Bio-Fuel Green Solid Waste

BIO-FUEL FROM GREEN SOLID WASTE
A report submitted to the Department of Mechanical Engineering, Khulna University of
Engineering & Technology in partial fulfillment of the requirements for the
“Course of ME 3100”
Supervised by Submitted by
Dr. Khandkar Aftab Hossain Md. Shariful Islam
Professor Roll: 1205004
Department of Mechanical Engineering Section: A
Khulna University of Engineering & Technology
August 2015
Department of Mechanical Engineering
Khulna University of Engineering & Technology
Khulna 9203, Bangladesh

i
Acknowledgements
All the praises to the almighty who makes author capable to complete this Special
work successfully. The author is very much indebted to his course Dr. Khandkar Aftab
Hossain , professor of Department of Mechanical Engineering, Khulna University of
Engineering & Technology, Bangladesh, for his wise inspiration to do such extraordinary
special work. The author expresses the heart- felt respect to him for his proper guidance and
all kind of support to perform and complete this special study.
The author is extremely grateful to Prof. Dr. Nawsher Ali Moral ,Head of the department of
Mechanical Engineering Khulna University of Engineering & Technology, Bangladesh,
to provide such a good opportunity to do the special work and for providing all other
supports.
May ALLAH bless the course teacher.
“Author”

ii
Abstract
Demand for energy is increasing in an alarming rate. This is due to the rapid outgrowth of
population and urbanization. Conventional energy sources are not sufficient to face the
phenomena of energy shortage. In this condition renewable energy can be a substitute of
conventional energy. Such as Bio- fuel can be a substitute general fuel diesel. Bio- fuel can
be used in boilers, furnaces, engines and turbines for electricity generation.
Pyrolysis process can successfully be applied for converting biomass (solid green waste) into
bio-energy (bio-fuel). Pyrolysis is a thermo-chemical decomposition of organic material at
prescribed temperatures. Among various types of pyrolysis process Fast pyrolysis process
can be used to produce biofuel. The Bio- fuel produced through Pyrolysis process is not
stable as conventional fuels. It has High density, High viscosity, Low pH, Low heating value,
highly oxygenated compounds etc.

iii
CONTENTS
Page
Acknowledgement………………………………………………………….…………….…i
Abstract……………………………………………………………………….….….………ii
List of Figures………………………………………………………………………………..v
List of Tables………………………………………………………………………………...vi
CHAPTER-І: INTRODUCTION
1.1 Introduction……………………………………………………………………………..2
1.2 Objectives……………………………………………………….……………………….2
CHAPTER-ІІ: LITERATURE REVIEW
2.1 Historical Background………………………………………………………...................4
2.2 Biomass …………………….………….…….…….…………………………………….4
2.2.1 Constituents of biomass…………….…….…………………………………….4
2.2.2 Sources of Biomass ………….….……………………………………………..6
2.3 Bio-diesel ……………….……………………………………………………………….9
2.3.1 Why Bio-diesel…………………………………………………………………9
2.4 Green Waste ………………………………………………………………..…………..10
2.5 Waste Disposal ………………….……. …………………………………………..……10

iv
2.6
Pyrolysis……………………………………………………………………………………..10
2.6.1 Types of pyrolysis……………………………………………………………...11
2.6.1 .1 Fast pyrolysis……………………………………………………….11
2.6.1 .2 Slow pyrolysis ……………………………………………………..12
2.6.1 .3 Flash Pyrolysis………………………………………….…………..12
2.7 Characteristics of pyrolysis oil …………………………………………..………….......13
2.8 Comparison of pyrolysis liquid and conventional fuel oil characteristics……………….13
2.9 Application of pyrolysis oil………………………………………...……………………14
2.10 Pyrolysis Economics ……………….…………………………………………………..15
2.11 Disadvantages of Bio-fuels…………………..…………………………………………15
CHAPTER-ІІІ
3.1 Pyrolysis Principle…………...………….………………………………………………18
3.2 Pyrolysis Process steps ………………..………….………….…………………………19
CHAPTER- ІV
4.1 Conclusion ……………………………………………………………………….……..21
4.2 Recommendations ………………………………………………………………………21
References………………………………………………………………………….………..22

