HomeMy WebLinkAboutVillage of Koyukuk Biomass Energy Preliminary Fesability Assessment 08-19-2012-BIO1
Dalson Energy Inc.
308 G St. Ste 303
Anchorage, Alaska 99501
907-277-7900
8/19/2012
Preliminary Feasibility Assessment
This preliminary feasibility assessment considers the potential for
heating community buildings in Koyukuk with woody biomass from
regional forests and river logs.
Biomass Energy Village of Koyukuk
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 2
Table of Contents
Project Summary .................................................................................................................................................................. 3
Summary of Findings .......................................................................................................................................................... 4
Wood fuel supply in Koyukuk ........................................................................................................................................... 5
Biomass Energy Operations and Maintenance ................................................................................................................ 7
Biomass Harvest Plan ...................................................................................................................................................... 7
Operations Plan ................................................................................................................................................................ 8
Community Facilities Information .................................................................................................................................... 8
Tribal Buildings ................................................................................................................................................................ 8
City & Tribal Building ................................................................................................................................................. 8
City Buildings ................................................................................................................................................................... 8
City House .................................................................................................................................................................... 8
Washateria ..................................................................................................................................................................... 9
School ................................................................................................................................................................................. 9
Recommended technology and fuel requirements ....................................................................................................... 10
Washateria ................................................................................................................................................................... 10
Cluster #1 .................................................................................................................................................................... 11
Initial investment ........................................................................................................................................................... 12
Washateria ................................................................................................................................................................... 13
Cluster #1 .................................................................................................................................................................... 14
Financial Analysis .............................................................................................................................................................. 15
Washateria ....................................................................................................................................................................... 16
Cluster #1 ........................................................................................................................................................................ 19
Summary of Financial Analysis ............................................................................................................................... 21
Conclusion .......................................................................................................................................................................... 22
Supplement: Community Wood Heating Basics ........................................................................................................... 24
Wood fuel as a heating option ......................................................................................................................................... 24
The nature of wood fuels .................................................................................................................................................. 24
The basics of wood-fueled heating .................................................................................................................................. 25
Available wood heating technology ................................................................................................................................ 27
Cordwood Boilers .......................................................................................................................................................... 28
Bulk Fuel Boilers ............................................................................................................................................................ 28
District heat loops .......................................................................................................................................................... 29
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 3
Figure 1: Land Ownership Surrounding Koyukuk, AK. ................................................................................................ 5
Figure 2: Koyukuk Timber from TCC Inventory, 1987 ................................................................................................... 6
Figure 3: Illustration of Unmanaged Wood Harvesting Efforts .................................................................................... 7
Figure 4: Illustration of Planned Wood Harvest by Harvest Area and Time Period. ................................................ 7
Figure 5: Koyukuk Washateria ........................................................................................................................................... 8
Figure 6: Cordwood ........................................................................................................................................................... 24
Figure 7: Ground wood chips used for mulch. .............................................................................................................. 24
Figure 8: Wood briquettes, as a substitute for cordwood. Cross sections of these briquettes make “wafers”
which can be automatically handled in biomass boiler systems. ................................................................................ 24
Figure 9: Wood pellets ....................................................................................................................................................... 24
Project Summary
Interior Regional Housing Authority (IRHA) and Tanana Chiefs Conference (TCC) contracted Dalson
Energy to do a Pre-Feasibility Study (Pre-FS) for biomass heating of community buildings in the
Native Village of Koyukuk.
Dalson Energy biomass specialists Thomas Deerfield and Wynne Auld visited the community on
June 15, 2012 for the initial assessment. Deerfield and Auld made their assessment based on available
data, interviews with local stakeholders and authorities, observations, and research and review of
previous studies done in Koyukuk.
It was noted that there are several other studies and reports that address various aspects of biomass
energy in Koyukuk, including Forestry Resource assessments done by TCC Forester Will Putman and
DNR Division of Forestry. Clare Doig of Forest and Land Management Inc. is also completing a forest
management plan for the regional corporation, Gana-A’Yoo. These previous studies are the
foundation for further evaluation of institutional heating with woody biomass in Koyukuk, as
exercised in this prefeasibility assessment.
This report was prepared by Thomas Deerfield, Wynne Auld, Louise Deerfield, and Clare Doig.
Contact and interviews with the following individuals in Koyukuk assisted in some of the
information gathering. Their contact information is as follows:
City - City of Koyukuk
P.O. Box 49
Koyukuk, AK 99754
Phone 907-927-2215
Fax 907-927-2230
Barbara Fleming, City Manager
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 4
Tribe-- Koyukuk Village, federally-recognized
P.O. Box 109
Koyukuk, AK 99754
Phone 907-927-2253
Fax 907-927-2220
Cynthia Pilot, Tribal Administrator
School—Koyukuk School
Josie Dayton, Principal/ teacher, jdayton@yksd.com
Summary of Findings
Currently, several of Koyukuk’s municipal buildings are excellent prospects for wood heating.
Containerized wood boiler systems are suggested as an expedient way to develop wood heating
plants in Koyukuk. Dalson Energy personnel got the impression that Koyukuk City, Tribe, and
School Administrators understand the potential for wood energy and support this type of renewable
energy system, but that more technical capacity is needed to operate and maintain a wood boiler
system. Depending on the labor force in Koyukuk, a new wood heating system may be an excellent
vehicle for additional workforce training for operating and maintaining heat energy systems,
including fuel oil and biomass.
The two identified projects are (1) the Washateria, and (2) Cluster #1, a small district heating system
serving the Washateria, School, and City and Tribal Office. Both of the candidate systems could be
served by HELE (high efficiency, low emission) cordwood boiler systems; or, alternatively, Cluster #1
could be served by a wood chip system.
The project’s success is dependent on a Biomass Harvest Plan and an Operations Plan. The need for
these project Plans are discussed in this Pre-Feasibility Analysis.
Dalson Energy provides this report to IRHA and TCC. Those agencies will determine the next steps
forward.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 5
Wood fuel supply in Koyukuk
Koyokuk, with a population of 97 (2011 Alaska Department of Labor Estimate), is located 30 miles
west of Galena and 290 air miles west of Fairbanks.
In 1987 Tanana Chiefs Conference completed a timber inventory of the ANCSA Native village lands
around Koyukuk. The village corporation, GANA-A'YOO, Limited, owns approximately 92,000
acres. Doyon, Limited, the regional corporation, is the other major landowner in the region, as
indicated by Figure 1: Land Ownership Surrounding Koyukuk, AK.
While these inventory figures indicate a substantial timber resource, sites supporting tree growth are
widely distributed and may be difficult to access because of the area characteristics and the lack of
existing roads. The Village is located along a major river system with expansive low elevation
wetlands, resulting in widely distributed higher elevation sites that support tree growth. These
factors impact the economics of fuel availability, which in turn impacts the size and fuel demand for a
wood fueled heating system in the community. Additional considerations include 1) the landowner’s
contractual agreement for harvest and compensation for the resource, 2) public acceptance of larger
scale timber harvest than has been experienced in recent history, and 3) total project (from timber
harvest to operation of the heating system) economic feasibility.
