BIOHEAT GUIDE FOR RURAL AND REMOTE - CRIBE
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A SOLID WOOD
BIOHEAT
GUIDE
FOR RURAL AND REMOTE
COMMUNITIES IN ONTARIO
special publication SP-537E
February 2020
A SOLID WOOD BIOHEAT GUIDE FOR RURAL AND REMOTE COMMUNITIES IN ONTARIO special publication SP-537E ISBN 978-0-86488-586-9 (Print) ISBN 978-0-86488-587-6 (Digital) ISSN 1925-0495 (Print) ISSN 1925-0509 (Digital) Glen Prevost, M.F.C., P.Eng. Industry Advisor, FPInnovations © FPInnovations 2020. All rights reserved. Unauthorized copying or distribution prohibited.
ACKNOWLEDGEMENTS Financial support for this guide was provided by the Northern Ontario Heritage Fund Corporation, FedNor, Ontario’s Ministry of Natural Resources and Forestry, and Natural Resources Canada. The author is grateful for the direction of the project’s steering committee that provided guidance and feedback throughout the development of this guide. The steering committee included staff from Ontario’s Ministry of Natural Resources and Forestry, Forest Industry Division; Natural Resources Canada, CanmetENERGY; and FPInnovations. Internal reviewers from FPInnovations provided important comments and suggestions on drafts. These reviewers included: • John Pineau • Christoph Schilling • Marian Marinescu • Sylvain Volpé • Luc Desrochers The following people provided their time, thoughts, and insight on bioheat technologies and biofuels. This information was critical in developing the guide. • Mike Rutter and Vince Rutter, Biothermic Wood Energy Systems • Colin Kelly, Confederation College • Andreas Wintzer, Viessmann Manufacturing Company Inc. • Todd Eastman, Ontario’s Ministry of Energy, Northern Development and Mines • Conrad Lacroix, LacWood Pellets (I.C.S. Lacroix Lumber) • Steven Law, Ontario’s Ministry of the Environment, Conservation and Parks • Terrence Sauvé, Ontario’s Ministry of Agriculture, Food and Rural Affairs • Jonathan Halasz, Ontario’s Ministry of Natural Resources and Forestry • Heather Reid, Abbey Gardens • Marc-Antoine Cantin, Stove Builder International Inc. (SBI) • Roland Kilpatrick, Innovation Initiatives Ontario North • Sally Krigstin, University of Toronto The author appreciates the work of the communications team at FPInnovations who coordinated the production of this guide.
Table of contents
6 EXECUTIVE
SUMMARY 12 3. SOLID WOODY
BIOFUELS
• Important properties of solid
7
1. INTRODUCTION woody biofuels
• Who will find this guide useful? • Cordwood
• What are biomass, biofuel, and • Wood chips
bioheat?
• Wood briquettes
• Are bioheat systems
• Wood pellets
complicated?
19
• What is included in this guide?
4. BIOHEAT COMBUSTION
SYSTEMS
9 2. BENEFITS OF
CHOOSING BIOHEAT
• Support for local jobs and
• Stoves
• Furnaces
economic development • Boilers
• A sustainable and renewable
fuel
• Low and stable energy costs 27 5. IMPORTANT FACTORS
TO CONSIDER WHEN
• Reliable fuel supply CHOOSING BIOHEAT
29
• Low-carbon fuel
6. NEW-BUILD BIOHEAT
• Lower environmental risk than
fossil fuels
INSTALLATIONS
COMPARED TO RETROFIT
• Bioheat systems are reliable
and easy to operate
INSTALLATIONS
30
• Stimulation of community
development
7. RESIDENTIAL BIOHEAT
PROJECTS
• Funding for local forest • Energy-efficient housing
stewardship activities
• Planning stages
• Relevant regulations
4 TABLE OF CONTENTS
32 8. INSTITUTIONAL AND
COMMERCIAL BIOHEAT 48 APPENDIX B: CASE
STUDIES
• Confederation College
PROJECTS
• Project planning • Abbey Gardens
• Sizing a bioheat system • Residential cordwood furnace
• Relevant regulations • Viessmann Manufacturing
• Funding a bioheat project Company Inc.
40 9. OTHER BIOHEAT
SYSTEMS 59 APPENDIX C: ADDITIONAL
RESOURCES
• Other bioheat guides and
• District heating systems
general resources
• Combined heat and power
systems • Residential and small
commercial pellet heating
41 10. REFERENCES
• Biofuels
• Additional case studies
44 APPENDIX A: • District heating
ENVIRONMENTAL • Combined heat and power
BENEFITS AND • Wood heat energy calculators
CONSIDERATIONS • Bioheat emissions
• Bioheat and the carbon cycle
• Bioheat and climate change
• Emissions
• Sustainable forest
• Sustainable forest
management in Canada and
management in Ontario
Ontario
• Ministry of Natural Resources
and Forestry district offices
• Ministry of the Environment,
Conservation and Parks
regional offices
TABLE OF CONTENTS 5
EXECUTIVE SUMMARY Modern wood heating systems using
This guide has been developed to provide local renewable solid woody biofuels can
people in Ontario’s remote and rural reduce greenhouse gas emissions, create
communities with the information and local clean energy jobs, keep money in
confidence to use wood from Ontario’s local communities, reduce the risk of
sustainably managed forests to produce fuel spills, and increase local energy and
space heat and domestic hot water. It economic security.
is aimed at community leaders such as
This guide provides detailed information
those found in municipal governments,
on solid woody biofuels that are available
band councils, school boards, churches,
in Ontario and the combustion systems
not-for-profit organizations, and
that can burn these biofuels. The four
small businesses, as well as private
types of solid woody biofuels considered
homeowners.
in this guide are cordwood (firewood),
Modern bioheat systems are highly wood chips, wood briquettes, and wood
engineered mechanical systems that pellets. The three types of combustion
provide space heat and domestic hot systems are stoves, furnaces, and boilers.
water for community buildings and The major considerations for sourcing
businesses, as well as for private homes. and using each type of biofuel and
This guide is applicable to systems that combustion system for institutional/
are less than 1 MW in size and that use commercial and residential applications
solid woody biofuels to produce heat. are outlined in this guide. The guide
Ontario has a large supply of woody addresses the planning steps and funding
biomass sourced from sustainably options for bioheat systems.
managed forests, including mill and
harvest residues and unmerchantable
standing timber, that could be used to
produce solid woody biofuel.