v
LIST OF FIGURES
Figure Title Page
Figure-2.1 Biomass composition in percentage………………………………………....5
Figure-2.2 A typical view of forest residue ……………….…………………………….6
Figure-2.3 A typical view of Industrial green Waste…………….………………….…..7
Figure-2.4 A typical view of Agricultural Residues………………….……………….…7
Figure-2.5 A typical view of Energy Crops……………………………….………….….8
Figure-2.6 Some biomass conversion processes………………………………………....10
Figure-2.7 Schematic diagram showing simple pyrolysis system……………………….11
Figure-2.8 Schematic diagram showing Fast pyrolysis product distribution…………....12
Figure-2.9 Schematic diagram showing slow pyrolysis product distribution……………12
Figure-2.10 Applications of pyrolysis product (pyrolysis oil)……………………………15
Figure-3.1 Schematic diagram showing fluid bed pyrolysis processes ………………….18

vi
LIST OF TABLES
Table Title Page
Table-2.1 Biomass composition of different sources of biomass …….…….…………8
Table-2.2 comparison of pyrolysis liquid and conventional oil ………….…………...13

1
Chapter I
 Introduction
 Objectives

2
1.1 Introduction:
Demand for energy and its resources, is increasing day by day. This is due to the rapid
outgrowth of population and urbanization. Present sources of energy are not sufficient to
overcome the increasing needs. The major energy demand is fulfilled from the conventional
energy resources like coal, petroleum and natural gas. The huge amount usage of fossil fuels
creates environmental threads.
Renewable energy can be a solution at this situation. A renewable energy system converts the
nature energy into usable form such as heat or electricity. Renewable energy sources offer
sustainable living due to being pollution free and economically feasible. There are various
forms of renewable energy such as Biomass, Geoenergy, Hydroelectric, solar, wind and
wave etc. Biomass is one of the promising environment friendly renewable energy options.
Different thermochemical conversion processes that include combustion, gasification,
liquefaction, hydrogenation and pyrolysis, have been used to convert the biomass into
various energy products. Pyrolysis can convert biomass directly into solid, liquid and gaseous
products by thermal decomposition of biomass in absence of oxygen. To obtain biofuel from
green solid waste the Pyrolysis process is preferred mostly. Fast pyrolysis is used to produce
BioOil.
1.2 Objectives:
The objectives of this special study is to
i. Study about a selected topic that is “Biofuel from green solid waste”.
ii. Present that selected topic.

3
Chapter II : Literature Review
 Historical Background
 Biomass
 Bio-diesel
 Green Waste
 Waste Disposal
 Pyrolysis
 Characteristics of pyrolysis oil
 Comparison of pyrolysis liquid and conventional fuel oil
characteristics
 Application of pyrolysis oil
 Pyrolysis Economics
 Disadvantages of pyrolysis oil

4
2.1 Historical Background:
Biodiesel is a renewable fuel which is in use throughout the world. Biodiesel is made
commercially from soybeans and other oilseeds in an industrial process, but it is also
commonly made in home shops from waste fryer grease.
Dr. Rudolf Diesel first demonstrated his diesel engine to the world running on peanut oil in
the early 1900’s. The high compression of diesel engines creates heat in the combustion
cylinder, and thus does not require a highly flammable fuel such as that used in gasoline
engines. The diesel engine was originally promoted to farmers as one for which they could
“grow their own fuel”. Diesels, with their high torque, excellent fuel efficiency, and long
engine life are now the engine of choice for large trucks, tractors, machinery, and some
passenger vehicles. Diesel passenger vehicles are not presently common in the United States
due to engine noise, smoky exhaust, and cold weather starting challenges. However, their
use is quite normal in Europe and Latin America, and more diesels are starting to appear in
the US market.
Over time, the practice of running the engines on vegetable oil became less common as
petroleum diesel fuel became cheap and readily available. Today, people are rediscovering
the environmental and economic benefits of making fuel from raw and used vegetable oils
[1].
2.2 Biomass:
Biomass is defined as organic materials which are derived from plants or animals sources. In
general it is difficult to find out the actual definition. Biomass is formed by the interaction of
CO2, water and sunlight. When a living being dies, microorganisms and bacteria break down
the constituents into elementary components like H2O, CO2, and energy. Since, plants use the
same the carbon dioxide at the time of photosynthesis, the amount of CO2 does not increase
in the earth. Biomass is a green house gas (GHG) emission neutral energy source.
2.2.1 Constituents of biomass:

5
The major constituents of biomass are cellulose, hemicelluloses and lignin [3].
Fig 2.1: Biomass composition in percentage
1. Cellulose: The primary organic component of cell wall is cellulose. It is represented by
generic formula (C6H10O5)n. It is crystalline in nature, resistant to hydrolysis, a large
molecular weight (∼500,000) due to the presence of a long chain polymer having high
degree of polymerization (∼10,000). Cellulose is primarily composed of dglucose, which is
made of six carbons.
2. Hemicellulose: Hemi cellulose is also one of the constituent of cell wall. It is represented
by the generic formula (C5H8O4)n. It has branched chain structure with groups of
carbohydrates and a lower degree of polymerization (∼100–200). The composition and
structure of hemicelluloses varies from biomass to biomass.
3. Lignin: The third important constituent of woody biomass is lignin, which is complex in
nature, highly branch polymer of phenyl propane. It is a three dimensional polymer. Lignin
is the binding agent for cellulose. It is highly insoluble; it does not even dissolve in sulphuric
acid.

