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BIOENERGY

1. Biomass: sources, characteristics & preparation:

• Sources and classification of biomass available for energy

production.

• Chemical composition and properties of biomass

• Energy plantations

• Preparation of biomass for fuel applications: Size

reduction, Briquetting of loose biomass, Drying, and

Storage and handling of biomass.

Reference book:

Renewable Energy Engineering and Technology: Principles &

Practice, Edited by V. V. N. Kishore, 2009 T E R I, N. Delhi.

Chapters12 to 15, pp 625 to 917.

SOURCES:

The material of plants and animals is called biomass.

Bio-energy is energy derived from biomass. Before the

development of technology based on coal, lignite, crude oil

and natural gas (fossil fuels) bio-fuels were the sources of

heat energy.

Woody biomass is product of forestry and trees from

different agro-forestry activities of smaller intensity. Timber

(used for commercial purpose) and fuel wood are obtained

from the forests besides minor forest produce. Commercial

plantations like rubber and plants/trees that yield

hydrocarbon can be a source of byproduct fuel.

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Agriculture yields by annual harvest a large crop residue

biomass part of which can be a source of rural biofuels.

Plants that grow in wastelands are also potential energy

crops. Nonedible oils from trees are a byproduct liquid fuel.

Non -edible vegetable oils can be used as liquid fuels. By

trans-esterification reaction between the oil and an alcohol in

presence of an alkaline catalyst, esters can be produced that

are potential substitute for diesel as engine fuel.

Biomass that is used for producing bio-fuel may be

divided into woody, non-woody and wet organic waste

categories. The sources of each are indicated below.

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Animal manures and wastewaters containing organic

putrefiable matter can be treated by anaerobic digestion or

biomethanation to produce biogas as a fuel. Starchy and

sugar wastewaters can be substrates for fermentation

processes that yield ethanol which is a potential liquid fuel.

Sources of three categories of biomass

WOODY NON-WOODY

(cultivated)

WET ORGANIC

WASTE

FORESTS FOOD CROPS ANIMAL WASTES

WOODLANDS CROP RESIDUES MANURE, SLUDGE

PLANTATIONS

(MULTI-

PURPOSE

TREES)

PROCESSING

RESIDUES

MUNICIPAL SOLID

WASTE

HYDROCARBON

PLANTS

NONEDIBLE OIL

SEEDS

WASTE STARCH &

SUGAR

SOLUTIONS

TREES FROM

VILLAGE

COMMON

LANDS

ENERGY CROPS:

(SUGAR CANE

BAMBOO)

OTHER

INDUSTRIAL

EFFLUENTS

(B O D)

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BIOMASS CONVERSION METHODS FOR PRODUCING

HEAT OR FUELS:

Controlled decomposition of low value biomass to derive its

energy content in a useful form is the purpose of the bio-

energy programs. Biomass energy conversion may give a

mixture of bio-fuel and. by product. Examples are given

below. Bio-fuels derived from biomass can be solid, liquid

and gas fuels that can be used for combustion in specially

designed furnace, kiln and burners.

PRIMARY

BIOMASS

SECONDARY

PRODUCT

CO-

PRODUCT

WOOD

CHAR (PYROLYSIS)

PYROLYSIS

OIL

WOOD

CHAR

(GASIFICATION)

PRODUCER

GAS

ANIMAL

MANURE

BIOGAS (AN.

DIGESTION)

FERTILIZER

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Bio-fuel production from primary biomass may utilize thermo-

chemical, biochemical and catalytic conversion processes

(see following table) Conversion process chosen depends

on the properties of the primary biomass available.

THERMOCHEMICAL

BIOCHEMICAL

CATALYTIC

CONVERSION

PYROLYSIS

ANAEROBIC

DIGESTION

HYDROGENATION

GASIFICATION

FERMENTATION

TRANS-

ESTERIFICATION

COMBUSTION

HYDROLYTIC

ENZYMES

SYN.GAS

PROCESS

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Forest resources of India:

India’s is sustaining 16 % of the world’s populatio n and

15 % of its livestock population on 2.47 % of worl d’s

geographical area and has just 1 % of world’s

forests.

o Forest area cover (i.e., the area notified as forest) in

1997: 76.52 million hectares, which is 23.28 % of the

total geographical area of India.

o The aggregate demand for fuelwood for the country in

1996 was 201 million tonnes, i.e., 213.8 kg per capita

per year for a population of 940 million. The current

sustainable production of fuelwood from forests is 17

million tonnes and from farm forestry and other areas is

98 million tonnes. There is a deficit of 86 million tonnes

of fuelwood, which is being removed from the forests as

a compulsion.

o Forest resource base has tremendous pressure on it

and availability is not catching up with demand for

firewood. World Environment Day: June 5

o State Forest Departments and Community based

organizations have Joint Forest Management Programs

to prevent degradation and to regenerate forest areas.

