This document discusses biofuels and biodiesel production. It defines biofuels as transportation fuels like ethanol and biodiesel that are made from biomass materials. The document outlines the process of biodiesel production, including using vegetable oils or animal fats and an alcohol like methanol through a transesterification process. It discusses important characteristics of biodiesel like viscosity, density, flash point and others. The advantages of biodiesel include being renewable, having lower emissions than diesel, and able to be used in conventional diesel engines. Disadvantages include slightly higher fuel consumption and issues with long term storage.

1. BIO-FUELS
Dr. Ajay Singh Lodhi
Assistant Professor
College of Agriculture, Balaghat
Jawahar Lal Krishi Vishwa Vidyalaya, Jabalpur (M.P.)

2. Bio-Fuels
 A biofuel is a fuel that is produced through
contemporary biological processes, such as agriculture
and anaerobic digestion, rather than a fuel produced by
geological processes such as those involved in the
formation of fossil fuels, such as coal and petroleum,
from prehistoric biological matter.
 Biofuels can be derived directly from plants (i.e. energy
crops), or indirectly from agricultural, commercial,
domestic, and/or industrial wastes.
 Renewable biofuels generally involve contemporary
carbon fixation, such as those that occur in plants or
microalgae through the process of photosynthesis.
 Other renewable biofuels are made through the use or
conversion of biomass (referring to recently living
organisms, most often referring to plants or plant-
derived materials).

3.  “Biofuels” are transportation fuels like ethanol and
biodiesel that are made from biomass materials. These
fuels are usually blended with petroleum fuels namely
with gasoline (petrol) and diesel fuel, but they can also
be used on their own. Ethanol and biodiesel are also
cleaner burning fuels, producing fewer air pollutants.
 Ethanol is a alcohol fuel made from the sugars found
in grains such as corn, sorghum, and wheat, as well as
potato skins, rice, sugarcane, sugar beets and yard
clippings by fermentation.
 Bio-diesel fuel can be made from renewable vegetable
oils, animal fats or recycled cooking oils by trans
esterification process.

4. THE FOLLOWING ARE SOME OF THE
CHARACTERS FOR THE EFFICIENT BIO-
DIESEL
Kinematic viscosity:
 Viscosity represents flow characteristics and the
tendency of fluids to deform with stress. Viscosity
affects injector lubrication and fuel atomization.
 Fuels with low viscosity may not provide sufficient
lubrication for the precision fit of fuel injection pumps,
resulting in leakage or increased wear. Fuel atomization
is also affected by fuel viscosity.
 Diesel fuels with high viscosity tend to form larger
droplets on injection which can cause poor combustion,
increased exhaust smoke and emissions.

5. Density:
 It’s the weight per unit volume. Oils that are denser
contain more energy. For example, petrol and diesel
fuels give comparable energy by weight, but diesel is
denser and hence gives more energy per litre.
 Biodiesel is generally denser than diesel fuel with
sample values ranging between 877 kg/m3 to 884 kg/m3
compared with diesel at 835 kg/m3. Thus, density of the
final product depends mostly on the feedstock used.
Calorific Value:
 Heat of combustion: Heating Value or Heat of
Combustion, is the amount of heating energy released by
the combustion of a unit value of fuels. One of the most
important determinants of heating value is moisture
content. Liquid biofuels however have bulk densities
comparable to those for fossil fuels.

6. Melt point or Pour point Melt or pour point:
 It refers to the temperature at which the oil in solid
form starts to melt or pour. In case where the
temperatures fall below the melt point, the entire fuel
system including all fuel lines and fuel tank will need
to be heated.
Cloud point:
 The temperature at which an oil starts to solidify is
known as the cloud point. While operating an engine at
temperatures below an oil’s cloud point, heating will be
necessary in order to avoid waxing of the fuel.

7. Flash point (FP) :
 The flash point temperature of diesel fuel is the
minimum temperature at which the fuel will ignite
(flash) on application of an ignition source. Flash point
varies inversely with the fuel’s volatility. Minimum flash
point temperatures are required for proper safety and
handling of diesel fuel. The flash point determines the
flammability of the material. Neat biodiesel has a flash
point (150°C) well above the flash point of petroleum
based diesel fuel (±70°C).
Acid value:
 The total acid number is an indication of the presence of
free fatty acids formed due to oil degradation and
combustion. It can also result from improper
manufacturing, through remaining catalyst or excessive
neutralization.