6
2.2.2 Sources of Biomass:
The common biomass sources are agricultural, forest, Industrial green Waste and Energy
Crops. The examples of sources are discussed below [2].
1. Forest Residues: Forest residues are defined as the biomass material remaining in
forests that have been harvested. for timber, and are almost identical in composition
to forest thinnings. Because only timber of a certain.
Forest residues consist of Cotton seed hairs, Tree branches, tops of trunks, stumps, branches,
and Leaves etc.
Fig 2.2: A typical view of forest residue
2. Industrial green Waste: Industrial waste is the waste produced by industrial
activity which includes any material that is rendered useless during a manufacturing process
such as that of factories, mills, and mining operations. It has existed since the start of
the Revolution.
Some examples of industrial waste are Citrus peels, sugarcane bagasse, milling residues,
olive husks.

7
Fig 2.3: A typical view of Industrial green Waste
3. Agricultural Residues: Field residues are materials left in an agricultural field or orchard
after the crop has been harvested. These residues include stalks and stubble (stems), leaves,
and seed pods. The residue can be sloughed directly into the ground, or burned first.
Includes corn stover, wheat husk and rice straw.
Fig 2.4: A typical view of Agricultural Residues
4. Energy Crops: An energy crop is a plant grown as a lowcost and lowmaintenance
harvest used to make biofuels, such as bioethanol, or combusted for itsenergy content to
generate electricity or heat. Energy crops are generally categorized as woody or herbaceous
plants; many of the latter are grasses (Graminaceae).

8
Examples are Sunflower shell, Switch grass, miscanthus, bamboo, sweet sorghum, tall
fescue, kochia, wheatgrass, and others.
Fig 2.5: A typical view of Energy Crops
Table 2.1: Biomass composition of different sources of biomass [712]:

9
2.3 Bio-diesel:
Biodiesel is a form of diesel fuel manufactured from vegetable oils, animal fats, or recycled
restaurant greases. It is safe, biodegradable, and produces less air pollutants than petroleum
based diesel. Biodiesel can be used in its pure form (B100) or blended with petroleum diesel.
Biofuels are obtained from living organisms. The fuel should consist of more than 80%
renewable materials to be considered as a biofuel.
In Europe, biodiesel is widely available in both its neat form (100% biodiesel, also known as
B100) and in blends with petroleum diesel. Most European biodiesel is made from rapeseed
oil (a cousin of canola oil). In the United States, initial interest in producing and using
biodiesel has focused on the use of soybean oil as the primary feedstock, mainly because this
country is the world’s largest producer of soybean oil.
2.3.1 Why Bio-diesel:
There are various advantages of substituting diesel fuel by BioDiesel. Such as [4]
i. It can reduce our dependence on foreign petroleum.
ii. It can leverage limited supplies of fossil fuels.
iii. It can help reduce greenhouse gas emissions.
iv. It can help reduce air pollution and related public health risks.

10
2.4 Green Waste:
Basically the “Green waste” is produced from regular maintenance of gardens and parks. It
consists of all plant materials: branches, logs, leaves, stumps, grass, sticks, paper, cardboard,
and other woody materials. It also contains large quantities of waste paper and cardboard,
waste timber, old wooden pallets and sawmills wastes. The largest single component of
municipal waste is green waste and traditionally it takes up a significant quantity of landfill
volumes. All of those wastes are suitable for biodiesel and energy production [5].
2.5 Waste Disposal:
Green waste can be disposed in many ways: Burying in landfills, using as mulch, composting
and then used in crop production, vermincomposting and used in plant production, used as a
landscape mix in landscaping, biochar and biooil preparation (pyrolysis)etc[5].
Biomass can be converted into heat and electricity in a number of ways. Depending on its
source, these processes include: combustion, pyrolysis, gasification, liquefaction, anaerobic
digestion or fermentation.
Fig 2.6: Some biomass conversion processes
To obtain biodiesel from green solid waste the Pyrolysis process is preferred mostly.
2.6 Pyrolysis:

11
Pyrolysis is a thermochemical decomposition of organic material at temperatures
between 400 ° C and 900 °C without the presence of oxygen or other reagents. The
pyrolytic breakdown of wood produces a large number of chemical substances. Some of
these chemicals can be used as substitutes for conventional fuels. The distribution of the
products varies with the chemical composition of the biomass and the operating conditions
[2].
Fig 2.7: Schematic diagram showing simple pyrolysis system
2.6.1 Types of pyrolysis:
The process pyrolysis occurs in three different ways, namely fast pyrolysis, slow pyrolysis
and flash pyrolysis.
2.6.1 .1 Fast pyrolysis :
In fast pyrolysis process the feed stock is rapidly heated (high rate of heating) in absence of
oxygen at high temperature. During the decomposition, vapours and char are formed.
After condensation of the vapours, a dark brown liquid is obtained. Fast pyrolysis is an
advanced process which can be controlled to produce higher yields of liquid products.
Fast pyrolysis process produces 6075% liquid biooil, 1525% char and 1020% non
condensable gases. The biooil and char can be used as source of fuel and the non
condensable gases can be recycled back in the process [3].

12
Fig 2.8: Schematic diagram showing Fast pyrolysis product distribution
2.6.1 .2 Slow pyrolysis
In slow pyrolysis, pyrolysis is carried out at a slow heating rate of 510 o
C/min. Product
yields from slow pyrolysis are approximately 35% biochar,30% biooil, and 35% gaseous
products.
Fig 2.9: Schematic diagram showing slow pyrolysis product distribution
2.6.1 .3 Flash Pyrolysis:
In flash pyrolysis the reaction time is in the range of 30 – 1500 ms. This process increases the
amount of liquid product decreasing the char amount. Upon cooling, the condensable vapor

13
is then condensed into a liquid fuel known as biooil. Such an operation increases the liquid
yield (70–75%) while reducing the char production. There are four different methods
of flash pyrolysis viz, flash hydropyrolysis, solar flash pyrolysis, vacuum flash
pyrolysis and rapid thermal process [3].
2.7 Characteristics of pyrolysis oil:
BioOil or BioDiesel is not stable as conventional fuels [2].
 Highly oxygenated compounds
 High density
 High viscosity
 Low pH
 Low heating value
 CO2 neutral
 No SOx and low NOx
BioOil can be combusted directly in boilers, gas turbines and slow and medium
speed diesels for heat and power applications.
2.8 Comparison of pyrolysis liquid and conventional fuel oil characteristics:
Table 2.2: comparison of pyrolysis liquid and conventional oil: [2]

14
2.9 Application of pyrolysis oil:
The biooil obtained from pyrolysis can have the following industrial applications:
 Combustion of fuel
 power generation
 extraction of chemicals and resins
 production of laevoglucose
 binding agents
 blending with diesel
 biooils can be used in making adhesives

15
Fig 2.10: Applications of pyrolysis product (pyrolysis oil)
2.10 Pyrolysis Economics:
Economic viability is the key factor in the development of commercial pyrolysis processes.
Currently, pyrolysis products are unable to compete economically with fossil fuels due to
high production costs. The pyrolysis technology has to overcome a number of technical and
nontechnical barriers before industry can implement their commercialization and usage.
Production cost of pyrolysis product is higher compared to production of fossil fuel. The
main component of pyrolysis plants are the reactor, although it represents only 10%–15% of
the total capital cost. The rest of the cost consists of biomass collection, storage and handling,
biomass cutting, dying and grinding, product collection and storage, etc [7].
2.11 Disadvantages of Bio-fuels: [6]
1. High Cost of Production: Even with all the benefits associated with biofuels, they are quite
expensive to produce in the current market. As of now, the interest and capital investment
being put into biofuel production is fairly low but it can match demand.
2. Monoculture: Monoculture refers to practice of producing same crops year after year,
rather than producing various crops through a farmer’s fields over time.

16
3. Use of Fertilizers: Biofuels are produced from crops and these crops need fertilizers to
grow better. The downside of using fertilizers is that they can have harmful effects on
surrounding environment and may cause water pollution.
4. Shortage of Food: Biofuels are extracted from plants and crops that have high levels of
sugar in them. However, most of these crops are also used as food crops.
5. Industrial Pollution
6. Water Use: Large quantities of water are required to irrigate the biofuel crops and it may
impose strain on local and regional water resources, if not managed wisely resources.