6 EXECUTIVE SUMMARY
1. INTRODUCTION
Who will find this guide useful?
This guide has been developed to provide band councils, school boards, churches,
people in Ontario’s remote and rural not-for-profit organizations, and small
communities with the information and businesses, as well as private homeowners.
confidence to use wood from Ontario’s This guide contains enough detail that
sustainably managed forests to produce consultants, engineers, and suppliers of
space heat and domestic hot water. It woody biomass combustion systems and
is aimed at community leaders such as biofuels will also find it useful.
those found in municipal government,
What are biomass, biofuel, and bioheat?
Biomass includes “all organic materials of biological origin” and can originate from
forestry, arboricultural, agricultural, horticultural, and aquacultural operations (CSA
Group, 2015). When biomass is processed and used as fuel to produce heat and/or
power, it is called biofuel. The heat produced when biofuel is burned is called bioheat.
This guide discusses only solid woody biofuel produced from forest resources. The four
categories of solid woody biofuel are cordwood (firewood) (Figure 1), wood chips
(Figure 2), wood briquettes (Figure 3), and wood pellets (Figure 4).
Are bioheat systems complicated? professionals in Ontario are highly
Bioheat systems are not complicated. qualified and eager to help those who
The technology is well-developed and want to install a bioheat system. Any
widely used in Europe, Alaska, and the complexity that readers may perceive is
northeastern United States, as well as due to the newness of bioheat systems
across Canada. Bioheat systems are in the province, not because the systems
relatively new to Ontario, and that is why themselves are complex.
this guide has been developed. Bioheat
INTRODUCTION 7
What is included in this guide?
This guide is applicable to systems that
are smaller than 1 MW thermal output in
size and that use solid woody biofuel to
produce heat. This guide does not discuss
outdoor boilers, combustion systems
of greater than 1 MW thermal output,
combined heat and power systems of
any size, or liquid biofuels made from
Figure 2. A high-quality wood chip (left) and a
solid wood. The guide includes the lower quality wood chip (right).
following sections:
• Section 1: Introduction
• Section 2: Benefits of choosing bioheat
• Section 3: Solid woody biofuels
• Section 4: Bioheat combustion systems
• Section 5: Important factors to
consider when choosing bioheat
• Section 6: New-build bioheat
installations compared to retrofit
installations
• Section 7: Residential bioheat projects Figure 3. Various types of wood briquettes.
(Photo: CanmetENERGY, Natural Resources
• Section 8: Institutional and commercial Canada)
bioheat projects
• Section 9: Other bioheat systems
Figure 4. Wood pellets.
Figure 1. Stacked and covered cordwood.
8 INTRODUCTION
2. BENEFITS OF CHOOSING BIOHEAT Low and stable energy costs
Support for local jobs and Biofuel is often the cheapest heating
economic development fuel available. It can cost between 34%
Biofuel is usually sourced locally or and 81% less than other heating fuels,
regionally, which means that most of the depending on the biofuel used and
economic benefits stay local or regional. the fuel it replaces. The price of biofuel
Local labour is required to harvest, also tends to be more stable than that
process, and deliver the biofuel. It is of other fuels. Switching to bioheat
also required to operate and maintain reduces heating costs and insulates the
combustion systems. All of this creates community against the price fluctuations
opportunities for individuals and of fossil fuels. Natural gas is often cheaper
businesses to develop and grow. Keeping than bioheat, but it cannot provide the
money local and having lower energy same social and economic benefits of
costs provides an economic advantage locally sourced solid woody biofuel.
to rural and remote communities. When
fossil fuels or electricity are bought, much Reliable fuel supply
of that money leaves the community. Biofuel production is well established
and increasing worldwide as more
Solid woody biofuels are often made with people realize the benefits of switching
poor-quality or underutilized biomass. to bioheat. Cordwood and pellets are
Finding a market for this biomass reduces readily available in many locations in
costs for local forestry companies, creates Ontario. Wood chips are widely available,
new local jobs, and diversifies the forest but care must be taken to ensure that
product mix. local manufacturers can provide the right
quality of chips. In some locations, wood
A sustainable and renewable fuel chips may already be committed to
Ontario has a large, sustainable supply other users.
of woody biomass that includes mill and
harvest residues and standing timber Low-carbon fuel
that can be used to produce solid Many people do not realize that
woody biofuel. Ontario’s Crown Forest bioheat is a low-carbon fuel. Biofuel is
Sustainability Act requires that all Crown a renewable resource that produces
forests be sustainably managed, and fewer greenhouse emissions than fossil
Ontario uses a rigorous science-based fuels, as long as the forest is sustainably
approach for managing Crown forests. managed. When fossil fuels are burned,
As a result, consumers of biofuel from ancient carbon is released into the
Ontario’s Crown forests can be confident atmosphere, and because it cannot be
that they are using a sustainable and returned into the original deposits, much
renewable fuel. More information on of this carbon remains in the atmosphere
sustainable forest management in and contributes to climate change. When
Ontario can be found in Appendix A. biofuel is burned, the carbon emissions
can be recaptured by the forest as new
BENEFITS OF CHOOSING BIOHEAT 9
trees grow to replace the trees that were with their fossil fuel counterparts. The
harvested to produce the biofuel. For emissions from new bioheat systems
more information on bioheat and carbon are constantly being reduced. For more
emissions, see Appendix A. information on bioheat and carbon
emissions, see Appendix A.
Lower environmental risk
than fossil fuels Liquid fossil fuels can pose a
Some people or communities believe that contamination risk if they spill. Solid
bioheat systems are big polluters and woody biofuel poses no spill risk. When
that fossil fuel systems are much cleaner. biofuel is spilled, it simply decomposes
This is not true. All types of combustion, naturally without any harmful effects on
including that of biofuel and fossil fuel, people or the environment.
produce emissions such as sulfur dioxide,
nitrous oxides, carbon monoxide, carbon Bioheat systems are reliable and
dioxide, volatile organic compounds, easy to operate
Bioheat systems have all the reliability and
and particulate matter. Today’s bioheat
features of any other new heating system.
combustion systems produce far smaller
Bioheat systems are highly engineered
amounts of emissions than residential
mechanical systems, not unlike electric or
wood stoves of the past, and are on par
fossil fuel systems. Most of these systems
include user-friendly automatic operation
and reliable performance, and all must
be designed and installed by qualified
professionals. However, there are
important differences between bioheat
systems and other heating systems that
potential owners and designers need to
be aware of. These differences include
necessary cleaning, maintenance, and
fuel management that bioheat systems
require. The benefits are often worth the
additional effort. With good design, the
labour requirements of bioheat system
operation can often be matched to the
capabilities of the owner or operator.