Figure 1: Land Ownership Surrounding Koyukuk, AK.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 6
Figure 2: Koyukuk Timber from TCC Inventory, 1987
The community of Koyukuk also practices river logging. Dependability and volume of river-caught
logs have not been documented.
Based on interviews with community leaders, there are 42 households in Koyukuk using an
(estimated) 5 cords per household. This information suggests community consumption of about 210
cords annually, if estimates are accurate. There is no documentation to confirm these estimates.
Koyokuk (1987)Acres Cubic Feet Board Feet
(thousands)
Saw Timber Types: (10.5"+ d.b.h.)
White Spruce 5,800 17,471,000 56,225
Cottonwood 2,207 5,483,000 18,306
Subtotal 8,007 22,954,000 74,531
Pole timber Types: (4.5" - 10.5" d.b.h.)
White Spruce 3,335 9,321,000 26,618
Cottonwood 984 1,846,000 3,210
Hardwood 7,501 13,110,000 22,010
Mixed White Spruce/Hardwood 1,611 4,596,000 11,104
Subtotal 13,431 28,873,000 62,942
Total 21,438 51,827,000 137,473
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 7
If the recommended project described in this study were undertaken (Washateria heating) the
community of Koyukuk would harvest about 50 additional cords of wood per year, increasing their
annual volume by about 24%.
Biomass Energy Operations and Maintenance
Biomass Harvest Plan
Wood cutting is a subsistence activity in almost all interior villages adjacent to forest land. This
subsistence resource must be carefully managed or biomass energy projects may be detrimental to
the Community.
If biomass harvests are unmanaged, the natural tendency is to harvest the most accessible wood
supply first, as illustrated below. The effect is increased scarcity and rising harvest cost, and,
consequently, biomass fuel costs, for both the project and household woodcutters. This puts
community members’ energy security and the project’s success at risk.
The project’s success depends on a well-developed and executed Harvest Plan. The Harvest Plan
accounts for the biomass harvests over the project lifetime, at least 20 years. It may also designate
areas for Personal Use (household wood cutting). The Harvest Plan also describes how who is
responsible for executing the Harvest Plan, and how access will be managed. Please see figure below.
Figure 3: Illustration of Unmanaged Wood Harvesting Efforts
Figure 4: Illustration of Planned Wood Harvest by Harvest Area and Time Period.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 8
Operations Plan
In many Villages biomass boiler projects will depend on collaboration among a variety of entities,
including contract wood cutters, forest landowners, the boiler technician, building owners and
operators, and various governmental entities.
A plan for collecting biomass, paying wood
suppliers, allocating costs among heat users,
and operating and maintaining the boiler and
heat distribution system is crucial to the
project’s success. Persons responsible for each
task must be identified.
Because the project’s success is dependent on
an Operations Plan, the Consultant strongly recommends developing this Plan prior to project
development.
Community Facilities Information
The community buildings in Koyukuk considered for biomass heating are City/ Tribal building, the
City house, the Washateria, and the School. These buildings are considered a cluster and evaluated as
a single heat plant.
Tribal Buildings
Tribal buildings include the City/Tribal Building.
City & Tribal Building
The City & Tribal Building houses both City and Tribal staff. The building uses one (1) Crown oil
furnace, model CHB68112L, to heat about 2,240 sq. ft. Last year, the City/ Tribal building used 750
gallons and 3 cords of wood for heating – the equivalent of 142 MMBTU, about 1,134 gallons of fuel
oil #1. In addition to the furnace, the City & Tribal building is equipped with a Laser 73 heater and a
woodstove.
City personnel communicated that the building is very cold in the winter, possibly due to undersized
or poorly designed heating infrastructure and poor weatherization of the building.
Because the City & Tribal building does not have an existing hydronic heating system, it would need
to be equipped with heat loops and unit heaters.
City Buildings
In addition to the City & Tribal building, the City of Koyukuk operates a City House, where the City
Manager lives, and the Washateria.
City House
The City House is heated by a Toyo-stove and uses approximately 250 gallons of fuel oil #1 per year.
This use was considered too small for integrating into a district heating system.
Figure 5: Koyukuk Washateria
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 9
Washateria
The Washateria is an older building, built in 1973. The facility will be retrofitted with new boilers in
the coming year. Currently, the facility’s space and domestic hot water needs are met by three units:
one (1) Bock domestic hot water heater with a capacity of 187,000 btu/hr; one (1) Bock domestic hot
water heater with a capacity of 200,000 btu/hr; and one furnace with a capacity of 120,000 btu/hr.
Last year, the Washateria used approximately 9,125 gallons of fuel oil at a cost of $54,750.
School
The Koyukuk School is located directly adjacent to the Washateria. Built in 1983, this School houses
educational centers for 12 students. As of mid-2012, Principal/ Teacher Josie Dayton manages it.
The school houses two boilers and accesses waste heat from the nearby power plant. Despite the
captured-heat access, last year the School had to buy 4,000 gallons of fuel oil #1. It is likely that the
captured-heat system is not operating properly.
The School houses two (2) Burnham V36 boilers with a capacity of 234,000 btu/hr each. One boiler
serves as back up. The boilers distribute heat via hot water radiators.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 10
Building Name City/Tribal
Office
City House Washateria School
Annual Gallons (Fuel Oil #1) 1,134 250 9,125 4,000
Building Usage During
workdays
only. No
weekends.
During
workdays only.
No weekends.
Seven days per
week.
During the
School year
Heat Transfer Mechanism Hydronic Hydronic Hydronic Hydronic
Heating infrastructure need
replacement?
No No Unknown No
Recommended technology and fuel requirements
The suggested system design for is a pre-fabricated, modular, containerized wood biomass boiler
unit. The suggested unit has been shown to be reliable and highly efficient. Because it is modular, it
has a lower installation cost. Because of the relatively low heat load, Dalson Energy suggests a
cordwood boiler unit.
From initial surveys of the Koyukuk area, it appears that Cottonwood and Black Spruce are relatively
abundant species, although neither is preferred as fuel for personal-use home heating. Cordwood
could be manufactured from Cottonwood, using chainsaws and a log splitter. Chips could be
manufactured from Black Spruce trees using a hand-fed chipper. If the harvest were properly
planned, use of these fuels would not threaten the supply of cordwood available for home heating.
Several options for biomass heating exist. The Washateria load is large enough to be served by a
stand-alone cordwood heating system. Alternatively, the Washateria load could be clustered with the
School and City & Tribal Hall dubbed “Cluster #1;” this load could be served by a semi-automated
woodchip system or a cordwood boiler system.
