This document discusses various sources of biomass that can be used for fuel applications. It describes how biomass from agriculture, forestry, plantations and animal husbandry can be processed into fuels. Primary sources include crop residues, woody biomass, animal waste and energy crops. Technologies for converting biomass include direct combustion as well as thermochemical and biochemical processes like pyrolysis, gasification and anaerobic digestion. The document also provides estimates of biomass potential from different sources in various countries and discusses preparation and densification of biomass through processes like drying, grinding and briquetting to improve its fuel properties.

1. Sources of biomass for fuel applications
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.
Primary activities of raising food crops, trees, animal husbandry and
degradable waste collection for disposal are the sources of biomass used as
fuels for energy recovery. Agriculture, forestry, plantations, dairies etc., produce
agro-residues, woody biomass and animal waste respectively which are
processed to produce fuels. Biofuels are mostly produced in rural areas and
utilized for such applications as domestic cooking, village industries and the
technology for conversion and end use devices are often primitive.
In rural India, biomass and human and animal energy continue to
contribute 80 % of the energy consumption. Cooking energy constitutes about 85
percent of our rural energy demand and has traditionally been met by biomass
fuels such as firewood, agricultural residues and animal wastes. Under the
National Programme on Improved Cookstoves, about 30 million cookstoves have
so far been installed, which are helping to cut back and conserve fuelwood use.
Energy plantations using appropriate fast-growing tree species have also been
established on marginal lands to provide fuelwood for use in efficient cookstoves
and biomass gasifiers.
Patterns of energy use are changing in urban areas, with greater use of
LPG and kerosene. It is, however, unlikely that fuelwood will be completely
replaced, as poorer sections of the community may continue to lack the cash
resources to purchase even minimal amounts of kerosene or LPG, or the
appliances to make use of these fuels.
It is now increasingly realised that there is considerable potential for the
modernisation of biomass fuels to produce convenient energy carriers such as
1