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Distribution of forest areas in States:

o In Andaman & Nicobar area, forests occupy 86.9% of

the total geographical area, whereas in Haryana,

forests occupy 3.8%.

o Arunachal Pradesh, Himachal Pradesh, Manipur,

Mizoram, Nagaland and Tripura have over 50% of their

land areas under forests while Gujarat, Jammu &

Kashmir, Punjab & Rajasthan have less than 10%. The

forest in other states range between 10 and 50 % of

their land areas and the per capita forest area of India

is 0.07 hectares.

Causes of deforestation:

o Exponential rise in human and livestock population puts

increasing demand on land allocation to alternative

uses such as agriculture, pastures, human settlements

and development activities.

o Insufficient availability of commercial fuels in rural areas

as well as the lack of purchasing power of the rural poor

and urban slum dwellers makes them dependent on

firewood and wood char as fuels for cooking.

Energy Crisis of Rural and Urban poor in India:

o Nearly 75% of the rural population of India is dependent

on bio-fuels (firewood, agricultural residues, and cow

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dung) for meeting 80% of their energy needs. Similarly

the urban poor, including the slum dwellers who

constitute 25 – 30% of the urban population are heavily

dependent on bio-fuels. This is because of their low

purchasing power and limited availability of the

commercial fuels-kerosene and LPG.

Consequences of inefficient and high consumption of

wood biomass for energy:

o Destroying biomass resources at a rate faster than that

of their regeneration may lead to depletion of forests

and desertification.

o Forests, which are earth’s largest depository (sink) of

carbon dioxide, diminish the green house effect.

Growing gap between biomass consumption and

regeneration leads to a crisis of sustainability.

WOODY BIOMASS USE SHOULD BE A BALANCED & EFFICIENT

ONE

o TECHNOLOGICAL INNOVATION ON BIOMASS

MUST CONCENTRATE ON: IMPROVING ITS

PRODUCTION, TRANSFORMATION AND

APPLICATIONS FOR ENERGY.

• WOOD BIOMASS IS AN ENDANGERED LIFE

SUPPORT SYSTEM.

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• IT SHOULD BE UTILISED IN A SUSTAINABLE

WAY.

TREES / WOOD:

Leucaena leucocephala (Subabul)

Acacia sp

Casurina sp

Derris indica (Pongam)

Eucalyptus sp

Sesbania sp

Prosopis juliflora

Azadiracta indica (Neem)

HYDROCARBON PLANTS : Euphorbia group

Euphorbia Lathyrus

OIL PRODUCING SHRUBS :

Euphorbia Tirucali

Soyabean

Sunflower

Groundnut

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Environmental impact of biomass utilization for ene rgy:

In developing countries, trees are often cut down because

they are the only source of fuel for the population. This can

lead to environmental damage. The habitats of wild animals

are destroyed. Soil is eroded because tree roots are no

longer present to bind it together. This soil may be washed

down into rivers, which then silt up and flood. But the

destruction of trees and forests is a worldwide environmental

problem with deforestation accounting for 18% of the

greenhouse effect today. New trees must

replace the ones that are cut down if we are to protect the

global climate and the lives of people in the developing

countries.

Reference: Forests as biomass energy resources in India by

B. N. Dwivedi and O. N. Kaul in Biomass Energy Systems,

Edited by P.Venkata Ramana and S. N. Srinivas,

British Council and T E R I, N. Delhi, 1996.

Energy Plantation:

Growing trees for their fuel value on ‘Wasteland’ or land that

is not usable for agriculture and cash crops is social forestry

activity. A plantation that is designed or managed and

operated to provide substantial amounts of usable fuel

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continuously throughout the year at a reasonable cost may

be called as ‘energy plantation’

Suitable tree species and land with favorable climate

and soil conditions of sufficient area are the minimum

resource required. Depending on the type of trees, the tree

life cycle, the geometry of leaf bearing branches that

determines the surface area facing the sun, the area

required for growing number of would be evaluated.

Combination of harvest cycles and planting densities that

will optimize the harvest of fuel and the operating cost, are

worked out. Typical calorie crops include 12000 to 24000

trees per hectare.

