HomeMy WebLinkAboutCity of Kotzebue Biomass Energy Project Feasibility Study Report - Dec 2012 - REF Grant 7040029KOTZEBUE BIOMASS FEASIBILITY STUDY
TABLE OF CONTENTS
ExecutiveSummary .............................................................................................................ES-1
1 Introduction............................................................................................................... 1-1
1.1 PROJECT OVERVIEW...........................................................................................................1-1
1.2 STUDY AND REPORT ORGANIZATION................................................................................1-1
2 Biomass Feedstock Assessment................................................................................. 2-1
2.1 MUNICIPAL SOLID WASTE (MSW) SUPPLY.........................................................................2-1
2.2 REFUSE -DERIVED FUEL.......................................................................................................2-3
2.3 MSW ENERGY CONTENT....................................................................................................2-7
2.4 CONSTRUCTION AND DEMOLITION WASTE(C&D)............................................................2-8
2.5 ALTERNATIVE FEEDSTOCK SOURCES..................................................................................2-9
3 Technology Evaluation............................................................................................... 3-1
3.1 ENERGY GENERATION TECHNOLOGIES..............................................................................3-1
3.2 ELECTRICITY PRODUCTION.................................................................................................3-4
3.3 PRE-PROCESSING AND STORAGE.......................................................................................3-6
3.4 TECHNOLOGY RECOMMENDATION...................................................................................3-9
4 Local Energy Demand and Facility Siting.................................................................... 4-1
4.1 LOCAL FACILITIES AND ENERGY DEMAND.........................................................................4-1
4.2 PROJECT SITING ASSESSMENT...........................................................................................4-5
5 Conceptual Engineering Design.................................................................................. 5-1
5.1 FACILITY DESCRIPTIONS.....................................................................................................5-1
5.2 SCENARIO 1— RDF BOILER SYSTEM...................................................................................5-1
5.3 SCENARIO 2 — MSW GASIFIER............................................................................................5-7
5.4 BIOMASS POWER PLANT OPERATIONAL CONSIDERATIONS............................................5-10
6 Permitting and Environmental Analysis..................................................................... 6-1
6.1 PERMITTING REQUIREMENTS FOR A BIOMASS ENERGY PLANT........................................6-1
6.2 EMISSIONS CONCERNS FROM COMBUSTION AND GASIFICATION OF WASTES................6-3
7 Project Financial and Economic Analysis.................................................................... 7-1
7.1 FACILITY CAPITAL COSTS....................................................................................................7-1
7.2 FINANCIAL MODELING INPUTS AND CONDITIONAL ASSUMPTIONS.................................7-3
7.3 PRO FORMA FINANCIAL MODELING AND PROJECTED RETURNS......................................7-5
8 Conclusions and Recommendations........................................................................... 8-1
APPENDIX A: LIFE CYCLE COST MODEL PROFORMA — RDF BOILER SYSTEM
APPENDIX B: LIFE CYCLE COST MODEL PROFORMA — MSW GASIFIER SYSTEM
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KOTZEBUE BIOMASS FEASIBILITY STUDY
FIGURES
N
Figure 2-1: Average U.S. MSW Composition................................................................................................1
Figure 2-2: Kotzebue Refuse Baler...............................................................................................................2
Figure 2-3: Photo of AC Cardboard Bales and Pallets...................................................................................4
Figure 2-4: Photo of Maniilaq Health Center Waste Stream.........................................................................5
Figure 2-5: Schematic of Materials Recovery Facility....................................................................................6
Figure 3-1: Waste -to -Energy Conversion Pathways......................................................................................1
Figure 3-2: Advanced Combustion 2-Stage Process Description.....................................................................
Figure 3-3: Generalized Decision Chart for MSW Based Energy Systems.......................................................5
Figure 3-4: MSW Shredder (Photo Courtesy of UNTHA)..............................................................................7
Figure 3-5: Wood Shredder (Photo courtesy of UNTHA)...............................................................................7
Figure 3-6: Biomass Pellets (Source www.cleantechloops.com).................................................................8
Figure 3-7: MSW Briquettes (Source www.bhsenergy.com)........................................................................8
Figure 4-1: Photo of Hillside Area and Site 2................................................................................................7
Figure4-2: Biomass Energy Plant Sites........................................................................................................9
Figure 5-1: Scenario 1— RDF Boiler Block Flow Diagram............................................................................5-5
Figure 5-2: Kotzebue Biomass Power Plant Facility Configuration (In -Town RDF Plant).............................5-6
Figure 5-3: Scenario 2 — MSW Gasifier Block Flow Diagram.......................................................................5-9
TABLES
Table 2-1: Kotzebue Municipal Solid Waste (MSW) Composition.................................................................2
Table 2-2: Kotzebue Municipal Solid Waste (MSW) Energy Content.............................................................8
Table3-1: CHP Generation - Best Case Scenario Analysis.............................................................................5
Table 3-2: RDF Storage Pile Volume Comparing Storage Scenarios...............................................................6
Table 3-3: Product Parameters Concerning Densification Technologies........................................................8
Table 3-4: Summary of Technology Parameters...........................................................................................9
Table 4-1: Kotzebue Government Building Heating Demands...................................................................... 2
Table 4-2: Scenario 1 Energy Uses...............................................................................................................3
Table 4-3: Kotzebue / KEA Add -Heat System Parameters.............................................................................4
Table 5-1: Scenario 1 Seasonal Variability.................................................................................................5-3
Table 5-2: Biomass Energy Plant Operating Parameters..........................................................................
5-11
Table 5-3: Biomass Energy Plant Inputs and Outputs..............................................................................
5-11
Table 6-1: Sample Performance Claim for Batch Gasification of MSW Application . ................................... 6-4
Table 7-1: Biomass Power Plant Capital Cost Estimate..............................................................................7-2
Table 7-2: Summary Financial Metrics......................................................................................................7-5
Table 7-3: Results of Baseline Scenario Financial Analysis.........................................................................7-6
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KOTZEBUE BIOMASS FEASIBILITY STUDY
ACRONYMS AND ABBREVIATIONS
24/7 24 Hours Per Day, 7 Days Per Week
APC Air Pollution Control
AC Alaska commercial company value center
AEA Alaska Energy Authority
AK DEC Alaska Dept. of Environmental Conservation
BTU British Thermal Unit
C&D construction and demolition
CHP
Combined Heat and Power
DOER
Massachusetts Department of Energy Resources
EPA
Environmental Protection Agency
EPC
Engineering, Procurement, and Construction
EPCRA
Emergency Planning and Community Right -to -know act
FIA
USFS Forest Inventory and Analysis National Program
HAPs
Hazardous air pollutants
IC
Interconnection Customers
IRR
Internal Rate of return
LHV
Lower Heating Value
MCF
Measured in cubic feet
MW
Megawatt
KEA
Kotzebue Electric Association
KIC
Kikiktagaruk Inupiat Corporation
KOTZEBUE
City of Kotzebue
MRF
materials recovery facility
MSW
Municipal Solid Waste
iii December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
a
NWI National Wetlands Inventory
PTE Potential to Emit
RCRA Resource Conservation Recovery Act
RDF Refuse derived fuels
REC
Renewable Energy Credits
SBA
Small Business Administration
SPEED
Sustainably Priced Energy Development Program
SCIA
Statement of qualification application
Syngas
Synthetic Gas Fuel
T&D
Transportation and Delivery
TCLP
Toxicity characteristic leading procedure
Tetra Tech
Tetra Tech Inc.
TPD
tons per day
UCF
University of Central Florida
WTP water treatment plant
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KOTZEBUE BIOMASS FEASIBILITY STUDY
N
EXECUTIVE SUMMARY
PROJECT OVERVIEW
The City of Kotzebue (Kotzebue) is the regional hub of Northwest Alaska, located roughly 20 miles above the
Arctic Circle on the Chukchi Sea. The city is currently reviewing an opportunity to generate energy from
waste through construction of a biomass -fired energy generation plant. Kotzebue has many existing features
that are advantageous for development of such a project. Fundamentally, the city is located in an isolated
region, and would benefit from the ability to produce its own energy and reduce dependence on expensive
energy imports. Furthermore, Kotzebue owns several government buildings and is responsible for treatment
and heating of citizens' water supply, either or both of which could absorb the energy produced by such a
plant and reduce the city's high energy costs. Kotzebue also has a readily available source of combustible
biomass in the form of municipal solid waste (MSW) that is currently being disposed in the local landfill.
The Alaska Energy Authority (AEA) sponsored this analysis into the viability of a biomass -fired community
energy project in Kotzebue. Engineering firm Tetra Tech, Inc. (Tetra Tech) and project partner DOWL HKM
(DOWL) conducted the evaluation.