Washateria
For the Washateria, a containerized HELE (high efficiency, low emissions) cordwood boiler is
recommended. These types of systems are produced by GARN, TARM USA and others. These units
have 120,000 – 700,000 BTU/hr output capacity and store 415,000 or more BTU in hot water tanks.
One such unit, the GarnPac, has an output of about 350,000 BTU output and is currently being
employed in Thorne Bay.
This type of system is recommended because it has demonstrated reliability, uses an accessible fuel
(cordwood), and meets the heat load requirements of the Washateria.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 11
Other communities operating HELE cordwood boilers of a similar size, such as Dot Lake and Ionia,
report 2 cordwood stokings per day and 0.125 – 0.5 FTE 1 (Full-time equivalent employee) per boiler.
The load variance throughout the year is difficult to calculate, because the amount of heat used for
space heating versus domestic hot water is unknown. If the load covered only space heating, it would
vary from 150,000 – 450,000 btu/hr during the heating season. Correct boiler sizing could be subject
to further feasibility study.
For the purposes of this study, Dalson Energy employs a biomass boiler capacity of 350,000 btu/hr
for the Washateria, offsetting 75% of the load with 58 cords of wood.
Cluster #1
Cluster #1 represents the largest heat load project, serving the Washateria, City & Tribal Office, and
School. The load is an estimated 200,000 btu/hr – 700,00 btu/hr during the heating season.
This heat load could employ a cordwood boiler system, a small wood chip system, or a wood pellet
system, depending on user’s preferences and access to biomass. Pellets would need to be imported
from outside the Village, but woodchips and cordwood could be procured from local forests given an
effective Harvesting Plan and investment in the appropriate equipment.
To produce woodchips, the Community would need an effective way of harvesting, processing, and
handling chips. Small trees, such as Black Spruce, could be hand-felled and hand-fed into a grinder
and then automatically fed into a storage bin or chip van. Saw log or cordwood quality segments
could be separated and merchandised separately. Screens would be utilized to control chip size and
consistency. Additionally, chips would be managed with a bobcat or other loading device to improve
air flow and decrease moisture content.
While the chip processing and handling infrastructure is more expensive, the Community would
benefit from automated boiler operation and reduced operating costs, as well decreased pressure on
the Cordwood supply and access to a wider range of tree sizes and species.
Small wood chip systems are sold by TARM USA, ACT Bioenergy, and others. Containerized wood
chip systems are sold by Froling Energy, Wisewood, and others.
Without a biomass supply inventory or harvest plan in place, Dalson Energy cannot recommend the
best system for the client. It is likely that all three types of infrastructure would prove technically and
economically viable, although the system reliability and economic, social, and environmental aspects
would differ.
For the purpose of this prefeasibility analysis, the Consultant has chosen a representational boiler,
one (1) 700,000 btu containerized cordwood boiler, offsetting 90% of the Cluster #1 load using an
estimated 108 cords of wood.
1 Nicholls, David. 2009. Wood energy in Alaska—case study evaluations of selected facilities. Gen. Tech. Rep. PNW-GTR-793. Portland,
OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 33 p.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 12
The buildings’ existing Fuel Oil infrastructure would be retained to meet peak demand and as back
up in every project building.
Initial project development costs for a wood heating system costs may include:
Capital costs: boiler, hydronic pipe and other hardware, wood storage shelter, fuel-handling
equipment, shipping costs.
Engineering: storage design, plumbing integration, fuel-handling infrastructure.2
Permitting: no permits required. In lieu of permits, all regulations must be met.
Installation: Site work, installation, and integration into existing system.
Fuel storage: storage building, firewood chutes, or preparation of existing storage room.
System building: (if required).
Ongoing operational costs may include:
Financing: Principal and interest payments from project debt, or profits from project equity
investment. In Village projects, financing costs likely do not apply.
Wood fuel purchases.
Amortization costs: capital equipment and other infrastructure.3 When projects are grant
financed, amortization does not apply.
Operations and Maintenance (O&M) labor.
Fossil fuel purchases and labor.4
Initial investment
The Washateria has an estimated Capitalization Cost of $272,000.
Cluster #1 has an estimated Capitalization Cost of $540,700
3 Cash and accrual basis are two different accounting methods for project investment. Accrual accounting amortizes
project investment over the project lifetime (“lifecycle costs”). This method results in monies to reinvest in new
equipment at the end of its lifetime. Cash basis is simply on the dollars spent to operate, maintain, and finance the project.
8 The existing oil heat infrastructure will be retained for supplement heat and back-up. Therefore, the fossil fuel system
has ongoing O&M costs, albeit lower than if used as the primary heat source.
Assumptions:
16 MMBTU/ Cord Cottonwood
0.1350 MMBTU per gallon Oil #1
Annual
Gallons
Annual
MMBTU
Annual
Cords
(maximum)
Washateria 9,125 1,232 77
School 4,000 540 34
City/Tribal Office 1,134 153 10
Cluster #1 14,259 1,925 120
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 13
See charts below for cost estimates and sources. Full feasibility analysis and/or bids would provide
more detailed numbers.
Washateria
Biomass System
Rating -- Btu/hr 350,000
Btu stored 415,000
footnote notes
$ 31,320
(58 cds @ 20 sq. ft.
/ cd.)
Pre-Fabricated Boiler System
Base price A 100,000$
Shipping to Hub B 20,000$
Bush Delivery B 10,000$
Plumbing and electrical B 2,500$
B 4,500$
Integration (Wash + Waterplan B 15,000$
Subtotal-B&E Costs 183,320$
Contingency -- 20% 36,664$
Grand Total 219,984$
Soft Costs $
B 17,599$ 8% of B&E
B 13,199$ 6% of B&E
B pre-approved
Equipment Commissioning and B 4,000$
Construction Management B 17,599$ 8% B&E
Subtotal -- Soft Costs 52,396$
Recommended Project Budget -- Design a 272,380$
footnote
A Based on quotes from viable suppliers
B Estimate
Building and Equipment Costs (B&E) $Fuel Storage Building
(fabricated building, gravel pad,
$27/sf)
Site Prep
Project Management
A/E Design Services
Fire Marshall Plan Review
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 14
Cluster #1
Biomass System
Rating -- Btu/hr 700,000
footnote notes
A $ 58,320 (108 cds) @ $27 / sq. ft.
Boilers
Base price B 175,000$
Shipping to hub city C 30,000$
Local delivery C 15,000$
Plumbing and electrical C 7,500$
Installation C 6,500$
6,000$
District loop & building integration C 53,750$
Subtotal-B&E Costs 352,070$
Contingency -- 20% 70,414$
Grand Total 422,484$
Soft Costs $
33,799$ 8% of B&E
50,698$ 12% of B&E
included in design
Equipment Commissioning and Training C included with boiler price
Construction Management 33,799$ 8% of B&E
Subtotal -- Soft Costs 118,296$
Recommended Project Budget -- Design and Construction 540,780$
Building and Equipment Costs (B&E) $
Fuel Storage Building
Site prep
Project Management
A/E Design Services
Fire Marshall Plan Review
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 15
Financial Analysis
Please note that the local market price for household cordwood is reportedly determined by the TCC
price, currently $300/cord. In the course of modeling this project, Dalson Energy has used $250/cord
to represent the price per cord of Cottonwood and other non-preferred species, which appear to be
more accessible than White Spruce and other preferred species.