2. electricity, gases and transportation fuels whilst continuing to provide for
traditional uses of biomass. The modernisation of biomass and the necessary
industrial investment is already happening in many countries. However, it is
important to emphasise that the future use of bioenergy must be strongly linked
to high energy efficiency, and environmentally sustainable production and use.
Woody biomass is product of forestry and trees from different agroforestry 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.
Non -edible vegetable oils from tree borne oil seeds 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.
Agriculture yields by annual harvest a large crop residue biomass part of
which can be a source of rural biofuels. Sugar cane yields bagasse as a
byproduct of agro-industry. Plants that grow in wastelands are also potential
energy crops.
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.
Biomass that is used for producing bio-fuel may be divided into woody, nonwoody and wet organic waste categories. The sources of each are indicated in
Table 1.
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3. Table-1. Sources of three categories of biomass
WOODY
NON-WOODY
(cultivated)
FORESTS
FOOD CROPS
WOODLANDS
CROP RESIDUES
PLANTATIONS
PROCESSING
(MULTIPURPOSE RESIDUES
TREES)
HYDROCARBON
NONEDIBLE OIL
PLANTS
SEEDS
WET
ORGANIC
WASTE
ANIMAL WASTES
MANURE, SLUDGE
MUNICIPAL
SOLID
WASTE
TREES FROM
VILLAGE COMMON
LANDS
OTHER INDUSTRIAL
EFFLUENTS (B O D)
ENERGY CROPS:
(SUGAR CANE
BAMBOO)
WASTE STARCH &
SUGAR SOLUTIONS
Sources of Woody Biomass:
India has low forest cover which is under high pressure. With only around
one percent of the world’s forests, India has to sustain nearly 16 percent of the
world’s human population and almost 15 percent of the world’s livestock. India
has 63.3 million hectares of forest land – 19.27 percent of its total land area.
According to estimates, some 80 percent of the country’s energy requirement is
met from non-commercial energy sources, of which firewood is a major
component. Within a total land area of nearly 3 million km2, India’s forest land
covers some 640 000 km2, or 21.6%. Biomass fuels contributed 41% of total
inland primary energy supplies in 1998; in India’s rural areas, the percentage
supplied by biomass (wood, animal dung and agricultural residues) rises to about
95. Whereas the use of dried dung and waste as fuel is widespread in
agriculturally prosperous regions, wood is still the principal domestic fuel in
poorer and less well-endowed regions. Overall, fuelwood is estimated to provide
almost 60% of energy in rural areas and around 35% in urban areas.
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4. Current annual consumption of fuelwood is estimated at 217 million tonnes,
of which only about 18 million tonnes constitutes sustainable availability from
forests: approximately half of fuelwood supplies is derived from TOF (trees
outside forests) sources, such as farms, village woodlots, small plantations on
private or government land, and trees or shrubs alongside roads, railways,
canals, ponds etc. The balance of fuelwood supply represents non-sustainable
drawings from forest areas plus miscellaneous gathering of woody material.
Besides its primary use as the almost universal rural fuel for domestic cooking
and heating, fuelwood is also used in bakeries, hotels, brick and tile manufacture,
and numerous small cottage industries.
It is to be noted that estimates of Indian fuelwood production/consumption,
and especially of the breakdown by source or sector, are extremely conjectural,
varying widely from agency to agency and from one estimate to another.
Consequently any levels quoted above should be regarded as, at best, indicative.
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
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
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5. 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 multipurpose tree species most suited for bioenergy 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.
Sources of Crop and agro-industry residues:
Agriculture yields by annual harvest a large crop residue biomass part of
which can be a source of rural biofuels. There are other or alternative uses of
residues e.g. feed, their role in reducing erosion, stabilisation of soil structure,
enhance moisture content, use as animal bedding or use as fertilisers (dung).
Availability for fuel use also depends on variation in the amount of residue
assumed necessary for maintaining soil organic, soil erosion control, efficiency in
harvesting, losses, non- energy uses, etc.
Hall et al (1993) have estimated that using the world's major crops only (e.g.
wheat, rice, maize, barley, and sugarcane), a 25% residue recovery rate could
generate 38 EJ and offset between 350 to 460 Tg C/yr.
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6. AGRO-RESIDUE IN INDIA (POTENTIAL AVAILABILITY - 1995-96)
MT = Million tons
Agro-residue
Wheat Straw
Rice Husk
Maize Cobs
Pearl Millet straw
Sugar Cane Bagasse
Coconut shell
Coconut pith
Groundnut shells
Cotton Stalks
Jute Stalks
India, MT
83.3
39.8
2.8
9
93.4
3.4
3.4
2.6
27.3
2.7
T.Nadu, MT
9.2
3.3
0.6
0.4
0.6
0.8
Bioenergy Technologies:
Biomass energy technologies can be roughly divided into three main
groups e.g. direct combustion processes, thermochemical processes and
biochemical processes. The first process is in principle directly concerned with
primary fuels e.g. the fuels are used as they are found or after some form of
processing such as size reduction, drying, compaction through briquetting,
carbonization, etc. The latter two are basically processes in which the primary
fuel is converted into a secondary fuel. In thermochemical and biochemical
conversion processes the biomass is converted from a solid form into either a
gas or a liquid through pyrolysis, gasification or catalytic liquefaction or through
fermentation and other related processes such as hydrolysis with acids or
enzymes, etc.
There is no single best way to use biomass for energy, and
environmental acceptability will depend on sensitive and well informed
approaches to new developments in each location. It is clear that biomass for
energy can be environmentally friendly, and steps must be taken to ensure that it
is, if biomass is to be accepted as an important fuel of the future, and the
implications for the agricultural sector thoroughly assessed.
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7. 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
CO-PRODUCT
PRODUCT
WOOD
CHAR (PYROLYSIS)
PYROLYSIS
OIL
WOOD
CHAR (GASIFICATION)
PRODUCER
GAS
ANIMAL MANURE
BIOGAS
(ANEROBIC DIGESTION)
FERTILIZER
7