Kotzebue has pioneered renewable energy projects in the past in conjunction with the local energy utility
Kotzebue Electric Association, including a 2.94 MW wind farm, solar thermal projects, and waste -heat
capture, amongst other projects. Therefore, the desire for renewable energy projects fits well with the
progressive government approach to locally produced energy.
Converting waste to energy, while new to the region, is a proven and commercialized technology field. There
are over 100 MSW energy projects operating in the world, processing over 40 million metric tonnes of waste
per year and producing over 26 million megawatt -hours (MWh) of electricity and 7.4 million MWh of thermal
energy per year'. Versions of this technology have been in operation at large scale since the 1970's.
Community -scale projects, such as those for remote towns, and military bases, have been developed in the
last several decades in response to the rise in basic energy costs, and as process technologies have advanced
to manage the material inputs and emission outputs associated with MSW.
The State of Alaska has unique intrinsic characteristics that provide opportunities for waste to energy
applications. 90% of rural, remote Alaskan villages dispose of combustible waste in landfills that are often not
compliant with EPA's Resource Conservation and Recovery Act (RCRA) standards2. Meanwhile, the villages
' http://wteplants.com/
2 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.
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KOTZEBUE BIOMASS FEASIBILITY STUDY
pay approximately $7 to $10 per gallon for heating fuel and diesel powered electric generation. These fuels
are often barged or airlifted to the rural villages, a non -sustainable energy cycle. While many of these
villages, such as Kotzebue, have seemingly viable conditions for a waste to energy system, it is required that
logistical, technical, and organization issues are carefully evaluated to lay out a sound strategy and plan.
WASTE STREAM FEEDSTOCK
One of the primary goals of this study was to evaluate the biomass material available in Kotzebue that could
be used as feedstock to generate energy. This study focused primarily on waste -based feedstocks. It was
found that the energy content of Kotzebue's Municipal Solid Waste (MSW) stream is equivalent to nearly
120,000 gallons of fuel oil per year. In just the wood -based combustible materials (e.g., paper, cardboard,
and wood -based materials), over eight billion Btu's of are thrown into the Kotzebue landfill annually,
equivalent to over 62,000 gallons of fuel oil. Assuming that all commercial enterprises in Kotzebue
separated their garbage before disposal (i.e., in a source -separation program), there is a potential to
capture 250 tons per year of refuse derived fuels (RDF) feedstock. The wood -based materials (e.g., paper,
cardboard, and wood) from the overall waste stream, referred to as RDF, would be the material of interest
for a waste to energy project. Laboratory analysis of the city's waste stream is recommended to confirm
these estimates prior to final engineering of a biomass energy plant to ensure anticipated values are
consistent with the waste composition. Source separation of wastes is preferred over post -consumer
separation of RDF materials. The City of Kotzebue recently implemented a waste can separation collection
system for its residents. The program has already achieved success, and is a good sign for the
implementation of a more formalized source -separation and/or recycling program in the city.
Wood pellets or briquettes are an additional supplementary biomass feedstock that can be purchased and
imported to Kotzebue to supplement waste -derived feedstock supplies. On an energy value basis, bulk -
purchase pellets are significantly less expensive than fuel oil, and complement RDF fuels in boiler systems by
promoting a more efficient and complete combustion.
FEASIBILITY STUDY CONCLUSIONS AND RECOMMENDATIONS
Waste to energy technologies have advanced significantly in recent years and are currently available for
commercial applications. Numerous technologies were investigated in this study; however two technologies
including gasification of unsorted MSW and the combustion of sorted refuse derived fuels (RDF) were
identified as options carried forward in detailed analysis. Gasification is a more sophisticated technology
which can convert nearly the entire waste stream into energy extracting the maximum energy possible, while
RDF combustion technologies offers a more commonly used technology and presents an opportunity to
operate in conjunction with a city recycling program. These scenarios are referred to as MSW Gasification
and RDF Boiler scenarios, respectively. The relatively small scale of both analyzed systems precludes
electrical generation or combined heat and power. However, both systems clearly aim to turn Kotzebue's
waste streams into valuable resources.
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KOTZEBUE BIOMASS FEASIBILITY STUDY
These attributes, as well as other logistical considerations, were evaluated in the feasibility study. Two (2)
potential operational scenarios were developed. One system envisions combustion of a combination of RDF
briquettes and wood pellets to produce building heat at the public works campus; the second evaluated
gasifying all of Kotzebue's MSW at an off -site location to potentially pre -heat city raw water supplies.
Conceptual designs of both biomass energy plant scenarios were created based on the evaluation, and
financial viability of the project was evaluated.
The evaluation determined that both project scenarios are technically and financially viable prospects. Both
technologies are commercially available from multiple vendors, and both are robust for harsh climate and
remote locations such as Kotzebue. As analyzed, each scenario is able to repay project debt obligations
within a reasonable timeframe, while covering operating costs, employee wages, maintenance and materials,
and produce a small additional annual income for the city. Revenue for the projects is derived in the form of
avoided fuel oil purchases. The RDF Boiler scenario can support one additional full-time licensed boiler
operator position, while the MSW Gasifier scenario will require four (4) full-time staff positions. The RDF
Boiler scenario is highly sensitive to project capital cost and throughput (i.e., RDF capture rate). It is likely
that improvements can be made to the conservative capital expense estimate, which includes a nearly 200%
remote Arctic construction cost factor increase, as well as the conservative capture rate of RDF (estimated to
be 50%, but could be improved to 60% + through source -separation programs).
While both scenarios require additional city planning and detailed engineering steps typical for projects of
this nature, Tetra Tech recommends pursuing either of the two scenarios. An RDF Boiler located on the
Public Works campus is an immediately implementable project contingent only on securing financing for the
project. The MSW Gasifier scenario is contingent on re -development of the city's water treatment system at
an off -site location, likely a long-term project. Additionally, the reduced capital expense of the RDF Boiler in
comparison makes it a more attractive near -term investment.
Tetra Tech also recommends laboratory analysis of representative samples of Kotzebue's waste stream. The
scope of the study only allowed for empirical review of available information and estimation of Kotzebue's
waste composition. Analysis of combustible materials from the city's waste stream will determine the actual
energy content of the material, as well as contaminants and other values that will affect subsequent
engineering. Analysis can also help to indicate expected product capture rate of RDF. Laboratory
characterization of the feedstock source should be combined with test -burns in the selected conversion
technology to solidify burn characteristics, emission profile, and required equipment for combustion (pre-
processing, ash handling, etc).
Kotzebue's remote location is also a project driver. The difficulty of transporting materials to Kotzebue
significantly increases capital cost, as noted in the project report. However, cost to import fuel must be borne
throughout project lifespan, whereas a biomass energy system has locally -produced and reliable fuel source
in the city's waste stream. A prospective deep -water port being planned to service Kotzebue from Cape
Blossom would likely reduce material costs (steel, concrete, and equipment) to support capital projects, but
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KOTZEBUE BIOMASS FEASIBILITY STUDY
is unlikely to have much effect on fuel costs, which are tied to global increases in energy demand and
expense.
The findings of this study should be considered applicable in corollary for the region, not only the City of
Kotzebue. The smaller villages in the Northwest Arctic Borough have expressed interest in similar waste -to -
energy solutions, scaled to fit the feedstock sources and heating needs of the respective villages. The
difficulty and expense in sourcing fuel oil shared by all of these communities presents similar opportunity for
biomass energy systems as Kotzebue's opportunity. The concept in theory has been shown to be viable, but
each situation should be carefully evaluated for its technical and logistical viability, financial cost, and
approval within the respective communities.
In conclusion, what can be determined from this study is that a significant amount of Kotzebue's trash is
being unnecessarily landfilled, and could instead be used as a sustainable source of energy. The city could
also avoid importing a significant amount of fuel oil with the development of a biomass energy plant. Total
energy production of the RDF Boiler scenario would displace over 30,000 gallons of fuel oil each year, and
divert over 300 tons of waste from the local landfill annually. This project exemplifies the type of sustainable
energy project that can win support at the local, state, and national level for its ability to reduce fuel imports,
increase community self-sufficiency, and improve waste management and disposal practices. This biomass
energy project can be a model program for other Alaskan villages, continuing the tradition of Kotzebue in
pioneering sustainable and renewable energy practices.
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KOTZEBUE BIOMASS FEASIBILITY STUDY
1 INTRODUCTION
1.1 PROJECT OVERVIEW
N
The City of Kotzebue (Kotzebue) is the regional hub of Northwest Alaska. The port city is located roughly 20
miles above the Arctic Circle on the Chukchi Sea. Kotzebue has engaged Tetra Tech, Inc. (Tetra Tech) and
project partner DOWL HKM (DOWL) to review the feasibility of a biomass -fired community energy project,
assisted through funding from the Alaska Energy Authority (AEA).
