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8/12/2019 Assessment of Agricultural Residuals as Fuel for Power Generation for OPG - 2010
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Contents
Acknowledgements i
Executive Summary iii
Chapter I Description & Overview of Agricultural Residuals 1
Chapter 2 Characteristics of Agricultural Residuals, Fuel ImprovementOptions & Harvesting Technologies 14
Chapter 3 Sustainable Harvesting of Agricultural Residuals 36
Chapter 4 Supply Chain Analysis & Potential Suppliers 48
Chapter 5 Economic Evaluation of Agricultural Residuals as a Biomass Fuel 63
Chapter 6 Potential Issues in the Agricultural & Political Arenas 83
Chapter 7 Summary, Conclusions & Recommendations 88
References 95
AppendicesAppendix A OPG Agricultural Residuals Study Outline 100
Appendix B Ontario Agricultural Census Regions & Constituents 103
Appendix C Summary of Agricultural Statistics for Ontario 105
Appendix D Determination of Water-Soluble Alkali 109
Appendix E CEN/TC 335 Biomass Standards 110
Appendix F Inspection Procedure for Ships that
Carry Grain and Grain Products 112
Appendix G Experimental Results on the Use of
Fuel Improvement Additives 115
C
ontents
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Executive SummaryThis study examines the sustainable removal of
agricultural residuals from Ontario farms for use as a
fuel alternative to coal by Ontario Power Generation (OPG).
The quantity of agricultural residuals which can be
sustainably harvested from Ontario farms was estimated
based on the preservation of soil organic matter (SOM)
and the minimization of soil erosion. Chemical charac-
teristics of agricultural residuals, fuel improvement
options and harvesting technologies were investigated
and assessed. The development of the supply chain
was analysed and included the identification of stake-
holders and recommended features. The cost ofbiomass fuel from agricultural residuals in various
forms was estimated at the OPG gate. Potential issues
in the agricultural and political arenas were identified,
which may arise due to a development of the bio-
energy sector based on residuals. Conclusions regarding
the feasibility of the utilization of agricultural residuals
as biomass fuel at OPG generating stations were
drawn and recommendations are provided for the
implementationof the biomass fuel industry in Ontario.
A total of 4.5 million tonnes of agricultural residualscan be sustainably harvested for energy applications
in Ontario in 2014.The sustainably harvestable amount
of residuals represents approximately 20% of the total
above ground agricultural residual biomass produced
in Ontario. This 20% quantity is based on the soi l
organic matter budget analysis and soil erosion
calculation. The current provincial crop mix and yields
suggest that a total of 2.8 million tonnes of residuals
could have been sustainably harvested in 2009. For a
conservative average crop yield improvement of 1%
annually, the sustainably removable quantity ofresiduals would increase to 4.5 million tonnes by 2014,
when OPG may require the biomass fuel. Corn stover
and cobs, cereal straws and soybean stover
altogether represent approximately 90% of the total
above ground residuals produced by Ontario f ield
crops. The susta inably harvestable quantity and type
of residual is farm-specific and depends on the
crop rotation, tillage practices, slope of the land,
availability of o ff-farm organic materials, SOM
level o f the land and the incorporat ion of
additional best farm management practices. In
Ontario, corn stover and cereal straws are expected
to be the major biomass fuels from agricultural
residuals due to their higher residual yields per hectare.
The nutrient content of agricultural residuals in their
natural state pose challenges to the combustion
process. However, a number of relatively simple fuelimprovement options are available which include
over-wintering, natural or controlled washing and the
use of additives. Corn cobs provide the best fuel qual-
ity of the major agricultural residuals in the province,
whereas corn stover and wheat straw contain higher
potassium and silicon contents, respectively. Natural
rain washing of agricultural residuals in the field is an
attractive option for fuel improvement and returns NPK
(Nitrogen, Phosphorus, Potassium) to the soil. NPK
and other nutrients in agricultural residuals may also
be recovered by existing and emerging technologies.Phosphorus recovery techniques for municipal wastes
have the potential to recover NPK from agricultural
residuals. Chemical additives could also help improve
the fuel quality of residuals during combustion. A
promising fuel improvement process is the torrefaction
of biomass which produces a high quality fuel and can
be used in combination with other fuel improvement
options. Fuel improvement technologies are expected
to be commercialized once a strong market for biomass
fuel from agricultural residuals has been established.
There is a need to develop the residual biomass
fuel supply chain, specifically fuel aggregators and
processors across Ontario, to meet the OPG demand
in 2015. Agricultural residuals are presently available
as a feedstock since Ontarios farmers produce these
materials as a co-product of their crops each year.
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Cereal straws and soybean stover can be harvested
using existing farm equipment. Specialized farming
equipment, which is soon to be commercialized, to
harvest corn residuals is necessary for greater
feedstock supply. Construction of fuel aggregators
and processors may take up to 18 months. This fits
within the 4 years required to establish the entire
biomass fuel supply chain. Participation of farm
co-operatives, existing or new generation, in the
biomass fuel business is the preferred option,
since it maximizes local community involvement.
Contracting with independent operators diversifiesthe supplier base for OPG. This option c an be
co up le d with farm co-operative suppliers. Third
party harvesting can play an important role in
the Ontario biomass supply chain due to the
narrow harvesting time window for grain corn, the
largest residual producing crop.
The total costs of cereal straw and corn stover
pellets at the OPG gate are $6.00/GJ and $6.57/GJ,
respectively, with a total potential supply of 4.5 million
tonnes in 2014. Pellets from cereal straws offer thelowest cost, however, the total supply of cereal straw
at this lower price is limited to 0.75 million tonnes due
to existing demands. Biomass fuel from agricultural
residuals is approximately 20% cheaper than from
energy crops due to lower raw feedstock costs. Pellets
from corn cobs and soybean stover have higher costs
compared to pellets from cereal straws and due to
lower yields per hectare. These economics may result
in farmers leaving low yielding residuals in the field for
SOM replenishment. Torrefied pellets are gaining
attention from biomass fuel consumers due to theirsuperior fuel quality along with better fuel handling
and storage properties. The establishment of commer-
cial scale torrefaction plants in Europe are expected
to lead to the deployment of this fuel improving and
processing technology in North America. The cost of
torrefied biomass from agricultural residuals at the
OPG gate could be approximately 10% lower than
un-torrefied pellets, if the biomass is torrefied
pri or to the pel let ization process. This lower cost
is due to the reduced grinding, pelletization and
trans portation costs of torrefied biomass. If the
biomass must be pelletized before it is torrefied,
the cost of torrefied pellets will be higher than
untorrefied pel lets at the OPG gate.
Adoption of conservation tillage, use of best farm
management practices, and understanding the
relationship between different crop rotations and thequantity of residuals sustainably removed, are critical
to the use of residuals in energy applications. To ease
concerns regarding soil degradation due to the
removal of residuals from the field, OPG should
collaborate with organizations such as the Ontario Soil
and Crop Improvement Association (OSCIA) and the
Ontario Federation of Agriculture (OFA) to develop
guidelines and monitoring processes for sustainable
harvesting of agricultural residuals. Potential stake-
holders are aware of the risks associated with investing
in fuel aggregators and processors due to the currentlow price of natural gas and the over capacity situation
of the Canadian biomass densification industry.
Investors, which may be farm co-operatives, need
a guaranteed market with long-term contracts and
attractive pricing to develop the new industry. Trade
agreements between the provinces and territo-
ries of Canada as well as the North American Free
Trade Agreement (NAFTA) may require that OPG
considers biomass fuels sourced from outside the
province. This could be a potential trade dispute issue,
if the biomass fuels are sourced only from Ontario.
The benefits of utilizing agricultural residuals as a
biomass fuel includes the continued viability of the
agricultural sector, rural development and job
creation, enhanced income distribution, greenhouse
gas emission reductions and a basis for future
ExecutiveSum
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biorefinery infrastructure. These benefits should be
quantified and communicated to policy makers.
Biomass supply contracts should be in place approxi-
mately 4 years before the biomass supply is required.
This allows the development of the biomass supply
chain, especially biomass processing facilities. Some
risk-sharing mechanisms, such as linking a portion of
the biomass fuel supply to the price of crude oil,
may be required during the initial stages of supply
development. A biomass fuel specification should be
developed and modified in stages to allow for the
utilization of emerging fuel improvement technologies.
A number of fuel aggregators and processors can beconstructed with concerted efforts by all stakeholders
to meet the demand in 2015. However, there will likely
be a price premium associated with the rapid estab-
lishment of this new industry. OPG should explore the
option of acquiring biomass from sources outside the
province during the initial stage of industry development.
