Assessment of Agricultural Residuals as Fuel for Power Generation for OPG - 2010

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

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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

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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



Dr. Aung Oo

Project Researcher

Commericalization Consultant



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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

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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.

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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&


esiduals


14/123

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


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)


15/123

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&


esiduals


16/123

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



17/123D

escription&


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





18/123

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



19/123

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&


esiduals


20/123

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


21/123CharacteristicsofAgriculturalResiduals,

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)


22/123

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)




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


Water SolubleAlkalis %

(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





24/123

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







arvesting

Technologies

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)


26/123

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




Figure 2.5 Barley Straw (with unharvested grain)

Sulphur




arvesting

Technologies

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





28/123

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


Water Soluble

Alkalis %(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





29/123

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,

CharacteristicsofAgriculturalResiduals,


arvesting

Technologies


30/123

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




arvesting

Technologies

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

8/12/2019 Assessment of Agricultural Res

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