Kotzebue sees an opportunity to generate energy from waste through construction of a biomass -fired energy
generation plant. The area has many existing features that are advantageous for development of such a
project. Fundamentally, the city is located in an isolated region, and would benefit from the ability to
produce its own energy and reduce dependence on expensive energy imports. Furthermore, Kotzebue owns
several government buildings and is responsible for treatment and heating of citizens' water supply, any of
which could absorb the energy produced by such a plant. Kotzebue also has a readily available source of
combustible biomass in the form of municipal solid waste (MSW), which can be converted into energy.
1.2 STUDY AND REPORT ORGANIZATION
The City of Kotzebue project analysis and report is organized to address the five key aspects requested within
the project RFP. These are:
1. Paper and Wood Stream Analysis for Kotzebue
2. Identification and Evaluation of Viable Technologies
3. Conceptual Design and ROM Cost Analysis
4. Permitting and Environmental Analysis
5. Economic and Financial Analysis
The report is formatted in such a way as to track the flow of materials utilized by and produced from the
waste -to -energy plant, starting with a review of MSW supply. The report finishes with a review of permitting
and environmental requirements and a financial analysis of the project.
The report contains the following sections:
An Executive Summary to summarize the findings of the study.
Section 1 includes this introduction to the project that provides the background and explains the scope and
purpose of this study.
Section 2 provides an assessment of the MSW (feedstock) availability in the city. The analysis also addresses
feedstock energy content and logistics associated with collecting and sorting MSW. This section also
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introduces the potential use of supplementary feedstocks (wood pellets/briquettes) and estimates the cost
for such feedstocks to be delivered for use at the project.
Section 3 reviews available technologies for conversion of MSW to thermal energy, and recommends two
potential technologies for this application. Based upon the needs of these technologies, MSW handling and
processing equipment sets were reviewed for use at the project site.
Section 4 reviews the current energy demand profiles of Kotzebue controlled facilities, and reviews potential
project sites in light of available infrastructure and interconnection logistics. Three potential project sites are
identified and further evaluated.
Section 5 provides process descriptions and conceptual engineering design of two project scenarios found to
be technically viable for converting MSW to energy in Kotzebue. The facility process and engineering is
carried out to a standard 10% design completion for both scenarios.
Section 6 reviews permitting requirements for all aspects of the reviewed technologies. Environmental
concerns relating to air emissions from reviewed technologies are also addressed, and contact information is
provided for various regulating agencies.
Section 7 includes an estimation of the capital and operational costs, energy savings and revenues for the
most likely facility operational range. These estimates are included into a financial model for the site.
Section 8 discusses the final conclusions and recommendations of the study.
Tetra Tech extends our appreciation to the City of Kotzebue for the opportunity to work on this project.
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KOTZEBUE BIOMASS FEASIBILITY STUDY
2 BIOMASS FEEDSTOCK ASSESSMENT
N
Feedstock supply is the single most important aspect of a biomass energy project. Consistent volumes of
underutilized energy sources are critical to a project's operational and financial viability. In this task, Tetra
Tech has analyzed the available and accessible volume of biomass supply in the Kotzebue, Alaska region. The
following section quantifies the waste -derived biomass feedstock supply potential in and around Kotzebue, in
terms of supply volume, consistency, and fuel quality.
2.1 MUNICIPAL SOLID WASTE (MSW) SUPPLY
Municipal Solid Waste (MSW) management is a more acute problem in Alaska than elsewhere in the world.
Export of materials for disposal, or even recycling, is rarely cost-effective, and the vast majority of waste
products end up in city landfills. In addition, 90% of rural Alaskan villages dispose of waste in open dumps not
compliant with EPA's Resource Conservation and Recovery Act (RCRA) standards3.
Below is the standard percentage composition of waste materials in the U.S., according to the Environmental
Protection Agency (EPA)'.
Figure 2-1: Average U.S. MSW Composition
Average U.S. MSW Compostion Data
�r
Source: US EPA
3 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.
' http://www.epa.gov/epawaste/nonhaz/municipal/index.htm
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KOTZEBUE BIOMASS FEASIBILITY STUDY
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Data concerning the composition of waste materials in Kotzebue was gathered through interviews with the
city's Refuse Manager and empirical data regarding waste composition.
Kotzebue, with a population of 3,201 as of the 2010 US Census, is large by Alaskan village standards, and has
a relatively sophisticated waste management system to process and dispose of its citizen's trash. Each year
approximately 1,625 tons of raw MSW are disposed in the city's landfill. Kotzebue's landfill is currently
classified as a 'Class II' landfill by RCRA and meets EPA operational guidelines.
Wastes are collected throughout the town and brought to a central processing point on the Public Works
campus, known as the Bailer building. Hazardous materials are separated for processing, and the remainder
of the refuse is compacted into approximately 1800 lb, 4 foot by 4 foot cubes to reduce landfill space and
reduce waste dispersion in the landfill.
Figure 2-2: Kotzebue Refuse Baler
A breakdown of the distribution of materials (i.e., the percentage of paper vs. plastic. vs. cardboard, etc) in
Kotzebue's waste was calculated based on US EPA aggregate data. Due to its remote location, Kotzebue's
distribution values will likely differ from that of a standard US mainland city. The two expected major
deviations from the norm are 1) lawn and yard biomass of which there is none produced, and 2) cardboard
content. Cardboard content is expected to be approximately 20% higher than average due to packaging and
shipping of consumer content to the city. These numbers present a conservative overview of the composition
of Kotzebue's waste stream, specifically the divertible material (paper products and wood). Laboratory
analysis of the city waste stream is recommended prior to final engineering of a waste -to -energy system to
ensure expected values are consistent with the waste composition.
The resulting estimated MSW composition breakdown for Kotzebue is displayed in Table 2-1.
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KOTZEBUE BIOMASS FEASIBILITY STUDY
Table 2-1: Kotzebue Municipal Solid Waste (MSW) Composition
0
Material
Wet Weight
N
Wet Weight
(ibs/day)
Avg. Moisture
Content
Dry Weight
(Lbs/day)
Dry Weight
(tonslyr)
Cardboard
18.7%
1,665
5%
1,582
290
Food Waste
18.6%
1,656
70%
497
90
Paper
14.1%
1,255
6%
1,179
220
Plastics
12.3%
1,095
4%
1,047
190
Metal
8.6%
766
2%
752
140
Wood
6.5%
579
40•%
347
60
Glass
4.8%
427
3%
417
80
Textiles
2.8%
246
10%
222
40
Rubber
2.8%
246
0%
246
40
Leather
2.8%
246
13%
216
40
Garden Trimmings
0.0%
-
60°%
-
-
Other
8.1%
721
0%
721
130
Total
100.0%
8,900
7,200
1,310
Paper, Cardboard & Wood Fraction
39.3%
3,500
3,100
570
Source: EPA, Tetra Tech analysis
2.2 REFUSE -DERIVED FUEL
Refuse derived fuel (RDF) is a separated combustible portion of MSW. RDF is processed to be a consistent,
homogenous fuel, free of contaminants, dirt, glass, metals, and other non-combustible materials. Large-scale
RDF production and combustion systems, process non -recyclable plastics, food wastes, and other
combustible materials. It is expected that an RDF system employed at Kotzebue will focus on wood -based
materials, specifically lumber, paper, and cardboard. Careful attention must be paid tin the sorting process to
avoid contaminants, such as plastic, painted or stained wood, or other materials that may foul an RDF boiler
or produced unwanted air emissions from combustion.
RDF is often compressed in to pellets or briquettes after processing to further improve combustion
characteristics and efficiencies. Densification and stabilization of RDF feedstock is discussed in more detail in
Section 4.
2.2.1 SOURCE SEPARATION OF RDF FEEDSTOCK
The easiest way to avoid contamination of the cardboard -paper -wood fraction of Kotzebue's waste stream is
to divert those products prior to entering the mass waste stream. Source -separation systems are likely to be
employed at the only the largest RDF producers in the area. The two primary producers are Alaska
Commercial Company Value Center (AC), and the Maniilaq Health Center. Secondary point -source producers
of RDF materials are the school buildings, cafeterias, and maintenance buildings of the Northwest Arctic
Borough School District, Nullagvik Hotel, Rotman's Store, and the various restaurants in town. Another
source of wood (pallets) are the local air cargo firms that supply this regional trading hub, which include
Alaska Airlines, Arctic Transportation Service, Lynden Air Cargo, Northern Air Cargo, and Village Aviation, Inc.
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• AC Value Center. The Alaska Commercial Company Value Center produces the largest volume of
cardboard waste of any single entity in Kotzebue, through the packaging of all of the products it sells.