17
Chapter III
 Pyrolysis Principle
 Pyrolysis Process steps

18
3.1 Pyrolysis Principle:
Pyrolsis is a thermochemical decomposition process which is found to be the best suited for
conversion of biomass to carbonrich solid and liquid fuel. The process of pyrolysis of
organic matter is very complex and consists of both simultaneous and successive reactions
when organic material is heated in a non reactive atmosphere. In this process, thermal
decomposition of organic components in biomass starts at 350–550 0
C and goes up to 700
800 0
C in the absence of air/oxygen suggested by Fisher et al. The long chains of carbon,
hydrogen and oxygen compounds in biomass break down into smaller molecules, in the form
of gases, condensable vapors (tars and oils), and solid charcoal under pyrolysis conditions.
Rate and amount of decomposition gases, tars and char depends on the process parameters of
the reactor (pyrolysis) temperature, heating rate, pressure, reactor configuration, feedstock’s
variation. Following figure shows schematic diagram for fast pyrolysis processes [5].
Fig 3.1: Schematic diagram showing fluid bed pyrolysis processes

19
3.2 Pyrolysis Process steps:
Pyrolysis process is a combination of some steps. All the steps simply categorise as feed
stock preparation, Feed stock drying, thermochemical conversion in the reactor, ash
separation and liquid collection. Different reactor needs different sizes particle, that is why
cutting and grinding is needed. Drying is essential to avoid adverse effects of water on
stability, viscosity, corrosiveness and other liquid properties in the pyrolysis product. After
drying and grinding, the biomass is fed into the reactor and the pyrolysis process takes place.
Char removal cyclones are used to separate char. Pyrolysis liquid is collected after quenching
the volatile material by the vapors liquid condensers [5].

20
Chapter IV
 Conclusion
 Recommendations

21
4.1 Conclusion:
Energy recovery from green waste through pyrolysis process has been discussed in this report.
Pyrolysis technology has strong adaptability to green waste to produce liquid fuels. It offers a
convenient solution for solid green waste management systems. In spite of comparatively lowgrade
biofuels obtained from biomass; it has some promising properties to become a suitable substitute
of fossil fuel. In future successful research and improvement of biofuel quality can lead to huge
production of bioenergy from green waste commercially. It is important to optimize the process by
maximizing product quality and minimizing costs and environmental concerns.
4.2 Recommendations:
 Biooil production through pyrolysis is still an immature technology and is not
commercially feasible yet. Pyrolysis biooil needs to overcome many technical,
economic and social barriers to compete with traditional fossil fuels.
 Along with pyrolysis technology, proper biomass selection is also a critical issue to
achieve high biooil yields. Biomass with high cellulose content could be chosen, as
biooils are mainly derived from it. In addition, biomass with low water content is
desirable to reduce drying costs and improve oil quality.

22
References:
[1]:http://www1.eere.energy.gov/education/pdfs/biomass_creatingbiodiesel.pdf
[2]:http://www.oeaw.ac.at/forebiom/WS1lectures/SessionII_Uzun.pdf
[3]:ethesis.nitrkl.ac.in/5735/1/110CH04642.pdf
[4]:http://www.nrel.gov/docs/legosti/fy98/24772.pdf
[5]:www.wseas.us/elibrary/conferences/2012/Kos/.../WEGECM13.pdf
[6]:http://www.conserveenergyfuture.com/advantagesanddisadvantagesofbiofuels.php
[7]: Abbasi, T.; Abbasi, S.A. Biomass energy and the environmental impacts associated with
its production and utilization. Renew. Sustain. Energy Rev.2010, 14, 919–937.
[8]: Yang, H.; Yan, R.; Chen, H.; Lee, D.H.; Zheng, C. Characteristics of hemicellulose,
cellulose and lignin pyrolysis. Fuel 2007, 86, 1781–1788.
[9]: Demirbas, A. Calculation of higher heating values of biomass fuels. Fuel 1997, 76, 431–
434.
[10]: Demirbas, A. Current technologies for the thermoconversion of biomass into fuels and
chemicals. Energy Source Part A 2004, 26, 715–730.
[11]: Fahmi, R.; Bridgwater, A.V.; Donnison, I.; Yates, N.; Jones, J.M. The effect of lignin
and inorganic species in biomass on pyrolysis oil yields, quality and stability. Fuel 2008,
87, 1230–1240.
[12]: Wang, J.; Wang, G.; Zhang, M.; Chen, M.; Li, D.; Min, F.; Chen, M.; Zhang, S.; Ren,
Z.; Yen, Y. A comparative study of thermolysis characteristic and kinetics of seaweeds and
firwood. Proc. Biochem. 2006, 41, 1883–1886.

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