For each building, Dalson Energy estimated the percentage of heating oil offset by considering a
heating degree day model of the buildings’ energy load. For Cluster #1, a 750,000 btu/hr boiler was
assumed to offset 90% of the Cluster’s fuel oil load.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 16
Washateria
Project Description
Community
Nearest Fuel Community
Region
RE Technology
Project ID
Applicant Name
Project Title
Category
Results
NPV Benefits $389,992
NPV Capital Costs $264,447
B/C Ratio 1.47
NPV Net Benefit $125,545
Performance Unit Value
Displaced Electricity kWh per year -
Displaced Electricity total lifetime kWh -
Displaced Petroleum Fuel gallons per year 6,003
Displaced Petroleum Fuel total lifetime gallons 228,125
Displaced Natural Gas mmBtu per year -
Displaced Natural Gas total lifetime mmBtu -
Avoided CO2 tonnes per year 61
Avoided CO2 total lifetime tonnes 2,315
Proposed System Unit Value
Capital Costs $272,380$
Project Start year 2013
Project Life years 25
Displaced Electric kWh per year -
Displaced Heat gallons displaced per year 6,844
Displaced Transportation gallons displaced per year 0.00
Renewable Generation O&$ per BTU
Electric Capacity kW 0
Electric Capacity Factor %0
Heating Capacity Btu/hr.350,000
Heating Capacity Factor %86
Base System Unit Value
Diesel Generator O&M $ per kWh 0.033$
Diesel Generation Efficien kWh per gallon
Parameters Unit Value
Heating Fuel Premium $ per gallon 2.30$
Transportation Fuel Premi $ per gallon 1.00$
Discount Rate % per year 3%
Crude Oil $ per barrel EIA Mid
Natural Gas $ per mmBtu ISER - Mid
Washateria
Koyukuk
Rural
Woody biomass heat
Village of Koyukuk
17
Annual Savings (Costs)Units 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
Entered Value Project Capital Cost $ per year 272,380$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$
Electric Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Heating Saving (Costs)$ per year $18,354 $18,775 $19,068 $19,467 $20,000 $20,497 $20,964 $21,387 $21,770 $22,053 $22,338 $22,586 $22,800
Transportation Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Total Savings (Costs)$ per year $18,354 $18,775 $19,068 $19,467 $20,000 $20,497 $20,964 $21,387 $21,770 $22,053 $22,338 $22,586 $22,800
Net Benefit $ per year ($254,027)$18,775 $19,068 $19,467 $20,000 $20,497 $20,964 $21,387 $21,770 $22,053 $22,338 $22,586 $22,800
Annual Savings (Costs)Units 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 PV
Entered Value Project Capital Cost $ per year -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ $264,447
Electric Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Heating Saving (Costs)$ per year $22,980 $23,095 $23,143 $23,151 $23,109 $23,003 $22,839 $22,680 $22,501 $22,350 $39,089 $38,760 $389,992
Transportation Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Total Savings (Costs)$ per year $22,980 $23,095 $23,143 $23,151 $23,109 $23,003 $22,839 $22,680 $22,501 $22,350 $39,089 $38,760 $389,992
Net Benefit $ per year $22,980 $23,095 $23,143 $23,151 $23,109 $23,003 $22,839 $22,680 $22,501 $22,350 $39,089 $38,760 $125,545
Heating Units 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
Renewable Heat gallons displ 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844
Entered Value Renewable Heat Scheduled Rep$ per year 300$ 303$ 306$ 309$ 312$ 315$ 318$ 322$ 325$ 328$ 331$ 335$ 338$
Entered Value Renewable Heat O&M $ per year 12,361$ 12,485$ 12,610$ 12,736$ 12,863$ 12,992$ 13,122$ 13,253$ 13,385$ 13,519$ 13,654$ 13,791$ 13,929$
Entered Value Renewable Fuel Use Quantity (Bcords 58 58 58 58 58 58 58 58 58 58 58 58 58
Entered Value Renewable Fuel Cost $ per unit $250.00 $253 $255 $258 $260 $263 $265 $268 $271 $273 $276 $279 $282
Total Renewable Fuel Cost $ per year 14,436$ 14,580$ 14,726$ 14,873$ 15,022$ 15,172$ 15,324$ 15,477$ 15,632$ 15,788$ 15,946$ 16,106$ 16,267$
Remaining Fuel Oil (supplementgallons rema 2281 2281 2281 2281 2281 2281 2281 2281 2281 2281 2281 2281 2281
Total Fuel Cost (supplement)$ per year 14,834$ 15,061$ 15,247$ 15,469$ 15,736$ 15,993$ 16,240$ 16,474$ 16,694$ 16,883$ 17,074$ 17,252$ 17,421$
Proposed Heat Cost $ per year 41,931$ 42,429$ 42,889$ 43,387$ 43,933$ 44,472$ 45,004$ 45,525$ 46,037$ 46,519$ 47,006$ 47,484$ 47,955$
Fuel Use gallons per y 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125
Fuel Cost $ per gallon $6.50 6.60$ 6.68$ 6.78$ 6.90$ 7.01$ 7.12$ 7.22$ 7.32$ 7.40$ 7.48$ 7.56$ 7.64$
Entered Value Fuel Scheduled Repairs $ per year 200$ 202$ 204$ 206$ 208$ 210$ 212$ 214$ 217$ 219$ 221$ 223$ 225$
Entered Value Fuel O&M $ per year 750$ 758$ 765$ 773$ 780$ 788$ 796$ 804$ 812$ 820$ 828$ 837$ 845$
Fuel Cost $ per year 59,335$ 60,245$ 60,988$ 61,875$ 62,945$ 63,970$ 64,960$ 65,894$ 66,777$ 67,533$ 68,295$ 69,009$ 69,684$
Base Heating Cost $ per year 60,285$ 61,204$ 61,957$ 62,854$ 63,933$ 64,969$ 65,968$ 66,913$ 67,806$ 68,572$ 69,344$ 70,069$ 70,755$
Proposed
Base
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 18
Heating Units 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 PV
Renewable Heat gallons displ 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844 6,844
Entered Value Renewable Heat Scheduled Rep$ per year 341$ 345$ 348$ 352$ 355$ 359$ 362$ 366$ 370$ 373$ 377$ 381$ $5,813
Entered Value Renewable Heat O&M $ per year 14,068$ 14,209$ 14,351$ 14,494$ 14,639$ 14,786$ 14,933$ 15,083$ 15,234$ 15,386$ 15,540$ 15,695$ $239,497
Entered Value Renewable Fuel Use Quantity (Bcords 58 58 58 58 58 58 58 58 58 58 58 58
Entered Value Renewable Fuel Cost $ per unit $285 $287 $290 $293 $296 $299 $302 $305 $308 $311 $314 $317
