quick lighting, rapid burn
with good space heating, low ash
Hardwoods / Deciduous
Birch (Betula genus)
- Dense hardwood, prized for quality burn characteristics
- Bark used for basket weaving
- Less prevalent than other species
Tamarack / Larch (Larix genus)
- Tamarack larch is a coniferous species, more similar to spruces and pine trees than birch, aspen
or cottonwood, but the tree is deciduous, dropping its leaves /needles at the end of each
growing season.
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Upper Kobuk Biomass Project
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Aspen (Populus tremuloides)
- Common, fast growing tree in the area
- Often mixed in stands with spruces
- Low density wood, but standing dead is well-dried
Balsam Poplar (commonly known as cottonwood)
- Faster, taller growth than spruce; 50-yr rotation
- Used for firewood, but ashy burn not desired
- Near rivers, dispersed amongst spruce and birch
Shrub / Brush
Willow and Alder
- Brushy growth, usually near water
- Willows used for baskets, etc.; Otherwise few uses. Not used for firewood currently
- Desired biomass plant feedstock (“green” trees) by Ambler Tribal Manager, Virginia
Table 9 – Density and Energy Value of Woody Biomass Species at 20% Moisture Content
Tree Species
Green Density
(lbs/Cubic Feet)
Air-Dry Density
(Lbs/Cubic foot)
Air-dry Weight
(tons/cord)
Heating Value
(MMBtu/cord)
White spruce 36 31 1.31 18.1
Black spruce 32 28 1.19 15.9
Paper birch 48 38 1.62 23.6
Aspen 43 27 1.15 16.6
Balsam poplar 38 24 1.02 15.0
Tamarack 47 37 1.57 16.0
Source: Wood density figures reprinted from TCC "NANA Region Native Allotment Forest Inventory" -
White spruce, Paper birch, Aspen and Balsam poplar figures are from the State of Alaska, Department of Commerce
(http://www.commerce.state.ak.us/ded/dev/forest_products/forest_products5.htm);
Black spruce figures are maintained by Lakehead University in Ontario (http://www.borealforest.org/);
Tamarack figures are from an engineering website (http://www.engineeringtoolbox.com/weigt-wood-d_821.html);
Heating Value from Alaska Division of Forestry "Purchasing Firewood in Alaska"
(http://forestry.alaska.gov/wood/firewood.htm)
Willow and alder species are not commonly considered firewood material, but can be combusted in
commercial-scale ground-wood or chip- wood biomass boiler equipment.
For the reasons of efficient energy production per unit weight harvested, and additionally to reduce
conflict with traditional firewood harvest, it is recommended that hardwood species be sought for the
public / commercial energy production systems.
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Upper Kobuk Biomass Project
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Wood density (dry) for combustion properties and heating value is one of the key features determining
the relative rank of each species. Moisture affects density, and requires additional effort to transport
and produces less heating per unit mass transported.
The recently-completed Upper Kobuk Valley Wood Biomass Study concluded that “The focus of
managing for biomass should be on cottonwood, aspen and birch, due to their growth rates, and
suitability for growth on much of the area.” (Forest and Land Management, Inc., 2010)
There are a number of benefits to the forest of sourcing primarily deciduous trees:
regrowth
Fire protection
Competition
Possible habitat – moose browse
The spruce species are considered the best-burning firewood choices, due to their even burn rate and
low ash production. As such, these species are prized for traditional residential fireplaces. To reduce
potential conflict with traditional firewood gathering, efforts will be made to focus the study on
alternate species. Birch has very high density and heating value, but as with many hardwood species,
produces significant ash. Aspen, cottonwood, and tamarack are similar in this respect.
Figure 8 shows a photo of a harvest area near Ambler, noting mature 30- to 40-foot aspen trees and
piles of discarded tree limbs which could be utilized as biomass energy material.
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Figure 8 – Photo of Representative Upper Kobuk Aspen Stand near Ambler
1.4. Resource Management Plan
Sustainable harvesting of wood resource to supply the proposed biomass energy projects is critical to
the success of the program. Throughout the completion of this study, information received indicates
that the majority of current wood harvest in the region is conducted in a sustainable manner developed
through generations of reliance on wood heating in the area. The wood volumes required for a project
any of the villages, particularly Kobuk and Ambler, are well within the sustainable output range of the
surrounding forests. The demand required for a single project of approximately 40 cords per year, place
very little strain on the available capacity and are well below the growth-to-drain ratio threshold that
would provoke concern over forest health.
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Based on the ample supply of wood resource available in the Upper Kobuk region, a dispersed, crowd-
sourced, village supplied model patterned after current wood biomass harvest and distribution is likely
to provide continued sustainable wood supply for the region while being easily and inexpensively
adopted by the villages. The price for fuel has been set for modeling purposes at $70/sledload in
Ambler, $80/sledload in Shungnak.
Ample forest inventory exists to provide fuel for the project while allowing for regeneration and
maintained forest health, as long as the impact of harvesting is distributed evenly in the forested areas.
As well, adherence to applicable forest management best practices and regulations will ensure a
sustainable wood resource supply for current as well as future generations. The scale of the proposed
projects does not trigger state forestry management regulations.
However, as noted by TCC in its forest management proposal to Kobuk, adherence to state forest
management regulations may be difficult at project scale (TCC DRAFT Nov. 2013). Alaska forest
regulations call for clearly-defined harvest areas, managed as a portion of an annually-updated harvest
plan. This is consistent with more formal methods implemented for larger harvests, and has the benefit
of delineating wood harvest for the biomass energy project and reducing the potential for conflict with
residential-based harvests.
The downsides to a systematic harvest acreage designation fall primarily under the argument that such a
program would be unnecessarily onerous for smaller-scale project situations, as proposed in this study.
The forest management program would be 1) is costly to develop, 2) difficult to enforce, and 3)
unnecessarily concentrates harvest activities to one area, instead of distributing the impact over the
broad acreage of forested area that is currently accessible to woodcutters, and does not give those
woodcutters the freedom to choose their own harvest areas.
Either harvest method is viable and could be successful. Final determination of the best solution for the
Upper Kobuk region will need to be made in formal consultation with all relevant stakeholders: local
governments, both civil and tribal, regional landholders and regulatory bodies, and state forestry agency
representatives.
The following provides guidance for forest best practices for the harvest of wood that would be followed
under either methodology.
Applicable Forest Health Regulations and Guidance
Alaska Forest Resources and Practices Act
The Alaska Forest Resources and Practices Act (FRPA) “governs how timber harvesting, reforestation,
and timber access occur on state, private, and municipal land.” According to the current interpretation
of the FRPA ‘commercial operation’ regulations as they apply to harvest for biomass energy, a project
would need to harvest, at minimum, 30,000 board feet per year, or the equivalent of 80 cords of woody
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biomass (TCC DRAFT Nov. 2013). As such, all of the proposed projects are well below this threshold and
would not be considered commercial operations. Concurrent with the recommendations of the Kobuk
Biomass Harvest Plan, it is recommended that the project submit a ‘voluntary plan of operations’ to the
Alaska Department of Forestry before commencement of harvest.
The FRPA does establish a number of best management practices for the harvest of timber that are
recommended to be followed under any circumstances. These include but are not limited to:
66 foot setbacks from rivers
66-100 foot setback for commercial operations or impacting fish habitat
Other protections of riparian, wetland and low-lying areas
Road and trail construction guidelines
The Division of Forestry has published a booklet called Implementing Best Management Practices for
Timber Harvest Operations that is used to ensure compliance with the Forest Resources and Practices
Act and Regulations. The booklet is available at www.forestry.alaska.gov/pdfs/05FRPAfieldbookfinal.pdf.
Figure 9 – Photo of an Arctic Tundra Trail near Ambler
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Upper Kobuk Biomass Project
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The photo above, taken just outside of Ambler, illustrates the difficulty developing and maintaining
summertime trails in the Arctic tundra.
NANA Forest Stewardship Plan
The majority of the cutting area falls within NANA-owned lands. Therefore, collaboration with the
Regional Corporation should be conducted as early as possible in the project development phase.
According to the NANA Forest Stewardship Plan (NANA, 2011, pg. 19 of 89):
“NRC will work with the local communities that develop a systematic biomass utilization
program to develop an appropriate use and payment system. A five-year harvest and
regeneration plan will be developed for each of the communities that use biomass at a
commercial level approved by the NRC Land Department.
NRC current policy is, in consultation with each village IRA Council, and KIC for 12(c) selections
around Kotzebue, and in accordance with its timber management plan, designate areas around
each village as firewood cutting areas and mark trees to be cut.”
NANA allows harvests for shareholders and non-corporations, but charges an administrative fee to non-
shareholders for firewood cutting commercial permits of $0.10 per linear foot, roughly equal to $25 per
sled load. Whether this administrative feed applies to a non-commercial project operated by the city is
unknown at the present time, and will have to be worked out as the project progresses.
Additionally, TCC recommends a number of BMP’s in its study report for Kobuk (TCC DRAFT, Nov 2013)
Harvesting in small patches, no larger than 200 feet in width.
Retain a minimum of 50 feet uncut forest between patches, with an overall retention of 30% or
more of the forest area in a stand.
In the patches, remove all material feasible for cordwood utilization, down to 4” DBH. Tree
falling is to be done by chain saw, with felled trees topped, limbed and bucked on site with slash
material to be lopped and scattered. Log lengths will depend on the specifications and
limitations of the technology or vehicles to be used for skidding and transport of the logs to the
village.
Where possible, retain healthy vigorous advance regeneration.
Rely on natural regeneration in the patches from existing advance regeneration and seeding
from adjacent retained timber.
1.5. Waste and Refuse-Derived Fuels (RDF)
90% of rural Alaskan villages dispose of waste in open dumps not compliant with EPA’s Resource
Conservation and Recovery Act (RCRA) standards (Colt, 2003). The Upper Kobuk region also follows this
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Upper Kobuk Biomass Project
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trend, with the responsibility on each resident to collect and bring refuse materials to the dump. No
central waste collection or recycling efforts are in practice at the villages. Shungnak recently upgraded
its dump and provides maintenance activates at the site, but does not have a central waste collection
system. Kobuk, is the only village of the three with a permitted landfill (AK DEC Permit # SW3A093-17).
All three landfills are designated Class III by the AK DEC.
Without a central waste collection point, such as a transfer station, where waste materials can be
separated into combustible and non-combustible materials, it is prohibitively difficult to operate a
waste-to-energy facility. This is the case in all villages of the Upper Kobuk. However, should the villages
have the opportunity to develop a centralized waste collection effort, perhaps combined with a hybrid
waste and biomass boiler system, an analysis of the available waste stream was conducted.
Below is the standard percentage composition of waste materials in the U.S. The average person
produces 4.34 pounds of mixed waste materials daily. Both figures are per the Environmental Protection
Agency (EPA)
2.
Figure 10 – Average U.S. MSW Composition
Source: US EPA
Shungnak, Ambler, and Kobuk’s populations are 262, 259, and 110 people, respectively, according to
NANA’s latest community profiles
3. Based on these figures, the villages of Shungnak and Ambler could
each support a wintertime paper, cardboard, and wood boiler with an average wintertime output of
187,000 Btu (roughly 50 kW), from their production each of 72 tons per year of paper, cardboard, and
wood waste materials. Kobuk could only support a boiler rated at 79,000 Btu output (20-25 kW).
2 http://www.epa.gov/epawaste/nonhaz/municipal/index.htm
3 http://nana.com/regional/about-us/overview-of-region/
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Table 10 showsthe waste production and estimated energy value of this wasteat the villages.
Table 10 – Waste-Derived Feedstock Potential of Upper Kobuk Villages
Shungnak Ambler Kobuk
Population 262 259 110
MSW (pounds per day)1137 1124 477
MSW (tons per year)208 205 87
Paper, Cardboard, Wood (Dry tons/yr)72 72 37
PC&W Heat Value (MMBtu/yr)1,041 1,029 437
PC&W Btu's/hr boiler output
(8 months operating time w/ 18-hr heat cycle)189,000 189,000 79,000
It does not appear that the waste production of the villages alone could support a waste-to-energy
system, even if all of the waste produced was transported to a central location and sorted. Tetra Tech is
not aware of a boiler small enough to run properly with this small volume of fuel. The smallest MSW-
capable boiler units available are rated at approximately 1,500,000 Btu (1.5 MMBtu) or 440 kW, which is
necessary to reach the required temperature for total material destruction and to permit the required
complex combustion and emissions control equipment.
The City of Kotzebue is considering a boiler of this scale to combust its fiber-based waste (paper,
cardboard, wood). The boiler is slightly oversized for the heating load of the buildings the boiler will
service, but is required to handle the type of material it will be processing. The larger population (and
resulting waste production) of Kotzebue versus the smaller Upper Kobuk villages is the critical factor
determining the viability of a waste-to-energy project.
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Upper Kobuk Biomass Project
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2. Biomass Energy Potential in Upper Kobuk Villages
This section reviews the various potential parcels of land available for siting the prospective biomass
energy facilities. Site surveys were conducted in each village included in the study (Ambler, Kobuk, and
Shungnak). A number of factors, including logistical considerations like proximity to thermal energy
users, feedstock, and other infrastructure, were compared to community benefit factors and villagers’
willingness to initiate a new “micro-economy” collecting and selling wood to the biomass project for the
benefit of the community. A survey gauging community interest in biomass energy was also conducted
by NWAB in support of the project. Survey results can be found in Appendix 2.
The initial opportunity analysis is followed by a more detailed site analysis of the primary chosen
scenarios.
2.1. Market Conditions
The Northwest Arctic Borough has some of the highest fuel prices in the state of Alaska, perhaps the
highest in the entire US. Below are listed the various energy prices in borough towns, as of December
18, 2013.
Table 11 – NWAB Energy Prices, December 2013
Gasoline/G Stove Oil/G Propane/23G Kwh (1-500)KwH (500-700)
Kotzebue $7.95 $6.32 $186.79 $0.17 $0.44
Ambler $10.75 $11.00 $285.00 $0.20 $0.77
Kobuk $10.46 $9.65 $270.00 $0.21 $0.83
Shungnak $10.59 $10.59 $330.00 $0.21 $0.83
Kiana $7.00 $6.50 $270.00 $0.20 $0.66
Noorvik $7.37 $7.31 $278.00 $0.20 $0.65
Selawik $7.75 $7.50 $264.55 $0.20 $0.61
Buckland $6.50 $6.50 $271.00 $0.20 $0.47
Deering $6.75 $6.50 $285.00 $0.20 $0.70
Kivalina $6.72 $6.45 $285.00 $0.20 $0.65
Noatak $9.99 $9.99 $311.00 $0.21 $0.88
Source: NWAB and various fuel outlets
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Based on these figures, and assuming a cord of firewood at $210 (based on $70/sledload, equivalent to
1/3 cord), the cost to produce 1 MMBtu of heat from fuel oil and wood are shown below. Even when
taking into account wood boilers’ slightly lower conversion rate, 1 MMBtu of energy from wood will cost
residents of the Upper Kobuk area approximately $16.00. To make the same energy from fuel oil will
cost $87.33, a savings of over $70 per MMBtu when fuel oil use can be displaced with locally-available
biomass, as shown below.
Table 12 –Levelized cost of Fuel per MM Btu Output
2.2. Project Site Opportunity Analysis
Potential project sites were initially identified and reviewed on August 19-22, 2013. Conditions,
circumstances, and environmental surroundings were reviewed for those conducive to or detrimental to
the addition of biomass energy system(s).
Ambler Opportunity Analysis
The village of Ambler also resides on the Kobuk River, just downstream of the confluence with the
Ambler River. The community has 259 residents living in 130 houses, according to NANA. Most residents
are Kuuvangmiut Iñupiat Eskimos.
Public services buildings in Ambler consist of an electricity generating station operated by AVEC, a water
treatment plant operated by ANTHC, a health clinic operated by Maniilaq Association, and an airport.
The Native Village of Ambler also operates an office building, as does NANA. The water treatment plant
has integrated renewable energy in the form of add-heat from the energy plant, and an array of four
solar power installations. ANTHC’s Division of Health and Engineering has a small office building and
maintains a fleet of loaders, dump trucks, and other heavy equipment in Ambler. It is unknown which
pieces of equipment are permanently located in town. The village has a Title 1 rural school building with
61 children attending from pre-kindergarten through 12
th grade.
Levelized Fuel Cost CordWood Fuel Oil
Btu Output(1Mmbtu) 1,000,000 1,000,000
Conversion efficiency 75% 85%
Btu Inputneeded 1,333,333 1,176,471
ProductUnit Cord Gallon
Btu/ProductUnit 17,500,000 130,000
Amnt of Product needed 0.08 9.05
Cost/Unit of Product $210.00 $9.65
Cost/MMBtuOutput $16.00 $87.33
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Upper Kobuk Biomass Project
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Other commercial and community buildings include a recently built combination community building,
which houses city services, and a washeteria. Several stores, hotels, and other private businesses
operate in town aswell.
Ambler city services purchases fuel separately from the general public at wholesale. Anecdotal evidence
places the general landed fuel cost at $7-10/gallon, but the city must transport, store, and distribute the
fuel to its various tanks, adding operational cost. The margin between wholesale and retail fuel cost is
assumed to be very small in the region as the local fuel distributors are often the local city or tribe
providing services for the residents.
Ambler has a small, non-permitted and non-regulated trash dump. There is no centralized waste
collection in the village. No programs are planned to centralize waste collection to allow for diversion
projects.
The most favorable option for biomass energy integration in Ambler is the village City Hall building. The
building was originally heated using small oil-fired Toyotomi stoves. A planned expansion to include a
Washeteria, jail, showers, and other associated community services and heated by two Weil-McLain oil-
fired boilers was undertaken, designed, and began construction in 2012. The project has since stalled.