10 BENEFITS OF CHOOSING BIOHEATStimulation of community Funding for local forest
development stewardship activities
Bioheat systems, especially larger, Biofuel production can provide a
community-based systems, require mechanism to fund forest stewardship
partnerships with local groups. This can activities, such as pre-commercial
lead to new opportunities for community thinning of forests, forest restoration,
development, such as employment, and FireSmart initiatives. FireSmart
training, and social interactions. The social initiatives reduce the risk of wildfire
benefits can often be the deciding factor damage by removing some of the forest
when assessing the viability of a bioheat fire fuel (trees and deadwood) near
project. Potential social benefits include: buildings and communities.
• Energy security
• Locally sourced renewable energy
• Local employment
• Bonding the community through a
collaborative project
• Confidence in the community’s future
• The opportunity to build new
partnerships and collaboration within
the community
BENEFITS OF CHOOSING BIOHEAT 113. SOLID WOODY BIOFUELS
This section describes each solid woody biofuel considered in this guide. Residential
systems generally do not use wood chips, so those interested in residential systems
can skip the section on wood chips. Table 1 provides a summary of the key properties
of each fuel type, including approximate costs. The provided costs are broad estimates
and should not be used for planning purposes. Fuel costs should be verified with local
suppliers. The content of this section was adapted from Natural Resources Canada’s
Solid biofuels bulletins (Natural Resources Canada, n.d.-a,b,c,d,e,f,g). These bulletins
are recommended reading for more detail on woody biofuel standards, sources, and
descriptions of each type of fuel.
Table 1. Comparison of fuel properties and costs in Ontarioa
Fuel Moisture Typical Typical Typical Peak Nominal Delivered
content range range range of heating delivered fuel cost
of ash of bulk higher demand of cost ($ ($/GJ)
content (% density heating buildingb per unit
dry basis) (kg/m3) value volume)
(MJ/kg)
Cordwood 10 kW to $400 per
1 MW
dried) packed tonne
Heating oil 20 kW to
N/A N/A 850 42 $1.14 per L $33
(No. 2) >1 MW
20 kW to
Propane N/A N/A 1.7 50 $0.8 per L $35
>1 MW
20 kW to $0.25 per
Natural gas N/A N/A 0.7–0.9 43 $6.70
>1 MW m3
20 kW to $0.18 per
Electricity N/A N/A N/A N/A $50
>1 MW kWh
a
osts are rough estimates only and should not be used for detailed planning. Costs should be verified with a supplier. (Adapted from Natural
C
Resources Canada, n.d.-a,b,c,d,e,f,g; cost estimates are based on 2018 market rates.)
b
An upper limit of >1 MW has been used in this table to be consistent with the scope of the guide. Larger systems are available.
c
Costs for bulk delivery in totes, vacuum truck, or pallets.
d
Wood chips can be dried to lower than 45%. When mechanically processed, 25% is achievable.
N/A: Not applicable
12 SOLID WOODY BIOFUELSImportant properties of solid handling systems, respiratory health, and
woody biofuels combustion emissions and efficiencies
The CAN/CSA-ISO 17225 Solid Biofuels (Marinescu, 2013).
Standards are voluntary fuel standards
Moisture content is the amount of water
and have been adapted from the
that a fuel contains, expressed as a
solid biofuels standards set out by
percentage of the weight of the fuel. It
the International Organization for
is measured on a percent wet basis or
Standardization (ISO) (Natural Resources
percent dry basis. High moisture content
Canada, n.d.-c; CSA Group, 2015). The
has several disadvantages, such as
standards establish grades for each type
increased transportation costs per unit of
of solid woody biofuel (cordwood, wood
energy, increased air emissions, risks of
chips, wood briquettes, and wood pellets)
degradation through fungal and bacterial
based on the source and properties of
activities during storage (composting),
the biofuel. Standards are important
self-heating, and off-gassing. High moisture
because biofuel quality can vary greatly
content also lowers the amount of useful
depending on the source and processing
energy captured from combustion as more
methods. The quality of the biofuel
energy is required to evaporate water.
affects the efficiency of combustion, the
When wet fuel is burned, a considerable
life of the combustion system, and the
amount of energy is spent evaporating
released emissions. Canadian vendors
water instead of providing useful heat.
and purchasers of solid woody biofuels
can use these standards to communicate
biofuel
information about the needs for with
biofuel quality and to develop purchase
agreements. Ontario uses the CAN/CSA- 20%
moisture content
ISO 17225 Solid Biofuels Standards in its
can produce approximately
17 MJ/kg
air quality regulations and guidelines for
small wood-fired combustors (bioheat
systems).
There are five fuel properties that should a difference
of almost
30%
be considered when selecting a fuel. In
order of importance, these include particle
size, moisture content, ash content, bulk
density, and energy content. biofuel
with
50%
Particle size is a measurement of the
size of the individual pieces of biofuel.
Combustion systems are designed to moisture content
operate using biofuel of a certain particle can produce approximately
size. Particles that are too large or too
small can cause problems for fuel-
12 MJ/kg
SOLID WOODY BIOFUELS 13For example, biofuel with 20% moisture when burned. This value may be
content can produce approximately presented as a higher heating value (HHV)
17 MJ/kg, whereas biofuel with 50% or lower heating value (LHV). The HHV
moisture content can produce assumes that all the water vapour formed
approximately 12 MJ/kg. This is a difference during combustion will be condensed and
of almost 30%, meaning that if a system all possible heat will be recovered. The
was burning biofuel with 50% moisture LHV assumes that the water contained in
content, it would need to burn 30% more the fuel is vaporized and is not recovered.
fuel to produce the same amount of heat HHV is the most commonly reported
as biofuel with 20% moisture content. value in Canada (Marinescu, 2013).
When buying biofuels, the moisture Moisture content is the most important
content should be guaranteed. factor affecting energy content.
Ash is the residue that remains after
combustion occurs, and it must be
disposed of in some way on a regular basis.