Cardboard is separated from the common waste stream and baled onsite. The AC produces between 9-
12 bales per week, at 100-150 Ibs per bale, the pre-sorted output of this facility is estimated at 25 to 50
tons per year. Paper and wood (pallets, etc) can be separated by employees in the same bin that baled
cardboard is for pick-up. Including paper and wood, the AC may produce as much as 100 tons per year of
source -separated RDF raw material. Figure 2-3 below shows a pile of pallets and baled cardboard, which
constitute a ready supply of ideal RDF feedstock.
Figure 2-3: Photo of AC Cardboard Bales and Pallets
• Moniilaq Health Center. The local Health Center is one of the largest institutions in Kotzebue. Waste is an
issue at the health Center; currently the space available for refuse containers is not sufficient for the
volume of waste produced by the hospital. Figure 2-4 shows an overflowing roll -off at the hospital, and
also clearly shows the large percentage of cardboard and paper materials in the waste stream.
A container for cardboard, paper, and wood only can be placed in another location and reduce the
congestion of waste at the Health Center. Specific volumes of RDF produced by the Health Center are
unknown; it is expected that the cardboard volume, supplemented by significant paper waste, could rival
the tonnage produced by the AC.
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KOTZEBUE BIOMASS FEASIBILITY STUDY
Figure 2-4: Photo of Maniilaq Health Center Waste Stream
O
Assuming all commercial enterprises in Kotzebue were incorporated into a source -separation project,
there is the potential to capture 250 tons/year of ready RDF feedstock.
AC has the potential to provide up to 100 tons per year of primarily cardboard and pallets, and Maniilaq can
potentially add an equal volume of cardboard and paper product. Source -separation at other installations
may provide 5-10 tons/year each, or 30-50 tons/yr aggregate to supplement.
2.2.2 INCENTIV/21NG SOURCE SEPARATION
An incentive program will be greatly improve the chances of success, at least initially, of Kotzebue's RDF
sorting system. This will likely be required for several years, and then the system will become standard
operational procedure for customers. Incentives can be applied through the rate system, whether it is
reduced fees for companies participating in the program, or increased fees for other waste materials.
A model program that this can be based on is Sitka, a town roughly twice the size of Kotzebue but with a
similar opportunity to reduce landfilled waste. Sitka's voluntary recycling program diverts over 1.4 million
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pounds of material from landfills each year. According to the city recycling website, RecycleSITKAs, in one
month in 2011 over 50 tons of cardboard, newspaper, and mixed paper were brought to the city recycling
center 6. Adjusted for Kotzebue's size, that is equivalent to over 300 tons per year of feedstock diverted from
the waste stream.
This program can also be implemented along with a recycling program in Kotzebue to divert additional
materials from the local landfill. Aluminum and tin, which are easy to separate and are the most cost-
effective materials to recycle, can be removed from the waste stream either in conjunction with a source -
separation program, or as post -consumer sorting.
The City of Kotzebue recently implemented a can waste collection system for its residents. The program has
already met with success, and is a good sign for the implementation of a source -separation and/or recycling
program in the city.
2.2.3 POST -CONSUMER MATERIALS RECOVERY
RDF feedstocks not separated at the source need to be removed from the waste stream at the waste transfer
point. This would likely occur at the Bailer building. Post -consumer refuse separation occurs in a materials
recovery facility (MRF). MRF's are common only in large cities, where waste volumes warrant large-scale
recycling efforts. Figure 2-5 is a stylized schematic of a mechanized RDF system in operation.
Figure 2-5: Schematic of Materials Recovery Facility
Waste (paper,
glass, plastic,
metals, )
stone
bottles
Sieve
Cork, paper,
Source: Based on "Energie en grondstoffen in de toekomst" by Robbin Kerrod
s http://www.sitka.net/sitka/utilities.html
5 http://www.cityofsitka.com/government/departments/publicworks/RecycleSitka.html
3-6 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
N
The majority of MRF's, even in large metropolitan areas, are mostly or entirely operated manually, with
employees separating various contaminants and recyclable materials from the waste stream. Due to the
relatively small volumes of material being processed, a mechanized system does not make financial sense.
Manual processing into large rolling bins is the likely mode of RDF separation. It is assumed this will occur in
the Bailer building, with the discard material continuing to be baled.
2.2.4 RDF SUMMARY
A RDF-based biomass energy system in Kotzebue is conservatively assumed to achieve 50% recovery of the
desired cardboard -paper -wood fraction, due to the difficulties inherent with hand -sorting and emphasis on
avoidance of contaminants in the RDF stream. Rather than sorting the contaminants out of the RDF stream,
which leads to a certain amount passing unnoticed into the energy plant, this methodology will separate
cardboard, paper and wood from the waste stream. Total capture is 320 tons per year of material. If the
capture rate is increased to 60%, that number jumps to over 380 tons per year, an achievable rate with a
well -organized source -separation system in place.
An RDF sorting system can also be combined with a recycling effort in the city, separating recyclable metals
(tin, aluminum) and potentially glass form the Kotzebue waste stream. Even assuming a capture rate of 50%
acquisition of RDF material, combined with recycling of aluminum and tin, can equal a reduction of almost
30% of material going into Kotzebue's landfill. If all combustible materials are captured, the amount going to
the landfill is nearly halved.
2.3 MSW ENERGY CONTENT
Energy content of the materials in Kotzebue's waste stream was calculated based on generally -accepted
vales for the materials' Btu content. A study of tested values for sorted MSW material Energy contents,
conducted by UCF7 was used as the basis of the analysis.
7 Reinhart, Debora. Estimation of Energy Content in MSW. University of Central Florida. 2004.
htto://www.msw.cecs.ucf-edu/Thermachemicai%2OConversion.or)t
3-7 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
Table 2-2: Kotzebue Municipal Solid Waste (MSW) Energy Content
Material
Heat Value
Btujlbd weight)
Heat Value
(Btu/day)
Heat Value
(MM Btu lyear)
Cardboard
7,000
11,072,705
4,041.5
Food Waste
2,000
993,699
362.7
iPaper
7,200
8,488,045
3,098.1
Plastics
14,000
14,658,230
5,350.3
Metal
-
-
-
Wood
8,000
2,778,082
1,014.0
Glass
-
-
-
Textiles
7,500
1,662,842
606.9
Rubber
10,000
2,463,470
899.2
Leather
7,500
1,616,652
590.1
Garden Trimmings
2,800
-
Other
-
-
'Total
32,661,000
11,921
Paper, Cardboard & Wood Fraction
22,339,000
8,1M
Source: University of Central Florida, Tetra Tech analysis
N
The theoretical limit energy content available from Kotzebue's waste stream is 11,921 MM Btu per year. The
paper, wood and cardboard (RDF) fraction of waste, if 100% captured and utilized, contained a maximum of
8,154 MM Btu per year.
Tetra Tech recommends laboratory analysis of representative samples of the combustible material to
determine actual energetic value of the material, as well as contaminants and other values. Collection of
sample product can also help to indicate expected product capture rate. Laboratory characterization of the
feedstock source should be combined with test -burns in the selected conversion technology to solidify burn
characteristics, emission profile, and required equipment for combustion (pre-processing, ash handling, etc).
2.4 CONSTRUCTION AND DEMOLITION WASTE (C&D)
2.4.1 PRIMARYSOURCED
Pallets are a likely additional resource an RDF boiler system. A portion of the used pallet supply in Kotzebue is
collected by city residents to be burned in home fireplaces. It is expected that the biomass energy plant will
source the pallets not collected for this purpose. The total supply can be increased by requesting wood
pallets for shipping instead of plastic pallets.
Construction and demolition wastes are also considered as additional feedstock. This category involves wood
waste derived from byproducts of the construction industry, such as warped or otherwise unusable wood
planks, and materials removed from buildings during remodeling or demolitions. This category only refers to
non -contaminated wood products, and does not include wood with coatings or treatments, such as paints or
stains, preservatives, etc. or wood with plaster or other construction materials imbedded or stuck to the
3-8 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
wood. Nails, staples, and other inert metals are safe for use in an RDF combustion system and will be
removed with the bottom ash at the end of the combustion cycle.
2.4.2 LANDFILL 'MINING'
It is expected that landfill mining will be limited to choice picking of uncontaminated wood and cardboard
from the city landfill. Transport of entire bales for deconstruction and harvesting of 'feedstock' is likely a net
loss; it does not produce an equivalent amount of energy as that required for the harvesting process. The
practice may also conflict with several state waste control regulations.