The Weil-McLain boilers have not been put in service, and the building is only partially heated via
Toyotomi stoves and plug-in electric baseboard heaters. The jail, Washeteria room, and several other
rooms in the building currently have no heat source. Addition of a wood-fired biomass boiler to the
semi-complete project will improve its overall heating efficiency and improve the comfort level of the
building, and will be less expensive than a new biomass boiler integration because the heating
distribution system is already in place.
An opportunity for biomass heating also exists at the Ambler IRA building, another heavily-used
community building in the village. The IRA building was formerly heated by a wood-fired boiler, but the
boiler appears to be defunct and current heating services are provided by a single Weil-McLain boiler.
There appears to be space available in the boiler room and an associated storage room to install a
biomass boiler. A photo of the Ambler IRA Boiler room is below.
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Upper Kobuk Biomass Project
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Figure 11 – Photo of Ambler IRA Boiler Room
The Site Survey matrix for Ambler is provided below. Blocks are color coded to represent no concerns
(green), need for proceeding with caution (yellow) and probable impediments to the projects (red).
Table 13 – Ambler Opportunities Analysis Matrix
Ambler Hybrid Biomass / Waste District
Energy
Biomass – only Community
Building Heating
System of Individual Housing
Boilers
Feedstock Supply
Woody Biomass Supply good
Waste supply poor
Woody Biomass Supply excellent Woody Biomass Supply excellent
Feedstock
Collection System
no centralized waste collection
Woodcutters available but
unorganized (i.e., no market
system)
Distributed Woodcutters
Thermal Energy
Users
Washeteria
IRA offices
school building
Washeteria
IRA offices
school building
148 Households (168 bldgs.)
106 Owner-occupied
259 Residents
Utility Availability DE piping not available
Oil boiler present, can be
supplemented survey interest
Community
Benefit Unknown High Med
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Shungnak Opportunity Analysis
Shungnak is 10 miles downriver from Kobuk. The village has approximately 262 current residents living
in approximately 77 occupied homes. Another 10 unoccupied homes are in the town. Population data is
according to NANA’s village profile
4.
Commercial and public buildings include a diesel fuel-fired power plant operated by AVEC, which
provides electricity for Shungnak and Ambler. The town also has a water treatment plant, a building
housing city works and IRA, a public safety building, a post office, a community building, airport, and a
village health clinic run by Maniilaq Association. The Shungnak school is a Title 1 facility and serves 76
students pre-kindergarten through 12
th grade5.
Commercial buildings in Shungnak include two stores, a pool hall, a National Guard Armory (defunct),
plus three churches: Friends, Baptist and Seventh-Day Adventist. A general store and several other
commercial and public buildings exist. An ‘add-heat’ system is under development to utilize waste heat
from the power plant at the water treatment plant.
Most buildings within the village are located on a compact footprint common in rural Alaska, but the
commercial buildings are interspersed with residences. This increases the difficulty of a district energy
heat loop tying together the villages commercial buildings.
Shungnak recently completed a new city landfill that is maintained with a trailer and a full-track tractor.
There is no centralized waste collection effort in the village. Disposing of waste in the town dump site is
the responsibility of individual residents.
Based on detailed discussions with several village and community dignitaries followed by an exploratory
evaluation, it was determined that the best opportunity for biomass energy utilization in town is at the
proposed Community Center or 'Coffee House' public meeting space. The facility is currently in the
design process, which often allows for efficient and cost-effective integration of biomass energy. This
represents the most positive biomass energy opportunity in the village.
The Site Survey matrix for Shungnak is provided below.
4 http://nana.com/regional/about-us/overview-of-region/shungnak/
5 http://alaska.hometownlocator.com/schools/profiles,n,shungnak%20school,z,99773,t,pb,i,1002207.cfm
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Table 14 – Shungnak Opportunities Analysis Matrix
Shungnak Hybrid Biomass / Waste District
Energy
Biomass – only Community
Building Heating
System of Individual Housing
Boilers
Feedstock Supply
Woody Biomass Supply good
Waste supply poor
Woody Biomass Supply good Woody Biomass Supply good
Feedstock
Collection System
no centralized waste collection
Woodcutters available but
unorganized (i.e., no market
system)
Distributed Woodcutters
Thermal Energy
Users
5-6 dispersed commercial / public
buildings
coffee house (proposed)
IRA / City Works building
55 Households (65 bldgs.)
270 Residents
Utility Availability DE piping not available
New build can design in wood
system survey interest
Community
Benefit Unknown High Med
Kobuk Opportunity Analysis
The village of Kobuk stands the furthest upstream from Kotzebue of the three villages comprising the
Upper Kobuk region, and the smallest village in the Northwest Arctic Borough. The village was settled in
1899 as the Village of Shungnak, but was flooded in May 1973 and was moved 10 miles downstream to
the current site of Shungnak. The original village was resettled and remaining inhabitants renamed the
town Kobuk. Currently the village has between 110 and 115 inhabitants, 45 residential structures exist in
town but roughly only half of them are inhabited, according to NANA’s village profile
6. Another 6-7
public buildings exist, including a store, airport, fuel depot, community center, government building,
water treatment plant, and recently completed school building.
A biomass energy system has been proposed and approved, and is in the process of being constructed at
the Kobuk water treatment facility. The project is being built by the Alaska Native Tribal Health
Consortium (ANTHC). The project is currently in detail design phase and expected to commence
construction summer 2014.
The school building, shown nearly complete in Figure 12, represents the best available opportunity for
additional biomass energy installations in Kobuk. The Title 1 school building serves 46 students from pre-
kindergarten through 12
th grade. The school building is heated by a set of six (6) identical Weil-McLain
oil-fired boilers set in a free-standing boiler room. An unused building sits adjacent to the boiler room,
and could be used as a biomass boiler facility. The biomass boiler could be integrated with the existing
HVAC system and be used to supplement some or all of the heating capacity of the oil-fired boilers.
6 http://nana.com/regional/about-us/overview-of-region/kobuk/
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Figure 12 – Photo of Kobuk School (under construction in summer, 2013)
There is no centralized waste collection system at Kobuk, impacting the viability of waste-to-energy in
the village.
Flood conditions in the village of Kobuk are a concern for the construction of a biomass energy project,
as it is for any construction in the village, which has lain within the floodplain for its history. Below is a
picture of flooding that occurred in spring of 2013 (Figure 13).
It is recommended that a biomass energy project involving the Kobuk school (or other buildings) be put
on hold until the water treatment plant project has been constructed and operated for 2-3 yrs. Because
of the limited manpower available to gather feedstock for the plant and other potential unknowns to
development of previously-unknown biomass energy in the village, it is not recommended to have
multiple projects in development at the same time.
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Figure 13 – Photo of Flood Stage in Kobuk
Source: DOWL-HKM
The initial project opportunity matrix for Kobuk is provided below. As can be seen in the graphic, there
are more yellow (caution) and red (no-go) designation than there are green (go) opportunity areas.
Table 15 – Kobuk Opportunities Analysis Matrix
Kobuk Hybrid Biomass / Waste District
Energy
Biomass – only Community
Building Heating
System of Individual Housing
Boilers
Feedstock Supply
Woody Biomass Supply good
Waste supply poor
Unlikely to avoid feedstock
competition w/ ANTHC project
Woody Biomass Supply excellent
Feedstock
Collection System
no centralized waste collection
Woodcutters available but
unorganized (i.e., no market
system)
Distributed Woodcutters
Thermal Energy
Users 2-3 commercial / public buildings School 25 Households (45 bldgs.)
115 Residents
Utility Availability DE piping not available
Oil boiler present, can be
supplemented survey interest
Community
Benefit Unknown
Limited - ANTHC water treatment
plant biomass project under
construction
Med
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2.3. Project Scenario Selection
Upon completion of the matrix analysis of each village, the most plausible scenarios have been defined.
The primary focus has largely been driven by a project that will provide the most value to the overall
local community. More specifically, it is focused on a “community building” that is owned, managed,
and operated by the community. While few “community buildings” exist in each town after exclusion
of some buildings that are not owned by the local community (e.g., school), there are several good
opportunities to host a biomass boiler.
Several projects appear to meet defined criteria. Project scenarios were selected with the assistance
and input of local stakeholders, notably NWAB.
Primary project scenarios selected include:
Ambler City Hall / Washeteria
o Retrofit of existing building and energy system to incorporate biomass boiler for building
heating, hydronic dryers, and/or hot water heating.
o Perform Engineering and financial model of retrofit existing building and energy system
Proposed Shungnak Community Center / Coffeehouse
o Installation of biomass boiler energy system in the future building
o Integrate with design process currently underway by the Village of Shungnak and
Spenard Builders
o Perform Engineering and financial model of biomass energy installation in new build
In addition, several project scenarios were identified through the initial site evaluation but were not able
to be pursued under this scope. These are identified below as candidates for future analysis. A cost-
benefit analysis of these scenarios is provided in Section XX to review general project economics
Model Residential Home
o Advanced gasification boiler installation at “typical” model home based on Northwest
Inupiat Housing Authority (NWIHA) housing design.
o Cost-benefit analysis based on Alaska Cold Climate Housing Research Authority building
specs and thermal demand.
Amble IRA Building
o Cost-benefit analysis of installation in standardized local building, based on IRA
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o The Ambler IRA office contains a formerly operational but now defunct biomass boiler,
and the IRA has expressed interest in incorporating a biomass boiler to supplement
existing oil-fired heating.
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3. Technology and Equipment Evaluation
An evaluation of available combustion technologies was conducted to determine the optimal equipment
to specify for each installation proposed. The technology evaluation process took into consideration the
characteristics of feedstock selected in the feedstock analysis, and the form of heat and power energy
required, determined through the initial site selection and scenario development. As well, the
evaluation considered other technical as well as economic factors.
The options evaluated included, initially, bulk-wood and chip-wood combustion units along with cord-
wood (also known as stick-fired) heating solutions. All technologies evaluated used locally-available
wood products as their fuel, though some units could co-combust fuel oil or coal for fuel.
Each of these technologies was evaluated to determine which technology platform can most cost-
effectively utilize the available fuel source, is fairly easy to implement considering the site operations
and location, has a history of success under similar operating conditions, and is commercially available
for full scale operation. Evaluations are based on previous experience with comparable projects.
Ultimate selection of technology may depend on the preferred vendor, as vendors may include specific
proprietary improvements, modifications, and interpretations to each given technology.
3.1. Biomass Boiler Technologies
Combustion can be defined as the burning of fuel to produce power and heat. The combustion process
is highly developed commercially and is robust, relatively inexpensive, and available in numerous vendor
specific designs. Complete combustion occurs in an environment with excess oxygen to rapidly
complete the thermal oxidation reaction. It is critical to maintain correct airflow and exposure of the
fuel bed to ensure complete, clean, and efficient combustion. This is done by a combination of methods,
including rotating kilns and traveling grates. All of the systems work in conjunction with any number of
controlled air flow systems including induced draft, forced air, and over fire/under fire systems.
The scale of the energy demand, either heat, electricity, or both in a combined hand-fed units burning
cut and split wood, are generally appropriate for smaller applications where the maximum heating
demand ranges from 100,000 to 900,000 British thermal units (Btu’s) per hour (30-250 kW). Over one
million Btu (1 MMBtu) demand generally is served by an automatic-feed bulk-wood or chip-wood
system (Miles 2006, cited Nichols 2009). Electricity generation with biomass is generally cost effective
only with systems producing over 10 MMBtu. Though the extreme high electricity prices rural Alaskan’s
face may reduce the threshold for electricity production, electricity production is unlikely to be viable
for any of the scenarios evaluated for the Upper Kobuk villages.
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Chip-wood, Waste Pelletizing, and Other Bulk Fuel System
The characteristics of the fuel supply available in the Upper Kobuk region are also a major factor in
determining what type of combustion technology will be utilized. Linking together several buildings’
heating systems to form a district energy piping arrangement has been shown to produce enough
demand for a larger-scale automated bulk fuel (pellets, chip wood, microchips, and other uniform
feedstock) system. These are regularly found in the lower 48 as well as in other Alaskan villages, such as
in Tok, AK and proposed at Fort Yukon. Technologies including stoker boilers, advanced combustion with
2-stage starved-air processes, grinding and pelletizing of fuel, and other methodologies are available to
serve this market.
Figure 14 below shows a generalized bulk-fuel boiler system. Feedstock is fed via screw auger or
conveyor to the system, providing a steady supply of fuel 24/7. The combustion chamber continues to
move fuel through via traveling grates or step-down system, and often has automatically-controlled
over fire or under fire air injection to improve combustion efficiency and reduce emissions. Ash falls to
the waste bin, and combusted gasses travel up through a heat exchanger to produce hot water or steam
which is then distributed to the end users. Bulk fuel systems require feedstock holding and processing
areas, which may be as simple as a hopper filled several times per day, up to a room with walking floor
that can accept a full truckload of feedstock at a time.
Figure 14 – Bulk Fuel Boiler Operational Diagram
Source: AESI, Inc.
The benefit of bulk fuel boilers is in their automated feed and operation. These systems do not need to
be stoked several times a day as do cord-wood systems. Maintenance is generally more than for an
equivalent-size oil-fired boiler in order to maintain a steady supply of feed fuel and keep processes from
fouling.
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For Alaskan communities considering these types of systems, a major consideration and a requirement
for successful operation is a consistent supply of fuel for the equipment. As was shown in the project
feedstock assessment, which concurs with previous similar assessments identified in the feedstock
analysis, the villages Ambler and Shungnak do not have a waste-stream large enough to support a
waste-based system. As well, the equipment and logistics necessary to operate a bulk-wood or chip-
wood operation are also outsized for the villages.
Due to these observations and concerns, the focus of energy systems for the region moved to small-
scale, hand-fed cordwood boiler systems. While these systems are smaller and have less automated
operations (i.e., require more manual labor) than bulk-wood systems, there have been significant
advances in technology in the last few decades that have led to impressive results in efficiency,
emissions, and ease of operation. Moreover, the labor required creates an opportunity for the local
community.
2-stage Advanced Combustion / Gasification
Cord-wood boilers are available in a number of size and type configurations. One of the most prominent
is the single-stage outdoor wood boiler (OWB) developed over 30 years ago. There have been recent
advances in combustion technology at this scale, approach to the system complexity and precision of
gasification. Advanced combustion boilers increase efficiency as compared to stoker boilers by
separating the combustion process into 2 phases. In these processes, biomass feedstock is broken down
into gases in an oxygen starved pre-burn chamber. The wood gas is immediately burned in a second
combustion chamber or used as a fuel in an attached combustion device. This secondary combustion of
wood gases occurs at a higher temperature, 1700-2100 °F.
Figure 15 displays a cut-away view of a cord-wood system gasification system in operation.
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Figure 15 – Cord-wood Gasification Boiler Operational Diagram
Source: Tarm Froling
Utilizing aspects of gasification theory in a specifically designed gas combustion chamber results in
higher combustion efficiency and less air emissions as compared to traditional incineration/combustion.
The most efficient units offer ‘lambda control’, an oxygen sensor controlling airflow in the combustion
chamber. Government regulations towards stricter emissions and efficiency are slowly phasing out
single-stage OWB’s in favor of two-stage advanced combustion.
Multi-Fuel Boilers
Several manufacturers make multi-fuel boilers capable of burning wood, oil, coal, and natural gas, or
some combination thereof. Combination boilers can be an excellent solution for residential
applications, where the versatility of a back-up fuel source (such as fuel oil) is necessary and space does
not permit multiple boilers. Efficiency for each fuel source is likely to be lower than for a similar single-
purpose boiler because the unit cannot be optimized for the combustion characteristics and energy
density of a single fuel. However, those limitations are expected to be small, and outweighed by the
versatility of the system when applied to the correct application.
Multi-fuel boilers are produced by BioMass NextGen (Combo 25, 40, 60 and 80, rated in kW output),
ATMOS (DC 18 SPL, DC 25 SPL, DC 32 SPL), and the WoodGun from Alternate Heating (wood/coal and
wood/coal/oil). Tetra Tech was unable to find testing or emissions certification data from vendors or
other sources for any of the available multi-fuel boilers. Despite this limitation there is reason to
consider this technology further as the versatility it provides offers considerable value when fuel wood
or oil may be scarce over limited periods.
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3.2. Project Scenario Technology Evaluation
This study focused primarily on high-efficiency, low-emissions multi-stage boilers. A number of the units
available are similar in appearance and function. However, there are a few critical factors separating
units, including:
Scale (output) of available systems
Internal thermal storage (water jacketed) versus external thermal storage
Emissions and efficiency certifications, and
Automated Controls
Technology supply firms meeting initial evaluation criteria and providing equipment in the scale
required for the projects include:
GARN
Froling (Tarm)
EKO (Orlan)
BioMass NextGen
AESI
A summary of each vendor offering is provided at the conclusion of this section.
System Scale
Properly scaling equipment to the heating demand it will serve is important to reduce unnecessary
upfront capital expenditure as well as inefficient operation of equipment due to from de-rating to match
a lower than expected load profile.
For the Ambler City Hall / Washeteria project, a design load of 199,000 Btu/hr or 56 kW (building heat
only) is slightly over the scale Tarm’s Fröling can produce, and well within the range of offerings by EKO,
BioMass NextGen, and GARN. AESI equipment is oversized for the application.
For the proposed Shungnak Community Center, a design load of 86,000 Btu/hr (25 kW) is well under the
production minimums of the GARN and AESI offerings, and met by Tarm, EKO, and BioMass NextGen.
The residential energy scenario has a design load of 70,000 Btu/hr or 20 kW, a load small enough that it
is met efficiently only by the smallest Tarm Fröling (FHG-L model 20). The smallest EKO and BioMass
NextGen units, at 25kW or 85,000 Btu/hr rated output, are expect to perform reasonably well in this
environment. The BioMass Combo 25 is the same size, and with its versatility may be well-suited for the
application.