Fuels with low ash content reduce handling Cordwood
and disposal costs. Higher bark content Cordwood (Figure 1), or firewood, is the
or contamination with dirt and rocks will most unprocessed and recognizable
increase ash content. Low ash content form of solid woody biofuel. It is made by
should be sought when sourcing biofuel cutting logs to length and then splitting
(Marinescu, 2013). Clean ash can be used as needed. It is expensive to transport
as a soil amendment on private lands, and so is often sourced from local forests.
municipal lands, and Indian reserve lands, Hardwood species such as maple and
but not on Crown Land (except for special birch have a higher energy density
cases such as research trials). Care should (kJ/kg of wood) than softwood species
be taken to ensure that the ash is clean and such as pine and spruce. Combustion
contains no heavy metals or trace elements. systems using hardwood will require less
frequent fueling. It is best practice to
Bulk density is how much the fuel weighs
process and burn cordwood locally and
per unit of volume (for example, kg/m3)
not move it long distances to reduce the
and includes the airspace between fuel risk of moving invasive species.
particles. The denser a solid biomass fuel
is, the more energy it contains per unit Cordwood fuel handling and storage
volume. Solid woody biofuels with greater Cordwood is often sold on a volume
bulk density are more economical to basis, such as by the cord (sometimes
transport and take up less storage space called a bush cord) (3.62 m3, 4 ft. x 8 ft.
(Marinescu, 2013). x 4 ft., stacked), or it can be processed
by the end user if they have access to a
Energy content is the amount of energy wood supply. Residential users can obtain
per unit weight (for example, MJ/kg or a fuelwood licence from the Ministry of
MJ/m3 of biofuel) the biofuel provides Natural Resources and Forestry to harvest
14 SOLID WOODY BIOFUELScordwood on Crown land for personal
heating use. A stumpage fee must be paid
to the government based on the amount
of wood harvested. The fee for 2018 was
$4.64/m3, which is approximately $11.70
per bush cord of wood (accounting for
30% airspace in the pile) (Government of
Ontario, 2018). Figure 5. This bioheat wood chip production
facility has an asphalt pad to eliminate dirt
and sand contamination and keeps the chips
Cordwood should be dried to 20% covered to allow them to dry. It has a storage
moisture content for two seasons of drying capacity of 1 000 oven-dry tonnes.
(Photo: Biothermic)
time (spring and summer) and covered
from the elements (Figure 1). Cordwood
that is not covered or dried long enough
will have a high moisture content and
will create more emissions and burn
inefficiently, requiring more wood to
provide the same amount of heat.
Cordwood is the most labour-intensive fuel Figure 6. Hog fuel (pictured here) cannot be
for the end user. Pre-processed cordwood used in the combustion systems discussed in
this guide.
can be purchased and delivered, but
the user must often stack the cordwood as energy chips, are different than pulp
themselves. If the end user decides chips. Pulp chips often have a higher
to harvest and process the cordwood quality requirement. Chip properties
themselves, it will be more work but can vary significantly, depending on the
can result in cost savings. It is difficult to source and the production method. The
automate cordwood handling systems, combustion systems discussed in this
so someone must be present to load the guide require chips of consistent size,
combustion system every few hours. composition, and moisture content. Wood
chips are cheaper to manufacture than
wood pellets but are more expensive to
transport because they have a higher
moisture content and lower bulk density.
Wood chips
Automated fuel handling systems can
Wood chips (Figure 2 and Figure 5) are
be used to fuel wood chip combustion
produced by chipping or grinding wood,
systems. Lower quality wood chips,
followed by screening the chips to make
often called hog fuel (Figure 6), can be
sure they are uniform in size. They are
of various sizes and content (wood,
generally made of mill residues, such as
bark, twigs, rocks, dirt) and are not an
slabs, bark, or shavings, and from logging
appropriate fuel for the combustion
residues. Biofuel wood chips, also known
systems discussed in this guide.
SOLID WOODY BIOFUELS 15Wood chip fuel handling and storage weeks) and in large quantities can begin
Chips are generally delivered by truck to pose safety and fuel quality risks
to a holding bin or room located near from decomposition, off-gassing carbon
the combustion system. There must be monoxide, and spontaneous combustion.
space near the storage facility for delivery Most combustion systems use the chips
access. A larger storage facility means before they begin to pose any risk. It is
fewer deliveries, but it requires more best to pile the logs and then chip them
space. The fuel storage area should be as needed to avoid these issues. The
sized such that delivery vehicles can always Guide to Wood Chip Fuel: Characteristics,
deliver a full load and so that there is Supply, Storage and Procurement (CSA
sufficient supply for two to four weeks of Group, 2019) provides more detailed
operation for smaller systems (consistent size make them well suited is currently available in some areas of
for transportation. It is not common in Ontario (central and northwest).
Canada to use additional binders in the
manufacturing process to hold briquettes
together.
Wood briquette fuel handling and storage
Briquettes are sold by the bag, box, or
pallet. They can be manually loaded into
a combustion system, or an automatic
loading system can be installed.
Figure 7. Pellets can be delivered in 18 kg bags
Briquettes must be kept completely dry or on a wrapped pallet (left) or in large tote bags
they will deteriorate and disintegrate. (right). (Photo: ICS Lacroix)
Wood pellets
Wood pellets (Figure 4) are made
by compressing sawdust into small,
cylindrical pellets that are 6 or 8 mm
in diameter and up to 40 mm long. Figure 8. A residential wood pellet storage set-
up for storing and transporting bagged wood
Lignin, naturally found in wood, holds pellets. (Photo: Innovations Initiatives Ontario
the pellets together. It is not common North)
in Canada to use additional binders Pellets will last for a long period of
in the manufacturing process to hold time if kept dry but will deteriorate and
pellets together. Wood pellets have disintegrate into sawdust if exposed to
highly consistent properties, resulting in even small amounts of moisture. Pellets
consistent combustion system operation. stored in bags should be kept in a dry
They are cheap to handle and transport place, such as a basement or enclosed
and are well suited to automated fuel shed, or be covered with plastic (Figure 8).
handling systems. If wood pellets are delivered in bulk by
Wood pellet fuel handling and storage truck, then an outside (Figure 9) or an
Pellets are sold by the bag or by bulk inside (Figure 10) storage bin is required.
truck delivery. Bulk delivery can be by tote Indoor storage bins can be above ground
(Figure 7) or pallet (Figure 8), or direct or below ground. They can be custom-
delivery by vacuum truck to a holding made, as long as they physically contain
bin or silo, eliminating the need for the pellets and dust and keep pellets
end users to handle pellets themselves dry. Agricultural silos are often used
(Figure 9). Vacuum truck delivery is the as outdoor storage (Figure 9). The fuel
most convenient delivery method and storage area should be sized such that
SOLID WOODY BIOFUELS 17delivery vehicles can always deliver a full Combustion system manufacturers will
load and so that there is sufficient supply also provide guidance for pellet storage.
for operation for two to four weeks for As of late 2019, new standards for pellet
smaller systems (1–2 MW) (Community CSA Group.