2.5 ALTERNATIVE FEEDSTOCK SOURCES
The project scope also called for evaluation of alternative feedstock sources. Tetra Tech found only one such
alternative feedstock source for the proposed biomass energy system; wood pellets / briquettes imported
into Kotzebue from elsewhere in Alaska or from abroad. Pellets and briquettes produced as byproducts from
wood harvests or mill operations are a rapidly growing heating fuel source, with over 14 million tons
produced worldwide as of 2010. If produced from timber industry byproducts, pellets and briquettes have
been found to carry significant life -cycle emissions and other environmental benefits to fossil fuel use.
Superior Pellet Fuels of Fairbanks is the only Alaskan producer of volume, but Canada and the lower 48 are
producing significant volumes available for export to Kotzebue. Prices are quoted in the range of $300 per
delivered ton.
Pellets as a supplementary fuel carry several benefits. For one, vendors have noted that blending wood to a
high cardboard -content material improves combustion characteristics in their RDF boilers. As well,
purchased pellets can be used to increase the output of a system limited by locally -available feedstocks,
better matching the demand needs of the end user of the produced energy. Particle size is the major
difference between pellets and briquettes; either would be satisfactory additions to an RDF boiler.
Pellets are also much more cost-effective than heating fuel. At current heating fuel prices of $6.04/gallon, it
would cost $45.00 for 1 MM Btu of heating value. That same 1 MM Btu of heating value in pellet would cost
only $21.50, less than half the price of heating fuel. It therefore makes financial sense to purchase pellets or
briquettes, in addition to the environmental benefits of the biomass fuel.
3-9 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
3 TECHNOLOGY EVALUATION
O
Tetra Tech reviewed major biomass energy generation technology options that are applicable to the general
project conditions thus far determined. The following section identifies the most likely process technology
for a biomass energy plant in Kotzebue.
3.1 ENERGY GENERATION TECHNOLOGIES
The options evaluated included standard combustion systems for the paper, cardboard and wood fraction of
MSW and gasification systems for bulk unsorted MSW. 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.
Figure 3-1 illustrates the various pathways to produce energy from wastes. This project will focus on thermal
conversion pathways of combustion and gasification, more applicable to the scale and feedstock available in
Kotzebue than pyrolysis or biochemical conversion pathways.
Figure 3-1: Waste -to -Energy Conversion Pathways
TNT[ria Bloch
eR lcM
Elms Padia No
Oxygen Oxygen Oxygen
_ _ _ Pretreatment � fliPk PV10WA
gest�an
yr
fermentation
1� 4 Transesterifi[ation
Heat Fuel Gases [ r, gases, aerosols
{Producergas) (syngas)
4W*HrFCQ
4r
lq� 4 41
Source: NREL
3-1 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
3.1.1 COMBUSTION
a
Combustion can be defined as the burning of fuel to produce power and heat. The combustion process is
highly developed commercially and is available in numerous vendor specific designs. It has been used
throughout the world for power generation and heating. Incineration technology is well -established and
easy to use, and systems using this process have evolved to be robust and long-lasting investments.
Combustion occurs with oxygen in slight stoichiometric excess to rapidly complete the thermal oxidation
reaction. Waste products are an ash residue and an off gas made up of predominantly nitrogen (NA carbon
dioxide (COZ), and water vapor. The off gas must be treated to meet regulatory requirements for chemical
pollutants and particulates. The emissions will vary considerably from one vendor to another. Most vendors
prefer to select and design specific Air Pollution Control (APC) equipment for each project that addresses
pollution and particulate emissions.
Combustion is a highly exothermic (net heat output) process; therefore, the technology lends itself to heat
recovery in many applications. 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,
fluidized bed reactors, 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.
Stoker boilers are most commonly used in existing industrial operations due to their ease of use and
maintenance. The stoker boiler process simply involves traditional combustion of feedstock in an oxygen
enriched environment, with the thermal energy generated from the combustion used to generate steam.
The system is robust and proven over many applications.
Boilers may either produce steam or hot water for use as a working fluid. More commonly, these are known
as steam boilers or hydronic boilers. The working fluid is used as a medium to transport thermal energy
produced by the boiler to the desired user. Steam is a more efficient medium for heat transfer, however it
requires a greater rate of thermal input from the feedstock than hydronic boilers. Steam boilers are generally
used for industrial applications, while hydronic boilers are more than sufficient to provide building heat.
Hydronic boilers recommended of Kotzebue have a working fluid operating at approximately 230°F and 58
psi.
3.1.2 GASIFICATION
Gasifier boilers increase efficiency as compared to stoker boilers by separating the combustion process into 2
phases. In these processes, a 'synthesis gas fuel' (syngas), also called 'producer gas' is created from the MSW
in an oxygen starved pre -burn chamber. The syngas is immediately burned in a second combustion chamber
or used as a fuel in an attached combustion device. Figure 3-2 provides an outlined illustration of this
process.
3-2 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
Figure 3-2: Advanced Combustion 2-Stage Process Description
•Raw MSW input
•Starved Oz
environment
•1200-1500°F
•Wastes turned
to ash &
combustible
'syngas'
•Syngas
combusted in
afterburner
•1800°F
•Retention time
2-3 seconds
•Combination of
temp. and time
destroys many
POPS
N
•Thermal energy
from stage 2
•Non -hazardous
ash from stage 1
•Air emissions
(see table 6)
This second destruction stage results in a higher efficiency of conversion for the fuel, and improved
environmental and energy performance. The key to this improved performance is the conversion of the fuel
source from a solid to a gas in the stage 1 primary chamber. This is because gaseous fuels can be combusted
at higher temperatures and pressures than solid fuel. Combustion at higher temperatures and pressures
increases the maximum operational efficiency of any system according to Carnot's rule of thermodynamics.
These higher temperatures and pressures also allow for easier removal of sulfur and nitrous oxides (SOX, and
NOx), and trace contaminants such as mercury, arsenic, selenium, cadmium, etc.8 Environmental
improvements provided by increased temperatures also allow for the environmentally responsible use of
other MSW combustibles such as non -recyclable plastics within the fuel source.
Gasifier systems offer the benefit of being able to accommodate a wide range of feedstocks, thus limiting the
need for preprocessing and sorting of the MSW feedstock in question. This added feedstock flexibility would
improve overall system efficiency by: decreasing the man-hours needed to separate wastes, significantly
reducing the need for pre-processing of waste material, increasing the system's energy generation potential,
and increasing reliability by diversifying the project feedstock portfolio. Feedstocks that can be
accommodated by this technology include: untreated/unsorted MSW, construction and demolition waste,
tires, fish and animal remains, waste wood, and others. Inert materials such as glass and metals that may be
mixed in with MSW can more easily be separated from the ash after the reaction is complete and later
recycled (if desired).
8 National Renewable Energy Laboratory. Advantages of Gasification.
http.1/www,neti,doe.govLtechnologies/cloalpowerasification asifi edia 7-advanta es index.html
3-3 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
Gasifiers are offered in one of two feedstock delivery configurations, batch or continuous. Batch gasification
systems operate by loading large quantities of feedstock into the primary reaction chamber, where the
feedstock is heated in a starved oxygen environment to generate syngas. This primary reaction is allowed to
continue to completion, and then the system is shut down to remove ash before re -loading. Conversely,
continuously fed systems introduce feedstock to the gasifier at a constant rate, and are shut down only to
perform maintenance.
Previous gasification applications installed in Alaska (Barrow, Egegik, Skagway) have been almost entirely of
the batch variety, due to these systems relative ease of operation and lessor infrastructure requirements. For
the proposed systems involving energy production as well as waste destruction, a continuous -feed system is
recommended. A drawbacks of batch systems is that, due to their long periods of down -time (10-12 hours
per day), are unable to provide a steady source of thermal energy for heat recovery activities. Furthermore,
the need to constantly re -start the batch system from a cooled stage greatly increases the need for fuel oil
which initiates the primary reaction. Information for the vendors indicated that fuel oil requirements for a
batch system would be nearly equal to the fuel oil displaced by gasifying MSW. A continuously fed system
will come at a higher initial price, but will solve the issues presented by collecting heat from a batch system.
This system is expected to require only 2.5 gallons of fuel oil per hour to supplement the MSW feedstock.
Waste oils can be used for this requirement.
3.2 ELECTRICITY PRODUCTION
Biomass -fired stoker boilers and gasifiers can be coupled with turbines to produce electricity. In this process,
water is heated to generate high pressure steam by the boiler. The pressurized steam is expanded to lower
pressure in a multistage turbine as it expands energy to rotate the turbine and generator. The steam is then
either condensed or, more often in biomass -based combined heat and power (CHP) installations, sent as low
pressure stream or hot water to process heat, space heating, or other applications. Steam turbine technology
is well understood and steam turbines enjoy the benefit of a relatively long lifespan.