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Below is a graphic showing the range of outputs from the various equipment vendors.
Figure 16 – Range of Energy Output from Vendor Boilers
Thermal Storage
To achieve the highest efficiency, cord-wood gasification boilers in a single intense burn, as opposed to
the damped long-term burn of many OWB’s. To provide on-demand consistent heat to the end user,
most systems require a thermal storage media - usually water or glycol. Some systems jacket the boiler
in water to capture heat energy from combustion, while others pump water through the boiler to an
insulated tank. Storage required is a function of the heat demand and the configuration of the boiler,
but a common rule of thumb is to allow for 13 gallons of water storage for every 1 kW of boiler capacity.
External thermal storage systems are almost exclusively pressurized (up to 30 psi), glycol-based systems,
similar to common oil-fired boilers. Some jacketed systems are also pressurized. The system made by
GARN is unique, in that it is an unpressurized, open system, requiring addition of water to make up
evaporated losses. Interface from a GARN to an existing pressurized distribution system requires a heat
exchanger to keep the water loops separate.
The majority of the units tested were of a European modular design that removed fuel storage to an
external tank. These included Tarm / Froling, Eko, and Nextgen Biomass. Garn, and to a lesser degree,
AESI, keep the heat energy within the boiler in a jacketed setup.
0
250,000
500,000
750,000
1,000,000
1,250,000
1,500,000
1,750,000
2,000,000
TARM EKO BioMass GARN AESI EOSRated Output (BTU)
Boiler Equipment Suppliers & Output Range
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Boiler Certification
A number of wood-fired boiler emissions and efficiency test methods exist. These are a driver for the
selection of technology in many states, despite a lack of consensus amongst the federal agencies and
states regarding testing procedures, applicability to various configurations of boiler, and viability of
results.
The State of Alaska does not currently have a regulation regarding wood-fired boiler or fireplace
emissions for small-scale units (above its standard Clean Air Act regulations).
7 Pressurized vessels
installed in commercial operations are required to be certified to UL and ASME standards. Some states
are allowing variances for units certified to the similar European EN-303-5 standard. Other low-pressure
systems can be installed in open or unpressurized configurations to eliminate the requirement for
certification.
US EPA is in the process of promulgating New Source Performance Standards (NSPS) for emissions
related to wood-fired heaters, including hydronic boilers. In the currently draft version (as of April
2013), the standard appears to be set for no more than 4.5 grams of fine particulate emissions (PM2.5)
per hour, which is equivalent to the EPA ‘Partnership Phase 2’ voluntary regulation that have been in
place since 2008, and have been adopted as regulation in approximately 10 states.
8
The emissions limit for a ‘Phase 2 qualified model’ is a model that achieves an average emissions level of
0.32 lbs/million Btu heat output or less and did not exceed 18.0 grams/hr in any individual test run. EPA
Phase II only tests for particulate matter in emissions. 36 hydronic heater models (27 cordwood and 9
pellet models) built by 17 U.S. manufacturers have already been qualified at this level.
9 EPA appears to
prefer a 2-stage plan for hydronic boilers in the future, requiring the EPA Partnership Phase 2 level at
first, then after 5 years stepping up to a ‘Best Systems’ approach.
A number of other testing procedures and certifications also exist, including:
EPA Hydronic Heater Program (Phase I and Phase II)
ASTM Method 2618
EN 303-5
EPA Method 28 WHH
EPA New Source Performance Standards (NSPS)
IRS Certificate of Boiler Efficiency Eligibility for the American Recovery and Reinvestment Act of
2009
7 http://www.alaskawoodheating.com/boilers.php
8http://forgreenheat.blogspot.com/2013/04/epa-changes-strategy-again-will-now.html#sthash.4Vvgh5hE.dpuf
9 http://www.epa.gov/burnwise/pdfs/owhhphase2agreement.pdf
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The Alaska Energy Authority (AEA) currently only approves projects using boilers that have been
independently 3
rd party certified to meet ASTM Method E2618:13 (2013 version of the test) as eligible
for construction funding under its Renewable Energy Fund. The ASTM Method measures for particulate
emissions and overall efficiency.
GARN is the only manufacturer to have obtained this certification. Below is shown the official boiler
‘hangtag’ for the GARN model WHS 2000, indicating that it performs to an annual efficiency rating of
86.7% (based on the commonly-used lower heating value) and particulate emissions averaging 1.65
grams/hr.
Figure 17 – GARN Model WHS-2000 Emissions and Efficiency Hangtag
Source: Intertek, Report Number: G100463637MID-005
It is likely that once EPA NSPS standards are adopted, the State of Alaska will follow suit for regulation as
well as eligibility for funding.
The ASTM testing does not account for units with external storage. The Brookhaven Institute‘s Partial
Thermal Storage Test Method, which was developed as a modification to EPA’s Method 28 WHH for
units requiring external thermal storage, was developed to be used as a substitute. The Tarm – Fröling
FHG model 20 Wood Hydronic Heater was tested under this procedure. The system achieved an annual
average thermal efficiency of 69.8% and emissions of 2.0 grams/hr. Based on this evaluation, the unit
‘hangtag’ is shown below.
Figure 18 – Tarm Froling FHG Model 20 Emissions and Efficiency Hangtag
Source: Brookhaven National Laboratory
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Many of the European gasification boiler designs are tested only to meet EN 303-5, including the multi-
fuel boilers from BioMassNextGen and Atmos.
As a final note regarding emissions and efficiency testing, the certification process is expensive and
onerous for the boiler manufacturers, resulting in most having been testing for just one certification, if
any at all. Boilers that are not certified to a specific standard may produce emissions or overall efficiency
equivalent to meet that standard but have not gone through the testing process. However, the only way
to be sure it meets these standards is to buy a “certified boiler”.
Management and Controls
Many advanced combustion boilers have automated airflow management technologies. This allows the
systems to be controlled by remote thermostats and produce different heating levels for different
zones, similar to a standard oil-fired boiler. All boilers reviewed contain or are compatible with
automated controls capable of mating with exiting thermostat systems.
For example the RK 2001 UA control panel compatible with EKO and BioMass NextGen boilers, offers
the following features. A photo of a unit in operation in provided below.
Interaction with circulating pump,
Interaction with room temperature sensor, installed in the room and connected with the boiler
regulator by two-strand wire
Modulation of fan rotation, and
Boiler output adapting to actual weather conditions.
Figure 19 – Example Gasification Boiler Control Module
Source: Orlan EKO
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Upper Kobuk Biomass Project
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3.3. Technology Vendors
There are a number of technology firms that provide wood-fired boilers in the output range required by
a residential or small commercial – community building. A small sample of these are identified below.
This list is not intended to be a comprehensive list, nor does inclusion or exclusion indicate endorsement
of technology by Tetra Tech or any of its affiliates.
Manufacture: GARN (Dectra Corp.)Contact
Information
http://www.garn.com/
Models Offered WHS-1000, 1500, 2000, 3200
Rated Power
Output
kW Btu: 180,000; 250,000; 325,000;
700,000
Manufacture
Standard Rated
ASTM Method 2618
Emissions and
Efficiency Rated
WHS-1500: 2.87 grams/hr at 81%
efficiency, WHS-2000: 1.65 grams/hr
at 87% efficiency
Other Features Integrated combustion; secondary
combustion (gasification) chamber;
non-pressurized thermal storage;
double lock safety handle; air cooled
door; combustion air supplied from
outside; available electric backup
Manufacture: EKO (Orlan)Contact
Information
http://www.newhorizoncorp.com/products/wood-
boilers/eko-line-boiler/
Models
Offered
Line-25, 40, 60,80
Rated Power
Output
kW Btu: 85,000; 137,000; 205,000; 275,000
Manufacture
Standard
Rated
EN 303-5
Emissions
and
Efficiency
Rated
91% efficiency
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Other
Features
Equipped with electronic regulator and room
temperature sensor; unusually high overall
efficiency due to use of wood gasification
combustion; can be used for heating any kind of
building (mostly used in one-family houses, drying
houses, workshops, halls, or greenhouses)
Manufacture: Tarm Biomass –Froling FHG-L Contact
Information
http://www.woodboilers.com/
Models Offered 20, 30, 40, 50
Rated Power
Output
Btu/Hr: 70,000; 102,500; 136,560;
170,700
Manufacture
Standard Rated
Brookhaven Institute‘s Partial
Thermal Storage Test Method
EN 303-5
Emissions and
Efficiency Rated
Over 80% efficient
Other Features Uses down draft gasification
technology to achieve its efficiency;
large loading door allows free access
to firebox; external heat exchange
cleaning lever dramatically reduces
the need for brushing ash; fast
ignition access door; built-in thermal
storage controls and monitoring
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Manufacture: NextGen BioMass Contact
Information
http://www.newhorizoncorp.com/products/
wood-boilers/biomass-gasification-boiler/
Models
Offered
BioMass-25, 40, 60, 80, 100
Rated Power
Output
kW Btu: 85,000; 140,000; 205,000; 275,000;
342,000
Manufacture
Standard
Rated
EN 303-5
Emissions
and
Efficiency
Rated
BioMass 25: 91.2%; BioMass 40: 91%;
BioMass 60: 91%; BioMass 80: 91%; BioMass
100: 90%
Other
Features
Extracts maximum heat for system by using
gasification process and secondary
combustion, resulting in practically emission-
free burning
Manufacture: Alternative Energy Solutions
International (AESI)
Contact
Information
http://www.aesintl.net/
Models Offered EOS 15, 20, 25, 30, 35
Rated Power
Output
15-594,850k Btu; 20-793,133k Btu;
25-991,417k Btu; 30- 1,189,700k Btu;
35- 1,387,983k Btu
Manufacture
Standard Rated
n/a
Emissions and
Efficiency Rated
80-86% efficiency
Other Features Hybrid combustion system with fixed
and moving grates; utilizes a wide
range of biomass fuels; utilizes fossil
fuels as a backup fuel; automatic
ignition system, fuel feed system,
ash extraction, cleaning soot
blowers, and combustion
modulation;
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4. Detailed Energy and Site Analysis of Selected Projects
This section describes the site analysis conducted for the two project scenarios selected for engineering;
wood-fired biomass boilers serving the Ambler City Hall / Washeteria building and the proposed
Shungnak Community Center.
4.1. Site and Energy Audit – Ambler City Hall / Washeteria
Site Description
The proposed Biomass facilities will be used for heating the City building in conjunction with the City’s
existing oil boiler furnace. The biomass boiler will be located in a stand-alone building directly north of
the City building in Ambler. Refer to Figure 20 for Ambler site-selection details.
Climate Information
Ambler is in the transitional climate zone. Temperatures average -10 to 15 degrees Fahrenheit (°F)
during winter and 40 to 65 °F in the summer. Temperature extremes have been recorded from -74 to 92
°F.
Annual snowfall averages 80 inches, with 16 inches of total precipitation. The Ambler City Hall design
used a live load for snow was 40 pounds per square foot (lbs/ft2).
The Alaska Energy Authority’s 2006 Wind Resource Assessment for Ambler listed the prevailing wind as
northeast at the airport. The annual average wind speed at 10 meters was measured at 11.9 mph. The
American Society of Civil Engineers (Volume 7-10) has the community of Ambler in a design wind speed
zone of 120 miles per hour (mph).
Table 16 – Ambler Climatic Design Criteria
Design Temperature -74 °F to 90 °F
Design Wind Speed 120 mph
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Figure 20 – Ambler Site Plan
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Heating Demand Served
The Ambler City Hall has several heating demands or loads. Space heating has been selected as the
primary need. The City Hall construction project involved 6 dryers that are supposed to be hydronic
(operate by hot water as opposed to electricity) but cannot be verified. As well, there is a large 80-100
gallon, 415,000 Btu hot water heater in the mechanical room that has not been put into service.
Based on these conditions, and a design criteria of -47 degrees F (ASHRAE 97.5% for Fairbanks, AK), the
maximum thermal demand for the building are shown below. Detailed heating calculations are available
in Appendix A.
Table 17 – Ambler City Hall Heating Demand
City Hall and Heating Loads Btu/hr
Building Heat Load 199,056
Dryers Heat Load 109,627
Hot Water Heat Load (shower, laundry)415,900
Total 724,583
Figure 21 – Photos of Ambler City Hall Boiler Room (a) and (b)
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Utilities
Ambler has a piped community water and sewer system, both of which are buried in insulated arctic
pipe. Burial depths vary, but the minimal burial depth is 2 feet. Design drawings indicate the water main
is 4-inch polyvinyl chloride (PVC) pipe with a 12-inch insulated jacket. Design drawings also indicate the
sewer main is 6-inch high density polyethylene (HDPE) pipe with a 12-inch insulated helical aluminum
jacket. The community gets its water from groundwater (Public Water System ID# AK2300214). The
sewer is piped out to a sewage treatment lagoon along the Ambler Airport Road. The Alaska Native
Tribal Health Consortium (ANTHC) Remote Maintenance Worker for Ambler is Jeff Luther (Phone 907-
442-7172).
Alaska Village Electric Cooperative runs a diesel generator in Ambler, which provides power to the
community. The generator has a total capacity of 1,115 kWe. The residential rate is $0.63 per kilowatt
per hour (kWh).
The proposed site currently has water, sewer, and electrical services. The City Hall water and sewer
services run toward Ambler Avenue. The City Hall electric service connects by an overhead pole to the
electric line west along Zane Street. There are water mains along all four sides of the property. There is a
sewer along the southeast side of the property, crossing Ambler Avenue. There are overhead electric
lines along three sides of the property; Zane Street, Dahl Avenue, and Ambler Avenue.
There are no known issues with providing water, sewer, or electric utilities for the project.
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Land Ownership
The proposed site is on the same property as the City Hall building. The property is listed as Survey U.S.
Survey No. 5013. The Alaska Division of Community Regional Affairs (DCRA) Ambler Community Profile
Map (1997) listed the property in the ownership of the City of Ambler by a Quitclaim Deed from NANA
(Book 46, Pg. 854.)
Flood Plain Considerations
The flood hazard for Ambler is very low. Ambler village sits approximately 75 feet above the Kobuk and
Ambler Rivers. Flood events were documented in 1968 and 1973, but the maximum record flood
elevation was 47.90 feet, well below the community. There is minimal risk of flooding for the project
site. The United States Army Corps of Engineers (USACE) does not have a recommended building
elevation for Ambler because of the low risk of flooding.
Wetlands Considerations
The United States Fish and Wildlife Service’s (USFWS) National Wetland Inventory mapper has
insufficient data to accurately determine the presence or absence of wetlands within the immediate
project areas of the Ambler City Building and Public City Hall. However, aerial photo-interpretation
(Figure 1) supports the absence of wetlands and waters of the U.S. at the proposed project site. The
project site is within the highly developed and disturbed community limits of Ambler. With close
proximity of new developments abutting existing development, field observations are not necessary at
this time.
Geotechnical Considerations
Ambler is on an alluvial deposit that likely varies laterally and with depth across the village.
Approximately 800 feet to the west of the proposed site, a fairly consistent soil profile was observed in
test borings. The soil profile consisted of approximately 4 feet of sandy silt (ML) above approximately 3
feet of silty sand (SM). Below this depth, the borings encountered highly variable alluvial soils that
included clayey sand, clayey sand with gravel, clayey gravel with sand, sandy lean clay, and lean clay (SC,
GC, and CL) to termination depth of 31.5 to 41.5 feet below the ground surface (bgs).
No groundwater was observed at the time the above-mentioned borings were drilled, but that was likely
due to seasonally low water levels. Groundwater may be encountered at depth as shallow as 10 feet bgs
at the proposed site based on the river elevation, but is likely at greater depths.
Permafrost was not detected in the test borings and thermistor measurements confirmed the absence
of permafrost on site. Seasonal freezing up to depths of 10 feet bgs or greater is expected at the
proposed site. The native soils on-site are expected to be highly frost-susceptible.
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Gravel Considerations
Gravel will likely be required for development of the site, and as part of the building foundation and
access ramp. Ambler has a developed gravel source, for community projects. It is operated by NANA,
the Alaska native regional corporation. There are also several other potential gravel sites that have been
investigated around the community. NANA owns the majority of subsurface rights in the Shungnak area,
and has authority to charge royalties for gravel extraction and permit its use. NANA may reduce or
waive gravel royalties for community projects it deems beneficial to their shareholders.
Naturally occurring asbestos has been detected in gravel samples obtained from the Ambler gravel pit,
the vicinity of the airport, various alluvial deposits around Ambler, and an in-stream bar deposit in the
Kobuk River adjacent to the community. It is reasonable to assume there is the possibility of naturally
occurring asbestos being present at the proposed site.
It is recommended that gravel permitting responsibility be placed on the construction contractor.
Depending on the selected Contractor they may elect to bring gravel in from a non-local source.
4.2. Site and Energy Audit – Proposed Shungnak Community Center
Site Description
The selected site is north by northwest of the proposed Shungnak Community Center, aka the ‘Coffee
house’. Shungnak IRA council intends to construct the community building with funds secured through
a NANA Village Economic Development grant. This central location could allow the biomass facility to be
used for heating of other community-based buildings, such as the City Hall and Village Public Safety
Officer (VPSO) housing. Refer to Figure 22 for Shungnak site-selection details.
Climate Data
Shungnak is in a transitional climate zone. Temperatures average -10 °F to 15 °F during winter and 40 °F
to 65 °F in the summer. Temperature extremes have been recorded from -60 °Fto 90 °F.
Annual snowfall averages 80 inches, with 16 inches of total precipitation. The American Society of Civil
Engineers lists Kotzebue as the nearest community and designates a snow load of 60 lbs/ft2. The
American Society of Civil Engineers (Volume 7-10) has the community of Shungnak in a design wind
speed zone of 120 miles per hour (mph).