Energy Association, 2014). Where space is
available, systems can be designed such
that delivery occurs only once per year.
Figure 9. Delivery truck unloading pellets into a water-tight
agricultural silo using a vacuum hose. An automatic control
system tells the combustion system when to move pellets from
the silo to the combustion system.
(Photo: Biothermic)
Figure 10. An indoor
pneumatic pellet
delivery system automatically moves pellets from the pellet
storage room (right) and delivers them to the combustion
system (left). (Photo: Biothermic)
18 SOLID WOODY BIOFUELS4. BIOHEAT COMBUSTION 1 MW thermal output capacity. Wood
SYSTEMS pellets and wood chips are the most
Bioheat combustion systems are commonly used biofuels. Approximately
highly engineered mechanical systems 10% of those installations are in Ontario.
with many similarities in efficiency, Bioheat projects have successfully
performance, and emissions to modern been implemented in all industries,
fossil fuel and electric heating systems. with institutional installations making
Bioheat combustion system technology up the majority (S. Madrali, personal
is well established and is continuing to communication, January 7, 2019).
expand worldwide and in Ontario. These
Each combustion system considered in
technologies are popular in Europe
this guide is described in this section.
and the northern United States and
Table 2 provides a summary of the typical
have been widely implemented across
use of each combustion system and the
Canada. In addition to many wood stoves,
estimated costs. These costs are broad
approximately 400 facilities between
estimates and should not be used for
50 kW and 5 MW thermal output were
planning purposes. Table 3 shows the
operating in the commercial, institutional,
types of fuels that can be burned in each
and agricultural (such as greenhouses)
type of combustion system.
industries in Canada as of late 2017.
Most of these systems were less than
BIOHEAT COMBUSTION SYSTEMS 19Table 2. Typical application for different combustors and the associated fuel types,
installed cost, and approximate annual biofuel usagea
Nominal
Typical application and annual fuel
Installed costb efficiency
consumption
rangec
Cordwood stove $750 to $7 500
58% to 87%d
Pellet stove $1 750 to $7 500
(2.7 to 12 tonnes per year)
Cordwood furnace $3 000 to $11 000 33% to 79%
Residential
(18 to 225 tonnes per year)
Pellet furnace $6 500 to $13 000 48% to 89%
Institutional
Cordwood boiler 60% to 83%
and district heating
(>1 000 tonnes per
Twice the cost of a
Large institutional
Pellet boiler 85% to 90%
fossil fuel systeme
year)
Wood chip boiler 85% to 90%
a
Adapted from Becker et al. (2014) and conversations with manufacturers and suppliers.
b
Based on conversations with manufacturers and suppliers.
c
From USEPA 2018a, 2018b, 2018c. Efficiency measurements for stoves based on Canadian Standards Association (CSA) B415.1; all others based
on HHV. Boiler efficiency only considers systems with buffer tanks.
d
Data did not allow differentiation between cordwood and pellet stoves.
e
Boiler systems vary significantly in size and cost based on site-specific factors. Citing a dollar range is therefore not as useful.
Table 3. Fuels burned in each type of combustion systema
Combustion system Fuels burned Application
Residential
Stove Cordwood, briquettes, pellets
(10 kW to 50 kW)
Residential, commercial, and institutional
Furnace Cordwood, briquettes, pellets
(30 kW to 500 kW)
Residential, commercial, institutional, and
Cordwood, briquettes, pellets,
Boiler small district heating
wood chips (15 kW to 1 MW)
a
Individual combustion systems are usually designed to burn only one type of fuel. For example, a stove can burn cordwood or pellets,
but not both.
20 BIOHEAT COMBUSTION SYSTEMSStoves Stoves offer some important advantages Stoves (Figure 11) are heating appliances over other combustion systems. These most commonly used for heating individual include ease of operation, low initial cost rooms or single-family homes. They can to purchase and install, and the ability of be designed to burn cordwood and users to produce their own fuel if they briquettes or pellets. Traditionally, stoves use cordwood and can access a private had poor efficiencies (
Figure 13. Wood pellet furnace with indoor
pellet storage. (Photo: SBI)
Figure 12. Pellets are loaded into the hopper
of the pellet stove, as shown. A control system
then automatically moves the pellets to the
stove’s combustion chamber as required.
(Photo: Innovations Initiatives Ontario North)
Furnaces
Furnaces (Figure 13 and Figure 14) can
be used for heating small spaces, such as
single-family homes or small commercial
or institutional buildings. They can be
designed to burn cordwood and briquettes Figure 14. A cordwood furnace with electric
backup and indoor wood storage.
or pellets. They look and function similar
to a fossil fuel furnace and are installed in
the same location, such as a utility room in
the basement. Furnaces use a fan and duct
system to move hot air throughout the
home and are controlled using a central
thermostat (Figure 15).
New models come with controls to
regulate combustion, temperature, airflow,
and pellet flow (for pellet furnaces). These
controls can reduce emissions, improve
Figure 15. Modern thermostats control
combustion efficiency, and lower fuel combustion systems. (Photo: SBI)
consumption. A backup heating system is
usually required if using a furnace; units Labour requirements are modest and
can be bought with a built-in propane or include cleaning the ash tray and loading
electric backup system. Cordwood furnaces cordwood or briquettes into the furnace.
are designed to operate with electronic Fuel handling can be highly automated
controls and a duct fan, but they can for wood pellet furnaces. Users can opt to
operate without electricity (with decreased load pellets into a hopper on the back of
performance) in case of an outage. the furnace every few days or use a larger
22 BIOHEAT COMBUSTION SYSTEMS(utility room, heated shed, or boiler
room) or can be bought as a packaged
unit in a container (Figure 18 and Figure
19). A backup system may be required
for peak heating on the coldest days or
when people are not available to load the
system. The backup system is often an
electric hot water heater or boiler.
