1. Biomass: sources, characteristics & preparation:
Sources and classification of biomass available for energy
Chemical composition and properties of biomass
Preparation of biomass for fuel applications: Size
Briquetting of loose biomass, Drying, and Storage and
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
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.
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.
Sources of three categories of biomass
WET ORGANIC WASTE
NONEDIBLE OIL SEEDS
WASTE STARCH &
TREES FROM VILLAGE
ENERGY CROPS: (SUGAR
EFFLUENTS (B O D)
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
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 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.
BIOGAS (AN. DIGESTION)
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.
Forest resources of India:
India’s is sustaining 16 % of the world’s population and 15 % of its
livestock population on 2.47 % of world’s geographical area and has
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
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 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 biofuels. 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
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
o TECHNOLOGICAL INNOVATION ON BIOMASS MUST CONCENTRATE
IMPROVING ITS PRODUCTION, TRANSFORMATION AND
APPLICATIONS FOR ENERGY.
WOOD BIOMASS IS AN ENDANGERED LIFE SUPPORT
IT SHOULD BE UTILISED IN A SUSTAINABLE WAY.
TREES / WOOD: Leucaena leucocephala (Subabul) (50 m3/ha/year)
Derris indica (Pongam)
Azadiracta indica (Neem)
HYDROCARBON PLANTS: Euphorbia group
OIL PRODUCING SHRUBS:
Environmental impact of biomass utilization for energy:
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.
British Council and T E R I, N. Delhi, 1996.
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
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 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.
Agriculture yields by annual harvest a large crop residue biomass part of
which can be a source of rural bio-fuels.
AGRO-RESIDUE IN INDIA (POTENTIAL AVAILABILITY - 1995-96)
MT = Million tons
India, MT T.Nadu, MT
Pearl Millet straw
Sugar Cane Bagasse 93.4
Table: Estimated potential for biomass energy : 1015 J y-1(1015 J y-1 =
320MW) Estimated total potential bio-fuel resources harvested per year for
Present national energy
Ratio potential to
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
Estimated quantity of waste generated in India (1999):
Municipal solid Waste
27.4 million tones/year
Municipal Liquid Waste
12145 million liters/day
(121 Class1 and 2 cities)
Distillary (243 nos)
9 million tones/year
Food and Fruit processing waste 4.5 million tones /year
Dairy industry Waste
50 to 60 million litres / day
(C O D level2 Kg/m )
Paper and Pulp industry Waste
1600m3 waste water/day
52500 m3 waste water/day
Tannery (2000 nos)
Source:IREDA News, 10(3):11-12, 1999, V.Bhakthavatsalam
Properties of Biomass
Particle Size and Size distribution
Bulk Density &
Ash or mineral content
Chemical composition and heat content:
Higher Heating Value:
Total Ash %,
Solvent soluble %,
Water Soluble %,
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
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.
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
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
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) email@example.com
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,