Total Renewable Fuel Cost $ per year 16,430$ 16,594$ 16,760$ 16,927$ 17,097$ 17,268$ 17,440$ 17,615$ 17,791$ 17,969$ 18,148$ 18,330$
Remaining Fuel Oil (supplemen gallons rema 2281 2281 2281 2281 2281 2281 2281 2281 2281 2281 2281 2281
Total Fuel Cost (supplement)$ per year 17,579$ 17,717$ 17,833$ 17,937$ 18,025$ 18,093$ 18,143$ 18,195$ 18,242$ 18,299$ 23,987$ 23,987$
Proposed Heat Cost $ per year 48,418$ 48,864$ 49,292$ 49,710$ 50,116$ 50,505$ 50,879$ 51,259$ 51,636$ 52,027$ 58,052$ 58,393$ $823,876
Fuel Use gallons per y 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125 9,125
Fuel Cost $ per gallon 7.71$ 7.77$ 7.82$ 7.86$ 7.90$ 7.93$ 7.95$ 7.98$ 8.00$ 8.02$ 10.51$ 10.51$
Entered Value Fuel Scheduled Repairs $ per year 228$ 230$ 232$ 235$ 237$ 239$ 242$ 244$ 246$ 249$ 251$ 254$ $3,875
Entered Value Fuel O&M $ per year 854$ 862$ 871$ 879$ 888$ 897$ 906$ 915$ 924$ 934$ 943$ 952$ $14,531
Fuel Cost $ per year 70,316$ 70,867$ 71,332$ 71,747$ 72,100$ 72,372$ 72,570$ 72,780$ 72,966$ 73,194$ 95,947$ 95,947$ $1,195,461
Base Heating Cost $ per year 71,398$ 71,959$ 72,435$ 72,861$ 73,225$ 73,508$ 73,718$ 73,939$ 74,137$ 74,377$ 97,141$ 97,153$ $1,213,868
Proposed
Base
19
Cluster #1
Project Description
Community
Nearest Fuel Community
Region
RE Technology
Project ID
Applicant Name
Project Title
Category
Results
NPV Benefits $734,427
NPV Capital Costs $525,029
B/C Ratio 1.40
NPV Net Benefit $209,398
Performance Unit Value
Displaced Electricity kWh per year -
Displaced Electricity total lifetime kWh -
Displaced Petroleum Fuel gallons per year 6,003
Displaced Petroleum Fuel total lifetime gallons 356,475
Displaced Natural Gas mmBtu per year -
Displaced Natural Gas total lifetime mmBtu -
Avoided CO2 tonnes per year 61
Avoided CO2 total lifetime tonnes 3,618
Proposed System Unit Value
Capital Costs $540,780$
Project Start year 2013
Project Life years 25
Displaced Electric kWh per year -
Displaced Heat gallons displaced per year 12,833
Displaced Transportation gallons displaced per year 0.00
Renewable Generation O&$ per BTU
Electric Capacity kW 0
Electric Capacity Factor %0
Heating Capacity Btu/hr.700,000
Heating Capacity Factor %86
Base System Unit Value
Diesel Generator O&M $ per kWh 0.033$
Diesel Generation Efficien kWh per gallon
Parameters Unit Value
Heating Fuel Premium $ per gallon 2.30$
Transportation Fuel Premi $ per gallon 1.00$
Discount Rate % per year 3%
Crude Oil $ per barrel EIA Mid
Natural Gas $ per mmBtu ISER - Mid
Cluster #1
Koyukuk
Rural
Woody biomass heat
Village of Koyukuk
20
Annual Savings (Costs)Units 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
Entered Value Project Capital Cost $ per year 540,780$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$
Electric Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Heating Saving (Costs)$ per year $34,578 $35,369 $35,921 $36,670 $37,671 $38,605 $39,483 $40,278 $40,996 $41,530 $42,066 $42,532 $42,936
Transportation Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Total Savings (Costs)$ per year $34,578 $35,369 $35,921 $36,670 $37,671 $38,605 $39,483 $40,278 $40,996 $41,530 $42,066 $42,532 $42,936
Net Benefit $ per year ($506,202)$35,369 $35,921 $36,670 $37,671 $38,605 $39,483 $40,278 $40,996 $41,530 $42,066 $42,532 $42,936
Annual Savings (Costs)Units 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 PV
Entered Value Project Capital Cost $ per year -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ -$ $525,029
Electric Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Heating Saving (Costs)$ per year $43,274 $43,492 $43,585 $43,601 $43,524 $43,328 $43,022 $42,727 $42,392 $42,111 $73,501 $72,887 $734,427
Transportation Savings (Costs)$ per year $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Total Savings (Costs)$ per year $43,274 $43,492 $43,585 $43,601 $43,524 $43,328 $43,022 $42,727 $42,392 $42,111 $73,501 $72,887 $734,427
Net Benefit $ per year $43,274 $43,492 $43,585 $43,601 $43,524 $43,328 $43,022 $42,727 $42,392 $42,111 $73,501 $72,887 $209,398
Heating Units 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
Renewable Heat gallons displ 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833
Entered Value Renewable Heat Scheduled Rep$ per year 300$ 303$ 306$ 309$ 312$ 315$ 318$ 322$ 325$ 328$ 331$ 335$ 338$
Entered Value Renewable Heat O&M $ per year 22,848$ 23,077$ 23,308$ 23,541$ 23,776$ 24,014$ 24,254$ 24,497$ 24,742$ 24,989$ 25,239$ 25,491$ 25,746$
Entered Value Renewable Fuel Use Quantity (Bcords 108 108 108 108 108 108 108 108 108 108 108 108 108
Entered Value Renewable Fuel Cost $ per unit $250.00 $253 $255 $258 $260 $263 $265 $268 $271 $273 $276 $279 $282
Total Renewable Fuel Cost $ per year 27,070$ 27,341$ 27,614$ 27,890$ 28,169$ 28,451$ 28,735$ 29,023$ 29,313$ 29,606$ 29,902$ 30,201$ 30,503$
Remaining Fuel Oil (supplemen gallons 1426 1426 1426 1426 1426 1426 1426 1426 1426 1426 1426 1426 1426
Total Fuel Cost (supplement)$ per year 9,272$ 9,414$ 9,530$ 9,669$ 9,836$ 9,996$ 10,151$ 10,297$ 10,435$ 10,553$ 10,672$ 10,784$ 10,889$
Proposed Heat Cost $ per year 59,490$ 60,134$ 60,758$ 61,409$ 62,093$ 62,776$ 63,458$ 64,138$ 64,814$ 65,476$ 66,144$ 66,811$ 67,476$
Fuel Use gallons per y 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259
Fuel Cost $ per gallon $6.50 6.60$ 6.68$ 6.78$ 6.90$ 7.01$ 7.12$ 7.22$ 7.32$ 7.40$ 7.48$ 7.56$ 7.64$
Entered Value Fuel Scheduled Repairs $ per year 350$ 354$ 357$ 361$ 364$ 368$ 372$ 375$ 379$ 383$ 387$ 390$ 394$
Entered Value Fuel O&M $ per year 1,000$ 1,010$ 1,020$ 1,030$ 1,041$ 1,051$ 1,062$ 1,072$ 1,083$ 1,094$ 1,105$ 1,116$ 1,127$