Figure 16. A 30 kW cordwood boiler used
to provide heat for a home or small office
building. On the right is the hot water storage
tank (2 250 L) used to store energy and
increase system efficiency. (Photo: Biothermic)
holding bin that automatically loads the
hopper (Figure 9 and Figure 13). Chimneys
should be cleaned regularly to remove
creosote and should be inspected for any
defects. Furnace manufacturers provide
cleaning and safety recommendations for Figure 17. Wood chip boilers installed at
their products. Clean systems will operate Confederation College. Each boiler can provide
500 kW of baseload. These boilers provide
safely, cleanly, and efficiently and will 85% of the space heating needs of the 400 000
last longer. square foot facility. (Photo: Biothermic)
Boilers
Boilers can be used to provide space
heat and domestic hot water, eliminating
the need for a second system to heat
domestic water. For space heat, they can
be easily integrated into an existing hot
water heat distribution system (hydronic
heating system loop) or a system that uses
ducts and fans. They can be designed to
burn cordwood, wood chips, briquettes,
or pellets. They can be smaller systems Figure 18. A containerized pellet boiler system
with an agricultural silo for pellet storage used
(Figure 16), used to serve homes and
to heat a school. This type of containerized
small offices, or larger systems, used to system can be used for cordwood, wood chip,
serve large institutional buildings (Figure and pellet boiler systems.
17) or district heating systems. They have
highly sophisticated controls and high
efficiency. They can be installed indoors
BIOHEAT COMBUSTION SYSTEMS 23Figure 19. A pellet boiler used to heat an elementary school. Even these larger systems use hot water
storage to increase efficiency and regulate heat output. Ash removal systems in larger combustion
systems automatically deliver ash from the boiler to a bin. This wood pellet boiler delivers ash to
a waste bin on wheels (right) for easy and clean ash removal. Operators simply wheel the ash bin
away and empty it. This type of ash removal system would be typical for the systems used in larger
institutional or commercial spaces.
High-performance models come with
advanced controls (Figure 20) and
additional hot water buffer tanks to help
regulate heat output (Figure 16, Figure
19, and Figure 21). It is important to
distinguish between buffer tanks and
domestic hot water tanks. Buffer tanks
are heat storage units and supply heat
in the form of hot water to the heat
distribution system (heat exchangers, air
ducts, or hot water pipes). The water in
the buffer tanks is distributed in pipes Figure 20. Combustion systems can come
to deliver heat but is never consumed with sophisticated controls that manage
building temperature levels and schedules
as potable water. Domestic hot water and domestic hot water in addition to
tanks get their heat (but not water) from the combustion system itself. These
control systems ensure clean and efficient
the buffer tank using non-contact heat
combustion, monitor fuel levels, and control
exchangers and supply hot water for fuel conveyance systems. This is a control
consumption. system for a pellet boiler, but it would be
similar to other boilers as well.
24 BIOHEAT COMBUSTION SYSTEMSSpace
Heating
Buffer Tank
(75 L/kW)
Figure 21. A general diagram showing how a boiler
Air Separator system isProbe
Boiler Temperature configured. The combustor (left)
Pressure Relief heats
Valve
water that is stored in a tank (right). The tank then feeds hot water to the building’s heating and
domestic hot water system. In some larger systems, the distribution pipes can act as the storage tank.
Low Water Cut-off
Boiler systems ofBalancing
all fuelValve
types need some sortAuto Air Vent
of hot water storage to ensure efficient operation. The
red and blue lines indicate hot supply and cold return water, respectively. The dashed lines represent
electronic signalsCirculator
from temperature
& Mixing Valve sensors that feedGauge
Pressure information to the boiler’s control system so it
can manage combustion efficiently. (Photo: Biothermic)
The additional heat storage in buffer needs of the other heating system
tanks can be beneficial as it allows components (e.g., domestic hot water or
the boiler to operate at 100% output space heat temperature needs).
whenever it operates, greatly increasing
Maintenance requirements vary
efficiency and reducing fuel consumption.
depending on the type of fuel and size
For large systems, the hot water pipe
of system. Smaller cordwood systems
distribution system may be able to act as
(residential and small commercial/
the hot water storage system. Tank size
institutional) require weekly ash removal
and temperature depend on application
and cleaning, a task that takes five
and fuel burned and must be determined
to ten minutes (Figure 22). Smaller
on a case-by-case basis. The temperature
pellet systems (residential and small
in the buffer tanks is dictated by the
BIOHEAT COMBUSTION SYSTEMS 25commercial/institutional) can operate Only boilers intended for indoor
for one to two months without requiring installation (including sheds and
cleaning and ash removal. Larger containerized systems) with a separate
commercial or institutional systems buffer tank are recommended. Outdoor
require monthly cleaning and have boilers (often using cordwood) have poor
automatic ash removal systems that need system efficiency (20% to 30%), high
to be emptied only a few times per year emissions, and use large amounts of fuel
(Figure 19). Some systems come with (Burkhard & Russell, 2012). Therefore,
an alarm to alert users that the ash bin they are not recommended.
needs emptying. Chimneys should be
Figure 22. Ash removal systems in combustion
cleaned regularly to remove creosote systems are user friendly. This cordwood boiler
and should be inspected for any defects. ash removal system uses a custom-designed
scoop to easily and cleanly remove ash.
Boiler manufacturers provide cleaning This type of system would be typical for the
and safety recommendations for their smaller systems used in homes and smaller
institutional and commercial spaces. (Photo:
products. Clean systems will operate
Biothermic)
safely, cleanly, and efficiently and will
last longer.
26 BIOHEAT COMBUSTION SYSTEMS5. IMPORTANT FACTORS TO considered when making a decision to
CONSIDER WHEN CHOOSING implement a bioheat project.
BIOHEAT
How will the benefits be
There are a number of important factors
communicated to the community, and
to keep in mind when considering a
how will the community be involved?
bioheat combustion system and some
Common misconceptions about bioheat,
important questions that need to be
including environmental and health
answered at the outset of the project
impacts, costs, and what a modern
(Neave, 2013). Some of these factors will
combustion system design includes,
not be applicable to residential bioheat
should be addressed early in the process
systems.
by communicating the benefits to the
Who will be the project champion? community and involving the community
A common factor in successful community early and often.
bioheat projects is a strong project
Are there the local skills, resources,
champion. This person or organization
and labour to plan, build, and operate
will see the project through from initial
a bioheat system? Bioheat systems
planning to community engagement to
require one or more operators to manage
installation and operation. Without a
the fuel and operate the system. Local
champion, projects routinely fail.
trades will be required for construction
What are the goals of the project? and periodic maintenance and repair.