This will also allow for the continued development of
the residuals biomass supply chain in Ontario.
Dr. Don Hewson
Managing Director, Industrial Liaison
The University of Western Ontario Research Park
Sarnia-Lambton Campus
Dr. Katherine J. Albion
Project Researcher
Commercialization & Research Engineer
The University of Western Ontario Research Park
Sarnia-Lambton Campus
Dr. Aung Oo
Project Researcher
Commericalization Consultant
The University of Western Ontario Research Park
Sarnia-Lambton Campus
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Agriculture is an important economic sector in Ontario.
Approximately 50% of Canadas Class I and II lands are
located in the province. Farming activities produce
human food and animal feed, and generate significant
quantities of agricultural residuals each year.
In this chapter, a global review is provided on the use
of agricultural residuals for power generation. The
current demand for residuals in Ontario, generally
used for agriculture and livestock production, was
determined, and emerging technologies expected to
incorporate residuals as a feedstock were identified.The current production of residuals in Ontario was
determined, and the major residual producing crops were
identified and evaluated as a potential biomass fuel.
1.1 Overview of the Use of Agricultural Residuals in
Power Generation
Biomass combustion is an emerging technology
around the globe. In many countries there are power
stations co-firing biomass with coal to generate
electricity. A number of generating stations arecurrently in the process of conducting test burns of
various types of biomass and in different ratios with
coal. There are few dedicated biomass generating
stations, and these are generally small plants. The
majority of the power stations operate using a small
quant ity of biomass combined with coal. Large
facilities often have the goal of complete convers ion
to dedicated biomass facilities.
1.1.1 Drax Power Station
The Drax Power Station has the largest power generation
capacity in Western Europe, and produces 7% of the
United Kingdoms electricity supply. The power station is
located near the town of Drax, in North Yorkshire,
England. Drax has a total generation capacity of 3,960
MW, including co-fire generation (Drax Group plc, 2010a).
In 2009, Drax burned 381,000 tonnes of biomass
as a 10% replacement of coal in co-firing operations.
Biomass burned consisted of pelleted wheat straw,
willow, miscanthus and wood chips. Total power
production from biomass was 475 GWh. (Drax Group
plc, 2010a).
Drax has proposed the construction of three dedicated
biomass generating facilities, each with a generating
capacity of 290 MW. Two of these plants will be located
in the Port of Immingham with the third adjacent to
the existing Drax coal fired plant. It is expected that1.3 million tonnes per year will be required to support
each dedicated biomass facility. Drax plans to source
biomass in the form of sustainable wood-based
products, forestry residues and residual agricultural
products. Drax has secured a ready and flexible supply
of raw materials from producer groups in the forestry,
farming and agricultural industries. Biomass is
expected to be acquired from within the United Kingdom
as well as imported. A policy has been developed to
ensure that the imported biomass has been produced
in a sustainable manner (Drax Group plc, 2010b). Thetotal renewable generation capacity of the Drax
biomass combustion operations will be 1,400 MW, which
includes co-firing operations and the construction of
new facilities (Drax Group plc, 2010a).
It was anticipated that by the end of 2010, that
three new 290 MW biomass dedicated plants
would be approved. However, in February 2010, it
was reported that these initiatives were on hold
due to low government subsidies, low prices of
coal and n atur al gas and decreased revenues. Itwas less expensive to run gas-fired stations due to
a lower electricity demand (Mason, 2010).
Chapter1Description & Overview of Agricultural Residuals
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1.1.2 Elean Power Station
The Elean Power Station is the worlds largest straw
fired power plant, located in Ely, Cambridge, UK, and
is owned by Energy Power Resources (EPR) Ely Ltd.
This power plant began commercial operation in 2000.
It is a 38 MW plant with an electrical output of 270 GWh
annually (EPR, 2010). It burns 200,000 tonnes of cereal
straw and a small amount of natural gas annually.
The main feedstock is straw from wheat, oats, rye and
barley, however, test burns have been conducted using
miscanthus and oil seed rape.
1.1.3 Show Me Energy
Show Me Energy Co-operative is a non-profit,
producer-owned co-operative formed to support the
development of renewable biomass applications in
Centerview, Missouri. The co-operative was initially
founded with 400 members to construct a biomass
pelletization plant. Approximately $8 million was
capitalized to build the plant with the capacity to
process 75,000 tons per year, and was subsequently
expanded to produce 150,000 tons per year of biomasspellets. Construction of the plant began in May 2007,
and the first pellets were shipped in July 2008.
The co-operative membership expanded in early
2010 to approximately 650 members. The increase in
membership was to generate capital for the increased
production of biomass pellets and for future
pr oduc tion of cellulosic biofuels (Tietz, 2010).
The biomass pelletized by Show Me Energy
Co-operative includes switchgrass, native grasses,
corn stover, sorghum residue and weeds. Essentially,the co-operative accepts all biomass materials,
however, the payment made to farmers for the
materials is based on the energy value of the biomass.
Generally, the price paid to farmers ranges from $45-
60 per ton of biomass. The United States Department
of Agriculture (USDA) has developed the Biomass
Crop Assistance Program (BCAP) to encourage farmers
and landowners to develop the biomass supply chain
as well as accelerate energy independence, rural
economic development and renewable sources
of energy. BCAP through the USDA Farm Service
Age ncy assists biomass producers by providing
matching payments for the collection, harvest,
storage and transportation of eligible biomass
de livered to approved facilities for conversion into
biofuels. Show Me Energy was the first facility in
the United States to receive matching payments for
biomass acquisition (Library USDA, 2010). This
program provides farmers with a total of $90-120per ton for their biomass.
Sh o w Me E n erg y wi l l o n ly accep t b io mass
i f sus ta in ability practices are implemented. For
agricultural crop residuals such as corn stover, 30%
of the residual materials must remain on the field. For
prairie grasses, a killing frost must occur before the
harvest, and grasses must not be harvested around
water courses to minimize soil erosion (Ebert, 2008)
Large customers of Show Me Energy includeNorthwest Missouri State University with installed
commercial biomass burners for campus heating. The
biomass pellets have also been tested by a local
electrical utility for co-firing with coal to produce
electricity (Tietz, 2010). The Kansas City Power
and Light Sibley Generating Station has conducted
co-firing tests of Show Me Energys pellets at co-firing
concentrations of up to 40-50% biomass with coal
(Flick, 2009).
1.1.4 Global Biomass Combustion
There are more than 200 generating stations around
the world using biomass as a fuel. The majority of
these plants burn wood and wood residuals to generate
electricity and have a capacity of less than 50 MW. In
Canada, there are more than 20 independent power
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producers, mainly in pulp and paper mills which
process spent liquor, bark and wood residuals. In
Ontario, there are 4 co-generation plants which
combined produce 56 MW of power from wood
biomass. In the United States, there are more than 60
power plants co-firing biomass and coal with a total
co-firing capacity of 5,080 MW. The fuel sources
are mainly paper, wood products, corn, sugar and
agricultural residuals. In Europe, there are more than
100 generating stations co-firing biomass and coal
(Bradley, 2009).
As part of power generation initiatives, a number of
operations are incorporating a small percentage of
biomass, generally 10-30%, into the coal operations.
The fuel most widely used is wood and wood based
materials. Agricultural residuals and energy crops have
mainly been utilized in small quantities or in test burns.
There is a small scale power plant in the United Kingdom
which uses cereal straws as the feedstock to generate
electricity. There are no large scale dedicated biomass
power plants burning agricultural residuals worldwide.
1.2 Current and Emerging Demands
The bio-based industry is an emerging business due to
the development of many new products and business
processes that focus on the use of biomass as a raw
material. Along with these new developments, are the
traditional uses of biomass such as animal bedding,
animal feed and crop production. All these uses are
important to consider when determining all the amount
of agricultural residual material available in Ontario,
without depletion of the supply for traditional uses.
1.2.1 Current Uses of Agricultural Residuals
Currently, wheat straw is the most widely used agricul-
tural residual in Ontario. Wheat straw has traditionally
been used by livestock and in agriculture. Other residuals,
such as corn stover or corn cobs, are not currently used
on a large scale. Straw supply and price fluctuations
depend on the demand, availabili ty, and intended
use in specific geographical regions. Wheat straw has
also recently become a feedstock for the production of
cellulosic ethanol in the Ottawa region for Iogen
Corporation. Table 1.1 highlights specific applications
and quantities of wheat straw currently used in
Ontario. The estimates provided indicate that
approximately 1.5 million tonnes of wheat straw are
consumed in Ontario each year, mainly in the agricul-
tural and livestock sectors. The values presented inTable 1.1 are based on data provided by Statistics
Canada for the Province of Ontario, statistics on the
OMAFRA web site as well as personal communication
with stakeholders in the agricultural community.
