Difinition
Biodiesel refers to a non-petroleumbased diesel fuel consisting
of short chain alkyl (methyl or ethyl) esters,
made by transesterification of
vegetable oil, which can be used
(alone, or blended with
conventional petrodiesel) in
unmodified dieselengine vehicles.

Difinition
 Biodiesel is a renewable fuel which can be made from
vegetable oils, animal fats, or recycled restaurant
grease. Believe it or not, this can then be used in diesel
vehicles already on the road because its physical
makeup is similar enough to petroleum diesel, but it
burns much more cleanly. Biodiesel is also much safer.
Not only is it easier on the environment if spilled, but
it has a flashpoint of over 130 degrees celsius,
compared to 52 for normal diesel. Pure biodiesel,
known as B100, reduces carbon dioxide emissions by
more than 75% compared with normal diesel.

Biodiesel
 Biodiesel is a renewable fuel that is produced from a variety of
edible and non-edible vegetable oils and animal fats. It is
mainly used as Alternative Fuel in Diesel Engine The term
“biodiesel” is commonly used for methyl or ethyl esters of the
fatty acids in natural oils and fats, which meet the fuel quality
requirements of compression-ignition engines.
 Straight vegetable oils (SVO) are not considered as biodiesel.
The straight vegetable oils have a very high viscosity that makes
flow of these oils difficult even at room temperatures.
Moreover, presence of glycerine in the vegetable oil causes
formation of heavy carbon deposits on the injector nozzle holes
that results in poor and unacceptable performance and
emissions from the engine even within a few hours of operation.

Production of boidiesel
 Biodiesel is produced by reacting vegetable oils or
animal fats with an alcohol such as methanol or
ethanol in presence of a catalyst to yield mono-alkyl
esters.

Properties of biodiesel
 A variety of vegetable oils such as soybean, rapeseed, safflower,
jatropha-curcas, palm, and cottonseed oils have been used for
production of biodiesel. Waste edible oils left after
frying/cooking operation etc., have also been converted to
biodiesel for study of their performance. The biodiesel are also
known as fatty acid methyl esters [FAME]. Recently non-edible
oil produced from jatropha- curcas seeds has gained interest in
India as this plant can be easily grown on wastelands.
 The vegetable oil esters are practically free of sulphur and have a
high cetane number ranging from 46 to 60 depending upon the
feedstock. Due to presence of oxygen, biodiesels have a lower
calorific value than the diesel fuels. European specifications for
biodiesel or fatty acid methyl esters (FAME)

Emission of biodiesel
 The influence of biodiesel on emissions varies depending on the type of
biodiesel (soybean, rapeseed, or animal fats) and on the type of conventional
diesel to which the biodiesel is added due to differences in their chemical
composition and properties. The average effects of blending of biodiesel in
diesel fuel on CO, HC, NOx and PM emissions compared to diesel as base fuel
are shown in Fig.8.7.The Table 8.19 gives change in emissions with 20 % blend
of biodiesel in diesel and 100% biodiesel compared to diesel alone. These show
the average of the trends observed in a number of investigations.
 Use of biodiesel results in reduction of CO, HC and PM, but slight increase in
NOx emissions is obtained. Reduction in CO emissions is attributed to
presence of oxygen in the fuel molecule. A slight increase in NOx emissions
results perhaps due to advancement of dynamic injection timing with
biodiesel. The methyl esters have a lower compressibility, which results in
advancement of dynamic injection timing with biodiesel compared to diesel.
Lower SOF with biodiesel and advanced injection timing also results in lower
PM emissions.

Emission of biodiesel
 Volumetric fuel consumption with biodiesel is higher
than diesel due to its lower heating value. An increase
of 10-11 % in fuel consumption compared to diesel may
be expected when comparing their heating values. An
increase in volumetric fuel consumption by 0.9-2.1%
with 20% blends has been obtained.

Biomass
 Plant and animal
material, especially
agricultural waste
products, used as a
source of fuel.

Biomass Conversion Technologies
There are four types of conversion technologies currently available that
may result in specific energy and potential renewable products:
 Thermal conversion is the use of heat, with or without the presence
of oxygen, to convert biomass into other forms of energy and
products. These include direct combustion, pyrolysis, and
torrefaction.
1. Combustion is the burning of biomass in the presence of oxygen. The
waste heat is used to for hot water, heat, or with a waste heat boiler to
operate a steam turbine to produce electricity. Biomass also can be
co-fired with existing fossil fuel power stations.
2. Pyrolysis convert biomass feedstocks under controlled temperature
and absent oxygen into gas, oil and biochar (used as valuable soil
conditioner and also to make graphene). The gases and oil can be
used to power a generator and some technologies can also make
diesel and chemicals from the gases.
3. Torrefaction is similar to pyrolysis but in a lower operating
temperature range. The final product is an energy dense solid fuel
often referred to as “bio-coal”.