Clear goals and values will help guide This may be challenging in remote areas
the project, remind the planners why the where local skills are not available.
project is important, and communicate to
Is someone prepared to undertake
the community why the project is being
the day-to-day labour required to
pursued. Common goals include:
operate the system? Depending on
• Reliable and low heating costs
the type of system implemented, the
• Renewable energy development
labour requirements will vary, but bioheat
• Local employment
systems generally require more work
• Energy independence
than fossil fuel systems. Wood chip
• Community collaboration
and wood pellet systems can be largely
What are the benefits of using biofuel automated and require relatively little
over other fuel sources? In some cases, labour, while cordwood systems must be
the direct cost of biofuel will be cheaper loaded with wood multiple times per day.
than the cost of fossil fuels or electricity. All combustion systems require periodic
In other cases, it will be more expensive. cleaning and ash removal to ensure
However, there are many additional efficient and safe operation.
benefits bioheat can provide that fossil
fuels or electricity cannot. These benefits,
discussed in Section 2, should be
IMPORTANT FACTORS TO CONSIDER WHEN CHOOSING BIOHEAT 27Who are the project partners, and How will the project be funded?
what will the governance structure be? There are various methods of funding
Deciding on project partners and what bioheat projects, including financing,
the relationship will be between these government grants, and service contracts.
partners will improve decision-making Funding sources may affect or determine
processes and project success. important factors of the project, such
as what fuel sources are acceptable,
Is there a local and reliable source what technologies can be used, or what
of biofuel, and how much does it governance structure works best.
cost? A local and reliable biofuel source
is essential to the viability of a project. What types of government permits
Without a reliable, high-quality source are required? The Ontario Building Code
of biofuel, the project will fail in the should be consulted, and any permit
long term. Various factors affect biofuel requirements of the Ministry of the
reliability, such as local labour skills, Environment, Conservation and Parks
viability of biofuel production, local forest should be determined. The type of facility
resources, mill openings and closures, under consideration, the combustion
and government policies. system chosen, its thermal output, and
the type of biofuel(s) to be used will
determine the permits required.
28 IMPORTANT FACTORS TO CONSIDER WHEN CHOOSING BIOHEAT6. NEW-BUILD BIOHEAT If the current system is electric radiators
INSTALLATIONS COMPARED TO or a fossil fuel system where there are
RETROFIT INSTALLATIONS many unit heaters spread throughout
Making the decision to heat with wood the facility and combustion occurs at the
early in the design stage of new buildings unit heaters, retrofits become much more
will help ensure success and will make complex and costly. In these cases, it is
certain that all mechanical systems are most likely that a bioheat boiler would be
designed appropriately. In situations installed and then hot water pipes and
where a bioheat system is being retrofitted radiators would be installed throughout
into an existing building, integration into the building. It is usually a technically
the existing heat distribution system can viable option, but it can be costly.
vary from simple and relatively inexpensive
In many cases, there may not be room
to complex and expensive.
for a new bioheat boiler in the existing
Bioheat systems can be relatively easily boiler room, especially when the old
connected to central heating systems that system is being left in place for backup.
heat air or water. For hot water systems, In these cases, a new building could be
a bioheat boiler will simply replace the constructed, or a containerized system
current boiler. For forced air, a bioheat (Figure 18) can be installed to house the
boiler would usually be installed (rather bioheat system.
than a furnace), and a heating coil
would be installed in the duct system to
heat the air. A mechanical engineer or
contractor can help determine the retrofit
possibilities.
NEW-BUILD BIOHEAT INSTALLATIONS COMPARED TO RETROFIT INSTALLATIONS 297. RESIDENTIAL BIOHEAT PROJECTS walls, replacing old windows and doors
In a single-family home, wood heating can with energy-efficient ones, installing a
provide ambient heat to one room or the programmable thermostat, and sealing
entire home. The options for combustion air leaks.
systems are stoves, furnaces, and boilers.
For more information on ways to improve
Residential combustion systems typically
home energy efficiency, visit the Canada
burn cordwood, briquettes, or pellets.
Mortgage and Housing Corporation’s
Proponents who are interested in heating
website to view their Energy Efficiency &
multi-unit residential buildings should
Cost Savings fact sheets. Home energy
refer to Section 8, “Institutional and
retrofit consultants or contractors can
commercial bioheat projects.”
also determine energy savings costs and
Energy-efficient housing estimates for home energy retrofits.
A tightly sealed and well-insulated home
Planning stages
will reduce the amount of fuel consumed
The general steps required to plan and
in heating. Most homes, especially older
install a residential combustion system are
homes, are poorly sealed and insulated
outlined below. Those interested in greater
compared to modern, energy-efficient
detail on residential wood and pellet
homes. Simple retrofits can help reduce
stoves should refer to A Guide to Residential
heat loads and fuel costs while improving
Wood Heating, by Canada Mortgage and
comfort levels. Common upgrades
Housing Corporation (2002).
include adding insulation to the attic and
A TIGHTLY SEALED AND
WELL-INSULATED
HOME WILL
REDUCE
THE AMOUNT OF
FUEL CONSUMED
IN HEATING.
30 RESIDENTIAL BIOHEAT PROJECTSDetermine the type of combustion Select a contractor to install the system.
system to install: stove, forced air Select a contractor based on the quality
furnace, or boiler. Each combustion of their past work, reference feedback,
system has different capital costs, and system costs.
operating costs, and labour requirements.
Details about the combustion systems Relevant regulations
The main regulation that applies to
can be found in Section 4. Installing a
residential users is the Ontario Building
combustion system in an existing home
Code (O. Reg. 332/12). The building code
will have more constraints than installing
requirements for combustion systems
in a new-build. Consult Section 6 for more
may differ depending on the location.
information on installing a combustion
Operation and installations must adhere
system in a new or existing home.
to the building code requirements, and
Determine the desired fuel source. The homeowners need to understand who is
type of combustion system will determine responsible for the building code in their
the fuel type. The availability of the fuel and area. A building permit may be required.
the labour requirements of loading the fuel Residential users can get more information
into the system need to be considered. For on building code requirements at their
example, cordwood may be more readily local municipal building department.
available than pellets in a given community,
but the labour intensity of loading a A common requirement by municipalities
cordwood boiler is higher than loading or insurance companies is that the system
pellet systems, which are largely automatic. is inspected by a qualified professional.