1.2.1.1 Agricultural Residuals Consumption
by Animals
As of January 2010, the inventory of cattle in Canada
was at the lowest level in 15 years. However, in 2009,
the number of cattle increased in Ontario by 2.2%
Use Quantity
(tonne/year)
Livestock
Agriculture & Horticulture
Biofuels
Cattle BeddingHorse Bedding
Cattle Feed
Sheep Feed
Ginseng Production
Strawberry Production
Mushroom Production
Cellulosic Ethanol
Total Wheat Straw Usage in Ontario
1,154,200248,600
48,800
1,300
51,500
11,500
2,400
9,125
1,527,425
Table 1.1 Applications and Quantities of Wheat StrawUsed in Ontario
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from the 2008 inventory. The number of sheep in
Canada also declined between 2009 and 2010. The
reduction in cattle is due to market uncertainty and
rising input costs over the years. Draughts early in
the decade affected water and forage supplies
and damaged pastur es. The discovery of Bovine
Spongiform Encephalopathy (mad cow disease)
in 2003 stalled the Canadian cattle industry, and
resulted in a slow recovery of export markets,
increased processing and testing costs and low market
prices for beef cattle. In 2007, the production of grain
ethanol resulted in higher prices of feed grain whichincreased the cost of feed for livestock producers. The
export market for Canadian livestock was reduced
due to the introduction of the Country of Origin
Labelling regulations and the appreciation of the
Canadian dollar (Statistics Canada, 2010).
The statistics in Table 1.1 were used to determine the
amount of residuals used by livestock and other
animals as bedding and feed. The trends and factors
influencing the number of animals in Canada, and
specifically Ontario, can be used to predict the futurequantities of residuals that may be required by animals.
It is expected that the number of cattle in the province
will stabilize following the decline of the last 15 years.
(i) Agricultural Residuals as Animal Bedding
Animal bedding provides two essential purposes for
cattle and horses. The first is as protection from severe
weather including snow, ice and wind, and allows the
animal to reduce its surface area exposed to the
elements to minimize the risk of hypothermia andfrostbite in the winter months. Bedding is important
throughout the life of the animal and it is essential for
protection and survival of the calf. Secondly, the use
of bedding lowers the nutritional requirements of the
animal. Alternative bedding materials have been used
for cattle which include soybean stover, corn stover
and barley and oat straws. The best steer weight gain
occurred when wheat straw was used as bedding,
whereas for heifers, all bedding materials resulted in
similar weight gain (Ringwall, 2009). Industrial
waste materials have also been considered for use as
animal bedding as well as forestry by-products
such as wood chips and wood shavings, and switch-
grass. OMAFRA suggests that beef cattle require
approximately 4 lb/head/day of bedding (Kains et al.,
1997). This quantity was assumed also for dairy cattle
to determine the total amount of bedding required
for all Ontario cattle.
Bedding impacts the cost of housing the animals, the
labour involved in stall cleaning, manure storage
capacity and nutrient management. A number of
bedding materials are available for horses including
pine shavings, wheat straw, peat moss and coir.
Ultimately, it is the disposal cost of the bedding
material that governs the material choice. Straw
bedding is recycled to the mushroom industry. Wheat
straw also keeps horses clean and does not produce a
large amount of dust compared to other beddingmaterials (Molnar and Wright, 2006).
(ii) Agricultural Residuals as Animal Feed
Small quantities of agricultural residuals are used as
animal feed, specifically for cattle and sheep. Small
amounts of wheat straw have been included in horse
feed. Straw contains little nutritional value for horses,
but is a source of fibre. Straw bedding allows the
horse to chew and reduces wood-chewing behaviour,
if all other nutritional requirements are met (Ralstonand Wright, 2005).
Animals have a diet of grains and forages. Some
animals, including cattle and sheep will also consume
residuals as feed. Statistics Canada has provided an
estimate of livestock feed requirements, which
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in cludes roughages. Roughages consist of straw,
by-products, beet pulp and vegetables wastes. For the
purpose of this study, 75% of mass of the roughages
was assumed to be straw, in order to determine the
amount of straw consumed by animals. Beef cattle
were found to consume the greatest amount of
roughages, followed by dairy cattle and sheep
(Statistics Canada, 2002).
In the winter months, straws and stovers can be used
as a component of cattle feed as these residuals are
available at fractions of the cost of hay and can be usedto dilute high quality forages to meet the nutritional
requirements of pregnant cows. Cereal straws can
be used as a filler and energy for beef cows. This is
applicable to cows that are healthy and are more than 6
weeks away from calving since they have the lowest
nutrit ional requirements of the herd. Oat and barley
straws have the highest energy contents and are
preferred by cows, followed by wheat straw. OMAFRA
recommends that a 60-40 straw-hay mix can be sup-
plied as feed, and supplemented by energy and protein
(Hamilton, 2009). Corn stalkage has similar nutritionalcontent and fibre digestibility to wheat straw and is
under utilized as a low quality feedstuff in beef cow
feed. OMAFRA does not advise the use of a high
quantity (40% dry matter of the feed or greater) of corn
stalkage included in the feed for beef cows as it is not
palatable resulting in less feed consumption by cows
and reduced body weight (Wood and Swanson, 2009).
1.2.1.2 Use of Agricultural Residuals in Agriculture
and Horticulture
Historically, wheat straw has been the widely used
residual in agriculture and horticulture. Recently in
Ontario, with the emergence of ginseng production,
this has become the major application of straw for crop
production. Wheat straw is used as a mulch and bed-
ding medium in horticulture and for specialty crops.
Ginseng is a slow-growing herbaceous perennial plant
which is harvested 3-5 years after seeding. Ginseng is
cultivated for its root which is dried and sold whole,
powdered or sliced. It is one of the most widely used
medicinal herbs in the world. The ginseng root is used
in a wide range of products, including tea, candies,
beverages, tablets and capsules. One reason for the
increased demand is due to its use as a natural
supplement to help prevent the common cold and flu.
North American ginseng is also exported to Asian
markets to complement the benefits of Asian ginseng
(Agriculture and Agri-Food Canada, 2007).
Commercial cultivation of North American ginseng
began in Canada in the late 1890s, but it was not until
the early 1980s that ginseng production experienced
exponential growth due to lucrative profits. Ginseng
is an emerging crop in southern Ontario, specifically
in the sand plains north of Lake Erie where tobacco
was traditionally grown. Ginseng production has
increased dramatically in recent years to 2,896 ha
in 2006, from 1,813 ha in 2001. More than half of
the gin seng producing land is in Haldimand-NorfolkCounty with Brant and Oxford Counties being the
next largest producers respectively (Statistics
Canada, 2007).
Production of ginseng requires significant quantities
of straw. One acre of ginseng production requires
approximately 7 tonnes of wheat straw, in order to
cover the crop with 2 to 4 inches of straw. This straw
is used as a mulch for moisture retention and protection
of the ginseng root (Schooley, 2009).
Strawberry production in Canada has remained
relatively stable since 1995, at approximately 25,000
30,000 tonnes per year. Ontario produces 31% of
Canadas strawberry crop, and can be grown throughout
the province (Agriculture and Agri-Food Canada, 2008).
Strawberries are a shallow rooted perennial plant that
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are grown in every province of Canada. Straw is used
in the production of strawberries to protect the plant
against winter temperatures. Cold temperatures result
in damage to the plant roots, crowns and flower buds
and soil freezing and thawing lifts plants out of the soil
resulting in root breakage. Wheat, oat or rye straws
are ideal materials to protect the strawberry plant. The
straw requirement for winter protection is between 2.3-
3.2 tonnes/acre (Fisher, 2004). Straw is preferred to
other mulch materials such as hay and grasses which
lead to weeds or smother the strawberry plants. After
the winter, three-quarters of the straw is placed between
the rows of strawberry plants to prevent weed growth
and to keep the berries clean. A small amount of straw,
2-3 inches, can cover the plants during blossoming for
frost protection (Ricketson, 2004).
Canada has over 100 mushroom farms across the
country and produces approximately 105 million kg of
mushrooms annually. Approximately 57% of the
mushrooms grown are produced in Ontario. The
majority of the mushrooms produced are sold fresh in
Canada. Fresh mushrooms are also exported to the
United States, and canned mushrooms are exported to
China (Mushrooms Canada, 2010).
Straw is a significant component of mushroom
growth medium. The mushroom growing medium
is composed of straw, horse and chicken manures and
gypsum. Also included in horse manure is the horse
bedding which is mainly straw. The growing area of
mushrooms has been increasing over the last 10 years
from 129,447 m2 of growing area in 2001 to more than
418,000 m2 in 2009 (Statistics Canada, 2007, 2010).