However, it is the working experience of Tetra Tech and its network of preferred technology vendors that
electricity production via CHP or direct electricity production is not financially feasible for projects of the
scale available in Kotzebue. As well, producing electricity requires high-pressure steam production, driving
up boiler costs and operational expenditures. A generalized decision chart for waste to energy systems
based on TPD feedstock input is shown in the Figure below. For reference, all Kotzebue MSW (both
combustibles and non -combustibles) totals approximately 3.5 TPD.
3-4 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
Figure 3-3: Generalized Decision Chart for MSW Based Energy Systems
4— ELo WASTE sottmoHs
F Batch 11 Continuous Feed
2tpd 510 10tpd 10tpd 5010d-,
Hot Water
Source: Eco Waste Solutions
Electricity
N
Additionally, a simple scenario analysis was performed to evaluate electricity production in Kotzebue. The
analysis assumed best -case scenarios; 100% of all wastes could be used to generate a steady year-round
source of electricity and steam, and electrical efficiency was set at 30%, at the high- end of what is achievable
for a turbine of this scale. Using these aggressive numbers, generator capacity would be extremely low for
both scenarios (80 kW for a combustion boiler, 160 kW for a gasifier). Table 3-1 displays the parameters in
the analysis.
Table 3-1: CHP Generation - Best Case Scenario Analysis
Parameter
Combustion
Gasification
Feedstock MM BTU/day
22.3
43.7
Feedstock MM BTU/hr
0.93
1.82
Electrical Efficiency*
30%
30%
Output Capacity (kW)
80
160
* Electrical Efficiency = net electricity generate/total fuel into system;
A measure of the amount of fuel converted into electricity
Tetra Tech's experience with related projects suggests that the capital costs associated with generator
construction, increased costs for boiler upgrades and electrical interconnection equipment, and hiring skilled
labor to manage the electrical system, outweigh any financial savings realized by electricity production at this
scale.
3-5 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
3.3 PRE-PROCESSING AND STORAGE
N
Due to the seasonal variations in heating requirements, Kotzebue will find it necessary to store collected
feedstocks in seasons of low heat demand to supplement heat production later in the year. Storage of
biomass over prolonged periods of time presents a number of important but manageable challenges that will
need to be addressed by this system. These issues include feedstock homogenization, space management,
and moisture management.
• Feedstock Homogenization. In order to ensure a clean and even burn, boilers are designed to operate
optimally within a somewhat narrow range of feedstock energy values. Because MSW is a combination
of several types of feedstocks, and because these feedstocks can vary in Btu values from source to
source, shredding and/or densifying raw MSW fuel helps to maintain a consistent Btu flow.
■ Space Management. The combustible portion of MSW feedstocks available in Kotzebue consists
primarily of wood wastes, cardboard, and paper products. When loosely stored, the shape and structure
of these biomass sources will inherently generate a very porous storage pile. Practically speaking, this
means that if the biomass is left unprocessed, long term storage could require a significant geographical
footprint in Kotzebue. A maximum storage need (if used to supplement Add -Heat) is 6 months' supply.
Table 3-2 shows the benefit of densification in feedstock storage, reducing storage building space from
6,321 cu yd to just 584 cu yd. Densification also stabilizes the material and inhibits microbial and rodent
attacks on the feedstock supply.
Table 3-2: RDF Storage Pile Volume Comparing Storage Scenarios
RDF summer storage
Months of Storage
6
Separated Ibs /day
3,500
Total RDF mass for storage (tons)
319.20
Storage - loose (cu.yd)
6,321
Storage - densified (cu.yd)
584
• Moisture Management. Regardless of what method of biomass storage is used for the proposed system,
moisture management will be critical to reduce and eliminate rotting and other biological activity that
can lower the overall Btu value of the feedstock. Moisture management can involve both preliminary
drying (where necessary), and storage in a low moisture environment.
3.3.1 SHREDDING
The first step in many systems that address the issues of feedstock homogenization and storage space
management is mechanical shredding of the material. Shredding is recommended for both RDF and bulk
MSW systems. Shredders are widely used, robust pieces of machinery which can be provided by a number of
different vendors. Shredding advantages include:
3-6 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
N
• Improved handling material qualities
• Improved homogenization capabilities
• Improved fuel density
• Readies material for further processing
Figures 3-4 and 3-5 below depict generic shredders similar to those that may be employed in Kotzebue.
Figure 3-4: MSW Shredder (Photo Courtesy of
UNTHA)
3.3.2 PELLETIZATION $ BRIQUETTING
Figure 3-S: Wood Shredder (Photo courtesy of
UNTHA)
After the shredding phase, one way to further improve the storing and handling characteristics and process
efficiencies of the MSW is through densification. This is accomplished through one of two processes;
pelletization or briquetting. In pelletization, shredded MSW would be fed into a hammer mill reducing it to
sawdust sized particles. This material would then be mixed with a binding agent (such as waste oil), and
passed through a mechanical extrusion pelletizer. Briquetting also mechanically compacts shredded MSW,
though without the additional step of hammer milling. Despite the different processes, both methods
accomplish similar goals. These include:
• Densification — Storage space can be reduced by up to 50% over material that is only shredded.
• Transportability — The increased energy density of the pelletized/briquetted feedstock improves
transport efficiencies several orders of magnitude. Because of this pellets/briquettes could be imported
to supplement shortfalls, or increase anticipated system size.
• Homogenization - Wood, cardboard, paper, and (maybe) binder waste oil can be combined into a single
fuel source with a consistent density, BTU value, and thus consistent combustion properties.
3-7 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
0
Table 3-3 illustrates some of the key operating differences between pellets and briquettes and Figures 3-6
and 3-7 display the physical appearance of these feedstocks. As can be seen, both have their advantages.
Pellets are the more dense, durable, and commonly used option. They also hold an advantage in
transportability. However briquettes require less pre-treatment, are cheaper to produce, and the equipment
used is considered to be more robust. For these reasons, briquetting will likely be more a more attractive
option for the proposed plant.
Table 3-3: Product Parameters Concerning Densification Technologies
Parameter
Pelleting
Briquetting
Needs Binder
No (But helpful)
No
Pre -Conditioning
Shredding
Shredding
Hammer Milling
Drying (If MC> 20%)(a)
Drying (If MC> 15/)1a)
Moisture Resistant
Yes
Yes
Final Bulk Density (lb/ft)
34 — 41
28 — 33
Product Durability
Good
Fair
Estimated Production Cost ($/ton)
$30 - $40
$8 - $14
Estimated Cost of Purchasing
$300
$300
Additional Feedstock ($/ton delivered)
Additional Feedstock Availability
Very Good
Fair
(a) Kaliyan, N., Morey, R.V. (2009). Factors affecting strength and durability of densified biomass products.
Biomass Bioenergy 33 (3), 337-359.
(b) Based on conversations with CPM & FFS Pelleting companies
(c) Based on performance claims from Reinbold Briquetters & Nielson Briquetters
(htto://www.brlguettioltsy,stems.com/ieaselcosts.htm#nieIsen23 )
(b)&(c) Electricity costs set to $0.15 per kWh
Figure 3-6: Biomass Pellets
(Source www4e n echlo om)
Figure 3-7: MSW Briquettes
(Source www.bhsenerev.coml
3-8 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
3.4 TECHNOLOGY RECOMMENDATION
O
As can be seen, there are a number of factors that affect the ultimate technology selection and as many
different system arrangements for consideration. Table 3-4 below summarizes some of the critical project
parameters discussed in the preceding sections. This table also shows the two scenarios that will be carried
forward in the subsequent sections of this report.
Table 3-4: Summary of Technology Parameters
Parameter
Scenario 1: RDF Boiler
Scenario 2: MSW Gasifier
Feedstock Use
Paper
All MSW Combustibles
Cardboard
Wood
Feedstock Processing
Sorted Material
Unsorted MSW Shredding
Shredding
Densification
3.59
Feedstock TPD Produced
1.56
Feedstock BTU/Day Potential
22.3 MM
32.7 MM
Combustion Stages
1
2
Electricity Generation
Not economical
Not economical
Air Emissions
May not require
Within
permit
regulatory limits
Ash/Residuals
Non -hazardous
Non -hazardous
Ability to import additional
Yes
No
feedstock
Operational Concerns
Sorting process must
Potential for emissions
eliminate
within city limits
contaminants
Technically speaking and as shown in the above table, gasification holds an edge in the availability of
feedstock volume and pre-processing demands. As such, offers Kotzebue the greatest energy potential.
However, concerns over system footprint and the cost of storing MSW on site could de -rail the project. RDF,
on the other hand, has the advantage of being a better understood platform that can be supported by
imported feedstock thus increasing project stability.