Table 18 – Shungnak Climatic Design Criteria
Design Temperature -60 °F to 90 °F
Design Wind Speed 120 mph
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Figure 22 – Shungnak Site Plan
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Heating Demand Served
The proposed Shungnak Community Center is in the initial design stages. Design may be modified prior
to construction. At present, the proposed facility is a 1-story building of approximately 44 feet in length
by 32 feet in width, with 8 foot tall walls to eaves and a peaked roof. Based on these conditions, and a
design criteria of -47 degrees F (ASHRAE 97.5% for Fairbanks, AK), the maximum thermal demand for
the building is rated at 86,605 Btu/hr. Building heat is the only thermal energy demand that was
reviewed.
Detailed Thermal energy demand calculations are available in Appendix 4.
Utilities
Shungnak has a piped community water and sewer system, both of which are buried in insulated arctic
pipe. The community gets its water from a small tundra pond adjacent to the village (Public Water
System ID# AK2340361). The sewer is piped out to a sewage treatment lagoon north of the village.
Alaska Village Electric Cooperative runs a diesel generator in Shungnak, which provides power to
Shungnak and Kobuk. The generator has a total capacity of 1,200 kW. The residential rate is $0.73/kWh.
The ANTHC Remote Maintenance Worker for Shungnak is Jeff Luther (Phone 907-442-7172).
The proposed site currently has water, sewer, and electrical services. There are water mains along all
three sides of the property; Back Street, the north side, and Wendy Street. There is a sewer main along
Back and Wendy Streets, as well as overhead electric lines.
There are no known issues with providing water, sewer, or electric utilities for the project.
Land Ownership
The proposed site is adjacent to the existing City Hall Building and Community Center. The VPSO housing
is to the west. Both the existing Community Center and VPSO housing appear to straddle the Hall Street
right of way (ROW) and U.S. Survey No. 2047. The VPSO housing is almost completely within the Hall
Street ROW. The DCRA Community Profile Map lists U.S. Survey No. 2047 as being conveyed to the State
of Alaska by Quitclaim Deed. U.S. Survey 2047 was surveyed in 1937 as a School Reserve by the U.S.
Department of the Interior, General Land Office. In 2003, the State of Alaska did a quitclaim deed
granting the property to the Northwest Arctic Borough. No document detailing subdivision of the survey
was found.
Clarifying the ownership issues is critical for this proposed site. The property boundaries shown in Figure
2 are approximated from the DCRA Community Profile Maps (1999) and aerial photographs. For the
conceptual design, DOWL HKM will complete a title search to better gather site-ownership details.
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Depending on the finding of the title search, a boundary survey may be required to confirm the
proposed site’s relative location to existing property lines. Most state and federal agencies will require
documentation of land ownership, long-term lease, or Memorandum of Understanding (MOU) from the
landowner before funding a project.
Flood Plain Considerations
The flood hazard for Shungnak is very low. The majority of the homes and all public facilities are on a
bluff above the river, out of the flood plain. The lower areas around the village regularly flood. The flood
of record was in 1985, with a flood elevation of 30.2 feet. A 1937 flood was likely higher but there is no
recorded data. The USACE recommends a building elevation for Shungnak of 32.2 feet, well below the
project site. There is minimal risk of flooding for the project site.
Wetlands
The USFWS’ National Wetland Inventory mapper has insufficient data to accurately determine the
presence or absence of wetlands within the immediate project areas; however, aerial photo-
interpretation (Figure 2) supports the absence of wetlands and waters of the U.S., as both proposed
project areas occur within the highly developed and disturbed community limits. With close proximity of
new developments abutting existing development, field observations are not necessary at this time.
Geotechnical Considerations
Shungnak is located largely on an older alluvial terrace and partially on a modern point bar deposit. The
proposed site is on the older alluvial terrace material. Test borings completed in 1982 approximately
380 feet to the north revealed a soil profile of approximately 6 feet of peat and organic silts (OL)
overlying silty sand (SM). It is possible this organic layer was removed at the proposed site during
construction of adjacent structures, but this will need to be verified on-site before construction of a
foundation. Similar soil profiles were encountered in the test borings conducted for the airport
construction.
No groundwater was encountered within the extent of the test borings (15 feet bgs). Groundwater is
not expected to be encountered within depths of 15 feet bgs at the proposed site and is likely at depths
of 30 feet bgs or more, based on river elevation.
Permafrost was not detected in the test borings. Seasonal freezing up to depths of 10 feet bgs or greater
is expected at the proposed site. The native soils on site are expected to be highly frost-susceptible.
Gravel Considerations
Gravel will likely be required for development of the site, and as part of the building foundation and
access ramp.
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Shungnak has a developed gravel source, for community projects. It is operated by NANA, the Alaska
native regional corporation. There are also several other potential gravel sites that have been
investigated around the community. NANA owns the majority of subsurface rights in the Shungnak area,
and has authority to charge royalties for gravel extraction and permit its use. NANA may reduce or
waive gravel royalties for community projects it deems beneficial to their shareholders.
It is our understanding that naturally occurring asbestos has been reported in the area and may be
present in near-surface soils. Our records indicated asbestos testing was conducted in 2011 on samples
taken from a gravel bar east of the community and south of the current gravel pit. These tests showed
asbestos content was below the detectable level (0.25%).
Kobuk sandbars around the community have also been investigated for gravel. The gravels tend to be
poorly graded with sand but very little silt. This type of gravel tends to be acceptable for non-structural
berms and pads. Site specific testing is required to determine quality of gravel. Gravel below the average
high water mark is owned by the State of Alaska. State of Alaska’s Department of Natural Resources
(DNR) is responsible for permitting gravel extraction on state lands. DNR usually requires the
preparation of a mining site plan, an operations plan, and a reclamation plan.
It is recommended that gravel permitting responsibility be placed on the construction contractor.
Depending on the selected Contractor they may elect to bring gravel in from a non-local source.
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5. Boiler Facility Engineering Design
Tetra Tech reviewed major heating and power options that are applicable to the general project
conditions thus far determined for the proposed biomass energy facilities. The following section
identifies the most likely process technology for the heating units and describes the plant design. Final
project design and compliance with all applicable codes and regulations is the responsibility of the
contractor to submit building plans.
Tetra Tech designed two energy generation configurations in the Upper Kobuk Region, one serving the
Ambler City Hall / Washeteria and one at the proposed Shungnak Community Center.
The Ambler City Hall / Washeteria biomass boiler will combust cordwood up to 20” long and up to 6”
round in a small commercial-scale wood boiler. The boiler will reside in a stand-alone building adjacent
to the City Hall building, and an additional feedstock storage building will also be nearby. Thermal
energy produced will be used for heating the City Hall building, connection to the existing baseboard
heating system through the building mechanical / boiler room. The existing oil-fired boiler will be
retained for backup heating.
The second scenario is for a similar cordwood fired system built in Shungnak and used to heat the
proposed Shungnak Community Center building. Two potential options exist for this design, a stand-
alone boiler building similar to Ambler, or an integrated pressurized boiler within the building structure.
5.1. Foundation Design
For the Ambler City Hall / Washeteria biomass facility there will be two structures:
A 12’ by 16’ structure to house the boiler, and
A 16’ by 20’ feedstock storage building (two 8’ x 16’ structures spaced 4’ apart)
The important characteristics while considering foundations for the 12’ x 16’ boiler building are:
The weight of the structure is approximately 10,000 pounds (including boiler). Any foundation
should have bearing capacity to support the weight.
The building will be heated, so the structure should be elevated to protect the ground surface
from differential movement from the introduction of a new heat source.
It will be subjected to wind lateral loads. The American Society of Civil Engineers (ASCE
Reference Manual 7-10) places Ambler and Shungnak in a 120 mile per hour design wind speed
zone. The weight of the structure is sufficient to overcome uplift forces from the winds.
Any foundation should be able to protect against lateral loads.
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Moderate movement of the structure is acceptable because the building is unoccupied, and the
glycol pipes penetrating the building are flexible.
The important characteristics while considering foundations for the 16’ x 20’ feedstock building are:
The structure will be made of timber post and beam, with spaced lumber siding to allow for
maximum airflow through the structure for drying of the wood. The building will be covered
with a tin roof. The structure is open air, unoccupied, and unheated. This building does not need
to be elevated.
The weight of this structure is approximately 1,000 pounds. The main consideration for this
structure is protection from uplift forces from the wind. The ASCE (reference manual 7-10)
places Ambler and Shungnak in a 120 mile per hour design wind speed zone. Uplift forces will be
equivalent to 360 lbs/ft.
Movement is acceptable because the building is unoccupied and serves only as storage.
Geotechnical Considerations
As discussed in the Site Analysis memo, there is no geotechnical information available at the sites, but
information collected from elsewhere in the communities suggest:
Ambler
Permafrost is discontinuous. It was not detected at a site approximately 800 feet away.
Seasonal freezing depths are approximately 10 feet.
Naturally occurring asbestos (NOA) in subsurface materials is a concern. NOA has been detected
in gravel samples, in alluvial deposits around Ambler, and in in-stream bar deposits.
Considering these points, we recommend minimizing ground disturbance in Ambler. Gravels from the
Ambler area may be used but must be tested for NOA before use and a contractor must have an
approved plan for NOA control.
Shungnak
Permafrost is discontinuous. It was not detected in a site approximately 320 feet away.
A core sample 320 feet away revealed a 6 foot layer of peat and organics near the surface. If
ground disturbing activities were to occur, the peat and organics layer would need to be
removed and replaced with non-frost susceptible soil.
Seasonal freezing depths are approximately 10 feet.
NOA is a regional concern, but has not been detected in high levels in Shungnak. Gravels
available in Shungnak are poorly graded with sands. These are acceptable material for non-
structural bermsand pads, but not good for structural construction.
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Considering these points, we recommend minimizing ground disturbance in Shungnak. Gravel may be
used if it can meet the structural specification:
Sieve % Passing
No. 4 20-55
No. 200 0-6
Foundation Options
There are a number of different foundation options used in arctic regions. Those that minimize ground
disturbance are listed below:
wood cribbing
gravel pads
at grade concrete slabs
helical piers and driven piles
Each foundation option is described briefly and the memorandum concludes with a cost benefit analysis
for each of the buildings.
Wood Cribbing
Footings made of wood cribbing are common in arctic environments. This is a form of post and pad
construction. The cribbing is placed directly on the ground. Wood cribbing foundations are easy to
construct as they require no specialized equipment. If frost movement is an issue, another course of
cribbing could be added to level the building. Cribbing provides good bearing capacity, but no uplift
resistance. Also, cribbing does not provide any lateral (wind, earthquake) support for small footprint
buildings. To add lateral strength, cross beams can be added between the cribbing footings.
Many of the residences in Ambler and Shungnak are constructed on wood cribbing foundations. The
armory in Shungnak, near the proposed site is constructed on wood cribbing with lateral support cross
beams.
The Ambler City Hall is constructed on a post and pad system, with a series of adjustment bolts and steel
plates for leveling. Beneath the plates is a layer of wood cribbing, insulation, and non-frost susceptible
material. This system distributes the building’s weight and has the ability to level itself. The ability to
adjust the biomass facility or feedstock storage would be extraneous, as modest ground movement is
tolerable.
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Gravel Pad
Thick gravel pads can be used for a structural base if they are thick enough to thermally protect the
underlying native soils. We would recommend 4’ to 6’ thick pads. Polystyrene insulation can be
supplemented to decrease the thickness of the gravel pad. Approximately 1” of polystyrene adds the
same thermal protection as 1’ of gravel. If 4” of polystyrene is used the gravel pad thickness could drop
to 2’. The gravel pads are compacted.
Gravel pads will settle over time, so some structure movement would occur. Gravel pads will provide
good bearing capacity but no uplift resistance.
At Grade Concrete Slab
These foundations are constructed as floating reinforced concrete slabs. Gravel can be used to level the
site. Both proposed sites are located on flat ground, so only moderate leveling may be required. Rigid
polystyrene insulation is placed on top of the leveled surface. The reinforced slab is constructed on top
of the insulation. At grade slab could be used in conjunction with concrete block corner posts to elevate
the building, to allow for air flow beneath it.
At grade slabs provide good bearing capacity and good uplift resistance, serving as an anchor if
structures are bolted to them.
Helical Piers and Driven Piles
There are a number of different point penetration foundation styles. This class of foundation penetrates
the ground and elevates the building with a post. Piers or piles would be installed to a depth of at least
10 feet.
Driven piles are driven into the ground with a pile driver. The piles are often six to eight inches in
diameter, and do not have helixes. Thermal piles are a specific type of driven pile that actively use
convection to keep the ground frozen. The health clinics and schools in Ambler and Shungnak have
thermal piles. Given the scale of this project, mobilizing pile driving equipment to the site is cost
prohibitive.
Another type of point penetration foundation is helical piers. They are not as robust in design, and
typically have smaller diameters. They have helical plates that cut into the soil like an auger. Helical piers
can be installed with a hydraulic drive head that mounts to a working excavator, bobcat, or any other
piece of equipment with most types of working hydraulics.
Both driven piles and helical piers have good bearing capacity, good uplift resistance, and an ability to
resist seasonal movement. Driven piles are not considered an option for this project, but helical piers
are.
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Cost Benefit Analysis
Table 19 – Biomass Facility Cost Benefit Analysis
Foundation
Technique Advantages Disadvantages Probable Cost per structure*
Wood
Cribbing
-Good bearing capacity
-No special equipment
to level and construct
-Easily repaired
-No uplift resistance
$9,300
(Key Assumptions - Cribbing will be at
least 18” high with lateral cross beams.
Wage assumption based off Davis Bacon
wages for region- $52/hour. Weight of
treated wood is .025pounds/in
3)
Gravel Pad
-Good bearing capacity
-Easy to construct
-In Ambler, NOA free gravel
may not be obtainable,
-In Shungnak, structural
gravel may not be
obtainable.
-Bringing in gravel from not
local sources is risky with
river barging being nearly
impossible.
$12,200
(Key Assumptions- The contractor will be
able to get NOA free and structural gravel.
Cost of gravel assumed to be $300/yard).
At Grade
Concrete
Slab
-Not possible to level
-Slab may crack and
degrade
-Importation of aggregate is
risky (same reasons as
shown in gravel pad
disadvantages)
$18,200
(Key assumptions- 4.05 yards concrete at
$3,000/yard)
Helical Piers
-Good bearing capacity
-Complete resistance
to movement
-Requires working
excavators in communities
$6,300
(Key Assumptions- A working excavator
will be available in Ambler and Shungnak)
*Costs are installed costs, including shipping of materials to Ambler, and assume a 30% contingency.
Table 20 – Feedstock Storage Cost Benefit Analysis
Foundation
Technique Advantages Disadvantages Probable Cost per structure*
Wood Cribbing NOT AN OPTION NOT AN OPTION NOT AN OPTION
Gravel Pad NOT AN OPTION NOT AN OPTION NOT AN OPTION
At Grade
Concrete Slab
-High uplift resistance
-Good bearing
capacity
-Not possible to level
-Slab may crack and
degrade
-Importation of aggregate is
risky
$16,200
(Key Assumptions- 3.95 yards concrete at
$3,000/yard)
Helical Piers
-High uplift resistance
-Complete resistance
to movement
-Require working
excavators in communities
$12,600*
(Key Assumptions- A working excavator
will be available in Ambler and Shungnak)
*Costs are installed costs, including shipping of materials to Ambler, and assume a 30% contingency.
Foundation Recommendation
Helical piers are the project team’s recommended choice for both facilities in both sites. A Chance SS-5
pier at the corner of each structure would provide support for both facilities, and would resist frost
jacking and ground movement. The Chance SS-5 Piers are 1.5” Stainless Steel Posts. They are approved
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by national residential and commercial building code agencies. They are used in Alaska for buildings,
supports for above ground water and sewer pipes, and used for fences and roadway signs. Their
published strengths (shown below) are sufficient to resist uplift forces, and provide adequate bearing
capacity.
Chance SS-5 Product Rating
Ultimate Compression Capacity
(bearing capacity)
40,000lbs
Ultimate Tension Strength
(ability to resist uplift)
70,000lbs
This recommendation is being made with the assumption that an excavator or piece of equipment with
suitable hydraulics is available in both locations.
If the selected Contractor can show they can import NOA free gravel (in Ambler) and structural gravel in
Shungnak, gravel pads (as explained in earlier sections) would be acceptable for the boiler facility
foundations. This is especially a consideration in Ambler, where the State of Alaska Department of
Transportation has an upcoming airport project that will require gravel. It may be possible to purchase
reasonably priced gravel from their Contractor. At the time of this memo, fact-based recommendations
cannot be made assuming this will happen.
If the selected Contractor can show they can provide a foundation that resists uplift forces of 360 lbs/ft,
for the feedstock storage, an alternative foundation style would be accepted.
5.2. Ambler City Hall / Washeteria Biomass Boiler Engineering
Ambler City Hall / Washeteria Boiler System Description
The project team developed the following design for a cordwood-fired boiler at the Ambler City Hall.
The plant design is engineered and tailored to conditions specific to the site. The system process flow is
described in sequence in the following section and a corresponding site design drawing and process flow
diagram are supplied below. In the description below, the process has been broken down into its critical
components: boiler design, interconnection and energy distribution, boiler building design, and delivery
and constructionof equipment.
Boiler Design
Feedstock demand is calculated at approximately 30 (29.7) cords per year, offsetting 3,516 gallons
of fuel oil use annually. One sled-load is approximately 1/3 of a cord.