1.2.1.3 Use of Agricultural Residuals as a Biofuel
Iogen Corporation is a cellulosic ethanol producer with
a demonstration facility in the Ottawa region. This
small-scale facility was designed to process 20-30
tonnes/day of feedstock to produce 5,000 6,000 L/day
of ethanol. The ethanol produced by Iogen is used by
Shell in their fuel applications. The ethanol is also used
to partially power Ferraris Formula 1 Grand Prix race
car (Taylor, 2010).
The main feedstock used to produce this cellulosic
ethanol is wheat straw. The process has also been
tested using corn stover, switchgrass, miscanthus, oat
and barley straw, sugarcane bagasse and hard wood
chips. Wheat straw is collected by Double Diamond
Farms from wheat producers in northern and eastern
Ontario and shipped to Iogen. A full scale plant is
planned to be constructed in Saskatchewan. This plant
will use cereal straw as the feedstock and 600 farmers
have agreed to supply the facility (Taylor, 2010).
1.2.2 Emerging Uses of Agricultural Residuals
There are many emerging uses of agricultural residuals
that may result in competition for this feedstock
material. Many applications are under development
to utilize residuals as a feedstock for the production
of bioenergy, biochemicals and bioproducts.
Currently, corn stover is not widely used for the
production of bio-energy or bio-products. Processes
are under development for many new products and
fuels but are not yet at the large commercial
scale. These appli cations include:
Biocomposites: the fibre from corn stover is
used in the production of bio-composites for
the automotive and building industries.
The corn stover fibres reinforce a resin matrix
to replace composites of fibreglass, carbon fibre
and talc.
Bioethanol: ethanol is produced from lignocell-
ulose in the corn stover. This technology
is currently expensive, but is expected to
become less expensive as the technology
is improved and scaled up.
Description&OverviewofAgriculturalResiduals
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Pulp and paper: corn stover fibre is used in the
production of paper to replace wood fibre and
accounts for 5-10% of the worldwide paper
production. There are many disadvantages to
using corn stover in the pulp and paper
industry including the seasonal availability,
chemical recovery challenges, pulp brightness
and the requirement of large quantities of water
and energy during production.
Animal feed: OMAFRA has suggested that ewes
and wintering beef cows graze corn fields over
the winter months. This allows the animals toeat corn kernels and small cobs that passed
through the combine. This provides the animals
with increased nutrients early in the season
when more crop leftovers are in the field and
before the biomass is weathered.
Corn cobs are a residual receiving much attention and
many applications are under development for this
underutilized residual:
Chemicals: furfural can be produced from
corn cobs. Furfural is a solvent used in thepetrochemical industry to produce resins in
fibreglass manufacturing. To date, it is the high-
est valued chemical produced from corn cobs.
Sand blasting: corn cobs are reduced to a fine
particle size and used as a replacement for sand
in sand blasting applications. The ground corn
cobs clean and strip wood surfaces and are used
as a mulch following the blasting application.
Bioethanol: many ethanol producers, such as
Greenfield Ethanol, are developing technology
to use corn cobs as a feedstock for cellulosicethanol production. Although not yet at the
commercial stage, it is expected that cellulosic
ethanol will become mainstream in the future.
Wheat straw is widely used in agriculture, however, in
addition to ethanol production, bio-based products are
also being developed using wheat straw as a feedstock.
Automotive components: the automotive industry
is using wheat straw in reinforced plastics in
side cars, trucks and SUVs. The Ford Motor
Company is using 20% wheat straw as a bio-filler
in the third row storage bins of their Ford Flex
vehicles. These SUVs are built in Fords Oakville,
Ontario, assembly plant and the wheat straw is
supplied by 4 southern Ontario farms.
Barley straw applications have been developed,
however are not widely used. These applications include: Algae control in ponds: barley is the only straw
that can control the formation of algae in ponds.
Barley must be supplied to the pond prior to
algae bloom growth, in an adequate dosage with
adequate aeration, proper location and depth,
and water circulation. Although the mechanism
behind this growth inhabitation is unknown, it
is thought that the type of phenolics or lignin is
important and effects breakdown or provides a
carbon source for increased microbial growth
which limits phosphorus update by the algae. Housing insulation: the use of barley straw as an
insulation can double the R value of standard
homes. Straw bales are stacked in a similar
manner to bricks, off the ground. Homes with
straw insulation are finished with a common
brick or plaster exterior. Two-string bales are the
insulation standard, however, if larger bales are
used, it provides better insulation.
Agricultural residuals can also be used as a feed-
stock for thermochemical conversion technologies,such as pyrolysis. The pyrolysis process produces
bio-oils, bio-chars and syngas. Bio-oils can be
upgraded for the production of fuels and the
extraction of chemicals, syngas can be used as an
energy source and bio-chars may be used as a soil
amendment and activated carbon.
D
escription&
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The future demand for agricultural residuals cannot
be predicted with high confidence. There are manytechnologies that are currently under development
and undergoing scale-up and commercialization.
Many industries are interested in developing
processes that utilize biomass, including agricultural
residuals, to produce energy and products to replace
or supplement petroleum based feedstocks.
1.3 Above Ground Residuals Production in Ontario
Agriculture is a significant economic sector in Ontario.
The province is home to approximately 50% ofCanadas class I and II lands. Ontario also produces
about 75% of the nations soybeans. Figure 1.1
presents a snapshot of Ontarios agricultural land area
and its use. In Ontario, crop land represents 68% of the
total agricultural land in the province. The livestock
industry also has a critical role and generates close to
50% of the total farm cash receipts (OMAFRA, 2006).
The declining livestock industry, which is the major
consumer of agricultural residuals, may result in a
reduced demand for residuals. This would allow for
increased residual use in other applications suchas power generation.
Field crops are the largest share of crop land in theprovince. Table 1.2 provides t he harveste d and
unharvested hectares of major field crops. These data
are the 2003-2009 average, sourced from OMAFRAs
field crops statistics. There is a small percentage
of field crops left unharvested every year due to
poor yields or other factors, and these unharvested
crops could contribute to bio-energy production. As
seen in Table 1.2, hay crops are the most widelygrown field crop followed by soybeans, grain corn and
winter wheat. Hay crops produce little above ground
residuals and do not allow for economic harvesting,
therefore, residuals used for energy applications
should be sourced from the other major crops. Table
1.3 provides estimates of the residual-to-crop ratio for
major field crops. Due to uneconomical harvesting,
residuals from hay crops and fodder corn are not
expected. Cereal crops such as winter wheat, barley
and oats have higher residual-to-crop ratios. Different
varieties of a particular field crop, for instance varietiesof winter wheat, have a range of residual-to-crop
ratios, however, the average values are considered
in Table 1.3 t o simplif y the estimate of the total
agricultural residuals produced in the province.
Based on the harvested and unharvested acreages of
major field crops and the estimated residual-to-crop
ratios given in Tables 1.2 and 1.3, the above ground
residuals production from each major crop are
calculated and presented in Table 1.4. Approximately
13.7 million tonnes of above ground residualsare produced from field crops in Ontario. As high-
lighted in Table 1.4, gra in corn , winter wheat and
soybeans are the major residual producing crops,
representing almost 90% of the total residuals
from field crops. Grain corn generates the
largest amount of residuals, nearly half of the
total above ground residuals in the province.
Field crops, which occupy 3.36 million hectares of a
total of 3.66 million hectares of crop land in Ontario,
are not the only crops grown in Ontario. Other crops
such as field vegetables, apples, grapes and other
fruits also produce small quantities of agricultural
residuals. Figure 1.2 shows the total hectares of other
crops in comparison with field crops and the average
above ground residual production estimates in
tonne/ha, including the expected moisture content at
Description&Overvi
ewofAgriculturalResiduals
Total agricultural land in Ontario: 5.38 Mha
Crop land: 3.66 Mha
Pasture land: 0.75 Mha
Christmas trees,woodland, wetland: 0.75 Mha
Other: 0.22 Mha
Figure 1.1 Agricultural Land Use in Ontario
(OMAFRA Statistics)
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Field Crops Hectares Harvested* Un-Harvested Area*
(% of Hectares Harvested)
Hay
Soybeans
Grain corn
Winter wheat
Fodder corn
Barley
Spring wheat
Mixed grain
Dry field beansOats
Fall rye
Tobacco
Canola
971,082
893,580
692,319
366,975
122,788
82,822
61,191
53,499
29,38137,883
24,586
11,032
17,293
3,364,432Total
2.73
0.62
2.99
0.05
1.57
5.47
0.39
13.65
0.8413.46
3.00
1.00
5.35
N/A
Data acquired from OMAFRA (2010). *Calculations based on Field Crop Statistics from 2003-2009.