 Thermochemical conversion is commonly referred to as
gasification. This technology uses high temperatures in a
controlled partial combustion to form a producer gas and
charcoal followed by chemical reduction. A major use for
biomass is for agriculture residues with gas turbines.
Advanced uses include production of diesel, jet fuel and
chemicals.
 Biochemical Conversion involves the use of enzymes,
bacteria or other microbes to break down biomass into
liquids and gaseous feedstocks and includes anaerobic
digestion and fermentation. These feedstocks can be
converted to energy, transportation fuels and renewable
chemicals.
 Chemical Conversion involves the use of chemical agents
to convert biomass into liquid fuels which mostly is
converted to biodiesel.

 Combustion - direct combustion of biomass is the most
common way of converting biomass to energy - both heat
and electricity. Compared to the gasification and pyrolysis
it is the simplest and most developed.
 Gasification - gasification is a high-temperature (1200-1400
Degree Celsius)thermo chemical conversion process but
the process is used for production of gas, instead of heat.
 Pyrolysis - thermal decomposition occurring in the absence
of oxygen. We use pyrolysis to produce a liquid fuel, bio-oil
or pyrolysis oil.

Biogass
 Biogas is the gaseous emissions from anaerobic degradation of organic matter (from
plants or animals) by a consortium of bacteria. Biogas is principally a mixture of
methane (CH4) and carbon dioxide (CO2) along with other trace gases. Methane gas, the
primary component of natural gas (98%), makes up 55-90% by volume of biogas,
depending on the source of organic matter and conditions of degradation. Biogas is
produced in all natural environments that have low levels of oxygen (O2) and have
degradable organic matter present. These natural sources of biogas include: aquatic
sediments, wet soils, buried organic matter, animal and insect digestive tracts, and in the
core of some trees. Man’s activities create additional sources including landfills, waste
lagoons, and waste storage structures. Atmospheric emissions of biogas from natural
and man-made sources contribute to climate change due to methane’s potent greenhouse
gas properties. Biogas technology permits the recovery of biogas from anaerobic
digestion of organic matter using sealed vessels, and makes the biogas available for use as
fuel for direct heating, electrical generation or mechanical power and other uses. Biogas
is often made from wastes but can be made from biomass energy feedstocks as well.
 Getting energy out of biomass by burning
it, turning it into a liquid or by turning it
into a gas called bio gas.
• It contains about 65% of methane gas as a
major constituents

Biogas production stages
 Biogas is produced using well-established technology in a
process involving several stages:
 Biowaste is crushed into smaller pieces and slurrified to
prepare it for the anaerobic digestion process. Slurrifying
means adding liquid to the biowaste to make it easier to
process.
 Microbes need warm conditions, so the biowaste is heated
to around 37 °C.
 The actual biogas production takes place through
anaerobic digestion in large tanks for about three weeks.
 In the final stage, the gas is purified (upgraded) by
removing impurities and carbon dioxide.

Is biogas the same as biofuel
 Biogas is only one of many types of biofuels, which include solid, liquid
or gaseous fuels from biomass. Any combustible fuel derived from
recent (non-fossil) living matter (biomass) may be considered a
biofuel, including ethanol derived from plant products, biodiesel from
plant or animal oils, as well as, biogas from biomass. All biofuels are
produced from sources which are renewable and are included as a
subset of renewable energy sources that also include energy produced
from solar, hydro, tidal, wind, and geothermal sources. Biogas, like
natural gas, has a low volumetric energy density compared to the liquid
biofuels, ethanol and biodiesel. However, biogas may be purified to a
natural gas equivalent fuel for pipeline injection and further
compressed for use as a transportation fuel. Methane, the principal
component in biogas, has four times the volumetric energy density of
hydrogen (H2) and is suitable for use in many types of fuel cell
generators.

Examples of Biofuels
 Ethanol:
It is produced from sugarcane .Its CALORIFIC VALUE
is less than petrol. It also less heat when compare to
petrol.
 Methanol:
It is easily obtained from ethanol .Its CALORIFIC
VALUE is too low when compared to gasoline and
diesel.

Advantages
 It’s a renewable source of energy.
 It’s a comparatively lesser pollution generating energy.
 Biomass energy helps in cleanliness in villages and cities.
 There is tremendous potential to generate biogas energy.
 Biomass energy is relatively cheaper and reliable.
 It can be generated from every day human and animal
wastes, vegetable and agriculture left-over etc.
 Growing biomass crops use up carbon dioxide and
produces oxygen.

Disadvantages
 Cost of construction of biogas plant is high, so only rich people
can use it.
 Some people don’t like to cook food on biogas produced from
sewage waste.
 Biogas plant requires space and produces dirty smell.
 It is difficult to store biogas in cylinders.
 Transportation of biogas through pipe over long distances is
difficult.
 Crops which are used to produce biomass energy are seasonal
and are not available over whole year.

END