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Feedstock for this system will consist of cordwood collected and sold to the biomass energy project
by area woodcutters. Feed for the boiler will be spruce, birch, aspen, poplar, and tamarack logs to
up to 20” long and up to 6” round. Logs will be dried up to 6 months prior to use in the feedstock
storage buildings. The lower heat value of the feedstock fuel processed at the facility is expected to
be approximately 6692 Btu/lb, or 17.5 MMBtu/cord, with a feedstock input moisture expected at
20%, a standard measure for air-dried cordwood. Small wood processing equipment including
chainsaws, wheelbarrows, and a wood-receiving storage bin will be included in the project capital
costs for feedstock management.
The recommended boiler for the project is a GARN WHS-1000 or equivalent. This boiler system is an
advanced gasification hydronic wood boiler with internal water storage at atmospheric pressure,
producing a maximum rated output of 180,000 Btu/hr. The boiler holds 980 gallons of water for
thermal storage. Fill weight is 8,200 lbs. GARN boilers are certified to the highest standards by
ASTM methods for emissions and efficiency.
Existing oil-fired boilers are expected to be retained for backup or on-call peak heating needs.
Interconnects and Energy Distribution
The working fluid (here, water) is heated at atmospheric pressure to desired temperature (140-180
deg F) and stored in the GARN for distribution. Energy distribution will be accomplished through a 2-
loop system. The GARN unit is unpressurized system with no glycol additive to the boiler water. The
existing City Hall boiler system is pressurized (up to 30 psi) and uses glycol additive to reduce freeze
or burst potential.
Heat transfer will be accomplished in the boiler building using a flat-plate heat exchanger. The
existing thermal distribution system at the City Hall will be extended to the boiler building through
the use of flexible insulated piping (INSULPEX or similar). The flexible line will allow the boiler
building and the City Hall to move independently due to frost heave.
Successful completion of the biomass energy system requires bringing the existing oil-fired boiler
and distribution system to operational status. The system design utilizes the existing baseboard
heating distribution zones installed as part of the Washeteria addition. The system also relies on the
existing oil-fired boiler(s) for backup and peak heating needs.
Site Inspection of the existing system shows that it is not currently operational, but is approximately
80% complete. The system can be brought to operational status with our without the completion of
the washers and dryers in the City Hall, as its primary goal is heating the building. Early in the project
design it was determined that the load profile of the building heating alone best matched the
productive capacity of the selected boiler system. Hot water heating and operation of the
Washeteria dryers can be most effectively accomplished through existing onsite equipment (hot
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water heater, oil-fired boilers). It is recommended that the overall heating system be tested for
proper heating capacity for the lower heat range of the Garn system (140-160 deg vs 180 deg for oil-
fired boiler).
Plant operations are managed automatically via control panel and programmable logic controller
(PLC) systems. Wood-fired boiler controls and pumps will be tied to the building heat distribution
control system to maximize use of energy from the wood-fired system, while triggering the oil-fired
boilers to supply automatic backup heating when the wood-fired boiler is unattended.
Boiler Building and Feedstock Storage Building
The building housing the boiler will be an independent structure with dimensions of 12’ width x 16’
long x 10’ high to ceiling. The building will have 6’ wide double door on the west wall that open out.
The boiler will sit long east to west. Ceiling height will need to be 10’ due to man way and anode
access on top. Additional space for short-term wood storage and maintenance may be helpful to
include in final design engineering, insofar as it does not impact the overall capital cost of the
system.
The building will be constructed according to International Fire Code (IFC). Building plans will be
submitted to the Department of Public Safety (DPS), Fire and Life Safety, for approval.
The feedstock storage building will consist of two facing woodsheds, closed on three sides but open
to face each other. The buildings will measure 8’ x 16’ each, with a 4’ corridor between, for a total
footprint of 16’ x 20’. This will hold approximately 12-15 cords of wood.
The feedstock storage buildings will be constructed of lumber siding and tin roofing. Wall slats will
be spaced to allow airflow to assist in drying the stacked wood inside. Construction shall be
completed with treated lumber.
A fence can be added to additionally secure the boiler building and feedstock storage building.
Equipment Delivery and Construction
Equipment delivery to Ambler is expected via airplane from Fairbanks, for a quoted price of $13,900
for up to 4,800 pounds, which is sufficient for a boiler and associated equipment. This is cheaper and
more reliable than barge delivery, which was quoted at $15,000 for a 20 foot container weight
under 18,000# from Kotzebue to Ambler, based on 2013 figures. If a containerized boiler module
were to be used this would be the best solution. However, the cost and difficulty of constructing a
container in the continental US and shipping to Ambler, coupled with the uncertainty with barge
shipping on the Kubuk River in recent years, drove the selection of air transport for equipment
delivery.
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Construction management is expected as such:
o Oversight construction management firm (Prime Contractor). This position will complete
the detail engineering design of the project, manage bids and contracts with sub-
contractors, and provide as to construction cost, time, and system performance.
o Building Construction Contractor. A local building contractor will be hired to complete
the construction of the boiler building and feedstock storage building.
o Equipment Installation Contractor. A local HVAC contractor will be hired through
competitive bid process to set equipment and connect mechanical and plumbing in the
completed boiler building and its interconnection to the existing City Hall boiler system.
Ambler City Hall / Washeteria Boiler System Capital Cost
Tetra Tech developed capital costs for the proposed facility configurations based on a number of
communicationswith equipment vendors, publicly-available information, and internal databases, as well
as costs and operational parameters derived from engineering investigation of the proposed facility.
The capital cost below is therefore not representative of any single bid or vendor’s equipment profile.
Tetra Tech recommends that the project owner solicit final construction bids from prospective vendors
to confirm final project capital costs.
Note that the cost to install the boiler and connect to the existing boiler system is based on a bid
received without the contractor being able to perform a site inspection. Because of this, the pricing is
expected to include a bid premium to account for any potential unknowns. Additional costs included in
the bid for bringing the existing boiler up to functional condition and compliant with code were not
included in the capital cost estimate.
Table 21 shows the Ambler City Hall / Washeteria project estimated capital cost breakdown for process
equipment, building costs, development costs, startup, and contingency. The capital cost supplied is a
budgetary estimate, corresponding to the level of engineering detail that has been conducted at this
stage of the project. Budgetary quotes are defined by engineering’s governing body, AACE
International, as 10-15% design completion of the facility, and as such can only be held to a +30% to -
15% accuracy level. Adhering to this international standard, boiler system plant all-in capital cost is
projected to fall in the range of $243,000 to $373,000.
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Table 21 – Ambler City Hall Boiler Construction and Installation Cost
Ambler City Hall / Washeteria Boiler System Design Drawings
Engineering Design drawings of the Ambler City hall / Washeteria Biomass Boiler System follow. These
include a Site Plan, 3-D rendering of the boiler building and equipment, General Arrangement of
equipment, and a Process Flow Diagram.
Upper Kobuk Biomass Project
Budgetary Captial Expenditure Estimate
Ambler
City Hall / Washeteria
Process Equipment & Construction Costs
GARN Jr. WHS 1000 (delivered Fairbanks) $14,826
Boiler Bldg Connections and Equipment $4,134
Interconnection Equipment to Washeteria $1,787
Ancillary Feedstock Handling Equipment $3,000
Delivery Equipment Fairbanks-Ambler $13,900
Equipment Installation $118,000
Equipment Cost Subtotal $155,647
Building and Development Costs
Boiler Building Construction- Pole Building
(steel frame, spray insulation)*$52,213
Boiler Building Foundation* $6,298
Boiler Building Ramp $3,499
Feedstock Foundation* $22,691
Feedstock Construction* $6,298
Fire Marshall Review $1,000
Mobilization and Construction Management $39,200
Total Development and Start-up Costs $131,200
Total Uses $286,847
* Includes 30% Contingency addition to quoted values
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5.3. Proposed Shungnak Community Center Engineering
The Shungnak scenario has the potential to design a variety of solutions for its heating needs as a new
construction integrated design process.
The first option available to the village is a stand-alone boiler building housing a GARN boiler, similar to
the scenario proposed for Ambler. This boiler will feed thermal energy into the proposed Shungnak
Community Center via interconnection with its mechanical / boiler room. The option assumed the
building is separately designed with a small backup or base load boiler and water-based distribution
system. This option is the simplest logistically and to manage through the construction phase, as it does
not materially impact the design and construction of the primary building. The downside of this option is
the additional cost for the boiler building structures and interconnection.
The second option is an integrated mechanical room housing a pressurized gasification boiler unit. This
type of boiler can be designed as an integral portion of the building due to its smaller footprint, and is
therefore much less expensive to install. It is expected that the capital expenditure of the wood-fired
boiler will be rolled into Community Center and funded through a different vehicle than the Ambler
project. Using an alternate funding vehicle eliminates restrictions on boiler type.
The total maximum heat loss for the proposed Shungnak Community Center is calculated to be 87,000
BTU/hr. The recommended boiler for that application is a Fröling FHG-L Model 30. It is a high efficiency,
gasifier, pressurized type boiler. This model Fröling boiler has been tested by the Brookhaven National
Laboratory to a very low emission rate. The Model 30 is rated for 102,500 BTU/hr of heat output, or 30
kW. Because it is a pressure boiler a closed system of glycol based heat transfer fluid may be used. This
will eliminate concerns for freeze protection of the system. If the system is installed in an ‘open’ or
unpressurized configuration to bypass ASME certification regulations, the use of glycol is not
recommended.
The Model 30 is a relatively compact unit requiring minimal floor space. It does however require
thermal storage tanks (440 gallons) to maximize efficiency and minimize emissions. Floor space for the
boiler is 3’0 width by 7’0 long (21 square feet), the floor space required for the thermal storage tanks is
also 3’0 width by 7’0 long. The area of placement will need to support a load of 1500 pounds for the
boiler and 4000 pounds for the thermal storage tanks. It is likely that the boiler and associated thermal
storage tanks can be contained within the proposed building envelope. Additional space may be
considered in final design engineering to improve access for maintenance.
An example photo of an integrated boiler/mechanical room housing a Fröling wood-fired heating system
is shown below. Note the external thermal storage.
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Figure 23 – Photo Example of Pressurized Boiler System
Source: Tarm
Again a small backup oil-fired boiler is envisioned, however this can be a Toyostove or similar,
disconnected from the hydronic thermal distribution system. The closed system pressurized boiler units
are capable of using glycol blended working fluid, reducing the risk of freezing or bursting of pipes.
The site design is developed for the option requiring the largest footprint, a stand-alone building with a
GARN boiler. Design for smaller boiler room attached to Proposed Shungnak Community Center,
housing the pressurized boiler.
Site design shows feedstock storage in front of City Hall building, but would be more optimal on west
side of proposed Community Center. However, as discussed earlier, there are potential siting issues with
the Hall Street Row right-of-way, and to avoid conflict the feedstock storage is placed well within the
property boundaries. If it is determined through site survey that the right-of-way would not be
impacted, it is recommended that feedstock storage be moved.
Design engineering of the interconnection of the boiler with the proposed Community Center building
structure and heating distribution zones is premature without a solidified building design.
Recommended plumbing schematics are supplied below for reference.
Design Basis
The boiler is sized and designed for a Community Center with the following design criteria:
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32’ x 40’ 1-level building with 10’ x 16’ entry way
2x6” stick-frame construction, 8’ tall walls to eaves
Post-on-pad footers
OSB walls w/ moisture barrier house wrap and vinyl siding
Floors & Ceiling R-36 insulation
Walls R-21 insulation
Double-pane vinyl windows
Hydronic heating, baseboard throughout
Plans to integrate biomass heating, location as yet unknown
Proposed Shungnak Community Center Boiler System Description
Tetra Tech developed the following design for a cordwood-fired boiler at the proposed Shungnak
Community Center. The plant design is engineered and tailored to conditions specific to the site. The
system process flow is described in sequence in the following section and a corresponding site design
drawings, supplied below. In the description below, the process has been broken down into its critical
components: boiler design, interconnection and energy distribution, and delivery and construction of
equipment.
Boiler Design
Feedstock demand is calculated at 13.1 cords per year, offsetting 1,545 gallons of fuel oil use
annually.
Feedstock for this system will consist of cordwood collected and sold to the biomass energy project
by area woodcutters. Feed for the boiler will be spruce, birch, aspen, poplar, and tamarack logs to
up to 21.5” long. The lower heat value of the feedstock fuel processed at the facility is expected to
be approximately 6692 Btu/lb, or 17.5 MMBtu/cord, with a feedstock input moisture expected at
20%, a standard measure for air-dried cordwood. Small wood processing equipment including
chainsaws, wheelbarrows, and a wood-receiving storage bin will be included in the project capital
costs for feedstock management.
The recommended boiler for the project is a Fröling FHG-L model 30 or equivalent. This boiler
system is an advanced gasification hydronic wood boiler with internal water storage at atmospheric
pressure, producing a maximum rated output of 102,500 Btu/hr 30 kW), sufficient to serve the
maximum heat load calculated at 86,605 Btu/hr.
A small backup oil-fired heating unit is expected for backup and/or for on-call peak heating needs.
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Interconnects and Energy Distribution
The working fluid (here, glycol /water blend) is heated at atmospheric pressure to desired
temperature (140-180 deg F) and stored in external thermal storage tanks for distribution. Energy
distribution will be accomplished through a hydronic baseboard heating system. The system design
does not include the baseboard heating distribution system for the building, which will be the same
as a for an oil-fired hydronic boiler system. The design of the distribution system is expected to be
completed through the Community Center design process.
Plant operations are managed automatically via control panel and programmable logic controller
(PLC) systems.
Equipment Delivery and Construction
Equipment delivery to Ambler is expected via airplane from Fairbanks, for a quoted price of $13,900
for up to 4,800 pounds, which is sufficient for a boiler and associated equipment.
Construction management is expected as such:
o Building Construction Contractor. The Shungnak Community Center building
construction is expected to include the boiler room integrated into the construction
process. Specifications for space, power, and heating loop interconnections will be
provided by the boiler equipment installation contractor.
o Equipment Installation Contractor. A local HVAC contractor will be hired through
competitive bid process to set equipment and connect mechanical and plumbing.
Proposed Shungnak Community Center Boiler System Capital Cost
Tetra Tech developed capital costs for the proposed facility configurations based on a number of
communicationswith equipment vendors, publicly-available information, and internal databases, as well
as costs and operational parameters derived from engineering investigation of the proposed facility.
The capital cost below is therefore not representative of any single bid or vendor’s equipment profile.
Tetra Tech recommends that the project owner solicit final construction bids from prospective vendors
to confirm final project capital costs.
Table 22 shows the proposed Shungnak Community Center project estimated capital cost breakdown for
process equipment, building costs, development costs, startup, and contingency. The capital cost
supplied is a budgetary estimate, corresponding to the level of engineering detail that has been
conducted at this stage of the project. Budgetary quotes are defined by engineering’s governing body,
AACE International, as 10-15% design completion of the facility, and as such can only be held to a +30%
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to -15% accuracy level. Adhering to this international standard, boiler system plant all-in capital cost is
projected to fall in the range of $127,000 to $194,000.
A number of components of the proposed wood-fired boiler would also need to be installed for a
hydronic oil-fired boiler heating system (such as the Weil-McLain boilers found elsewhere in the region).
The incremental additional cost of the wood-fired boiler over the cost of an oil-fired boiler would be
approximately $29,700. This includes the higher cost of the boiler itself, the thermal energy storage
tanks, and delivery of the equipment to Shungnak minus approximately $4,500 for oil-fired unit landed
in Shungnak.
Table 22 – Shungnak Community Center Boiler Construction and Installation Cost
Note that a 20% contingency factor is also applied to the capital cost to account for additional cost
overruns. Actual costs will vary depending on the technology provider and general contractor chosen for
the project, material costs, and other factors in further facility engineering and procurement stages.
Proposed Shungnak Community Center Boiler System Design Drawings
Engineering design drawings of the proposed Shungnak Community Center Boiler System follow. These
include a Site Plan, General Arrangement of equipment, and a recommended piping layout (supplied by
Tarm Biomass).
Upper Kobuk Biomass Project
BudgetaryCaptial Expenditure Estimate
Shungnak
CommunityCenter
Process Equipment & Construction Costs (incremental)
Froling Model FHG-L 30 Boiler PKG $10,868
SHST440PAK Thermal Stg Kit $6,903
DeliveryEquipment $16,400
Incremental Cost Subtotal $34,171
Development and Start-up Costs (required all types)
Boiler Bldg Connections and Equipment $7,375
AncillaryFeedstock Handling Equipment $3,000
Equipment Installation $77,959
Backup Oil-fired Heating Unit $2,000
Total Development and Start-up Costs $90,333
Contingency20% $24,901
Total Uses $149,405
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6. Economic and Financial Analysis
To further analyze the financial costs and benefits of wood-fired heating installations in the Upper
Kobuk region, Tetra Tech prepared several financial modeling and economic performance projections of
the prospective biomass energy plant scenarios to determine if a biomass energy plant is economically
feasible for the Upper Kobuk region to pursue, and to identify key project parameters that most affect
the viability of the project.
Financial analysiswas conducted in two modes or methods:
1) Cost-benefit analysis of two generalized biomass energy scenarios; wood-fired heating for a
larger municipal or commercial facility, and wood-fired heat for a new-build residence.
2)Pro-forma model of Ambler City Hall / Washeteria and proposed Shungnak Community Center
projects, as engineered.
When possible, Tetra Tech solicited cost and operational parameters from equipment providers, and
supplemented that information with internal engineering analysis. The models evaluate the project
conditions evaluated in the study.
6.1. Cost-Benefit Analysis: Commercial and Residential Installation
Fuel cost savings is the primary financial driver of biomass energy systems, and most overcome higher
upfront capital expenditure and operations costs. A cost-benefit analysis of was conducted to analyze
general conditions associated with wood-fired boilers in two configurations; a commercial or community
building (corresponding to Scenario 3), and a model residential home (corresponding to Scenario 4).