Fuel Cost $ per year 92,718$ 94,140$ 95,302$ 96,688$ 98,359$ 99,962$ 101,508$ 102,968$ 104,348$ 105,529$ 106,719$ 107,836$ 108,891$
Base Heating Cost $ per year 94,068$ 95,503$ 96,679$ 98,079$ 99,764$ 101,381$ 102,941$ 104,416$ 105,810$ 107,005$ 108,211$ 109,342$ 110,412$
Proposed
Base
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 21
Summary of Financial Analysis
Estimated System Description
(abbreviated)
NPV Benefits PV B/C Ratio Simple Payback
Washateria One (1) 350,000 btu
containerized cordwood boiler
$389,900 $272,300 1.47 14.5
Cluster #1 (Washateria,
School, City/ Tribal Hall)
One (1) 700,000 btu
containerized cordwood boiler
743,400 $540,780 1.4 15.3
Heating Units 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 PV
Renewable Heat gallons displ 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833 12,833
Entered Value Renewable Heat Scheduled Rep$ per year 341$ 345$ 348$ 352$ 355$ 359$ 362$ 366$ 370$ 373$ 377$ 381$ $5,813
Entered Value Renewable Heat O&M $ per year 26,004$ 26,264$ 26,526$ 26,792$ 27,059$ 27,330$ 27,603$ 27,879$ 28,158$ 28,440$ 28,724$ 29,011$ $442,692
Entered Value Renewable Fuel Use Quantity (Bcords 108 108 108 108 108 108 108 108 108 108 108 108
Entered Value Renewable Fuel Cost $ per unit $285 $287 $290 $293 $296 $299 $302 $305 $308 $311 $314 $317
Total Renewable Fuel Cost $ per year 30,808$ 31,116$ 31,427$ 31,741$ 32,059$ 32,379$ 32,703$ 33,030$ 33,361$ 33,694$ 34,031$ 34,371$
Remaining Fuel Oil (supplementgallons 1426 1426 1426 1426 1426 1426 1426 1426 1426 1426 1426 1426
Total Fuel Cost (supplement)$ per year 10,988$ 11,074$ 11,147$ 11,211$ 11,267$ 11,309$ 11,340$ 11,373$ 11,402$ 11,438$ 14,993$ 14,993$
Proposed Heat Cost $ per year 68,141$ 68,798$ 69,448$ 70,096$ 70,740$ 71,377$ 72,009$ 72,649$ 73,290$ 73,945$ 78,125$ 78,757$ $1,159,793
Fuel Use gallons per y 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259 14,259
Fuel Cost $ per gallon 7.71$ 7.77$ 7.82$ 7.86$ 7.90$ 7.93$ 7.95$ 7.98$ 8.00$ 8.02$ 10.51$ 10.51$
Entered Value Fuel Scheduled Repairs $ per year 398$ 402$ 406$ 410$ 415$ 419$ 423$ 427$ 431$ 436$ 440$ 444$ $6,781
Entered Value Fuel O&M $ per year 1,138$ 1,149$ 1,161$ 1,173$ 1,184$ 1,196$ 1,208$ 1,220$ 1,232$ 1,245$ 1,257$ 1,270$ $19,375
Fuel Cost $ per year 109,879$ 110,739$ 111,466$ 112,114$ 112,666$ 113,090$ 113,400$ 113,728$ 114,019$ 114,375$ 149,929$ 149,929$ $1,868,064
Base Heating Cost $ per year 111,415$ 112,291$ 113,034$ 113,697$ 114,265$ 114,705$ 115,031$ 115,375$ 115,683$ 116,056$ 151,627$ 151,644$ $1,894,220
Proposed
Base
22
Conclusion
The village of Koyukuk has significant opportunities for biomass heating, owing to the high cost of
fuel oil, accessible cordwood supply, and community-scale heat loads that could be adequately
served by containerized biomass heating units.
For the purposes of this project, containerized cordwood boilers were scoped as the appropriate
technology. However, a project the size of Cluster #1 could employ woodchip boilers and chipping
equipment. This would be more technically complex than the cordwood option.
Cordwood is an accessible and sustainable biomass supply in the Village, if a Biomass Harvest Plan is
appropriately developed and executed. Because the project’s success is dependent on a Biomass
Harvest Plan, the Consultant strongly recommends developing this Plan prior to project
development. Additionally, because the project’s success is dependent on an Operations Plan, the
Consultant strongly recommends developing this Plan prior to project development.
Dalson Energy suggests prioritizing the Washateria project. This project is the most streamlined and
could be expanded to serve Cluster #1 in the future by adding an additional 350,000 btu/hr boiler.
All projects examined in this pre-feasibility report show cash savings. The Washateria project is the
most financially viable of those examined.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 23
Consultant/Authors of this report:
Dalson Energy is a Renewable Energy Consulting and Technology Research firm based in
Anchorage. Dalson staff and partners have decades of experience in construction project
management, project development consulting and renewable energy technology research. Dalson
teams with licensed engineers, architects and designers in Alaska, Canada and Lower 48.
Dalson Energy has worked with Alaska Energy Authority, Alaska Center for Energy & Power,
University of Alaska Fairbanks, Washington State CTED (Community Trade & Economic
Development) and California Energy Commission on biomass energy technology research.
Dalson’s President, Thomas Deerfield, has been involved in biomass energy RD&D since 2001,
winning grants and managing projects with NREL (National Renewable Energy Labs), USFS (US
Forest Service), and CEC (California Energy Commission).
Thomas managed the field-testing of biomass CHP systems, including the first grid-connected
biomass gasification CHP system in the US. (2007). Thomas coordinated the design and creation of
the first prototype Biomass “Boiler in a Box” in Alaska, in 2010. That Garn-based system is now
deployed in Elim, in the Bering Sea region.
Thomas founded Shasta Energy Group (SEG), a 501c3 nonprofit, and managed wind energy research,
biomass energy feasibility studies, energy efficiency for buildings, and hydronic heating system
research design and development (RD&D). He also initiated a rural economic development think
tank and has engaged his writing skills to assist many other renewable energy project initiatives.