8. Iodine value:
 It is an index of the number of double bonds in biodiesel,
and therefore is a parameter that quantifies the degree
of unsaturation of biodiesel. It is reported in terms of the
grams of iodine that will react with 100 grams of a fat or
oil under specified condition. It is a value of the amount
of iodine, measured in grams, absorbed by 100 grams of
given oil. It is commonly used as a measure of the
chemical stability properties of different biodiesel fuels
against such oxidation.
Carbon residue:
 This indicates the tendency of fuel to form carbon
deposits in an engine. An important indicator of the
quality of biodiesel is the carbon residue, which
corresponds to the content of glycerides, free fatty acids,
soaps, polymers and remaining catalyst.

9. Aniline point/Cetane number (CN):
 It is a relative measure of the interval between the
beginning of injection and auto-ignition of the fuel. The
higher the cetane number, the shorter the delay interval
and the greater its combustibility. Fuels with low
Cetane Numbers will result in difficult starting, noise
and exhaust smoke.
 In general, diesel engines will operate better on fuels
with Cetane Numbers above 50. Cetane number is
usually measured directly using a test engine. Cetane
tests provide information on the ignition quality of a
diesel fuel.
 Diesel fuel usually has a cetane rating between 45 and
50 while vegetable oil is 35 to 45. Biodiesel is usually
have in between 50 to 60.

10. Stability:
 Biodiesel ages more quickly than petroleum diesel fuel
due to the chemical structure of fatty acids and methyl
esters present in biodiesel. Typically there are fourteen
types of fatty acid methyl ester in the biodiesel.
 The individual proportion of presence of these esters in
the fuel affects the final properties of biodiesel. Poor
oxidation stability can cause fuel thickening, formation
of gums and sediments which in turn can cause filter
clogging and injector fouling.
 Biodiesel and biodiesel blends are much more thermally
stable than diesel. Biodiesel and its blends should not be
stored in a storage tank or vehicle tank more than 6
months. Depending upon the storage temperature and
other conditions suggest the use of appropriate
antioxidants.

11. Ash Percentage:
 Ash is a measure of the amount of metals contained in the
fuel. High concentrations of these materials can cause
injector tip plugging, combustion deposits and injection
system wear. The ash content is important for the heating
value, as heating value decreases with increasing ash
content.
 Ash content for bio-fuels is typically lower than for most
coals, and sulphur content is much lower than for many fossil
fuels.
Sulfur percentage :
 The percentage by weight, of sulfur in the fuel sulfur content
is limited by law to very small percentages for diesel fuel
used in on-road applications. First use vegetable oil and
animal fat based biodiesel has less than 15 ppm sulphur.
Many researchers claim that pure biodiesel is essentially
sulphur free and therefore biodiesel is an ultra-low sulphur
fuel.

12. BIODIESEL PRODUCTION
 Biodiesel is a liquid biofuel obtained by chemical
processes from vegetable oils or animal fats and an
alcohol that can be used in diesel engines, alone or
blended with diesel oil.
 ASTM International (originally known as the American
Society for Testing and Materials) defines biodiesel as a
mixture of long-chain mono-alkylic esters from fatty
acids obtained from renewable resources, to be used in
diesel engines.
 Blends with diesel fuel are indicated as ‘‘Bx’’, where ‘‘x’’
is the percentage of biodiesel in the blend. For instance,
‘‘B5’’ indicates a blend with 5% biodiesel and 95% diesel
fuel; in consequence, B100 indicates pure biodiesel.

13. FEEDSTOCKS USED IN BIODIESEL PRODUCTION
 The primary raw materials used in the production of
biodiesel are vegetable oils, animal fats, and recycled greases.
 These materials contain triglycerides, free fatty acids, and
other contaminants depending on the degree of pretreatment
they have received prior to delivery.
 Since biodiesel is a mono-alkyl fatty acid ester, the primary
alcohol used to form the ester is the other major feedstock.
 Most processes for making biodiesel use a catalyst to initiate
the esterification reaction. The catalyst is required because
the alcohol is sparingly soluble in the oil phase. The catalyst
promotes an increase in solubility to allow the reaction to
proceed at a reasonable rate.
 The most common catalysts used are strong mineral bases
such as sodium hydroxide and potassium hydroxide. After
the reaction, the base catalyst must be neutralized with a
strong mineral acid.

14. Typical proportions for the chemicals used to make
biodiesel are:
 Reactants •Fat or oil (e.g. 100 kg soybean oil)
•Primary alcohol (e.g. 10 kg methanol)
 Catalyst •Mineral base (e.g. 0.3 kg sodium
hydroxide)
 Neutralizer •Mineral acid (e.g. 0.25 kg sulfuric
acid)

15. ADVANTAGES OF THE USE OF BIODIESEL
 Renewable fuel, obtained from vegetable oils or animal
fats.
 Low toxicity, in comparison with diesel fuel.
 Degrades more rapidly than diesel fuel, minimizing the
environmental consequences of biofuel spills.
 Lower emissions of contaminants: carbon monoxide,
particulate matter, polycyclic aromatic hydrocarbons,
aldehydes.
 Lower health risk, due to reduced emissions of
carcinogenic substances.
 No sulfur dioxide (SO2) emissions.
 Higher flash point.