Facility parameters incorporated in the cost-benefit analysis include: Product yields; Product and raw
material pricing; Labor costs; and Energy consumption and pricing.
Commercial / Municipal Wood-Fired Boiler Cost-Benefit
A commercial or municipal installation, modeled after one that would be used at the Ambler IRA
community building, for example, would be expected to consume approximately 30-40 cords of wood
over the course of an 8-month heating season. The system requires a boiler with a rated heating
capacity of approximately 200,000 Btu/hr (55 kW). This system will produce an annual operating cash
flow of approximately $18,000, in the form of savings over the cost of purchasing fuel oil on the open
market. Modeling results are shown below in Table 23.
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Table 23 –Cost-Benefit Analysis of Municipal Cordwood-fired Boiler
Cost-Benefit Analysis
Cord-wood Combustion Systems versus Fuel Oil
Commercial / Municipal Installation
Large Building External
Boiler
Program Benefit
Unit Price Unit
Avoided Fuel Oil Purchase
Fuel Oil Use Avoided
1
3,776 gallons
Fuel Cost
2 $9.65 per gallon
Annual Fuel Savings $36,434
Maintenance and Operations Savings
Avoided Maintenance & Materials Cost
3 $550 per year
Avoided Operational Cost
4 $1,550 per year
Annual Avoided O&M costs $2,100
Annual Net Benefit $38,534
Program Cost
Cordwood Purchases
Fuel Wood Purchased
5 35.0 cords
Fuel Wood Cost
6 $210 per cord
Annual Fuel Cost $7,348
Maintenance and Operations Cost
Maintenance Parts and Labor
7 $550 per year
Operations Cost
8 $12,000 per year
Annual O&M Cost 12,550
Annual Program Cost 19,898
Annual Simple Cash Flow / Net Base Benefit $18,635
Notes:
1. Fuel usage based on equivalent Btu input of wood-fired boiler.
2. Fuel Cost lowest of Kobuk, Ambler, and Shungnak Dec 2013 NWAB fuel prices.
3. Oil-fired boiler maintenance based on representative data.
4. Oil-fired boiler operations based on representative data.
5. Fuel wood purchase based on capacity of GARN WHS-1000 over 8-month heating season.
6. Wood price based on $70 per sledload, estimate 3 sled loads per cord.
7. Maintenance cost based on representative data estimate.
8. Operations cost based on 47% of FTE labor at $40,000 per year salary.
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Residential Wood-Fired Boiler Cost-Benefit
Individual housing, especially new construction, are an excellent opportunity for biomass energy
retrofits. The Northwest Inupiat Housing Authority (NWIHA) leads most construction activities in the
area. According to their website, the generalized model home for construction “exceeded the State of
Alaska’s Building Energy Efficiency Standards (BEES), by receiving a 5 Star + rating. However, in regards
to heating sources, “a high efficient (85%+) oil-fired boiler system, with a wood stove as a back-up
heating source, isselected to ensure both adequate heat and cost effective to the homeowner
10.”
In contrast to a wood-fired heating system for a public community or commercial space, a cost-benefit
analysis was conducted for a smaller-scale residential application. This analysis was conducted using the
Northwest Inupiat Housing Authority (NWIHA) model home as a baseline. This model run assumes a fuel
wood use of 10 cords per year, displacing 1,077 gallons of fuel oil. NWIHA model home designs specify
area home of 1,485 square feet.
Data was obtained from the Cold Climate Housing Research Center for representative heating demand
for houses in Upper Kobuk region. To heat this structure, a boiler rated at the heating capacity of 70,000
Btu/hr (20 kW) is required, and will consume 10 cords of wood over the course of an 8-month heating
season.
With these parameters, the residential system achieves over $8,000 in cost savings annually. In a
residential application, it is assumed the homeowner provides the labor necessary to operate and
maintain the system at zero cost, greatly improving the project economics. Modeling results are shown
below in Table 24.
10 http://www.nwiha.com/newdevelopments.html
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Table 24 –Cost-Benefit Analysis of Residential Cordwood-fired Boiler
Cost-Benefit Analysis
Cord-wood Combustion Systems versus Fuel Oil
Residential Installation
Model Residential
Construction
Program Benefit
Unit Price Unit
Avoided Fuel Oil Purchase
Fuel Oil Use Avoided
1
1,077 gallons
Fuel Cost
2 $9.65 per gallon
Annual Fuel Savings $10,396
Maintenance and Operations Savings
Avoided Maintenance & Materials Cost
3 $360 per year
Avoided Operational Cost
4 $0 per year
Annual Avoided O&M costs $360
Annual Net Benefit $10,756
Program Cost
Cordwood Purchases
Fuel Wood Purchased
5 10.0 cords
Fuel Wood Cost
6 $210 per cord
Annual Fuel Cost $2,097
Maintenance and Operations Cost
Maintenance Parts and Labor
7 $500 per year
Operations Cost
8 $0 per year
Annual O&M Cost $500
Annual Program Cost $2,597
Annual Simple Cash Flow / Net Base Benefit $8,159
Notes:
1. Fuel usage based on equivalent Btu input of wood-fired boiler.
2. Fuel Cost lowest of Kobuk, Ambler, and Shungnak Dec 2013 NWAB fuel prices.
3. Oil-fired boiler maintenance based on 5-yr replacement cycle at $1,800 CapEx.
4. Oil-fired boiler operations minimal and assumed zero cost.
5. Fuel wood purchase based on capacity of Froling FHG-20 over 8-month heating season.
6. Wood price based on $70 per sledload, estimate 3 sledloads per cord.
7. Maintenance cost minimal, conservative estimate used.
8. Operations time is unpaid for residential system.
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Community Benefit
While the residential application can pay for itself in reduced fuel oil usage, the similar CBA analysis of
the two configurations indicates that, given a choice with limited funding of whether to construct a
municipal or residential project, the commercial project provides the best value to the community as a
whole. Reasons behind this include:
350% more wood usage results in larger savings, as wood usage and oil savings are the primary
monetary benefit
Larger wood usage also benefits the communities through wood purchases, which stay within
the community.
Job creation – the municipal project supports the creation of labor within the community
6.2. LCVA Financial Modeling Results
Tetra Tech conducted a Life-Cycle Value Analysis financial model for the Ambler City Hall / Washeteria
and proposed Shungnak Community Center projects to evaluate whether they are financially sound
business opportunities for the region to pursue. The financial pro forma analysis considered for two
project scenarios. The first scenario is an 180,000 Btu/hr (52 kW) cord-wood fired boiler system serving
the heating needs of the Ambler City Hall and Washeteria building, installed in a stand-alone boiler room
adjacent to the main structure.
The second scenario is a 102,000 Btu/hr (30 kW) cord-wood fired pressurized boiler serving the
expected heating needs of the proposed Shungnak Community Center. This unit has a smaller footprint,
and is expected to be included within the building design as an attached boiler room.
These scenarios are further evaluated in the section below. In addition to the fuel savings analyzed in
the cost-benefit review above, the scenario analysis takes into account project capital cost and life-cycle
maintenance and operations costs. A pro forma analysis was prepared corresponding to the base case
project assumptions, and additional analysis is provided to examine the primary factors affecting the
financial viability of the project scenarios.
Financial Modeling Parameters
A number of assumptions are made regarding capital costs for projects that are in early developmental
stages. The financial model is an estimate of potential project returns, based upon the most accurate
information available at present. To maintain project transparency, and to facilitate adjustments to
project goals as the project moves further in the development phase, an explanation of the inputs used
in the financial forecasts that have the greatest impact on the project risk and return follows.
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Process Equipment Scale and Cost.The Ambler City Hall and Washeteria scenario is an 180,000
Btu/hr cord-wood fired boiler system. Capital cost is expected at $286,847.
o The proposed Shungnak Community Center boiler is a 102,000 Btu/hr cord-wood fired
pressurized boiler. The capital expenditure assumed for the Shungnak project is set at
the incremental cost of installing a wood-fired boiler in place of an oil-fired unit,
approximately calculated to $29,000.
Feedstock Input.The prescribed feedstock input for both systems is cut, split, and seasoned
firewood. The Ambler City Hall / Washeteria is expected to consume approximately 30 cords of
wood (39 tons) per year. The proposed Shungnak Community Center is expected to consume
13.08 cords (17.13 tons) per year. Feedstock demand is calculated in Section 1.
Feedstock Input Cost.Feedstock price is set at $210/cord ($70/sledload and 1/3 cord in each
average sledload) in Ambler. Because wood feedstock requires more labor for delivery in
Shungnak, the price is set at $240/cord ($80 per sledload).
Thermal Energy Sale Value.The value of the thermal energy produced in both scenarios is based
on the local price of #1 heating fuel, determined on Btu basis taking into account the relative
efficiency of the diesel boilers serving the buildings. The average price of heating fuel in Ambler
for December 2013 was $11.00/gallon. The price of heating oil in Shungnak is $10.59. Efficiency
of those boilers is set at 86.7%.
Project Capital Cost.The capital costs for each project scenario include engineering,
procurement, and construction of the plants, and project development costs including start-up
costs. Capital Costs are expected at $286,847 for the Ambler City Hall and $29,671 for the
proposed Shungnak Community Center. Shungnak capital costs are expressed as the
incremental cost of installing a wood-fired boiler instead of an oil-fired boiler. This consists of
the increased cost of the boiler and thermal storage kit, and delivery of this equipment to
Shungnak. Project Costs are expected to be covered on a cash basis, without financing costs.
Operations and Maintenance Costs.Operations and Maintenance costs are set at $11,600 per
year. O&M costs are equal for both facilities, despite their differences in facility size. An
assumed maintenance event of $1,500 is included in years 5, 10, and 15.
Depreciation and Amortization.20-year straight line depreciation is used to depreciate the
installed cost of the biomass energy plant’s major equipment, at a standard discount rate of 5%.
Net Present Value (NPV) and Internal Rate of Return (IRR) calculation.Net Present Value and
Internal Rate of Return calculations are based on a 20-year run of the financial model. Simple
payback of the project is achieved when the cash flow end-of-year balance is net positive.
Project Financial Analysis Results
Based on the inputs included in the financial model, both project scenarios appear to be positive
investments. The Ambler City Hall / Washeteria project produces an annual cost savings averaging over
$32,000, an internal rate of return (IRR) of 8.8%, and a 20-year net present value (NPV) of $127,000. The
fuel savings repay the project capital cost in 11 years. The boiler for the proposed Shungnak Community
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Center produces an annual average net income of just over $5,000, and project lifespan Internal Rate of
Return (IRR) of 11.5% on a NPV of $29,000.
Table 25 –Summary Financial Metrics
On an ongoing operations basis, the facilities are self-sustaining, saving more in fuel costs
(approximately $55,000 and $23,000 annually, for Scenarios 1 and 2, respectively) than their operational
costs, maintenance, and employee pay (totaling approximately $22,000 and $18,000, respectively).
Each facility is financially sound on its own merits, and additional support in the form of grant funding to
reduce the cost of capital equipment will also improve project financial metrics.
The comparison between the two projects is somewhat skewed by the use of incremental cost for the
Shungnak project, as opposed to total capital cost for the Ambler project. If the Shungnak boiler were
considered as a retrofit to an existing building, the total project capital cost of nearly $150,000 would be
needed to be recovered through fuel cost savings. The system does not burn enough fuel to produce a
simple payback in its lifespan. The Ambler scenario creates enough cost savings through its much larger
wood use to repay capital expenditure.
Figures 24 and 25 below include pro forma cash flow models for the scenarios Ambler City Hall /
Washeteria production scenario. Positive net revenue for both projects, equal to cost savings from
avoided fuel purchases, is a very positive indication for project financial viability.
Financial AnalysisSummary
Kobuk Biomass Project
Ambler
City Hall / Washeteria
Shungnak
Community Center
(proposed)
Woody Biomass Feedstock Type Cord Wood Cord Wood
Woody Biomass Feedstock Used (cord)29.76 13.08
Fuel Oil Savings (gal annual) 3,516 1,545
20-yr Avg. Avoided Fuel Oil Cost ($/yr)$54,687 $23,135
20-yr Avg. Feedstock Cost ($/cord/yr)$8,837 $4,439
20-yr Avg. Net Revenue $32,214 $5,059
Simple Payback Year Year 11 Year 11
20-yr Net Present Value (NPV) $127,291 $29,098
20-yr Internal Return on Investment (IRR) 8.8% 11.5%
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Figure 24 – Ambler Project Life-Cycle Value Analysis
Figure 25 – Shungnak Project Life-Cycle Value Analysis
Year Construction Cords Wood Feedstock Operation and Avoided Cost Net End-ofYear
Inputs Processed Cost Maintenance (Fuel Oil) Revenue (Loss) Balance
Feedstock Material Cord Wood 0 ($286,847)30 ($6,250) ($11,600)$38,676 ($266,021) ($266,021)
Process Input (cords/yr) 29.76 1 30 ($6,250) ($11,600)$38,676 $20,826 ($245,194)
Process Input (tons/yr) 38.99 2 30 ($6,468) ($11,774)$40,030 $21,787 ($223,407)
Feedstock Cost ($ / cord) $210 3 30 ($6,695) ($11,951)$41,431 $22,785 ($200,622)
4 30 ($6,929) ($12,130)$42,881 $23,822 ($176,800)
Captial Expenditure (Net) $286,847 5 ($1,500)30 ($7,172) ($12,312)$44,382 $23,398 ($153,401)
O&MExpense (annual) $11,600 6 30 ($7,423) ($12,496)$45,935 $26,016 ($127,386)
7 30 ($7,682) ($12,684)$47,543 $27,176 ($100,209)
Fuel Oil Savings (gal annual) 3,516 8 30 ($7,951) ($12,874)$49,207 $28,381 ($71,828)
Fuel Oil Cost ($ / gal) $11.00 9 30 ($8,230) ($13,067)$50,929 $29,632 ($42,196)
10 ($1,500)30 ($8,518) ($13,263)$52,711 $29,431 ($12,765)
inflation rate 1.5% 11 30 ($8,816) ($13,462)$54,556 $32,278 $19,513 * Simple Payback
energy value inflation rate 3.5% 12 30 ($9,124) ($13,664)$56,466 $33,677 $53,190
Discount rate 5% 13 30 ($9,444) ($13,869)$58,442 $35,129 $88,320
O&Mcost adjustment factor 1 14 30 ($9,774) ($14,077)$60,488 $36,636 $124,956
15 ($1,500)30 ($10,116) ($14,288)$62,605 $36,700 $161,656
16 30 ($10,470) ($14,503)$64,796 $39,823 $201,479
17 30 ($10,837) ($14,720)$67,064 $41,507 $242,986
18 30 ($11,216) ($14,941)$69,411 $43,254 $286,239
19 30 ($11,609) ($15,165)$71,840 $45,067 $331,306
20 30 ($12,015) ($15,393)$74,355 $46,947 $378,253
$378,253
$127,291
8.8%
Life-Cycle Cost Model - Ambler Washeteria and City Building
Model 1 - Garn 1000 Cord Wood Boiler
Total Project Value (end of life)
Net Present Value (NPV)
Internal Rate of Return (IRR)
Year Construction Cords Wood Feedstock Operation and Avoided Cost Net End-ofYear
Inputs Processed Cost Maintenance (Fuel Oil) Revenue (Loss) Balance
Feedstock Material Cord Wood 0 ($29,671)13 ($3,139) ($11,600)$16,362 ($28,049) ($28,049)
Process Input (cords/yr) 13.08 1 13 ($3,139) ($11,600)$16,362 $1,622 ($26,426)
Process Input (tons/yr) 17.13 2 13 ($3,249) ($11,774)$16,934 $1,911 ($24,515)
Feedstock Cost ($ / cord) $240 3 13 ($3,363) ($11,951)$17,527 $2,214 ($22,302)
4 13 ($3,480) ($12,130)$18,140 $2,530 ($19,772)
Captial Expenditure (Net) $29,671 5 ($1,500)13 ($3,602) ($12,312)$18,775 $1,361 ($18,411)
O&MExpense (annual) $11,600 6 13 ($3,728) ($12,496)$19,432 $3,208 ($15,203)
7 13 ($3,859) ($12,684)$20,113 $3,570 ($11,633)
Fuel Oil Savings (gal annual) 1,545 8 13 ($3,994) ($12,874)$20,816 $3,948 ($7,685)
Fuel Oil Cost ($ / gal) $10.59 9 13 ($4,134) ($13,067)$21,545 $4,344 ($3,341)
10 ($1,500)13 ($4,278) ($13,263)$22,299 $3,257 ($84)
inflation rate 1.5% 11 13 ($4,428) ($13,462)$23,080 $5,189 $5,106 * Simple Payback
energy value inflation rate 3.5% 12 13 ($4,583) ($13,664)$23,887 $5,640 $10,746
Discount rate 5% 13 13 ($4,744) ($13,869)$24,723 $6,111 $16,856
O&Mcost adjustment factor 1 14 13 ($4,910) ($14,077)$25,589 $6,602 $23,458
15 ($1,500)13 ($5,081) ($14,288)$26,484 $5,615 $29,073
16 13 ($5,259) ($14,503)$27,411 $7,649 $36,722
17 13 ($5,443) ($14,720)$28,371 $8,207 $44,929
18 13 ($5,634) ($14,941)$29,364 $8,789 $53,718
19 13 ($5,831) ($15,165)$30,391 $9,395 $63,113
20 13 ($6,035) ($15,393)$31,455 $10,027 $73,141
$73,141
$29,098
11.5%
Life-Cycle Cost Model - Proposed Shungnak Community Center
Pressurized Wood Boiler - Froling FHG-30
Total Project Value (end of life)
Net Present Value (NPV)
Internal Rate of Return (IRR)
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Upper Kobuk Biomass Project
Page | 84
Sensitivity Analysis
Sensitivity analyses were conducted for both projects. The sensitivities considered low, medium, and
high pricing scenarios for cordwood and fuel oil. The low scenario is a worst-case view of high cordwood
pricing and low fuel oil prices offset by the boiler facilities. The high scenario is ‘best-case’, assuming low
cordwood pricing and high fuel oil prices. The medium case corresponds to the design basis.