Table 1.2 Harvested and Unharvested Hectares of Major Field Crops in Ontario
Field Crops Average Crop Yield (tonne/ha) Residual-To-Crop Ratio
Hay
Soybeans
Grain corn
Winter wheat
Fodder corn
Barley
Spring wheat
Mixed grain
Dry field beans
Oats
Fall rye
Tobacco
Canola
2.49
2.65
8.82
5.13
37.29
3.29
3.33
2.93
2.15
2.54
2.37
2.59
2.02
0.0
1.1
1.0
1.7
0.0
1.5
1.3
1.2
1.1
2.0
1.5
1.0
1.0
(OMAFRA publications, Communication with OFA personnel, Helwig et al. (2002))
Table 1.3 Crop Yield and Residual-to-Crop Ratio of Major Field Crops in Ontario
D
escription&
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esiduals
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harvest. As seen in Figure 1.2, other crops represent a
relatively small percentage of the total crop land in the
province. Field vegetables and greenhouse crops
produce higher residual tonnage per hectare. How-
ever, the moisture content of these residuals is too
high to be processed as a biomass fuel for OPG.
These high moisture agricultural residuals can be used
to produce compost that can be added to farm land
which grows field crops. This addition may allow for
the removal of a portion of relatively dry field crop
residua ls for bio-energy applications. Table 1.5
summarizes the total above ground agricultural
residual production in Ontario for all crop lands.
An additional potential source of agricultural biomass
fuel is pearl millets grown as a pest control measure
for potato, tobacco and strawberry crops (Anand
Kumer et al., 2009). Since there is a very limited market
for millets in Ontario, this pest control crop can
contribute to the bio-fuel supply. Pearl millet is a
Field CropsHectares
Harvested
Crop Residuals
(000 tonne)
Un-harvested
Residuals(000 tonne)
Total Residuals
(000 tonne)
Hay
Soybeans
Grain corn
Winter wheat
Fodder corn
Barley
Spring wheatMixed grain
Dry field beans
Oats
Fall rye
Tobacco
Canola
971,082
893,580
692,319
366,975
122,788
82,822
61,19153,499
29,381
37,883
24,586
11,032
17,293
3,364,431
0
2,601
6,107
3,200
0
409
265188
70
192
87
29
35
13,183
49
2,624
6,381
3,202
54
437
266223
71
221
90
29
38
13,685
49
23
274
2
54
28
135
1
29
3
0
3
502Total
Major Crops Hectares Harvested Residuals Produced(000 tonne)
Field crops
Fruits
Vegetables
Greenhouse crops
13,687
50
1,774
928
16,439
3,364,431
24,818
70,971
9,276
3,469,497Total
Table 1.4 Estimate of Annual Residual Production from Major Field Crops
Table 1.5 Total Agricultural Residual Production from Major Crops in Ontario
Description&Overvi
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escription&
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esiduals
Figure 1.2 Field Crops and Other Crops Hectares in Ontario with Residuals Estimates
high biomass yielding cereal crop which requires
low chemical inputs, has good draught resistanceand is effective in controlling some nematode
species. The potential biomass quantity from
pearl mil let is estimated and gi ven in Table 1.6.
It is assumed that millet is grown every three
years as a pest control crop and yields 13
tonne/ha of dry biomass.
1.4 Preliminary Evaluation of Agricultural Residuals
As presented in the previous section, three field crops,
namely grain corn, winter wheat and soybeans,
represent approximately 90% of the total above
ground residual production from field crops in Ontario.
These 3 field crops should be the agricultural resid-
uals considered for large scale power generation by
Crop Hectare Millet Hectares in
Rotation
Biomass Yield
(tonne/yr)
Potato
Tobacco
Strawberry
Total
15,441
12,816
1,717
5,147
4,272
572
66,911
55,536
7,436
129,883
Table 1.6 Potential Biomass Fuel from Pearl Millets in Rotation as a Pest Control
24,818
70,971
9,276
3,364,432
Field Crops
Fruit Crops
Vegetable Crops
Greenhouse Crops
Residual Estimates
4 tonne/ha @ 15% Moisture
2 tonne/ha @ 15% Moisture
50 tonne/ha @ 75% Moisture
100 tonne/ha @ 75% Moisture
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OPG. Each of these three major residual producing
crops has advantages and disadvantages w hen
used for bio -ene rgy appl ications . These advan-
tages and dis advantages are discussed below
through a preliminary evaluation. Detailed
analysis and evaluations reg ard ing the sustain-
a bi li ty a nd e c o n o m i c p e r s p e c t i v e s a r e
p ro vided in the following chapters.
Currently, the most used agricultural residual in
Ontario is cereal straw. This includes mainly winter
wheat straw and straws from other cereal crops suchas barley, spring wheat, mixed grain, fall rye and
canola. The total annual production of cereal straw in
Ontario is approximately 4.5 million tonnes, which
represents about 33% of the total above ground field
crop residuals. Advantages of cereal straw as a biomass
fuel include the ability to harvest using conventional
farming equipment and known market prices. There is
a cereal straw surplus in the province, and the declining
cattle industry should result in a decreasing straw
demand for animal bedding. Farmers usually harvest
and sell cereal straw when there is a market demand,therefore, harvesting practices are not new to the
farming community. The disadvantage of cereal straw
as a biomass fuel includes possible competition with
existing consumers. The demand beyond a certain
volume could lead to a sharp price increase.
Soybeans are the second largest field crop in Ontario
following hay crops. The annual above ground residual
production from soybeans is approximately 2.6 million
tonnes, which represents about 19% of the total resid-
uals production in the province. Advantages of soybeanstover as a biomass fuel include a lower moisture
content at harvest and limited market competition.
Soybean stover can be harvested using existing farm
equipment with slight modifications. The market price
may be relatively easy to estimate based on the
residuals yield and the activities involved in harvesting
and bailing. Some farmers harvest soybean stover,
although not frequently. Soybean stover may be
used as animal bedding when the wheat straw
price is high due to imbalanced straw supply an d
demand in a particular region.
Disadvantages of soybean stover as a biomass fuel
may include greater dust production during harvesting
of the stover, which is brittle. Soybeans are small
plants and do not produce a large quantity of above
ground residuals. Without incorporating farm manage-
ment practices such as growing cover crops, the
removal of soybean stover for energy applicationscould lead to greater soil erosion.
Grain corn generates the greatest quantity of
residuals, 6.4 million tonnes, of all the major field
crops. This represents about 47% of the total annual
above ground residual production in Ontario, and
consists of 5.7 million tonnes of corn stover and 0.7
million tonnes of corn cobs. Advantages of corn
residuals as a biomass fuel include limited market
competition, high residual yield, and the will ingness
of farmers to remove a portion if a market exists.In some Ontario regions, excess corn residual
biomass in the field prevents conservation
tillage, since residuals must be incorporated
into the soil through conventional ploughing to
ease planting in the next growing season.
Disadvantages of corn residuals as a biomass
fuel include the need for specialized harvesting
equipment, specifically for corn cobs, and additional
passes to harvest the residuals. Another major issue
regarding the corn residuals harvest may be thenarrow harvesting time window. Grain corn is usually
harvested between late October and early November,
where harvesting depends on the moisture content
of the grain. A combination of a humid summer and
an early snowfall may reduce the harvesting time
window for grain corn to a few weeks with a tight
time window to collect the residuals.
Description&Overvi
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Table 1.7 evaluates the three major residual producing
crops in Ontario as a biomass fuel at the commercial
scale. Since biomass fuel may be acquired by OPG in
the 2014 harvest season, the harvesting technology
development timing receives the highest weighting
followed by current harvesting practices. Cereal straw
receives the highest overall score of the major residual
producing crops. However, the amount of cereal straw
available for power generation may be limited due to
the existing market demand. Soybean stover and corn
residuals rank similarly in the evaluation as a biomass
fuel. As previously mentioned, growing cover crops
may be required following the soybean stover harvest
to prevent soil erosion. Corn stover and corn cobs
provide the largest quantity of agricultural residuals in
the province. The time required to develop and deploy
new harvesting equipment may be longer for these
residuals in comparison with other residual materials.
A corn residual supply chain must be developed to
ensure a stable supply of biomass fuel.