Wynne Auld is a Biomass Energy Specialist with Dalson Energy. She focuses on assessing and
developing woody biomass energy projects. Over the past few years, she has supported the business
development of integrated biomass energy campuses in Oregon and Idaho, especially related to their
energy initiatives. Her efforts have included marketing Campus biomass heating products to major
wholesalers and retail buyers, and planning and developing Campus sort yards and small-scale CHP.
Wynne also specializes in assisting commercial and municipal building managers in assessing the
feasibility of biomass heating, and implementing their projects. She works to ensure vibrant rural
communities through sustainable natural resource utilization.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 24
Supplement: Community Wood Heating Basics
Wood fuel as a heating option
When processed, handled, and combusted appropriately, wood fuels are
among the most cost-effective and reliable sources of heating fuel for
communities adjacent to forestland.
Compared to other heating energy fuels, wood fuels are characterized by
lower energy density and higher associated transportation and handling
costs. This low bulk density results in a shorter viable haul distance for
wood fuels compared to fossil fuels. However, this “limit” also creates an
advantage for local communities to utilize locally-sourced wood fuels, while
simultaneously retaining local energy dollars and excercising local resource
management.
Most Interior villages are particularly vulnerable to high energy prices
because the region has over 13,500 heating degree days 5 (HDD) per year –
160% of Anchorage’s HDDs, or 380% of Seattle’s HDDs. For many
communities, wood-fueled heating lowers fuel costs. For example,
cordwood sourced at $250 per cord is just 25% of the cost per MMBTU as
fuel oil #1 sourced at $7 per gallon. Besides the financial savings, local
communities benefit from the multiplier effect of circulating fuel money in
the community longer, more stable energy prices, job creation, and more
active forest management.
In all the Interior villages studied, the community’s wood supply and
demand are isolated from outside markets. Instead, the firewood market is
influenced by land ownership, existing forest management and ecological
conditions, local demand and supply, and the State of Alaska Energy
Assistance program.
The nature of wood fuels
Wood fuels are specified by moisture content, granulometry, energy density,
ash content, dirt and rocks, and fines and coarse particles. Each of these
characteristics affects the wood fuel’s handling characteristics, storage requirements, and combustion
process. Fuels are considered higher quality if they have lower moisture, ash, dirt, and rock contents;
consistent granulometry; and higher energy density.
5 Heating degree days are a metric designed to reflect the amount of energy needed to heat the
interior of a building. It is derived from measurements of outside temperature.
Figure 9: Wood pellets
Figure 7: Wood briquettes, as a
substitute for cordwood. Cross
sections of these briquettes make
“wafers” which can be
automatically handled in biomass
boiler systems.
Figure 6: Cordwood
Figure 8: Ground wood chips
used for mulch.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 25
Many types of fuel quality can be used in wood heating projects so long as the infrastructure
specifications match the fuel content characteristics. Typically, lower quality fuel will be the lowest
cost fuel, but it will require more expensive storage, handling, and combustion infrastructure, as well
as additional maintenance.
Projects in interior Alaska must be designed around the availability of wood fuels. Some fuels can be
manufactured on site, such as cordwood, woodchips, and briquettes. The economic feasibility of
manufacturing on site can be determined by a financial assessment of the project; generally speaking,
larger projects offer more flexibility in terms of owning and operating harvesting and manufacturing
equipment, such as a wood chipper, than smaller projects.
It is unlikely that interior communities will be able to manufacture pellets, from both a financial,
operational, and fuel sourcing perspective. However, some interior communities may be able to
manufacture bricks or firelogs made from pressed wood material. These products can substitute for
cordwood in woodstoves and boilers, while reducing supply pressure on larger diameter trees than
are generally preferred for cordwood. At their simplest, brick presses are operated by hand, but
require chipped, dry fuel.
The basics of wood-fueled heating
Biomass heating systems fit into two typical categories: first, stoves and fireplaces that heat space
directly through convection and radiation by burning cordwood or pellets; second, hydronic systems
where the boiler burns cordwood, woodchips or pellets to heat liquid that is distributed to radiant
piping, radiators or heat exchangers. The heated liquid is distributed out to users, then returned to
the heat source for re-heating.
Hydronic systems are appropriate for serving individual buildings, or multiple buildings with
insulated piping called heat loops. Systems that serve multiple buildings are called district heating
loops. District heating is common in Europe, where larger boilers sometimes serve entire villages.
Biomass boilers are dependent on the compatibility of the chosen fuel, handling system, and
combustion system. General categories for typically available biomass fuel systems follow:
Batch load solid chunk boiler
Semi-automated or fully-automated chipped or ground biomass boilers
Fully-automated densified-fuel boiler, using pellets, bricks, or pucks
The system application is typically determined by size of heat load, available wood fuels, and
available maintenance personnel. General categories for heat load and wood fuel follow:
Loads < 1 MMBTU often use cordwood or pellet boilers
Loads > 1MMBTU often use pellet or woodchip boilers
Loads > 10MMTU often use hog-fuel (mixed ground wood)
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 26
Each wood fuel type has different handling requirements and is associated with different emission
profiles. For example, industrial systems greater than 10 MMBTU often require additional particulate
and emission controls because of the combustion properties of hog-fuel.
One category of system that is particularly appropriate for remote rural communities is cordwood
boilers. Cordwood boilers are batch-loaded with seasoned cordwood. A significant advantage to
cordwood is that very little infrastructure is needed to manufacture or handle the heating fuel. At its
most basic, cordwood can be “manufactured” with a chainsaw (or handsaw) and an ax, and residents
of rural communities are often accustomed to harvesting wood to heat their homes and shops.
Harvesting in most Interior villages is accomplished with ATV’s, river skiffs, sleds and dog teams,
and snow machines. Since cordwood systems are batch loaded by hand, they do not require
expensive automated material handling systems. Covered storage is required; such storage may be as
simple as an existing shed or a vented shipping container, rather than newly constructed storage
structures.
Challenges to cordwood include higher labor costs associated with manual loading. Some LEHE (low
efficiency, high emission) technologies such as Outdoor Wood Boilers (OWBs) have been criticized
for their high emissions and excessive wood consumption.
Cordwood systems are typically less than 1 MMBTU. However, if needed, some types of cordwood
boilers can be “cascaded,” meaning multiple boilers can meet heat demand as a single unit. However,
above a certain heat load, automated material handling and larger combustion systems become
viable.
Woodchip systems can be automated and thereby less labor intensive. However, woodchip systems
have significantly higher capital costs than both cordwood and pellet systems. Additionally, a
reliable stream of woodchips typically depends on a regionally active forest products manufacturing
base in the area, and active forest management. In most Interior communities, institutional heating
with woody biomass does not justify the purchase of log trucks, harvesting, handling, and
manufacturing equipment.