The municipality or insurance company
Obtain quotes and check regulations. will specify the type of professional,
Seek onsite cost estimates and the qualifications that the professional
installation assessments from reputable will require, and what the inspection
contractors or dealers. They will be must include.
able to provide information on proper
installation and regulations and they Residential installations are exempt
can answer questions about local fuel from environmental monitoring and
supply and heating appliances. Request compliance requirements in buildings or
past customer references and seek their structures designed for the housing of
opinions on the system they chose, the not more than three families.
fuel they used, and the quality of the
contractor’s service.
Obtain the right insurance. A bioheat
system is reliable and insurable. There are
insurance companies in Ontario that will
insure bioheat systems, and a contractor
can help identify those companies.
RESIDENTIAL BIOHEAT PROJECTS 318. INSTITUTIONAL AND
COMMERCIAL BIOHEAT PROJECTS
This section provides guidance on
institutional and commercial bioheat
projects. It reviews the key planning steps,
community engagement, fuel supply
issues, selecting a technology, and sizing
a system.
Project planning
Facility energy audit
Before selecting and sizing a bioheat
system, it is important to assess how
the facility uses energy and heat. An
energy-efficient building will require less
energy to operate. If the facility requires
less space heat and domestic hot water
heat, a smaller combustion system can
be installed, reducing the capital and fuel
costs. These savings can be substantial. A
good way to reduce energy demands is to
complete an energy audit of the facility.
An energy audit is completed by an
engineering consultant who specializes
in energy management and can make
recommendations for reducing energy
consumption and costs. At a minimum,
the energy audit should include a site visit
by that individual, an energy bill analysis
to determine current energy use and
costs, and a list of recommendations,
with estimated costs, benefits, and
any applicable funding programs to
help offset costs. Larger facilities may
require temporary energy metering and
modelling of building energy use. The
cost of an energy audit can range from
hundreds of dollars for small facilities
(homes, small offices) to thousands of
dollars for larger facilities.
32 INSTITUTIONAL AND COMMERCIAL BIOHEAT PROJECTSThe costs of an energy audit are usually 2. Complete a pre-feasibility study and
relatively small in comparison with the preliminary plan
identified savings, especially as the size A pre-feasibility study and a preliminary
of the building increases. The findings plan (sometimes collectively called a
of the energy audit can be used to help feasibility study) provide the technical
accurately size a bioheat system and foundation for the project. These two
identify opportunities where systems documents will answer important
could be converted to use bioheat that technical questions and identify the
might not be obvious. The energy audit specific processes and steps needed
will provide a net benefit even if the to take the project from concept to
bioheat project does not move forward. completion. This information is used to
determine whether the project should
Planning stages move ahead, and if so, what that process
There are four broad planning stages would look like.
discussed in this guide to assist
proponents in planning a bioheat system. A pre-feasibility study is usually a desktop
These steps are general in nature, and study to review the financial viability of
guidance from external experts and an a bioheat project. It would determine
internal champion will be required to whether a bioheat system is theoretically
make any bioheat project successful. feasible. It can use an online calculator,
such as the Wood Energy Financial
1. Identify a champion, engage the Calculator (Biomass Thermal Energy
community, and develop goals Council, 2018), FPJoule (FPInnovations,
To implement a successful bioheat 2018), or RETScreen (Natural Resources
project, a project champion must Canada, 2018b), to determine fuel
be identified (Neave, 2013) and the consumption and costs (see Appendix C
community must be involved. The for links to calculators). Multiple biofuel
champion will guide the project, engage types and combustion technologies can
the community, and develop project be assessed to rank the potential options.
goals. Keeping the community engaged Some background knowledge about
will increase the chances of project bioheat systems and cursory research
success and increase the benefits to the into biofuel and combustion system
community. Community engagement costs would be required for this step. An
is discussed in more detail on page 35. external consultant could be hired for
Projects fail without a strong champion a modest fee to complete this task. The
and community support. For bioheat pre-feasibility study should identify the
systems owned by private organizations, following information:
community engagement requirements
• Basic justification for the system
may not be applicable.
• Anticipated project goals
• Potential installation location(s)
• Ranked fuel types
INSTITUTIONAL AND COMMERCIAL BIOHEAT PROJECTS 33• Potential fuel suppliers and fuel quality At this stage, community members can
(for chips and pellets) have meaningful input and assess the
• Approximate delivered fuel costs project against predetermined goals.
• Type of combustion system, fuel The preliminary plan can be used to
storage to be used, and potential help secure funding and shows potential
suppliers funders that the project has a solid
• Approximate installed cost of systems foundation (Cold Climate Housing
considered Research Center, 2017). An experienced
• Community engagement strategy engineering consultant or similar
(basic) professional will be needed to help
• Approximate costs and benefits complete this plan. Establishing reliable
(community, economic, environmental) fuel suppliers, understanding fuel qualities
• Potential barriers that are available from the suppliers, and
• Information gaps matching combustion technology to fuel
• Next steps qualities are critical for the success and
reliable operation of a bioheat project.
If the project appears theoretically
feasible, the pre-feasibility study can be 3. Develop a business plan and assess
expanded into a preliminary plan. The costs in detail
plan will (Neave, 2013): A business plan assesses the costs and
• Determine biofuel availability and benefits of the project in detail, including
quality the impact of regulatory requirements
• Estimate the system size (Neave, 2013). The business plan should
• Identify a location for the bioheat include a life cycle–cost analysis for the
system project. Costs for design and installation,
• Recommend a type of combustion labour, fuel purchase and delivery, fuel
system and fuel storage and handling handling, maintenance, and repair should
system be determined. It is important to run
• Determine how the bioheat several scenarios or sensitivity analyses
combustion system will be integrated under different conditions. These scenarios
with the existing heating infrastructure could investigate different fuel prices,
• Assess community capacity technology costs, funding options, and
• Estimate capital and operational costs labour rates. This information will tell
and savings project planners under what conditions
• Identify funding options and amounts the project is viable or not viable and
• Investigate relevant regulatory help identify any risks, such as fuel
requirements cost fluctuations (Community Energy
• Identify the next steps Association, 2014). Depending on the
complexity of the project and the skills
The pre-feasibility study and preliminary available in the community, this step will
plan are important because they provide likely require a professional with experience
the basis for future decision-making. in community energy infrastructure.
34 INSTITUTIONAL AND COMMERCIAL BIOHEAT PROJECTSYou can also read