Current
HarvestingPractices
Biomass
QuantityAvailable
Market
CompetitionFactors
SocialAcceptability
TotalScore
(Max 85)
Harvesting
TechnologyDevelopment
Timing
Weighting
Cereal
straw
Soybean
stover
Corn residuals
(stover &
cobs)
4
5
4
3
3
4
3
5
5
3
4
3
2
3
5
5
3
5
3
3
78
64
61
Table 1.7 Preliminary Evaluation of Major Agricultural Residuals for Energy Use
D
escription&
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esiduals
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In Ontario, biomass is a potentially large source of
fuel to replace coal for the production of electricity.
The fuel characteristics of biomass vary widely, and
a consis tent fuel s upply is nec essary to ensure
ma ximum combustion efficiency. Pre-treatment
options are under development to modify biomass
properties to achieve a set fuel specification.
Agricultural residuals vary greatly in terms of chemical
properties and the corresponding fuel properties.
Each crop residual will have differing chemical
characteristics and compositions. Therefore, acombination of various agricultural residuals may
provide the best option for use as a biomass fuel.
In this chapter, a description of agricultural residuals
produced in Ontario and their fuel properties is
provided. The various components of residuals
are discussed along with their effects on biomass
combustion. The challenges of agricultural residuals
combustion are identified as well as potential
solutions. Current harvesting technologies that can
be used for residual collection are reviewed along withdevelopments in residual harvesting technologies.
2.1 Biomass Chemical Analytical Methods
Biomass is a complex, heterogeneous mixture of
organic and inorganic matter containing solid and liquid
materials and minerals of various origins. The compo-
sition of each agricultural residual is unique, therefore,
each residual has different fuel properties. A number
of standard tests have been and are under
development to characterize solid biomass fuels.
Power generation stations analyse fuels prior to their
use in combustion to ensure compliance with specifi-
cations such as moisture, ash and heating values. The
quality of the biomass fuel is important to determine
the expected combustion performance. It is also
important to determine the chemical content of the
biomass to predict ash formation and behaviour
in the boilers.
It is critical to have a standard measurement procedure
to ensure that fuel analyses are reproducible and
unambiguous. Standard tests are under develop-
ment for the testing of biomass fuels. European
countries have developed a series of standard tests,
Chapter2Characteristics of Agricultural Residuals,Fuel Improvement Options & Harvesting Technologies
g
,
p
p
g
g
Analysis Test Procedure
Higher Heating Value
Proximate Analysis
Ultimate Analysis
Moisture
Carbon & Hydrogen
Nitrogen
Sulphur
Chlorine
Oxygen
Elemental Ash
Ash
Volatile Matter
Fixed Carbon
ASTM D2015 1
ASTM E711 1,2
ASTM E8711,2
ASTM D1102 1,2
ASTM E8301
ASTM E8721,2
ASTM E8971
By difference (percentage of
moisture, ash and volatile mattersubtracted from 100)1,2
Measure directly1
By difference (the percentage ofhydrogen, carbon, nitrogen,sulphur and chlorine subtractedfrom 100)2
ASTM E7771,2
ASTM E7781,2
ASTM E7751,2
ASTM E7761
ASTM D36821
ASTM D27951
Table 2.1 ASTM Standard Tests for Biomass Fuels
1 Miles et al. (1996) oxygen should be measured
directly since other elements such as chlorine may
distort the oxygen value
2 ASTM E870 Standard Test Methods of Analysis
of Wood Fuels
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FuelImprovementOptions&H
arvesting
Technologies
such as the CEN/TC 335 Biomass Standards from the
Biomass Energy Centre in the United Kingdom. ASTM
International has developed a series of tests for bio-
mass fuels, and Hazen Research Inc. in Colorado has
developed the procedure Determination of Water
Soluble Alkali to determine water soluble alkalis in
biomass. An ASTM Standard for this measurement
has not been developed. Examples of relevant fuel
quality tests for determining the fuel characteristics
of agricultural residuals are shown in Table 2.1.
2.2 Fuel Characteristics of Agricultural Residuals
Very little chemical composition information is avail-
able for agricultural residuals in terms of the biomass
and biomass ash. All agricultural materials have high
contents of ash, moisture, chlorine, potassium,
magnesium, nitrogen, sulphur, aluminum, calcium,
manganese and silicon compared fossil fuel sources.
The characteristics of biomass are very different from
coal. Along with the differing chemical compositions,
the higher heating value of residuals is generally lower
due to their higher moisture content.
The following tables provide the fuel characteristics
of a number of agricultural residuals. The average
value is provided and the range of values is given
in parenthesis.
2.2.1 Corn Stover
Corn is grown for the corn grains on the corn cob. In
Ontario, grain corn and sweet corn are produced.
Sweet corn is produced for human consumption, how-ever, the quantity produced is small in comparison to
grain corn. When corn is harvested in the fall, October
to early November, the corn ears are removed from the
stalk. Corn stover is the residual material following the
corn grain harvest which consists of long leaves and
the tall stalk of the plant. At the time of the grain
harvest, these materials have a low water content and
are bulky. For the analysis in this report, corn stover is
considered to be the leaves and stalk materials and
does not include the root system or crown. Corn cobs
are analysed separately. Figure 2.1 shows the corn
plant prior to harvest and Table 2.2 provides the fuel
characteristics of corn stover.
Figure 2.1 Corn Stover (with unharvested corn cobs)
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g
,
p
p
g
g
Proximate Analysis(wt% dry basis)
Water Soluble
Alkalis %(wt% dry basis)
Ultimate Analysis(wt% dry basis)
Elemental
Composition(wt% dry basis)
Alkali(lb/MMBtu)
Moisture
FixedCarbon
Volatile
Matter
Ash 4.0
(2.7-7.7)
20.6(19.2-22.0)
78.6
(73.1-84.0)
CaO
Na2O
K2O
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
Ash
Moisture
HHV
(BTU/lb)
Chlorine %
7942
(7604-8782)
46.9
(45.6-49.4)
5.5(5.4-5.8)
41.5
(39.7-43.3)
0.6
(0.3-0.8)0.04
(0.0-0.1)
SiO2
Al2O
3
TiO2
Fe2O
3
CaO
MgO
Na2O
K2O
SO3
P2O
5
CO2
Cl4.0
(3.7-4.4)
33.8(31.2-36.4)
0.5
(0.4-0.5)
0.6
6.7
(3.5-9.9)
3.6(3.0-4.3)
0.4
(0.1-0.7)
30.3(21.8-38.7)
1.9
(1.8-2.0)
5.7(2.2-9.2)
5.3
(2.8-8.0)
Table 2.2 Fuel Characteristics of Corn Stover
Energy Research Centre of the Netherlands, Phyllis Database (www.ecn.nl/phyllis/);
IEA Bioenergy Task 32, Biomass Database (http://www.ieabcc.nl/database/biomass.php);
Vienna University of Technology, BIOBIB Database (www.vt.tuwien.ac.at/biobib/search/html)
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FuelImprovementOptions&H
arvesting
Technologies
2.2.2 Corn Cob
Corn grains are grown on the corn cob. The cob is
the tough, central growth support for the corn
grains. When corn is harvested in October or early
November, the corn grain is gleaned from the corn
cob by the combine and the cob is returned to the
field. Technologies are under development for the
collection of corn cobs. Figure 2.2 shows collected
corn cobs, and Table 2.3 lists the fuel characteristics
of corn cobs.
Figure 2.2 Corn Cobs
Proximate Analysis(wt% dry basis)
Water SolubleAlkalis %
(wt% dry basis)
Ultimate Analysis(wt% dry basis)
ElementalComposition
(wt% dry basis)
Alkali(lb/MMBtu)
Moisture
Fixed
Carbon
Volatile
Matter
Ash 1.2
(1.0-1.4)
17.4
80.6
CaO
Na2O
K2O
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
Ash
Moisture
HHV
(BTU/lb)
Chlorine %
SiO2
Al2O
3
TiO2
Fe2O
3
CaO
MgO
Na2O
K2O
SO3
P2O5CO
2
Cl
40.3
4.1
1.3
2.5
1.2
2.0
8.7
6.9
47.8
(46.6-49.0)
7695
(7310-8090)
5.6
(5.4-5.9)
44.2
0.4(0.4-0.5)
0.1
Table 2.3 Fuel Characteristics of Corn Cob
Energy Research Centre of the Netherlands, Phyllis Database (www.ecn.nl/phyllis/);
IEA Bioenergy Task 32, Biomass Database (http://www.ieabcc.nl/database/biomass.php);
Vienna University of Technology, BIOBIB Database (www.vt.tuwien.ac.at/biobib/search/html)
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2.2.3 Wheat Straw
In Ontario, the main types of wheat grown are winter-
wheat and spring wheat. Winter wheat is planted in
the fall following the harvest of soybeans or corn. This
wheat winters under the snow and the majority of the
growth begins in March when the land begins to warm.
