• Shersingh Meena
Biofuels are produced from living organisms or from
metabolic by-products (organic or food waste
Solid biofuels are wood, sawdust, grass cuttings,
domestic refuse, charcoal, agricultural waste, non-
food energy crops and Dried manure (cow dung)
solid biomass to be converted into useful heat energy
it has to undergo combustion
There are three main stages to the combustion process:
Drying - all biomass contains moisture, and this
moisture has to be driven off before combustion
proper can take place. The heat for drying is supplied
flames and from the stored heat in the body of the
stove or furnace.
Pyrolysis - the dry biomass is heated and when the
temperature reaches between 200ºC and 350ºC the
volatile gases are released. These gases mix with
oxygen and burn producing a yellow flame. This
process is self-sustaining as the heat from the burning
gases is used to dry the fresh fuel and release further
volatile gases. Oxygen has to be provided to sustain
this part of the combustion process. When all the
volatiles have been burnt off, charcoal remains.
Oxidation - at about 800ºC the charcoal oxidises or
burns. Again oxygen is required, both at the fire bed
for the oxidation of the carbon and, secondly, above
the fire bed where it mixes with carbon monoxide to
form carbon dioxide which is given off to the
Combustion efficiency varies depending on many
2. moisture content
3. and calorific value of fuel, etc.
Wood as Solid Bio-fuel
Wood is important solid bio-fuel in the rural areas.
Wood has higher calorific value 14.4MJ per meter cube.
Chulha is important system based on wood.
It is good chulha used in rural area.
Users are households women.
Fuel used are firewood, dung cakes, agri-residue.
Efficiency(lab. tests)= 24.8%
Wood fuel saving(field tests) =30 - 40%
EmissionsCO/CO2 ratio: 0.03
Materials used is Sheet metal
(Wood Energy conversion)
Wood into Gas conversion –
Exposed wood to extremely high temperatures (900-
1,200°C) and pressure in a low oxygen environment to
produce syngas which is combustible and can be used
as a fuel source.
Exposing wood to certain bacteria in the absence of
oxygen to produce biogas
Use of gases obtained
heating water or buildings,
Wood into Liquid Oil conversion
Fast Pyrolysis -- Heating wood quickly to a high
temperature in the absence of oxygen for producing liquid
oil, char and a combustible syngas
Have higher amount of energy per unit volume than wood,
Easier and cheaper to transport than wood
Use of bio-oil
• Heat buildings
• In generators to produce electricity
Wood to Transportation fuels
Ethanol, methanol, or biodiesel
Fermentation (Ethanol prodution ) –
When woody biomass is gasified, the resulting gas can be
converted to a liquid
Oils extracted from wood are combined with alcohol and
a catalyst to produce diesel fuel
Ethanol can be used to power vehicles
Methanol can be used to fuel vehicles or to produce
other chemical products
biodiesel can be used to power machinery and
Called “Inverted downdraft gasifier“
Produce gas from wood and then burn the
gas, leaving ash and charcoal
They're clean, fast and efficient
They burn small pieces of wood, sticks, wood chips, corncobs or
nutshells, producing a clean, blue flame and no smoke
Wood Gas Generator
Provide emergency fuel for vehicles,such as tractors and trucks , in a
Advantages of Wood fuel over
Renewable resource, offering a sustainable,
Typically 90% less (CO2) emitted during the burning
Minimal amounts of sulfur and heavy metals
No threat to acid rain pollution,
Particulate emissions are controllable
Briquette as Solid Bio-fuel
Why should we use Briquette
Many of the developing countries produce huge quantities
of agro residues
Major residues:-rice husk, coffee husk, coir pith, jute
sticks, bagasse, groundnut shells, mustard stalks, rice
husk and cotton stalks.
These are used inefficiently causing extensive to the
The conversion efficiencies are as low as 40% with
particulate emissions in the flue gases in excess of, a large
percentage of unburnt carbonaceous ash has to be
Briquetting of the husk could mitigate these pollution
Appropriate Biomass Residues for Briquetting
Low moisture content
Moisture content should be as low as possible, generally
in the range of 10-15 percent.
High moisture content will pose problems in grinding
and excessive energy is required for drying.
Ash content and composition
The ash content of different types of biomass is an
indicator of slagging behaviour of the biomass.
The material should be granular and uniform so that it
can flow easily in bunkers and storage silos.