Both projects were cost-negative at $300/cord wood and $8.00/gallon fuel oil. The Ambler project
shows less sensitivity to the variations. The project would be cost-positive at either the high wood cost
or the low fuel oil cost, but not both. The Shungnak project is cost-positive with a rise in wood prices,
but loses money if fuel prices fall. Both projects perform very well as fuel prices rise and/or wood prices
fall, as expected. If both wood prices and fuel prices rise, the likeliest long-term scenario, both projects
perform better than the base case scenario.
Table 26 –Ambler Project Sensitivity Analysis
Table 27 –Shungnak Project Sensitivity Analysis
Low Med High
Fuel Oil $8.00 $11.00 $15.00
Cord Wood $300.00 $210.00 $150.00
NPV -$123,771.00 $120,982.17 $414,277.00
IRR -0.60%8.56% 17.1%
Low Med High
Fuel Oil $8.00 $10.59 $15.00
Cord Wood $300.00 $240.00 $150.00
NPV -$65,780.00 $22,789.81 $170,655.00
IRR N/A 10.01% 50.7%
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Upper Kobuk Biomass Project
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7. Environmental, Regulatory, and Permitting
Permitting and regulatory approval for both the Ambler City Hall / Washeteria Project and the proposed
Shungnak Community Center are expected to be relatively straightforward and simple. Neither boiler
system triggers federal regulatory restrictions or permit filings.
7.1. Equipment Safety and Boiler Certification
Dependent on size, boilers of various types require certified and trained operators for safe operation.
Alaska’s Department of Labor and Workforce Development oversees boiler operator and permitting in
the state. The boilers proposed for this project produce low pressure steam or hot water, and thus fall
to the low end of the spectrum in terms of regulatory oversight. Alaska Statutes, Sec. 18.60.210 (a) (9)
states that to be exempt from boiler inspections, operator certification, and licensing requirements, the
system must comply with all of the following (verbatim from statute):
(A) is equipped with a safety relief valve and operational controls required by the latest Boiler
Construction Code published by the American Society of Mechanical Engineers that has been
adopted by the Department of Labor and Workforce Development under AS 18.60.180;
(B) contains only water;
(C) does not exceed 120 gallons in capacity, a water temperature of 210 degrees Fahrenheit, a
pressure of 150 pounds of square inch gauge pressure, or a heat input of more than 200,000
BTU an hour; and
(D) contains a tempering valve that will regulate the outlet domestic water temperature at not
more than 140 degrees Fahrenheit.
7.2. Permitting Requirements
Federal Permitting Requirements
No federal nexus exists for this project as there are no federal permits needed, no federal money used,
and no federal land involved. The most likely federal permits would have been for air quality or wetland
impacts. A federal air quality permit is not needed as the biomass plants will not be incinerating medical,
commercial, or industrial waste.
11 Further, no Section 404 permit for wetland impacts would be
required. The USFWS’ National Wetland Inventory mapper was used to verify the presence/absence of
wetlands in the project area; however, the database lacked sufficient data to make this determination.
11 40 CFR 60, 40 CFR 62 or 40 CFR 63
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Upper Kobuk Biomass Project
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Aerial photo-interpretation (Figures 3 and 4) supports a conclusion of the absence of wetlands and
waters of the U.S., as both proposed project areas occur within the highly developed and disturbed
community limits of Ambler and Shungnak. With close proximity of new developments abutting existing
development, field observations are not necessary at this time; however, if either proposed project
shifts outside previously designated project limits of the Ambler City Building and City Hall or the
Shungnak Community Center, additional analysis will be necessary to confirm the presence or absence
of wetlands or waters of the U.S.
National Environmental Policy Act
A federal Environmental Assessment under the provisions of the National Environmental Policy Act
(NEPA) is not expected to be necessary for this project. The project does not, as far as can be
determined through the preceding study, 1) require federal funding, 2) be built on federal land, or 3)
disturb habitat or otherwise threaten any sensitive native species that may require additional review.
Air Quality Regulations and Permitting Requirements
Under current Alaska air-quality regulations, any device that can burn more than 1,000 pounds of waste
per hour must have an air-quality permit and be operated and monitored to minimize air pollution.
While neither project meets this threshold, the Alaska Department of Environmental Conservation (DEC)
will be contacted once plant specifications are developed to determine compliance for particulate
emissions and ambient air standards.
Title V Air Permit: Rated capacity is less than 1,000 pounds a day; no Particulate Matter (PM) limit.
Therefore, the project is not big enough to trigger CFR Title 40; Chapter 1; Subchapter C; Part 60
(Subpart E, Section 60.50): (threshold is 45 metric tons per day charging rate (50 tons/day). Consultation
with the DEC and Environmental Protection Agency (EPA) is recommended, though the units are too
small to require permits.
Title 9 Borough Permit
A Northwest Arctic Borough Title 9 Land Use Permit will be required. The permit will be filed as a
conditional use permit (CUP). A CUP will require a public hearing and take no less than 30 days to obtain.
Local Building and Fire Code
Building codes that will apply, include, but are not limited to the following:
International Building Code
Americans with Disabilities Act
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Upper Kobuk Biomass Project
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Since this building is not for public use, ADA may not apply. The building could be built to ADA standards
if desired by the Northwest Arctic Borough.
International Fire Code
International Mechanical Code
International Plumbing Code
National Electrical Code
The Department of Public Safety (DPS), Fire and Life Safety, has statewide jurisdiction for fire code
enforcement. Some of the large municipalities have adopted primacy, but the Northwest Arctic Borough
falls under DPS jurisdiction. Their plan review is completed within ten working days of submittal to DPS
of the Construction Drawings, and the associated fee (calculated by DPS). The associated fee depends on
the occupancy, building type, and initial construction cost estimate. For budgeting purposes, the plan
review fee will be approximately $1,000 per building.
Northwest Arctic Borough
Upper Kobuk Biomass Project
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8. Conclusion and Recommendations
Based on the analysis conducted in this study, the project team recommends that NWAB and the
villages proceed with further development of biomass boiler installations at the City Hall/Washeteria
and proposed Community Center location in Ambler and Shungnak, respectively. The projects appear to
be technically and financially sound. Benefits to the communities include economic development in the
form of increased wood harvest revenue to woodcutters, and local labor for construction and operation
of the boilers with funds generated from fuel cost savings. As well, the projects provide for renewable
and self-reliant energy generation, and reduced imports of fuel oil burned for heat.
A number of available options were evaluated, and at the current time it appears installation at the
Ambler City Hall / Washeteria and the proposed Shungnak Community Center are the most viable
options for a number of reasons, chief amongst these is the funding and construction development
efforts already underway for both buildings.
Other scenarios also appear positive, including the substitution of wood-fired boilers or combination
wood-oil fired boilers for new residential housing construction, and the potential retrofit of a wood-fired
boiler at the Ambler village IRA building to supplement and reduce the fuel oil usage there. These
projects are recommended for strong consideration for funding. Installation of a boiler in a new
residential housing construction will present a “model” to test and confirm the viability stated herein.
The Ambler village IRA building biomass project will have considerable value to the IRA community
which is a key organization in the community and will further provide an opportunity to encourage
others to utilize biomass.
Tetra Tech also recommends development of a wood-sourcing strategy with the input of local and
regional authorities to ensure a steady and sustainable flow of feedstock for the project(s). Guidelines
have been presented in this study but the final determination cannot be made by an outside entity. The
proposed project scales have small-enough wood harvest demand that they do not trigger the defined
harvest structure and management set in the Alaska Forest Resources and Practices Act, but can be
designed to comply with a number of the tenants of the Act. The majority of the cutting area falls within
NANA-owned lands, and collaboration with the Regional Corporation should be conducted as early as
possible in the project development phase to ensure compliance with the NANA Forest Stewardship
Plan.
Tetra Tech and DOWL HKM extend our appreciation to the Northwest Arctic Borough and Alaska Energy
Authority for the opportunity to work on this project.
Northwest Arctic Borough
Upper Kobuk Biomass Project
Page | 89
Appendix 1: Bibliography
Alaska Department of Natural Resources, Division of Forestry. “Alaska Forest Resources and Practices
Act: AS 41.17”. Reprinted May, 2013.
Alaska Wood Energy Associates. “A comparison of Automated and Hand-fed Boiler Systems for Upper
Kobuk Valley Villages.” Submitted to WHPacific, 2011.
Alaska Wood Energy Associates. “Wood Harvest Systems for the Upper Kobuk Valley.” Submitted to
WHPacific, 2011.
Colt, et al. “Sustainable Utilities in Rural Alaska; Effective Management, Maintenance and Operation of
Electric, Water, Sewer, Bulk Fuel, Solid Waste. ” University of Alaska Anchorage, 2003.
Forest and LandManagement, Inc. “Upper Kobuk Valley Wood Biomass Study.” Prepared for Alaska
Wood Energy Associates, September, 2010.
NANA Regional Corporation. “NANA Strategic Energy Plan & Energy Options Analysis.” USDOE Award
No. DE-FG36-07GO17091. March, 2009.
Nicholls, David and Tom Miles. “Cordwood Energy Systems for Community Heating in Alaska– An
Overview.” United States Department of Agriculture Forest Service (USFS), Pacific Northwest Research
Station; General Technical Report PNW-GTR-783, January, 2009.
Tanana Chiefs Conference (TCC), Forestry Program. “Assessment of Woody Biomass Energy Resources at
Villages in the Upper Kobuk Region of Northwest Alaska: Kobuk, Shungnak, and Ambler.” Presented to
Alaska Native Tribal Health Consortium, June, 2013.
Tanana Chiefs Conference (TCC), Forestry Program. “NANA Region Native Allotment Forest Inventory.”
Presented to Maniilaq Association, January, 2013.http://www.tananachiefs.org/wp-
content/uploads/2012/07/Maniilaq_Allotment_Forest_Inventory.pdf
Tanana Chiefs Conference(TCC), Forestry Program. “Kobuk Biomass Harvest Plan, DRAFT.” Presented to
Alaska Native Tribal Health Consortium, November, 2013.
T. R. Miles Technical Consultants, Inc. “Feasibility Assessment for Wood Heating: Final Report.” Prepared
for Alaska Wood Energy Development Task Group (AWEDTG), August, 2006.
US EPA, Office of Air Quality Planning and Standards. “Hydronic Heater Program Phase 2 Partnership
Agreement.” 10/12/11.http://www.epa.gov/burnwise/pdfs/owhhphase2agreement.pdf
Northwest Arctic Borough
Upper Kobuk Biomass Project
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WHPacific. “Upper Kobuk River Valley Biomass Preliminary Business Plan.” Presented to Northwest
Inupiat Housing Authority, 2011.
WHPacific. “NANA Forest Stewardship Plan.” Prepared for NANA Regional Corporation, April, 2011
Northwest Arctic Borough
Upper Kobuk Biomass Project
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Appendix 2: Upper Kobuk Public Meeting Survey
Biomass meetings were held for the general public in Kobuk on the 19
th, Ambler on the 20
th, and
Shungnak on the 21
st of August 2013. These meetings included representatives from the Northwest
Arctic Borough, Tetra Tec and the Alaska Energy Authority. These meetings described to the public what
equipment is available for biomass consumption, resources available in each community, what would be
required of the community if a project is put into place and the benefits of using biomass as an energy
source. Most importantly, the advice of community members was requested and the confirmation that
this is their project and is meant to meet their needs was reinforced.
In addition to presentations illustrating the various components and benefits of a biomass project,
surveys were distributed. These surveys asked the general public what type of boiler they have, if
propane is used for cooking, if they are interested in biomass projects for the, if they would be
interested in biomass for household use among other questions. The results of the survey are shown
below.
Table Appendix 1
Ambler Kobuk Shungnak
Wood Oil Both Wood Oil Both Wood Oil Both
Are you heating primarily with wood or oil 52%22%27%14 41 45 17%39%44%
Yes No Maybe Yes No Maybe Yes No Maybe
Do you have an oil furnace in your home?52%48%0%86%14%0%57%43%0%
Are you using Monitor or Toyo style heater?43% 57% 0% 41% 59% 0% 61% 39% 0%
Do you have a wood stove in your living
room?91%9%0%91%9%0%78%22%0%
Are you using Propane for cooking 9% 91% 0% 14% 82% 13% 0% 100% 0%
If funding available, would you replace your
oil furnace with a 78%13%9%55%18%27%74%17%9%
suggested high efficiency wood/oil
combination furnace?
If funding became available, would you like to
see a wood 91% 9% 0% 82% 10% 8% 87% 4% 9%
fired furnace/boiler for any of the community
buildings
Do you believe that you can effectively 83%17%0%55%45%0%65%17%18%
heat your house with only wood?
Old Demand None Old Demand None Old Demand None
Is your water heater old style or demand?35%13%52%14%73%13%43%22%35%
Number of participants 23 20 23
As Table Appendix 1 illustrates, most residents believe that they can heat their homes with only wood.
Additionally, there is overwhelming support for wood fired furnace/boilers for community buildings in
Northwest Arctic Borough
Upper Kobuk Biomass Project
Page | 92
each village. This response shows that residents are eager to find ways to mitigate the high cost of
heating in the area and that biomass is an attractive commodity that could help offset the high cost of
heating oil.
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Upper Kobuk Biomass Project
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Appendix A:
Ambler City Hall / Washeteria Design Package
Northwest Arctic Borough
Upper Kobuk Biomass Project
Appendix A - 0
APPENDIX A – AMBLER CITY HALL / WASHETERIA
ENGINEERING PACKAGE
---
A-1: Project Site Plan
A-2: Boiler Building Design Rendering
A-3: General Arrangement
A-4: Process Flow Diagram
A-5: Bill of Materials Estimate
A-6-7: Heat Loading Calculations
A-8: Wood Utilization and Fuel Oil Offset Calculations
A-9: Life-Cycle Value Analysis Pro Forma
SECTION A-A6"16'OUTSIDE12' OUTSIDE6' DOUBLE DOOR6"TYP.5'CLEARANCE12" TO ALLOWDOOR TOFULLY OPEN18" FROMFLUE TO WALL10'
ZONE 6ZONE 5ZONE 4ZONE 3ZONE 2ZONE 1EXPANSIONTANKVENT/DRAINNEWWOODFIREDBOILEREXISTINGOIL FIREDBOILERS(NOTE 1)CIRCULATING PUMPSNOTES:1. WEIL-McLAIN BOILER. MODEL WTGO-4SERIES 3, NO. 2 FUEL OIL.D.O.E. HEATING CAPACITY 145,000 BTU/HR2. GARN WOOD BOILER MODEL WHS-1000.180,000 BTU/HR.MECHANICAL ROOMOUTSIDEOUTSIDENEW BOILER HOUSEPLATE HEATEXCHANGER(NOTE 2)
Northwest Arctic Borough
Upper Kobuk Biomass Project
Appendix A - 5
Description Quanity Total Cost Vendor
GARN SystemincludingHeatExchanger
GARN Jr. WHS1000(deliveredFairbanks) 1 14,826.00$ DectraCorp.
Plate ExchangerB120Tx30 1 1,389.00$ DectraCorp.