Winter wheat has a high grain yield since it is in the
ground for nearly a year before the grain is harvested
in July. Increased winter wheat performace in the
southern region of the province is due to milder
winters. Spring wheat is planted in the spring following
g
,
p
p
g
g
Proximate Analysis
(wt% dry basis)
Water Soluble
Alkalis %
(wt% dry basis)
Ultimate Analysis
(wt% dry basis)
Elemental
Composition
(wt% dry basis)
Alkali
(lb/MMBtu)
Moisture
Fixed
Carbon
Volatile
Matter
Ash6.2(2.6-13.5)
21.5
69.4
CaO
Na2O
K2O
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
Ash
Moisture
HHV
(BTU/lb)
Chlorine %
SiO2
Al2O
3
TiO2
Fe2O
3
CaO
MgO
Na2O
K2O
SO3
P2O
5
CO2
Cl
44.3
(37.3-49.4)
7663
(5082-8788)
5.3(4.7-6.1)
39.8
(23.8-49.3)
0.6
(0.3-0.9)
0.1(0.03-0.4)
51.5
(1.8-72.5)
0.8
(0.0-3.5)
0.1(0.0-0.2)
0.4(0.0-1.0)
6.6(0.4-17.0)
1.7
(0.1-3.7)
1.9(0.1-3.5)
17.1
(0.4-26.2)
3.7
(0.8-6.6)
2.1(0.1-3.6)
2.0(0.3-3.8)
3.3(0.2-6.4)
Table 2.4 Fuel Characteristics of Wheat Straw
Energy Research Centre of the Netherlands, Phyllis Database (www.ecn.nl/phyllis/);
IEA Bioenergy Task 32, Biomass Database (http://www.ieabcc.nl/database/biomass.php);
Vienna University of Technology, BIOBIB Database (www.vt.tuwien.ac.at/biobib/search/html)
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the winter. The majority of this wheat is grown in
northern and eastern Ontario and is harvested in the
fall. Wheat grains grow on multi-seed heads at the top
of grass-like stalks which become the straw. The stalks
are cut above the ground during the grain harvest
and are left in the field to dry prior to straw baling.
Figure 2.3 shows the wheat crop prior to the grain
harvest and Table 2.4 provides the fuel characteristics
of wheat straw.
2.2.4 Soybean Stover
Soybeans are grown inside pods on the soybean
plant, where each pod contains 2 - 4 seeds. The
soybean plant consists of a stalk, leaves, roots and
soybean seed pods. The leaves of the soybean plant
usually drop off the stalk before the soybeans have
matured. The stalk of the soybean plant is the
available residual material at the time of harvest.
Soybeans are harvested once the moisture level has
reached approximately 14%. The current harvesting
practice is to cut the soybean plant during harvest of
the beans with return of the stalk to the field. Soybean
stover is cut into pieces by the combine chopper andreturned to the soil. In this analysis, soybean
stover is the cut above ground stalk and any remaining
leaves on the plant. Figure 2.4 shows a soybean
crop prior to harvest and Table 2.5 identifies the
fuel char acteristics of the soybean stover.
Figure 2.3 Wheat Straw (with unharvested grain)
Figure 2.4 Soybean Stover (with unharvested soybeans)
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2.2.5 Barley Straw
Barley grows on hollow, cylindrical stems, which
become the barley straw. Barley has 1 or 3 spikelets;
each spikelet contains 2 rows of kernels resulting in 2
or 6-rowed barley. The stems are cut above the ground
during the kernel harvest and are left in the field to dry
prior to straw baling. Barley straw is considered to be
the barley stems and leaves. Figure 2.5 shows the
barley crop prior to harvest and Table 2.6 provides
the fuel characteristics of barley straw.
g
p
p
g
g
Proximate Analysis
(wt% dry basis)
Water SolubleAlkalis %
(wt% dry basis)
Ultimate Analysis
(wt% dry basis)
ElementalComposition
(wt% dry basis)
Alkali
(lb/MMBtu)
Moisture
Fixed
Carbon
VolatileMatter
Ash 6
75.3
CaO
Na2O
K2O
Carbon
Hydrogen
Oxygen
Nitrogen
Sulfur
Ash
Moisture
HHV
(BTU/lb)
Chlorine %
SiO2
Al2O
3
TiO2
Fe2
O3
CaO
MgO
Na2O
K2O
SO3
P2O
5
CO2
Cl
44.3
(43.0-45.6)
7723
(7506-7940)
6.0(5.6-6.4)
45.7
(44.9-46.4)
0.7
(0.6-0.8)
0.1
Table 2.5 Fuel Characteristics of Soybean Stover
Energy Research Centre of the Netherlands, Phyllis Database (www.ecn.nl/phyllis/);
IEA Bioenergy Task 32, Biomass Database (http://www.ieabcc.nl/database/biomass.php);
Vienna University of Technology, BIOBIB Database (www.vt.tuwien.ac.at/biobib/search/html)
Figure 2.5 Barley Straw (with unharvested grain)
Sulphur
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Proximate Analysis
(wt% dry basis)
Water Soluble
Alkalis %
(wt% dry basis)
Ultimate Analysis
(wt% dry basis)
Elemental
Composition
(wt% dry basis)
Alkali
(lb/MMBtu)
Moisture
Fixed
Carbon
Volatile
Matter
Ash
18.5
CaO
Na2O
K2O
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
Ash
Moisture
HHV
(BTU/lb)
Chlorine %
SiO2
Al2O
3
TiO2
Fe2
O3
CaO
MgO
Na2O
K2O
SO3
P2O
5
CO2
Cl
44.3
(43.0-45.6)
7723
(7506-7940)
6.0
(5.6-6.4)
45.7
(44.9-46.4)
72.1(64-82)
5.5
(4.0-9.8)
0.7
(0.6-0.8)
0.1
50.8
0.2
(0.1-0.7)
0.1
(0.0-0.2)
0.1
(0.1-1.0)
8.1(3.2-14.7)
1.8(1.6-2.9)
1.0
(0.3-1.5)
18.5
(8.0-33.0)
2.5(1.8-3.1)
3.8(1.9-5.0)
0.4
8.2
(3.2-13.2)
Table 2.6 Fuel Characteristics of Barley Straw
Energy Research Centre of the Netherlands, Phyllis Database (www.ecn.nl/phyllis/);
IEA Bioenergy Task 32, Biomass Database (http://www.ieabcc.nl/database/biomass.php);
Vienna University of Technology, BIOBIB Database (www.vt.tuwien.ac.at/biobib/search/html)
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2.2.6 Hay
Hay can be grass, legumes or herbaceous plants that
have been cut, dried and stored for later use. Hay
includes timothy, fescue, alfalfa and clover. Hay
consists of the leaf, steam and seed components of the
plant. Hay is cut and dried in the field when the seed
heads are not mature but the leaf is fully developed.
Following drying, hay is raked into windrows for
bail ing. Figure 2.6 shows a Timothy Hay field, and
Table 2.7 provides the fuel characteristics of hay.
g
p
p
g
g
Figure 2.6 Timothy Hay
Proximate Analysis(wt% dry basis)
Water Soluble
Alkalis %(wt% dry basis)
Ultimate Analysis(wt% dry basis)
Elemental
Composition(wt% dry basis)
Alkali(lb/MMBtu)
Moisture
FixedCarbon
Volatile
Matter
Ash 5.7
1.6
CaO
Na2O
K2O
44.6(44.3-44.8)
7723
(7506-7940)
5.1
(5.0-5.2)
45.6
(42.5-48.6)
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
Ash
Moisture
HHV
(BTU/lb)
Chlorine %
SiO2
Al2O
3
TiO2
Fe2O
3
CaO
MgO
Na2O
K2O
SO3
P2O
5
CO2
Cl
0.13
7916(7105-8185)
Table 2.7 Fuel Characteristics of Hay
Energy Research Centre of the Netherlands, Phyllis Database (www.ecn.nl/phyllis/);
IEA Bioenergy Task 32, Biomass Database (http://www.ieabcc.nl/database/biomass.php);
Vienna University of Technology, BIOBIB Database (www.vt.tuwien.ac.at/biobib/search/html)
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2.3 Summary of Biomass Properties as a Fuel
Chemical properties of various biomass samples were
examined by researchers and are summarized as
follows: (Vassilev et al., 2010)
Agricultural residuals produce higher ash yields
than forestry biomass.
Annual and fast growing crops have the highest
contents of ash, moisture, Cl, K, Mg, N, P and S.
All biomass has similar contents of C, H and O
with differing N and ash forming elements.