On the basis of compaction, the briquetting
technologies can be divided into:
1. High pressure compaction
2. Medium pressure compaction with a heating device
3. Low pressure compaction with a binder.
Screw Press and Piston Press Technologies
High compaction technology or binder less technology
consists of the piston press and the screw press.
APPLIANCES FOR BIOMASS BRIQUETTES
Combustion in Stoves
Screw pressed briquettes (SPB) are easy to burn and give
better combustion than wood.
Since the density of these briquettes is higher than wood,
the amount of air required is correspondingly greater for
the same volume of briquettes.
Moreover, SPB should be placed in a vertical position as
far as possible so that the air can easily pass through the
APPLIANCES FOR BIOMASS BRIQUETTES
Boilers: For steam generation
Food processing industries : Distilleries, bakeries, canteens, restaurants
and drying etc.
Textile process houses : Dyeing, bleaching etc.
Agro-products: Tobacco curing, tea drying, oil milling etc.
Clay products : Brick kilns, tile making, pot firing etc.
Domestic: Cooking and water heating
Gasification: Fuel for gasifiers
Charcoal : Suitable for making charcoal in kilns
COW DUNG as a Solid Fuels
Deforestation and erosion have contributed to great
fuel wood shortages in many areas of central Asia
This was initially in response to the threat of
deforestation but has also been focused on the needs
of women to reduce fuel collection times.
Dung is considered to be one of the best fuels for the
traditional mud stove for the following reasons
it burns slowly
generates powerful heat compared to other sources of
fuel found locally
easy to store
Problems related to dung as a fuel are;
It burns faster than wood when it is not properly
It creats a great deal of smoke
It creats lots of ash
Great quantities of dung are dried and burned, often
very inefficiently, yet very little focus has been made in
the area of improving dung-burning stoves and most
stoves are built without consideration of advanced
combustion principles. Chulah-type stoves that are
simple u-shaped combustion boxes are used
throughout north India.
creating a great deal of smoke by reducing air flow
used for the slow heating of milk without boiling over
a few hours
•Available energy in bio mass fuel
due to a wide variety of compositional ash content
in dung, affecting the energy content
Heating Energy 1 Heating energy 2
Wood 20335 20000
Dung 17198 10000
Rice hulls 13944 13000
Fuel Efficient chulha
This is in a way a double walled cylindrical stove, the outer wall is
a thin plain sheet metal one while the inner one carries several
rows of small (a few mm dia) holes. The 2mm gap between the
walls is open towards the bottom of the stove while the top is
Some of the features of these improved stoves
• a chimney to remove smoke from the kitchen
• an enclosed fire to retain the heat
• careful design of pot holder to maximise the heat transfer from
fire to pot
• baffles to create turbulence and hence improve heat transfer
• dampers to control and optimise the air flow
• a ceramic insert to minimise the rate of heat loss
• a grate to allow for a variety of fuel to be used and ash to be
• metal casing to give strength and durability
• multi pot systems to maximise heat use and allow several pots to
be heated simultaneously
Agricultural waste, the unwanted or unrefined by-products of farm crops
and animals that are often thrown away by farmers
The major agricultural products can be broadly grouped into food ,fibers
,fuels and raw materials etc.
Efficient Utilization of Agricultural Wastes
Production of biogas for village/household use
Reduce the use of firewood and coal and the use of
Improve the micro-nutrients in the soil profile of degraded
Lower household costs
Reduce the destruction of forests
Improve air quality through reduction in the use of coal and
open burning of crop residue
Improve the utilization of limited and degraded farm land
Bio-char made from agricultural waste can substitute for wood charcoal
Biochar is charcoal created by pyrolysis of biomass
Its primary use is not for fuel, but for biosequestration or atmospheric carbon
capture and storage
Biochar is a way for carbon to be drawn from the atmosphere and is a solution
to reducing the global impact of farming
Biochar is a tool used to simultaneously slow down deforestation, increase the
food security of rural communities, provide renewable energy to them and
Pyrolysis is the thermal decomposition of biomass occurring in the absence
It is the fundamental chemical reaction in which the combustion and
gasification processes occurs naturally
The products of biomass pyrolysis include biochar, bio-oil and gases
including methane, hydrogen, carbon monoxide, and carbon dioxide
Pyrolysis will yield mainly biochar at low temperatures, less than 450 0C
and gases at higher temperatures and bio-oil at intermidiate temp.