GrundfosAlpha15-55FCastIronpump with terminal box (1½") 6 158.85$ pexsupply.com
Webstone SweatIsolatorFlange (pair1½") 1 63.45$ pexsupply.com
Watts1½"LF3001CXF DielectricUnion 1 68.30$ pexsupply.com
Watts1½"LFS777S Bronze Wye Strainer 10 91.45$ pexsupply.com
ClassA Through the Wall 6"Chimney kit 1 2,066.00$ woodlanddirect.com
Cello1½"Copper90°elbow 10 48.50$ pexsupply.com
Cello1½"copperx male adapter 4 25.60$ pexsupply.com
Cello1½"copperx female adapter 4 24.60$ pexsupply.com
CopperPipe 1½"10ftlengths 2 198.00$ Grainger
ExistingSystemtonewHeatExchanger
GrundfosAlpha15-55FCastIronpump with terminal box (1 ½")1 158.85$pexsupply.com
Webstone SweatIsolatorFlange (pair1½")1 63.45$pexsupply.com
Watts1½"LF3001CXF DielectricUnion 2 68.30$pexsupply.com
Watts1½"LFS777S Bronze Wye Strainer 1 91.45$ pexsupply.com
Cello1¼"x1¼"x1½"copperTee 6 92.40$pexsupply.com
Hydrovalve 1½"full portsweatball valve 1 26.55$pexsupply.com
Hydrovalve 1¼"full portsweatball valve 1 25.45$pexsupply.com
Cello1½"Copper90°elbow 10 48.50$ pexsupply.com
Cello1½"copperx male adapter 4 25.60$pexsupply.com
Cello1½"copperx female adapter 4 24.60$pexsupply.com
CopperPipe 1½"10ftlengths 2 198.00$GraingerSupply
1½"pipe insulation 1"Nomacokflex 2 128.80$GraingerSupply
Clamp for1½"PEX Pipe 6 40.80$BadgerInsulatedPipe
1½"x 1½"PEX Crimp MPT 6 119.34$BadgerInsulatedPipe
E-ZLay 1½"5wrapInsulated undergroundpipe OxygenBarrier(EZ450B)60 435.00$BadgerInsulatedPipe
Charlotte Pipe 6"x 10ft.Solid PVCSewerDrain Pipe 10 210.00$ Lowes
AmericanValve 8"dia. X 100'LGalvanized HangerIron 2 30.34$ Lowes
BoilerBuilding
2"x 4"Steel Studes 52 8 311.48$ Spenards
2"x 4"Steel Roof Joists 30 8 179.70$ Spenards
RimJoists, CenterBeam- 2"x 4"Steel 4 8 23.96$ Spenards
Sheet Aluminumforsiding 448 SF 576.43$ Spenards
Sheet Aluminumforroof 252 SF 324.24$ Spenards
Door 1 Each 400.00$ Garage Door- Spenards
2"x 12"FloorJoists 16 12 490.82$ Spenards
6"x 12"EndBeams forFloor 2 16 208.38$ Spenards
DeckSheething(Treated1") 192 SF 11,520.00$ Spenards
Mortarfor Floor 0.6 CY 1,777.78$ Drake-$3000/yardinstalled
Screws, fasteners, miscellaneous 1.0 Each 250.00$
Insulation 1536.0 SF 7,372.80$
FeedstockStorage Building
4"x 4"Posts 4 10 69.19$ Spenards
4"10"Beams 2 16 212.86$ Spenards- price for4"x 12"
2"x 6"SidingSide Planks 9 16 188.06$ Spenards
2"x 6"SidingPlans 18 8 188.06$ Spenards
Numberof IronFasteners 40 Each 280.00$ Spenards
Roof Joists 2"x 6" 16 10 240.00$ Spenards
Aluminum forroof 160 SF 205.87$ Spenards
Screws/Nails/Bolts 250.00$
Northwest Arctic Borough
Upper Kobuk Biomass Project
Appendix A - 6
DESIGN CONDITIONS
Design Indoor temp 70 F
Design Outdoor temp -47 F ASHRAE (97.5% for Fairbanks, AK)
Wall insulation R-24 0.0417
Roof insulation R-38 0.0263
Crawlspace insulation R-38 0.0263
Window rating R-3.2 0.3125
Door rating R-4 0.2500
EXPOSED SURFACE AREAS
WALLS Length Height Area
Original building ft ft ft
2
North Face 46.33 18 833.94
East Face (partial exposure) 34.25 8 274
South Face 46.33 18 833.94
West Face 34.25 20 685
Washeteria Addition
North Face 14 9 126
East Face 26.5 11 291.5
South Face 14 9 126
West Face 0 0 0
Windows (Qty (3) 4' x 5' and Qty (1) 3' x 3') 69
Doors 42
ROOF AND CRAWL SPACE
Original Building floor area 1180
Washeteria Addition floor area 371
Conductive Heat Loss U area delta T Heat Loss
(Btu/hr-ft2-F)(ft2) (F) (Btu/hr)
Total Wall Area 0.0417 3059 117 14,914
Window Area 0.3125 69 117 2,523
Door Area 0.2500 42 117 1,229
Total Roof Area 0.0263 1861 117 5,731
Total Crawl Space Area 0.0263 1551 117 4,775
Subtotal Conductive Heat Loss 29,172
Convective Heat Loss
Fenestration*
Ventilation Make-up rate* 605 cfm
Dryers qty 6
Dryers exhaust 220 cfm each
Dryers exhaust 1320 cfm
Total ventilation 1320 cfm
*(ignore due to dryer exhaust)
Subtotal Ventilation Heat Required 169,884 Btu/hr
Heat Required =1.1 x cfm exhausted x (design inside T - design outside T)
Total Building Heat Required 199,056 Btu/hr
City Hall / Washeteria Heating Requirements
Northwest Arctic Borough
Upper Kobuk Biomass Project
Appendix A - 7
The following assumesthat Dryers purchased for Washeteria are equivalent in heat demand to the
Speed Queen electric dryers specified by Larsen Consulting Group.
Dryers
Dryer Quantity 6 units
Dryer Heating Element 5350 watt each
Combined Dryer Heat Required 32,100 watt
Converting to BTU 109,627 Btu/hr
Subtotal Dryer Heat Required 109,627 Btu/hr
Hot water required for Showers and Washers
Specified Water Heater (oil fired) 415,900 Btu/hr
Subtotal Hot Water Heat Required 415,900 Btu/hr
Washeteria Laundry/Shower Heat Requirements
Northwest Arctic BoroughUpper Kobuk Biomass ProjectAppendix A - 8ASSUMPTIONS:1. Wood fired heater is fueled 7 days a week over an eight (8) hour period. It is estimated this will result in an average daily firing rate of 9 hours.2. Heat storage in wood heater jacket maintains building temperature until heat storage is exhausted3. Oil fired heaters kick on to maintain building temperature until wood fired heater is refueled and fired.DESIGN CONDITIONSJAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECDesign Indoor temp7070 70 70 70 70 70 70 70 70 70 70Avg Monthly High Outdoor temp3 11 25 44 61 717166 54 32 12 7Avg Monthly Low Outdoor temp-11 -7 2 21 36 48 51 45 34 16 -2 -8Avg Monthly Outdoor temp-42 13.5 32.5 48.5 59.5 61 55.5 44 24 5 -0.5Conductive Heat Loss UA249.3 249.3 249.3 249.3 249.3 249.3 249.3 249.3 249.3 249.3 249.3 249.3Convective Heat Loss factor1452 1452 1452 1452 1452 1452 1452 1452 1452 1452 1452 1452Avg Heat Load (Btu/hr)125,899 115,691 96,125 63,800 36,579 17,864 15,312 24,669 44,235 78,261 110,587 119,944Monthly Heat Load (Btu/month)90,646,937 83,297,186 69,210,161 45,935,948 26,336,610 12,862,065 11,024,627 17,761,900 31,848,924 56,348,096 79,622,310 86,359,582GARN Heat Storage Capacity540000 540,000 540,000 540,000 540,000 540,000 540,000 540,000 540,000 540,000 540,000 540,000Hours of storage4.29 4.67 5.62 8.46 14.76 30.23 35.27 21.89 12.21 6.90 4.88 4.50MAXFiring Time - GARN unit9 9 9 9 9 9 9 9 9 9 9 9Off Time - (heat storage)4.29 4.67 5.62 8.46 14.76 30.23 35.27 21.89 12.21 6.90 4.88 4.50Oil Firing Time10.71 10.33 9.38 6.54 0.24 0.00 0.00 0.00 2.79 8.10 10.12 10.50Fuel Oil Usage (Btu output/month)40,454,336 35,860,741 27,056,351 12,509,967 260,381 0 0 0 3,705,577 19,017,560 33,563,944 37,774,739Annual Heat Load (Btu/year) 611,254,347Annual Fuel Oil Heat Load (Btu/year) 210,203,596Annual Offset Fuel Oil (Btu Output/year) 401,050,750Conversion 8.766 gallon No.2 fuel oil/million Btu outputAnnual Fuel Oil Offset 3,516 gallons per yearWood Use 29.76 cords per yearAmbler City Hall / Washeteria Fuel Oil Offset
Northwest Arctic BoroughUpper Kobuk Biomass ProjectAppendix A - 9Year ConstructionCords WoodFeedstock Operation and Avoided Cost Net End-ofYearInputsProcessed Cost Maintenance (Fuel Oil) Revenue (Loss) BalanceFeedstock Material Cord Wood 0($286,847)30($6,250) ($11,600)$38,676($266,021) ($266,021)Process Input (cords/yr) 29.76 1 30($6,250) ($11,600)$38,676 $20,826($245,194)Process Input (tons/yr) 38.99 2 30($6,468) ($11,774)$40,030 $21,787($223,407)Feedstock Cost ($ / cord) $210 3 30($6,695) ($11,951)$41,431 $22,785($200,622)4 30($6,929) ($12,130)$42,881 $23,822($176,800)Captial Expenditure (Net) $286,847 5($1,500)30($7,172) ($12,312)$44,382 $23,398($153,401)O&MExpense (annual) $11,600 6 30($7,423) ($12,496)$45,935 $26,016($127,386)7 30($7,682) ($12,684)$47,543 $27,176($100,209)Fuel Oil Savings (gal annual) 3,516 8 30($7,951) ($12,874)$49,207 $28,381($71,828)Fuel Oil Cost ($ / gal) $11.00 9 30($8,230) ($13,067)$50,929 $29,632($42,196)10($1,500)30($8,518) ($13,263)$52,711 $29,431($12,765)inflation rate 1.5% 11 30($8,816) ($13,462)$54,556 $32,278 $19,513 * Simple Paybackenergy value inflation rate 3.5% 12 30($9,124) ($13,664)$56,466 $33,677 $53,190Discount rate 5% 13 30($9,444) ($13,869)$58,442 $35,129 $88,320O&Mcost adjustment factor 1 14 30($9,774) ($14,077)$60,488 $36,636 $124,95615($1,500)30($10,116) ($14,288)$62,605 $36,700 $161,65616 30($10,470) ($14,503)$64,796 $39,823 $201,47917 30($10,837) ($14,720)$67,064 $41,507 $242,98618 30($11,216) ($14,941)$69,411 $43,254 $286,23919 30($11,609) ($15,165)$71,840 $45,067 $331,30620 30($12,015) ($15,393)$74,355 $46,947 $378,253$378,253$127,2918.8%Life-Cycle Cost Model - Ambler Washeteria and City BuildingModel 1 - Garn 1000 Cord Wood BoilerTotal Project Value (end of life)Net Present Value (NPV)Internal Rate of Return (IRR)
Northwest Arctic Borough
Upper Kobuk Biomass Project
Page | 94
Appendix B:
Proposed Shungnak Community Center Design Package
Northwest Arctic Borough
Upper Kobuk Biomass Project
Appendix B - 0
APPENDIX B – PROPOSED SHUNGNAK COMMUNITY CENTER
ENGINEERING PACKAGE
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B-1: Project Site Plan
B-2: General Arrangement
B-3: Bill of Materials Estimate
B-4: Heat Loading Calculations
B-5: Wood Utilization and Fuel Oil Offset Calculations
B-6: Life-Cycle Value Analysis Pro Forma
COMMUNITYCENTER12'-0"12'-0"6"TYP.12"-20"CLEARANCE21" CLEARANCEMIN. 32" CLEARANCEENLARGED PLAN
Northwest Arctic Borough
Upper Kobuk Biomass Project
Appendix B - 3
Bill of Materials FrolingModel FHG-L30ShungnakCoffe House
Description Quanity Total Cost Vendor
FrolingModel FHG-L30BoilerPKG 1 10,868.00$ TARMCorp.
SHST440PAK Thermal StgKit 1 6,903.00$ TARMCorp.
Grundfos Alpha15-55F CastIron pump with terminal box (1 ½")1 158.85$ pexsupply.com
Assorted CopperPipe andFittingsto tie in to system byothers 1 900.00$ Grainger
Non-ToxicHeatTransferFluid (propylene glycol) 300 4,250.00$ pexsupply.com
Class A Through the Wall 6"Chimney kit 1 2,066.00$ woodlanddirect.com
Northwest Arctic Borough
Upper Kobuk Biomass Project
Appendix B - 4
DESIGN CONDITIONS
Design Indoor temp 70 F
Design Outdoor temp -47 F ASHRAE (97.5% for Fairbanks, AK)
Wall insulation R-21 0.0476
Roof insulation R-36 0.0278
Crawlspace insulation R-36 0.0278
Window rating R-2.4 0.4167
Door rating R-4 0.2500
EXPOSED SURFACE AREAS
Length Height Area
WALLS ft ft ft
2
North Face 54 8 432
East Face 32 8 256
South Face 54 8 432
West Face 32 8 256
qty
Windows (Qty (5) 3-0x4-0) 5 3 4 60
Doors 1 3 7 21
ROOF AND CRAWL SPACE
Building floor area 1568
Conductive Heat Loss U area delta T Heat Loss
(Btu/hr-ft2-F)(ft2) (F) (Btu/hr)
Total Wall Area 0.0476 1295 117 7,215
Window Area 0.4167 60 117 2,925
Door Area 0.2500 21 117 614
Total Roof Area 0.0278 1882 117 6,115
Total Crawl Space Area 0.0278 1568 117 5,096
Subtotal Conductive Heat Loss 21,965
Convective Heat Loss
Fenestration - lineal feet of crack 105 LF
Fenestration 1.05 cfm/LF
Fenestration subtotal 110 cfm
Ventilation rate (ASHRAE) 0.25 cfm/ft2
Ventilation subtotal 392 cfm
Total Ventilation 502 cfm
Subtotal Ventilation Heat Required 64,640 Btu/hr
Heat Required =1.1 x cfm exhausted x (design inside T - design outside T)
Total Building Heat Required 86,605 Btu/hr
Proposed Community Center Heating Requirements
Northwest Arctic BoroughUpper Kobuk Biomass ProjectAppendix B - 5ASSUMPTIONS:1. Wood fired heater is fueled 7 days a week over an eight (8) hour period. It is estimated this will result in an average daily firing rate of 9 hours.2. Heat storage in wood heater jacket maintains building temperature until heat storage is exhausted3. Oil fired heaters kick on to maintain building temperature until wood fired heater is refueled and fired.DESIGN CONDITIONSJAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECDesign Indoor temp7070 70 70 70 70 70 70 70 70 70 70Avg Monthly High Outdoor temp3 11 25 44 61 717166 54 32 12 7Avg Monthly Low Outdoor temp-11 -7 2 21 36 48 51 45 34 16 -2 -8Avg Monthly Outdoor temp-42 13.5 32.5 48.5 59.5 61 55.5 44 24 5 -0.5Conductive Heat Loss UA187.7 187.7 187.7 187.7 187.7 187.7 187.7 187.7 187.7 187.7 187.7 187.7Convective Heat Loss factor552.475 552.475 552.475 552.475 552.475 552.475 552.475 552.475 552.475 552.475 552.475 552.475Avg Heat Load (Btu/hr)54,776 50,335 41,822 27,758 15,915 7,772 6,662 10,733 19,246 34,050 48,114 52,185Monthly Heat Load (Btu/month)39,438,596 36,240,872 30,111,901 19,985,775 11,458,511 5,596,017 4,796,586 7,727,833 13,856,804 24,515,884 34,642,010 37,573,257GARN Heat Storage Capacity242000 242,000 242,000 242,000 242,000 242,000 242,000 242,000 242,000 242,000 242,000 242,000Hours of storage4.42 4.81 5.79 8.72 15.21 31.14 36.33 22.55 12.57 7.11 5.03 4.64MAXFiring Time - GARN unit9 9 9 9 9 9 9 9 9 9 9 9Off Time - (heat storage)4.42 4.81 5.79 8.72 15.21 31.14 36.33 22.55 12.57 7.11 5.03 4.64Oil Firing Time10.58 10.19 9.21 6.28 0.00 0.00 0.00 0.00 2.43 7.89 9.97 10.36Fuel Oil Usage (Btu output/month)17,389,123 15,390,545 11,559,938 5,231,109 0 0 0 0 1,400,503 8,062,428 14,391,256 16,223,286Annual Heat Load (Btu/year) 265,944,046Annual Fuel Oil Heat Load (Btu/year) 89,648,187Annual Offset Fuel Oil (Btu Output/year) 176,295,859conversion 8.766 gallon No.2 fuel oil/million Btu outputAnnual Fuel Oil Offset 1,545 gallons per yearWood Use 13.08 cords per yearProposed Community Center Fuel Oil Offset
Northwest Arctic BoroughUpper Kobuk Biomass ProjectAppendix B - 6Year ConstructionCords WoodFeedstock Operation and Avoided Cost Net End-ofYearInputsProcessed Cost Maintenance (Fuel Oil) Revenue (Loss) BalanceFeedstock Material Cord Wood 0($29,671)13($3,139) ($11,600)$16,362($28,049) ($28,049)Process Input (cords/yr) 13.08 1 13($3,139) ($11,600)$16,362 $1,622($26,426)Process Input (tons/yr) 17.13 2 13($3,249) ($11,774)$16,934 $1,911($24,515)Feedstock Cost ($ / cord) $240 3 13($3,363) ($11,951)$17,527 $2,214($22,302)4 13($3,480) ($12,130)$18,140 $2,530($19,772)Captial Expenditure (Net) $29,671 5($1,500)13($3,602) ($12,312)$18,775 $1,361($18,411)O&MExpense (annual) $11,600 6 13($3,728) ($12,496)$19,432 $3,208($15,203)7 13($3,859) ($12,684)$20,113 $3,570($11,633)Fuel Oil Savings (gal annual) 1,545 8 13($3,994) ($12,874)$20,816 $3,948($7,685)Fuel Oil Cost ($ / gal) $10.59 9 13($4,134) ($13,067)$21,545 $4,344($3,341)10($1,500)13($4,278) ($13,263)$22,299 $3,257($84)inflation rate 1.5% 11 13($4,428) ($13,462)$23,080 $5,189 $5,106 * Simple Paybackenergy value inflation rate 3.5% 12 13($4,583) ($13,664)$23,887 $5,640 $10,746Discount rate 5% 13 13($4,744) ($13,869)$24,723 $6,111 $16,856O&Mcost adjustment factor 1 14 13($4,910) ($14,077)$25,589 $6,602 $23,45815($1,500)13($5,081) ($14,288)$26,484 $5,615 $29,07316 13($5,259) ($14,503)$27,411 $7,649 $36,72217 13($5,443) ($14,720)$28,371 $8,207 $44,92918 13($5,634) ($14,941)$29,364 $8,789 $53,71819 13($5,831) ($15,165)$30,391 $9,395 $63,11320 13($6,035) ($15,393)$31,455 $10,027 $73,141$73,141$29,09811.5%Life-Cycle Cost Model - Proposed Shungnak Community CenterPressurized Wood Boiler - Froling FHG-30Total Project Value (end of life)Net Present Value (NPV)Internal Rate of Return (IRR)