8. Table-2. : Estimated potential for biomass energy :1015 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
2
11
66
1
5
Other
---
---
---
----
630
Total Potential
1000
4800
2100
200
1800
Present
180
2700
5800
1500
72000
1.8
0.4
0.13
0.03
Sewage
national
energy
consumption
Ratio potential 5.5
to
consumption
8

9. 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,pp125-73
Bio-fuel production from primary biomass may utilize thermo-chemical,
biochemical and catalytic conversion processes. 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
PREPARATION OF BIOMASS 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
9

10. biomass to moisture levels of below 20% (oven dry basis) enhances efficiency of
combustion in cook stoves and industrial boilers.
Estimated quantity of waste generated in India (1999):
Waste
Quantity
Municipal solid Waste
27.4 million tones/year
Municipal Liquid Waste
12145 million liters/day
(121 Class1 and 2 cities)
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
50 to 60 million litres / day
3
(C O D level2 Kg/m )
Paper and Pulp industry Waste
1600m3 waste water/day
(300 mills)
Tannery (2000 nos)
52500 m3 waste water/day
Source:IREDA News, 10(3):11-12, 1999, V.Bhakthavatsalam
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.
10

11. 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.
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.
11

12. 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.
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.
12

13. 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
Properties of Biomass
Physical, chemical and thermal properties of solid, liquid and gaseous bio-fuels
for required for energy conversion methods like combustion are determined
experimentally and data are used in design calculations.
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
Elemental Analysis:
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
13

14. Types
Wood
Oak(dry)
Pine(dry)
Peat
Lignite
Coal (Range
TABLE 3.TYPICAL COMPOSITIONS OF SOLID FUELS
Proximate Analysis
Ultimate Analysis
Moisture Volatile
Fixed
Ash
C
H
O
N
S
carbon
------
85.6
13.0
1.4
58.2
6.0
43.3
0.1
-
4622
-----56.8
34.8
3-20
87.0
26.0
28.2
16-40
12.8
11.2
30.8
4080
0.7
6.0
6.2
3.040
52.2
23.1
42.4
6050
7.0
9.6
6.7
3.0-6
40.2
59.6
43.3
3.06
0.2
1.3
0.7
11.5
0.4
0.7
0.34.3
----0.8
12.0
80.5
1.4
1.9
17.0
87.1
83.1
2.5
10.7
3.0
48
85
84
6.0
0.8
2.3
43.2
1.2
10.7
0.3
1.3
--
0.1
1.0
--
5338
4625
6110
4000
to
8000
4430
7105
7130
Of property)
Bagasse
Coke
Charcoal
Heating
Value,
dry
basis,
kcal/kg
Higher Heating value:
Gross calorific value or higher heating value of a fuel containing C, H and O is given by
the expression:
Cg =[C x 8137 + (H--O/8) x 34500]/100 where C, H and O are in % and Cg is in calories.
Net calorific value is the difference between GCV and latent heat of condensation of
water vapor present in the products
Chemical composition
Chemical Composition:
Total Ash %,
Solvent soluble %,
Water Soluble %,
Lignin %,
Cellulose %
Hemi-cellulose %
14

15. Table: x. Chemical composition of some biomass material
Species
Soft wood
Hard wood
Wheat
Straw
Rice Straw
Bagasse
Total
ash
%
0.5
0.3
6.0
16.1
2.2
Solvent
Soluble
%
2.0
3.1
3.1
Water
Soluble
%
7.1
Lignin
%
Cellulose
27.9
19.5
16.0
Hemicellulose
%
24.0
35.0
28.1
4.6
8.3
13.1
10.0
11.9
18.4
24.1
28.0
30.2
33.1
Properties of Wet and biodegradable biomass:
C O D value & B O D value,
Total dissolved solids & Volatile solids
15
40.8
39
39.7