(450 0C ,no air) Vapors Power
Uses of Biochar in Rural Areas
Use as a carbon sink
Biochar removes circulating CO2 from the atmosphere and stores it in
virtually permanent soil carbon pools, making it a carbon-negative process
The addition of biochar to the soil has been found to accelerate the
mineralization of the existing soil organic matter, probably from the
excessive potash and increased pH from biochar
Play a significant role in combatting global warming
Positive and Negative Effects on Soil
Soils require active carbon to maintain micro and macro populations, not the
inactive form found in biochar
Biochar can prevent the leaching of nutrients out of the soil
Increase water retention and reduce the amount of fertilizer required
Reduce the emmision of N2O (Nitrous oxide) and CH4 (methane) from soil
Also reduces GHG emissions
Biochar added at 10% levels reduced contaminant levels in plants by up to 80%,
while reducing total chlordane and DDX content in the plants by 68 and 79%,
Creates a higher crop uptake of nutrients, while also providing greater soil
availability of nutrients
Use as dietary supplement for animals, and traditionally as charcoal
biscuits for humans
Maintain a healthy digestive system, reduce flatulence(which is a
source of methane), and reduce the odour of ammonia emissions
Energy production: bio-oil
Can be used as a replacement for numerous applications where fuel
oil is used as in furnaces, and boilers
Can be used to fuel some combustion turbines and reciprocating
It can be directly substituted for any application that uses coal
Pyrolysis also may be the most cost-effective way of producing
electrical energy from biomaterial
Charcoal is the black residue consisting of impure
carbon obtained by removing water and other volatile
constituents from animal and vegetation substances
Charcoal have higher calorific value (33MJ/kg)than
The conversion of wood into charcoal is described by
Charcoal making technology
Charcoal making by two following method as given
Direct method (high emission of pollutant) -The
direct method uses heat from the incomplete
combustion of the organic matter, which is to become
Indirect method ( higher yield of high quality
charcoal)-Indirect method uses an external heat
source to "cook" organic matter contained in a closed
but vented airless chamber (retort)
It is made directly from hardwood material and usually produces far
less ash than briquettes.
It is made by compressing charcoal, typically made from sawdust and
other wood by-products, with a binder and other additives.
The binder is usually starch. Some briquettes may also include brown
coal , mineral carbon , borax, sodium nitrate , limestone , raw sawdust ,
and other additives like paraffin or petroleum solvents to aid in
It is made by extruding either raw ground wood or carbonized wood
into logs without the use of a binder.
The heat and pressure of the extruding process hold the charcoal
If the extrusion is made from raw wood material, the extruded logs are
then subsequently carbonized.
Use of charcoal
Charcoal briquettes are widely used for outdoor
grilling and barbecues in backyards and on camping
Historically, charcoal was used in great quantities for
smelting iron in bloomers and later blast furnaces and
In times of scarce petroleum, automobiles and even
buses have been converted to burn wood gas released
by burning charcoal or wood in a wood gas generator
Emissions and controls
There are five types of products and by products from
charcoal production operations:
1. Carbon monoxide (CO)
2. Carbon dioxide (CO2)
3. Methane, and ethane)
4. Pyroacids (primarily acetic acid and methanol)
5. Tars and heavy oils, and water. With the exception of charcoal ,
all of these materials are emitted with the kiln exhaust.
Advantages of the charcoal making
Livelihood for rural people
Clean Environment for women in cooking
Other Area of uses
Livelihood for rural people
The biomass charcoal technology will be led to significant
increase in the income of rural people (women).
As Capacity for construction, repair, and maintenance of new the
technology making –direct (wood pile), Missouri-type charcoal
Charcoal briquette production has provided opportunities for
income –generation activities and livelihood enhancement.
Other area of use
Dhania dal( coriander seeds )processing.
Agarbatti (incense) manufacturing
Charcoal, an old age refined from of wood fuel. It still
remainsan important energy source for domestic cooking.
Biomass Charcoal technology should be permitted in rural
area sothat we can conserve and optimize the use of
inefficient fuel wood, especially in the rural area.
Charcoal remains a neglected subject within the concerned
government departments/ministries. What is needed is a
bold policy statement making adequate financial,
administrative, and extension provisions to encourage
charcoal making as a vibrant activity.