Both technology platforms will be evaluated further in the study, to determine potential site locations
(Section 4), conceptual design of the processes (Section 5), permitting and environmental issues of each
(Section 6), and financial feasibility of the options (Section 7).
3-9 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
a
4 LOCAL ENERGY DEMAND AND FACILITY SITING
The following section describes the energy consumption in the project region, and identifies and quantifies
energy loads that can potentially be satisfied by a biomass -fired energy generator plant. Recommendations
for potential plant sites follow in the second portion of the section. This takes into consideration that
biomass plant siting must be in close proximity to the user groups of the energy produced.
4.1 LOCAL FACILITIES AND ENERGY DEMAND
Tetra Tech conducted a biomass energy use audit in the City of Kotzebue. Several facilities were identified as
beneficial users of thermal energy (heating) produced by the prospective biomass energy plant. The analysis
also evaluated interconnection of the energy customer facilities to the prospective plant.
4.1.1 DISTRICT ENERGY MULTI -BUILDING HEATING AT KOTZEBUE CITY -OWNED BUILDINGS
Space heating was indicated at the project outset as a focus area for use of the energy produced by a
biomass energy plant. Kotzebue heats most of its public buildings with diesel -fired boilers, supplemented by
electric heat, at a rapidly rising energy cost to the city.
Below are listed some of the city -owned facilities that were found to be viable options to use the energy
produced by a biomass energy plant. Bailer Building data was unavailable for the study and was estimated
based on Maintenance Building. Information displayed was gathered by the city of Kotzebue as part of an
EPA Energy Star energy use accounting program.
• Public Works Campus
• Water Treatment Facility
• City Maintenance Shop
• Refuse Bailer Building
• City Public Works Offices
• Kotzebue City Hall
• Kotzebue Recreation Center
• Kotzebue Fire Hall
• Kotzebue Police Station
• Kotzebue Corrections Facility
4-1 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
N
Table 4-1: Kotzebue Government Building Heating Demands
Water
Kotzebue City
Kotzebue City
Kotzebue
Kotzebue
Treatment
Maintenance
Bailer Building
KotxeWe PubiIt
Recreation
Kotzebue Fire
Kotzebue Palle
Corrections
Kotzebue City
Facility
Shop
(est)
Woda
carer
Hal)
$Won
FaciJity
Hall
January
7,864,266
4,314,803
257,810
106,620
6,561,515
3,353,003
298,097
3,789,581
664,939
February
7,871,092
6,404,768
S08,889
1KO06
7,963,897
6,402,359
0
7,510,959
1,062,078
March
12,117,572
9,789,307
693,722
252,836
7,777,948
6,912,993
528,547
7,167,405
913,045
F
April
5,168,530
3,299,432
267,167
96,689
6,498,402
5,292,877
1,461,479
5,211,353
1,110,650
v
May
6,643,068
3,739,939
297,454
84,952
4,609,327
2,036,944
169,977
2,135,462
309,593
S
liune
2,748,000
2,561,136
144,626
47,785
2,005,582
2,501,925
175,643
2,410,866
0
>
liuly
3,369,181
2,603,952
147,717
46,243
2,217,902
2,339,789
0
0
0
p
August
3,545,806
2,660,241
147,791
34,522
1,440,484
290,313
0
3,235,548
733,539
m
Sept
6,551,461
2,061,229
127,248
50,940
1,717,500
870,200
0
836,766
0
In
October
7,558,995
3,213,609
194,702
86,183
3,590,129
2,730,049
266,822
2,171,906
1,149,063
November
8,129,5W
4,465,500
254,444
279,889
7,497,918
6,812,292
427,314
11,965,479
905,924
December
14,032,529
1 10,362,619
231.295
230.724
10293,703
8,333.085
731,766
5,544,229
ma153
Average Daily load
BTUs/da
7.133,333
4.623,045
321,90S
122,616
5181,026
3,989,636
337.470
4,414,955
619,741
c
Average Annual Wad
m
(BTUs/year)
2611324,785
1697373,390
117,495469
61171&540
88971Z351
1,452,661,500
123,474,510
1,603,161.216
225.871,86D
<
Maximum Oberved Wad
(BTUs/day)
17,427,639
14,963,303
831,295
S,038,000
1Z47Z374
9,751,854
2,464,040
1$015,888
1,.826090
The total thermal energy demand of these buildings is 26.74 MM Btu/day, or 10,327 MM Btu/year.
Currently, over 94,000 gallons of fuel oil is purchased by the City of Kotzebue per year to heat this collection
of buildings. This is considered the primary opportunity for const savings through biomass energy use in
Kotzebue.
4.1.2 PRIMARY BUILDING HEATING SCENARIO
Total thermal demand of the city's public buildings is roughly equal to the total energy content in Kotzebue's
waste stream on a Btu basis. Once the inherent efficiency losses of a waste to energy conversion system are
factored, the heating demand in the city's public buildings is greater than the ability of a waste to energy
system to serve that need. A top -down selection process was employed to determine the most cost
effective buildings and energy systems to convert to biomass heat.
Of the Kotzebue public buildings, the top energy consumers are the Water Treatment Plant (WTP) and the
Maintenance Building. Upon further review, these buildings present as the logical choice for district energy
location. Their current heating plants are both diesel boilers, and are some of the oldest on the Public Works
campus. As well, the energy demand of these facilities closely matches available energy production from
biomass energy plant. These plants were factored into the conceptual design as the energy consumers of an
RDF plant in Scenario 1, discussed in Section 5.
4-2 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
Table 4-2: Scenario 1 Energy Uses
Kotzebue City
Water Treatment
Facility
Kotzebue City
Maintenance
Shop
Scenario 1 District
Energy System Total
January
7,864,266
4,314,803
13,759,170
February
7,871,092
6,404,768
16,438,102
March
12,117,572
9,789,307
25,290,465
AprilI
5,168,530
3,299,432
9,798,452
May
6,643,068
3,739,939
11,563,761
June
2,748,000
2,561,136
5,968,656
July
3,369,181
2,603,952
6,655,700
August
3,545,806
2,660,241
6,827,450
Sept
6,551,461
2,061,229
9,071,148
October
7,558,995
3,213,609
12,102,281
November
8,129,500
4,465,500
15,938,400
December
14,032,529
10,362,619
27,757,016
Average Daily Load
(BTUs/day)
7,133,333
4,623,045
11,756,378
Average Annual Load
(BTUs/year)
2,611L324,785
1,691,373,390
4,302,698,175
Maximum Oberved Load
(BTUs/day)
17,427,639
14,963.,303
32,390,942
N
Additional energy demand centers, such as the school district complex, Maniilaq Hospital, and others were
not polled for their interest level or logistical feasibility of converting to biomass -supplied energy. Metering
and sale of energy to third -party consumers adds a difficult, and as shown here, unnecessary, management
layer to a biomass energy plant's business plan. Recovery of capital expenditure through fuel savings and
avoided disposal costs is the simplest pathway form a business and logistics standpoint.
4.1.3 'ADD -HEAT' FOR CITY WATER SYSTEM
Another potential use for biomass -produced thermal energy is the Kotzebue 'Add -Heat' city water heating
system. The Add -Heat system currently heats treated water prior to distribution in the city water loops to
prevent freezes. Kotzebue Electric Association (KEA) provides waste heat from its diesel-electric generators
into the return portion of the lagoon Loop water line to serve this heating need, on a contract with the City.
The heated water is blended the rest of the city water supply. The water is heated to an average of 60 deg F,
at an average flow (return) of 193 gpm, resulting in an average heat input of 982,600 Btu/hr, or over 23.5
MMBtu/day. Additional diesel -fired heating is available at the WTP itself, but is reportedly rarely used.
Thermal energy is sold to the city based on Btu content, at approximately 87.5% of the price of heating fuel
(nearly $40/MM Btu going into the 2012/2013 heating season). Kotzebue requires an average of 171 heating
days to ensure steady water supply to its residents. Table 4-3 below shows the five-year historical Add -Heat
operating parameters.
4-3 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
Table 4-3: Kotzebue / KEA Add -Heat System Parameters
supply
eturn
Operating
Flow
emp.
Temp.