Raising multipurpose tree species on marginal lands is

necessary for making fuel wood available as well as for

improving soil condition. Trees for fuel wood plantations are

those that are capable of growing in deforested areas with

degraded soils, and withstand exposure to wind and drought.

Rapid growing legumes that fix atmospheric nitrogen to

enrich soil are preferred. Species that can be found in similar

ecological zones, and have ability to produce wood of high

calorific value that burn without sparks or smoke, besides

having other uses in addition to providing fuel are the

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multipurpose tree species most suited for bio-energy

plantations or social forestry programs.

AZADIRACTA INDICA (NEEM), LEUCAENA

LEUCOCEPHALA (SUBABUL), DERRIS INDICA

(PONGAM), AND ACACIA NILOTICA (BABOOL) are

examples of tree species for the above plantations.

AGRO-RESIDUES:

Biomass

[Year 2000]

Availability

Million tons/year

Coal equivalent

Million tons/year

Rice straw 100 60

Rice husk 30 20

Jute sticks 25 10

Wheat straw 50 38

Cotton stalks 20 17

Bagasse 30 25

Molasses 05 03

Coconut husk /

shell

02 03

Saw dust 05 06

Other 33 18

Total 100 200

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Estimated biomass residue production in India - 2010 Crop Area (Mha) Produce (MT) Residue

(dry) (MT)

R / P Type of

Residue

Rice 46.1 118.8 213.9 1.8 Straw, husk

Wheat 28.5 98.5 157.6 1.6 Straw

Jowar 5.3 6.1 12.2 2.0 stalk

Bajra 8.6 6.8 13.6 2.0 stalk

Maize 6.6 13.0 32.5 2.5 Stalk, cobs

Cotton 10.1 15.9 55.7 3.5 Seeds, waste

Jute 0.6 6.5 10.5 1.6 waste

Sugar Cane 5.5 463.5 185.4 0.4 Bagasse,

wastes

Source: Ravindranath et al, (2005)

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Table: Estimated potential for biomass energy : 10 15 J y -

1(1015 J y -1 = 320MW) Estimated total potential bio-fuel

resources harvested per year for various

countries(1978):

Source Sudan Brazil India Sweden U.S.A.

Animal Manure 93 640 890 18 110

Sugar Cane 660 1000 430 --- 420

Fuelwood 290 3200 420 160 510

Urban Refuse 5 94 320 23 170

Municipal

Sewage

2 11 66 1 5

Other --- --- --- ---- 630

Total Potential 1000 4800 2100 200 1800

Present national

energy consumption 180 2700 5800 1500 72000

Ratio potential to

consumption

5.5 1.8 0.4 0.13 0.03

Ref: Vergara, W. and Pimental, D.(1978)’Fuels from

biomass’, in Auer, P.,(ed.),

Advances in Energy Systems and Technology, vol.1,

Academic Press, New York, pp 125-73

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Estimated quantity of waste generated in India (199 9):

Waste Quantity

Municipal solid Waste 27.4 million tones/year

Municipal Liquid Waste

(121 Class1 and 2 cities)

12145 million liters/day

Distillary (243 nos) 8057 kilolitres/day

Press-mud 9 million tones/year

Food and Fruit processing waste 4.5 million tones /year

Dairy industry Waste

(C O D level2 Kg/m3 )

50 to 60 million litres / day

Paper and Pulp industry Waste

(300 mills)

1600m3 waste water/day

Tannery (2000 nos) 52500 m3 waste water/day

Source: IREDA News, 10(3):11-12, 1999, V.Bhakthavatsalam

For details of characterization of biomass and analytical

procedures for determining properties, refer chapter 12,

Renewable Energy Engineering and Technology: Principles &

Practice, Edited by V. V. N. Kishore, 2009, T E R I, N. Delhi.

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Properties of Biomass

Physical Properties :

Moisture Content,

Particle Size and Size distribution

Bulk Density &

Specific gravity

Proximate Analysis :

Moisture Content

Volatile Matter

Fixed Carbon

Ash or mineral content

Chemical composition and heat content:

Elemental Analysis :

Carbon

Hydrogen

Oxygen

Nitrogen

Sulphur

Higher Heating Value :

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Chemical Composition :

Total Ash %,

Solvent soluble %,

Water Soluble %,

Lignin %,

Cellulose %,

Hemi-cellulose % Wet and biodegradable biomass :

C O D value & B O D value,

Total dissolved solids & Volatile solids

BIOMASS PREPARATION FOR FUEL USE:

Preliminary treatment of biomass can improve its handling

characteristics, increase the volumetric calorific value, and

fuel properties for thermo-chemical processing. It can

increase ease of transport and storage.