Pellet systems are the most automated systems, and have lower capital equipment costs than
woodchip systems. Lower costs are due to the smaller size of required infrastructure and simplified
handling and storage infrastructure. However, pellet fuel and other densified fuels tend to be more
expensive than other wood fuels, and require reliable access to pellet fuels.
For any system, the mass of feedstock required annually is determined by three parameters:
1) Building heat load
2) Net BTU content of the fuel
3) Efficiency of the boiler system
Building heat loads are determined by square footage, orientation and usage, as well as energy
efficiency factors such as insulation, moisture barriers and air leakage. Usage is particularly
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 27
important because it influences peak demand. For example, a community center which is used only a
few times per month for events, and otherwise kept at a storage temperature of 55 d. F, would have a
much different usage profile than a City Office which is fully occupied during the work day and
occasionally during evenings and weekends.
Building heat load analysis, including the building usage profile, is a particularly important part of
boiler right-sizing. A full feasibility analysis would conduct analyses that optimize the return on
investment (ROI) of systems. Typically, optimizing a biomass project’s ROI depends on a
supplementary heating system, such as an oil fired system, to meet peak demand and prevent short-
cycling of the biomass boiler. Full feasibility analyses may not be necessary for small projects,
especially for those employing cordwood boilers.
Biomass boiler efficiencies vary from 60% to 80%, depending on the manufacturer and the field
conditions of the equipment. The efficiency is strongly influenced by the BTU value and MC
(moisture content) of the fuel. Wood fuels with greater than 50% MC generally result in lower
efficiency systems, because some energy is used to drive off moisture from the fuel during the
combustion process. The reduction in energy output is mathematically equal; 50% MC generally
means 50% reduction in potential BTU value.
Like other combustion-based energy systems, woody biomass boilers produce emissions in the
combustion process. Compared to fossil fuels (coal, natural gas, and fuel oil), wood fuel emissions
are low in nitrogen oxides (NOx); carbon monoxide (CO, a product of incomplete combustion); sulfur
dioxide (SO2); and mercury (Hg). Because these compounds are all products of the forest and CO
would release naturally during the process of decay or wildfire, they generally do not concern
regulatory agencies. For emission control agencies, the real interest is particulate matter (PM)
emissions, which affect the air quality of human communities. Some wood systems are extremely
sophisticated, producing less than 0.06 lb/ MMBTU of PM.
Effective methods of PM control have been developed to remove most of the particles from the
exhaust air of wood combustion facilities. These include introduction of pre-heated secondary air,
highly controlled combustion, and PM collection devices.
Biomass boiler systems typically integrate a hot water storage tank, or buffer tank. The storage tank
prevents short cycling for automated boilers and improves efficiency and performance of batch-fired
systems, by allowing project buildings to draw on the boiler’s hot water long after the combustion
process. The GarnPac boiler design incorporates hot water storage into the boiler jacket itself, storing
approximately 2,200 gallons of hot water. Other boilers are typically installed with a separate hot
water storage tank.
Available wood heating technology
This section will focus generally on manufacturers of the types of technology discussed previously.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 28
Cordwood Boilers
High Efficiency Low Emission (HELE) cordwood boilers are designed to burn cordwood fuel cleanly
and efficiently.
Cordwood used at the site will ideally be seasoned to 25% MC (moisture content) and meet the
dimensions specified by the chosen boiler. The actual amount of cordwood used would depend on
the buildings’ heat load profile, and the utilization of a fuel oil system as back up.
The following table lists three HELE cordwood boiler suppliers, all of which have units operating in
Alaska. Greenwood and TarmUSA, Inc. have a number of residential units operating in Alaska, and
several GARN boilers, manufactured by Dectra Corporation, are used in Tanana, Kasilof, Dot Lake,
Thorne Bay and other locations to heat homes, Washaterias, and Community Buildings.
HELE Cordwood Boiler Suppliers
Vendor Btu/hr ratings Supplier
Tarm
100,000 to 198,000 Tarm USA www.tarmusa.com
Greenwood 100,000 to 300,000 Greenwood www.greenwoodusa.com
GARN 250,000 to 700,000 Dectra Corp. www.dectra.net/garn
Note: These lists are representational of available systems, and are not inclusive.
Bulk Fuel Boilers
The term “bulk fuel” refers to systems that utilize wood chips, pellets, pucks, or other loose
manufactured fuel. Numerous suppliers of these boilers exist. Since this report focuses on village-
scale heating, the following chart outlines manufacturers of chip and pellet fuel boilers < 1 MMBTU.
HELE Bulk Fuel Boiler Suppliers
Vendor Btu/hr ratings Supplier
Froling 35,800 to 200,000; up to 4 can be cascaded as
a single unit at 800,000 BTU
Tarm USA www.tarmusa.com
KOB 512,000 – 1,800,000 BTU (PYROT model) Ventek Energy Systems Inc.
peter@ventekenergy.com
Binder
34,000 BTU – 34 MMBTU BINDER USA
contact@binder-boiler.com
Note: These lists are representational of available systems, and are not inclusive
The following is a review of Community Facilities being considered for biomass heating. The
subsequent section will recommend a certain type of biomass heating technology, based on the
Facility information below.
Dalson Energy Inc. – Koyukuk Preliminary Feasibility Assessment 29
District heat loops
District heat loops refers to a system for heating multiple buildings from a central power plant. The
heat is transported in a piping system to consumers in the form of hot water or steam.
These are the key factors that affect the cost of installing and operating a district heating system 6:
• Heat load density.
• Distance between buildings. Shorter distances between buildings will allow use of smaller
diameter (less expensive) pipes and lesser pumping costs.
• Permafrost. In the Interior, frozen soil could affect construction costs and project feasibility.
Aboveground insulated piping may be preferred to underground piping, such as the
cordwood system recently installed in Tanana, Alaska.
• Piping materials used. Several types of tubing are available for supply and return water. Pre-
insulated PEX tubing may be the preferred piping material for its flexibility and oxygen
barrier.
• District loop design. Water can be piped in one direction (i.e., one pipe enclosed) or two
directions (two pipes enclosed) for a given piping system. Design affects capital costs and
equality of heat distribution.
• Other considerations. Pump size, thermal load (BTUs per hour), water temperature, and
electrical use are other variables.
For the purposes of this study, the consultants have chosen to estimate the costs of district heat loops
using the RET Screen, a unique decision support tool developed with the contribution of numerous
experts from government, industry, and academia. The software, provided free-of-charge, can be
used worldwide to evaluate the energy production and savings, costs, emission reductions, financial
viability and risk for various types of Renewable-energy and Energy-efficient Technologies (RETs),
including district heat loops from biomass.
6 Nicholls, David; Miles, Tom. 2009. Cordwood energy systems for community heating in Alaska—an
overview. Gen. Tech. Rep. PNW-GTR-783. Portland, OR: U.S. Department of Agriculture, Forest
Service, Pacific Northwest Research
Station. 17 p.