STU1hrNov07-May08
Date
Days
(m
e .Fda
. f
173
239
5
63
995,000
Oct08Apr08
182
227
5
63
1,122,000
Nov09-Apr40
157
229
48
188
58
940,000
Nov1 Q-Apr11
147
239
47
200
58
1,100,000
Nov11-Ma 12
1196
224
471
1891
551
756,000
Avera a
171
232
49
1931
591
982.600
D lly Load
1 23,582.400
' Calculated using "Advantage Engineering BTU Calculator'
ht�:llwww.advarrtageemineeri ng.com/fyi/288/advantageFYl288.php
N
KEA is currently in the process of overhauling its energy generation portfolio, focusing on increasing reliance
on renewable energy with more turbines at the local wind farm and testing and potential rollout of solar
panels. As well, KEA is scheduled to replace several if its diesel —electric gensets with newer, more efficient
units that produce less waste heat. KEA has indicated that it can continue to provide as much Add -Heat from
its waste heat production as the city needs, but that issue will have to be revisited in future years as the new
equipment is installed. A biomass energy plant heating the WTP and Maintenance building, as described
above, can supplement the Add -Heat system if a shortfall arises. Considering the finite amount of biomass
feedstocks available, it is recommended that the city only supplement the Add -Heat system with biomass
energy, rather than replacing the system outright. The Btu's produced are better used to directly displace
fuel oil use elsewhere within Kotzebue.
4.1.4 PREHEATING 'ADD -HEAT' FOR CITY WATER SYSTEM
Alternately, Add -Heat energy can be injected into the front end of the water treatment to assist in the
treatment process, in addition to avoiding freeze -ups in the distribution pipes. The present treatment system
is expected to benefit somewhat from higher -temperature water, but this option becomes much more viable
if the proposed redesign of the WTP goes forward. The advanced water treatment technologies, including
micro- and nano -filtration, operate at an optimal water temperature of 457. The WTP may be re -designed at
the existing location at the Public Works campus, or it may be re -located to the Hillside area town, along the
raw water distribution line from Vortak Lake. This is therefore considered a long-term option, contingent
upon the construction of a new WTP. Ambient inlet water temperature at the WTP is a relatively steady
average of 347, based on monitoring conducted by WH Pacific, at a flow rate averaging 220 gpm. Heating
220 gpm from 347 to 457 is expected to consume 1,610,000 Btu/hr, or 38.68 MM Btu/day. This is greater
than the demand for heating all of the public buildings in Kotzebue, as calculated in Section 4.1.1..
After accounting for production and heat transfer inefficiencies, it is expected that output of the proposed
MSW gasifier system very closely matches the demand curve of an Add -Heat preheater for a re -designed
WTP. The RDF boiler scenario, as proposed, will supply approximately 25% of the needed energy.
4-4 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
4.2 PROJECT SITING ASSESSMENT
N
The selection of a proper site encompasses many issues, such as transportation (i.e., road access for
feedstock delivery trucks) and utility availability (i.e., electrical and substation access), but also should take
into account issues such as the environmental impact, the status of current and future production
technology, the ability to expand production as required, and more. Tetra Tech conducted a project siting
analysis with assistance from project partner DOWL HKM.
The drivers for siting of the biomass energy facility include (ranked in relative order of importance):
1. Proximity to energy user (load)
2. Land owned or controlled by project stakeholders
3. Compliance with city Zoning Code
4. Accepted by neighboring landowners
S. Compliance with County, State, and Federal regulations
6. Access to feedstock delivery and storage
Steam piping and hot water piping are predominantly the limiting factor in project siting, and a distance of
over 1,000' between source and use is not recommended due to piping cost and energy loss over the pipe
run. In this project as in most, proximity to the end users of the energy produced is the single largest
determining factor in facility siting.
The city of Kotzebue has no zoning laws, thus zoning is less important, but land ownership and potential
impacts to neighbors of the biomass plant are both critical siting factors. While the environmental impact of
a biomass power plant is minimal, there still remains a need to ensure that such a facility does not negatively
impact the community. The plant will also need to be designed with appropriate setbacks and safety
features to comply with applicable safety regulations.
At present it does not appear that the land and space requirements for either of the proposed plant
scenarios will be a limiting factor in site selection. Bulk feedstock storage appears to be minimal, and plant
processing equipment indicates the process building will be within the range of existing industrial buildings in
Kotzebue. Process building and storage requirements for the biomass energy plant are described in greater
detail in Section 5.
In and around Kotzebue are many areas with preliminary wetland designation in the Kotzebue National
Wetlands Inventory (NWI). Sites 2 and 3 are designated as 'freshwater emergent wetlands'. Site 1 does not
have a designation, but standing water was noted in one of the areas identified as suitable for plant siting.
These designations are for planning purposes only, and it is likely the sites will qualify for development under
a national Wide permit with the designations. An onsite delineation survey is recommended prior to final
site selection.
4.5 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
A map of Kotzebue identifying the prospective sites follows the discussion (Figure 4-2), and includes overlays
of the preliminary wetland delineations in the city.
4.2.1 SITE 1: PUBLIC WORKS FACILITY
Several available locations at the Kotzebue Public Works campus are suitable for construction of a biomass
energy plant, including to the west of the Bailer building and vehicle storage Quonset hut, and to the
northeast of the WTP and water tanks.
Siting at the Public Works campus carries a number of project benefits, including proximity (both to feedstock
source and energy users) and land ownership and control. Regarding distance to potential energy users,
producing renewable energy to serve either space heating at city -owned buildings or the city Add -Heat
system is logistically feasible at this prospective site. Hot water distribution piping is minimal in either plant
configuration. As well, Kotzebue already owns and controls access to this land, which will speed permitting
and reduce safety requirements at the site.
There are also potential drawbacks to these sites. For one, the available space is limited. Not only is
available unused land at a premium in the city, the site is bordered closely by facilities on all sides, and
residential property to the southeast. This is more of a challenge to a large-scale MSW gasification system
than a smaller -scale RDF boiler, which is expected to have greater noise, odor, and air emissions than a
facility processing pre-sorted feedstock. This location is the most sensitive of the sites identified to potential
noise, visual, emissions, or other impacts.
An additional consideration is that there is currently standing water in the area to the west of the bailer
Building. The city has considered filling the standing water area with dredged material from the upcoming
Swan Lake Boat Harbor upgrades project, thus creating a location for the facility.
4.2.2 SITE2: HILLSIDE
The Hillside area to the southeast of Kotzebue is also under consideration as a potential biomass energy
plant site. The city of Kotzebue has plans to develop areas of the hillside for residential use, and proposed in
the 2009 Sanitation Master Plan to locate a new water treatment plant on the east side of the Hillside area.
The area has been platted and lots subdivided, with the city of Kotzebue owning the majority of lots in this
area. Kikiktagaruk Inupiat Corporation (KIC) owns the surrounding land. Figure 4-1 is a picture of Hillside
area and approximate site location, from the city looking east.
4-6 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
Figure 4-1: Photo of Hillside Area and Site 2
N
The hillside siting offers the advantage that a proposed biomass facility could be located near the proposed
water treatment plant, making an "add heat" system logistically simple. Once again though, if the biomass is
insufficient in providing all the required "add heat", a separate "add heat" system would also be required.
Since this area is not fully developed, the facility size is not as important. Lots could be combined or a new
lot, altogether, could be developed for this facility. Large storage facilities could easily be located here.
This location has several advantages, including city ownership, and ample space available for siting and
configuration of any size facility.
The infrastructure on the hillside is underdeveloped. Site grading and connection to utility infrastructure
would be required for development of the site. Also, plans exist for developing this area, but it may be a few
years before construction begins.
Thermal energy produced by a facility at this location can only be used for heating city water, as a
supplement or a replacement to the current Add -Heat system. A redesigned Add -Heat system could absorb
the entire production of with an RDF Boiler or an MSW Gasifier system at this location. Outlets for any
additional produced energy would be limited to building heat for the redesigned WTP.
4.2.3 SITE 3: CITY INDUSTRIAL SECTOR NEAR KEA POWER PLANT
A third alternate plant site could be located near the KEA Power plant, in the industrial part of Kotzebue.
This location would allow smoke stack emissions to be concentrated in one area, instead of spreading them
out over the city. The lots directly south of the power plant are an option. These are owned by NANA
Regional Corporation, and it is likely that a transfer of ownership could be arranged for plant siting. While
4-7 December 2012
KOTZEBUE BIOMASS FEASIBILITY STUDY
0
relations between the city and NANA are strong, land conveyance processes are slow, however, and this
could present significant additional cost to the project.
The city of Kotzebue has plans to construct a designated Add -Heat line from the KEA power plant to the city's
water treatment and distribution center. Currently heated water is added to one of the city's distribution
loops. If the biomass were used for heating water in an Add -Heat system for the city's water system, this
location would be advantageous, because it could take advantage of planned infrastructure. However, if the
biomass energy potential is insufficient to provide all of the city's Add -Heat requirements the city would still
have to purchase Add -Heat from KEA, which it currently does on a fixed fee basis, and a new Add -Heat water
main would be required anyway. If the biomass is insufficient in providing all the required Add -Heat,
alternative facility types should be considered.
4-8 December 2012