The moisture in biomass is an aqueous solution
containing: Al, Ca, Fe, K, Mg, Mn, Na, Ti, Br, Cl,
carbonate, F, I, nitrate, hydroxide,
phosphate and sulphate.
Volatile matter appears as light hydrocarbons,
CO, CO2, H2, moisture and tars.
Tall grasses and straw have a naturally high
concentration of Si which provides the plant
with sturdiness and rigidity. Si may also be
introduced through sand, clay and soil
components collected during residual
harvest, transport or processing.
Biomass with a large annual growth rate has a
high content of alkaline elements since these
elements are readily absorbed from the soil.
Carbon dioxide and water react with alkaline and
alkaline earth oxides to form hydrates, hydroxides
and carbonates in the ash during biomass
oxidation and storage.
2 . 3 . 1 E f f e c t o n C o m b u s t i o n o f C h e m i c a l
E l e m e n t s f o u nd i n A g r ic u l t ur a l R e s i d ua l s
Biomass materials have a different chemical
composition in comparison to coal. Many inorganic
compounds occur naturally in biomass due to plant
uptake from a number of sources. These mineral
components pose challenges for biomass combustion.
Silicon, aluminum and titanium occur in plants in the
form of oxides, where silicon is the most abundant
component. These oxides are not water soluble andappear mainly in the plant residual material. These
oxides also do not vapourize or become mobilized at
combustion temperatures. Silicon has an important
role in plant structure. It is incorporated into the plant
through biological processes and is believed to provide
the plant with rigidity, to withstand wind and rain,
overall strength and has a small role in photosynthesis.
Aluminum and titanium oxides are generally found in
small to trace amounts in biomass fuels(Miles et al., 1996).
Alkali and alkaline earth metals are essential to plantmetabolism and are included in organic structures or
in mobile inorganic forms. Potassium and calcium
are commonly found elements in biomass. High
concentrations of potassium are generally found in
herbaceous biomass fuels. The majority of the
potassium in biomass is water soluble and is an
essential nutrient for plants as a facilitator for osmotic
processes. The high potassium content of agricultural
residuals is likely due to the use of fertilizers (Werther
et al., 2000). Calcium is commonly found in cell walls
and organic components of cell structures. Sodiumand magnesium are generally found in small quantities.
Potassium and sodium are also common components
of clay soil (Miles et al., 1996).
Alkalis, such as sodium and potassium, are susceptible
to vapourization. Alkaline earth metals, such as
calcium and magnesium, are less likely to volatilize,
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and during combustion are more likely to form stable
compounds that are less volatile than alkali materials.
Non-metallics, such as chlorine and sulphur, are plant
nutrients. Chlorine has an active role in inorganic
compounds reactions. Chlorine and alkali metals
react to form volatile and stable alkali chlorides, where
chlorine is the facilitator for vapourization. Chlorides
condensate on cooler surfaces in the presence of
sulphur which results in sulphate formation that can
lead to corrosion. Stab le chlorine cont aining
vapours generated during combustion include alkali
chlorides and hydrogen chloride. Sulphur is a trace
component of biomass with the exception of
straws, but has a large role in ash deposition,
where deposits are based on sulphate formation.
Most forms of sulphur wil l oxidize during
combustion and many then react with alkali metals
to form su lphates. Alkali sulphates are unstable
at combustion temperatures. Phosphorus is a
component of biomass fuels and its behaviour
has not been characterized during combustion
(Miles et al., 1996). Biomass generally contains
low concentration s of iron. It is believed that iron
generally has a small role in the formation o f
ash deposits (Miles et al., 1996).
2.3.2 Factors Effecting the Chemical Compositions of
Residuals
Agricultural residuals from a specific crop can have a
range of chemical composition values. This range is
influenced by a number of factors introduced during
crop production which affect the natural biomass
properties. These factors include: (Vassilev et al., 2010)
Type of plant: species and the component of the
plant (stalk or leaves)
Growth processes: ability of the plant to uptake
nutrients from the water, air and soil and transport
and store these materials in various plant tissues
Growing conditions: amount of sunlight,
geographic location, climate, soil type, water
availability, soil pH, nutrient availability,
proximity to forested areas, waterways and
pollution sources
Age of the plant when harvested
Harvest time and collection technique for the
residual harvest
Residual transport and storage conditions
Fertilizer and pesticide usage
Collection of external materials, such as soil,
during the harvest of residuals
A number of relationships have been identified
between the activities and the environment involved
in biomass production and the fuel properties.
Researchers have suggested that the plant species has
a more important role than the soil type, growing
region and fertilizer treatment (Vassilev et al., 2010).
More research is required to confirm this hypothesis.
2.3.3 Inherent Undesirables in Biomass Residual Fuels
Contamination will occur if biomass fuels are not
collected according to proper harvesting procedures
as well as transport, storage, pre-treatment and
processing techniques. Growing conditions also
effect the concentrations of some elements in the
biomass. For instance, the content of aluminum in
plants is effected by the pH of the soil (Cowan, 2010).
Aluminum can inhibit plant growth and can be toxic
to plants. Depending on the soil pH, aluminum can
have different effects on the plant. At a pH below 5,
aluminum can inhibit plant growth, at a pH between
5.5 and 6, a luminum is in hydroxyl form and is not
toxic to plants. Above a pH of 6, aluminum does not
have any effect (Kessel, 2008). Exposure to pollution
sources such as groundwater and aerosols can
result in increased elemental concentrations.
Contaminat ion of agricultural residuals can also
occur at various points along the supply chain. This
contamination will also affect the fuel quality. Fur-
g
,
p
p
g
g
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ther discussion on biomass contamination through-out the supply chain is discussed in Chapter 4.
2.4 Challenges Associated with Biomass Combustion
The utilization of biomass as a fuel sets new demands
for boiler process control, boiler design and for com-
bustion technologies including fuel blend control and
fuel handling systems. Most of the challenges related
to biomass combustion are the result of the biomass
fuel properties. Understanding of combustion
mechanisms are required to achieve high combustionefficiency and effective design and operation of
combustion systems.
The high moisture content of the biomass can lead to
poor ignition, and reduces the combustion tempera-
ture which hinders combustion of the reaction
products and affects the combustion quality. A large
quantity of flue gas is formed during the combustion
of high moisture content fuels which eventually leads
to large size equipment for flue gas treatment (Werther
et al., 2000).
Efficient ash removal equipment is required to reduce
or eliminate particulate pollution. Agricultural residu-
als combustion produces low melting temperature ash
due to the presence of high concentrations of
potassium oxide in the residual biomass. This results
in fouling, scaling and corrosion of heat transfer
surfaces (Werther et al., 2000).
A large quantity of volatile matter is present in agricul-
tural residuals compared to coal. This indicates thatagricultural residuals are easier to burn but may lead to
rapid combustion that may be difficult to control.
Attention must be given to the combustion control system
of residual fuels to ensure complete combustion of
volatiles, high combustion efficiency and low emissions
of CO, hydrocarbons and PAH (Werther et al., 2000).
The presence of sulphur, nitrogen, chlorine and otherchemical elements in the biomass result in the
formation of gaseous pollutants such as SOx, NOx,
N2O, HCl, dioxins and furans. Unburned pollutants
may include CO, hydrocarbons, tar, PAH, CxHy and char
particles. These unburned pollutants are generally the
result of poor combustion due to low combustion
temperatures , insufficient mixing of the fuel with
combustion air and too short of a residence time of
the gases in the combustionzone. Lower emissions are
achieved if combustion is conducted with a h igher
burn out efficiency through efficient mixing of thecombustion air with the co mbustibles (Werther et
al., 2000). Ash is also a potential pollutant that is
carried by the flue gas from the furnace. Fine fly ash
is generally derived from easily leached elements
from the biomass (Veijonen et al., 2003). Ash emis-
sions are a function of the fuel feedrate, ash
content, excess air ratio and the distribution
of the combustion air (Werther et al., 2000).
2.5.1 Devolatilization
Common characteristics of most biomass are the low
temperature devolatilization and combustion properties.
Complete devolatilization of agricultural residuals and
char combustion can occur at relatively low tempera-
tures. The quantity of volatiles produced at a specific
temperature is dependent on the biomass particle size.
During devolatilization, agricultural residuals undergo
a thermal decomposition to release volatiles and form
tar and char. The amount of these products formed
depends on the residual and the combustion conditions
(Werther et al., 2000). For example, as the devolatilizationtemperature increases, CO2 production decreases
while H2 and CO formation quickly increase.
The high volatile matter content of agricultural residuals
has a significant effect on combustion mechanisms
and consequently on the design and operation of
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