Examples: CHIPPING, CHOPPING, DRYING, GRINDING,

BRIQUETTING ETC.

Fuel wood requires drying in air and chopping for best result

in cook stoves. Saw dust requires drying and briquetting to

increase its bulk density. Industrial boilers require uniformly

smaller sizes of wood for feeding their furnaces. Predrying of

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biomass to moisture levels of below 20% (oven dry basis)

enhances efficiency of combustion in cook stoves and

industrial boilers.

For production of high or medium pressure steam by

using biomass the best choice of equipment is the water

tube boiler. It has a large combustion area surrounded by

banks of vertical water tubes, which makes it suitable for

biomass fuels. Biomass fuels have a high content of volatile

matter and lower density and bulk density compared to solid

fossil fuels; as a result , biomass fuels need a large space

(relatively ) above the fuel bed to prevent flaring volatile

material from impinging upon the chamber wall and causing

damage to it over a period of time. Shell boilers are

unsuitable for biomass fuels because of the restricted

diameter of the furnace tube and high risk of damage to the

tube wall by flame impingement. Additionally demand for

uniform fuel quality and size by shell boilers are relatively

stricter.

Other types of end use equipment that are suitable for size

reduced biomass include cyclone furnaces, fluidized bed

systems and the controlled combustion incinerator. Cyclones

furnaces are adaptable to use of wood waste s fuel.

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Briquetting technologies:

Reference: ’Biomass feed processing for energy conversion’

P. D. Grover, in Biomass Energy Systems, Ed. P. Venkata

Ramana and S. N. Srinivas , T E R I and British Council, N.

Delhi(1996) pp 187-192

The proven high pressure technologies presently employed

for the briquetting of biomass are by the piston or the ram

type press and the screw or the extruder type machines.

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Both the machines give briquettes with a density of 1-1.2

gm/cc and are suitable as industrial solid fuels. The screw

type machines provide briquettes with a concentric hole that

gives better combustibility and is a preferred fuel. These

briquettes can also be more conveniently deployed in small

furnaces and even cook-stoves than solid briquettes

generated by a ram press.

Biomass densification-A solid(fuel) solution. N.Yuvraj,

Dinesh Babu, TERI, New Delhi. TERI Newswire, 1-15

December, 2001, page 3.

In India, briquettes are mostly made from groundnut

shell, cotton stalk, saw dust, coffee husk, bagasse, mustard

stalk and press mud. While the Southern region of India

produces briquettes mostly from groundnut shell and saw

dust, Western and

Northern regions produce bagasse, groundnut shell, cotton

stalk, mustard stalk and press mud briquettes. As a recent

addition municipal solid waste is also densified for use as

fuel in process industries (tea, tobacco, textile, chemical,

paper, starch, tyre re-treading, tiles, etc) for thermal

applications.

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Biomass & Bio-energy 14, no5-6, pp 479-488, 1998

‘A techno-economic evaluation of biomass briquetteing in

India’ A.K.Tripathi, P.V.R.Iyer and Tarachand Khandapal (I I

T, N.Delhi) tarak@ces.iitd.ernet.in

Various types of raw materials used for briquetteing are:

ground-nut shells, cotton stalks, bagasse, wood chips, saw

dust, and forest residues. Pyrolysed biomass can also be

used. Materials can be fine granulated, coarse granulated or

stalky. Material may be dry or wet with various moisture

content. After a material is dried and crushed the pellets may

be formed under pressure with effect of heat,

Biomass & Bio-energy 18(3):223-228(2000)

‘Characteristics of some biomass briquettes prepared under

modest die pressures’ Chin, O.C and Siddiqui, K.M,

Universiti Sains Malaysia,31750,Perak, Malaysia

kmust@hotmail.com

1. Discuss the sources and major kinds of biomass

available in India. How is the use of biomass for energy

justified? Explain biomass characteristics, propert ies

and suitable energy conversion methods.

2. For solid biomass used for combustion, what is t he

significance of Proximate and Ultimate Analysis and

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HHV? Give typical values for saw dust, bagasse and rice

husk.

3. Discuss the woody, non-woody and organic waste

biomass available in India as resource for rural

supplementary energy / electricity.

4. How is sustainable use of biomass as energy sour ce

possible and justified?

5. Explain biomass characteristics, properties and

suitable energy conversion methods.