16.  May be blended with diesel fuel at any proportion; both
fuels may be mixed during the fuel supply to vehicles.
 Excellent properties as a lubricant.
 It is the only alternative fuel that can be used in a
conventional diesel engine, without modifications.
 Used cooking oils and fat residues from meat processing
may be used as raw materials.

17. DISADVANTAGES OF THE USE OF BIODIESEL
 Slightly higher fuel consumption due to the lower calorific value
of biodiesel.
 Slightly higher nitrous oxide (NOx) emissions than diesel fuel.
 Higher freezing point than diesel fuel. This may be inconvenient
in cold climates.
 It is less stable than diesel fuel, and therefore long-term storage
(more than six months) of biodiesel is not recommended.
 May degrade plastic and natural rubber gaskets and hoses
when used in pure form, in which case replacement with Teflon
components is recommended.
 It dissolves the deposits of sediments and other contaminants
from diesel fuel in storage tanks and fuel lines, which then are
flushed away by the biofuel into the engine, where they can
cause problems in the valves and injection systems. In
consequence, the cleaning of tanks prior to filling with biodiesel
is recommended.
It must be noted that these disadvantages are significantly
reduced when biodiesel is used in blends with diesel fuel.

18. Fats and Oils:
 Choice of the fats or oils to be used in producing
biodiesel is both a process chemistry decision and an
economic decision. With respect to process chemistry,
the greatest difference among the choices of fats and oils
is the amount of free fatty acids that are associated with
the triglycerides. Other contaminants, such as color and
odor bodies can reduce the value of the glycerin
produced, and reduce the public acceptance of the fuel if
the color and odor persist in the fuel.
 Most vegetable oils have a low percentage of associated
free fatty acids. Crude vegetable oils contain some free
fatty acids and phospholipids. The phospholipids are
removed in a “degumming” step and the free fatty acids
are removed in a “refining” step. Oil can be purchased
as crude, degummed, or refined. The selection of the
type of oil affects the production technology that is
required.

19.  The options for the triglyceride choice are many. Among
the vegetable oils sources are soybean, canola, palm, and
rape. Animal fats are products of rendering operations.
They include beef tallow, lard, poultry fat, and fish oils.
Yellow greases can be mixtures of vegetable and animal
sources. There are other less desirable, but also less
expensive triglyceride sources such as brown grease and
soap stock.
 The free fatty acid content affects the type of biodiesel
process used, and the yield of fuel from that process. The
other contaminants present can affect the extent of
feedstock preparation necessary to use a given reaction
chemistry.

20. Alcohol:
 The most commonly used primary alcohol used in biodiesel
production is methanol, although other alcohols, such as
ethanol, iso-propanol, and butyl, can be used. A key quality
factor for the primary alcohol is the water content. Water
interferes with transesterification reactions and can result in
poor yields and high levels of soap, free fatty acids, and
triglycerides in the final fuel. Unfortunately, all the lower
alcohols are hygroscopic and are capable of absorbing water
from the air.
 Many alcohols have been used to make biodiesel. As long as
the product esters meet ASTM 6751, it does not make any
chemical difference which alcohol is used in the process.
Other issues such as cost of the alcohol, the amount of alcohol
needed for the reaction, the ease of recovering and recycling
the alcohol, fuel tax credits, and global warming issues
influence the choice of alcohol. Some alcohols also require
slight technical modifications to the production process such
as higher operating temperatures, longer or slower mixing
times, or lower mixing speeds.

21. Catalysts and Neutralizers:
 Catalysts may either be base, acid, or enzyme materials.
The most commonly used catalyst materials for
converting triglycerides to biodiesel are sodium
hydroxide, potassium hydroxide, and sodium methoxide.
 Most base catalyst systems use vegetable oils as a
feedstock. If the vegetable oil is crude, it contains small
amounts (<2%) of free fatty acids that will form soaps
that will end up in the crude glycerin. Refined
feedstocks, such as refined soy oil can also be used with
base catalysts.
 The base catalysts are highly hygroscopic and they form
chemical water when dissolved in the alcohol reactant.
They also absorb water from the air during storage. If
too much water has been adsorbed the catalyst will
perform poorly and the biodiesel may not meet the total
glycerin standard.

22.  Although acid catalysts can be used for
transesterification they are generally considered to be
too slow for industrial processing.
 Acid catalysts are more commonly used for the
esterification of free fatty acids. Acid catalysts include
sulfuric acid and phosphoric acid.
 Solid calcium carbonate is used as an acid catalyst in
one experimental homogeneous catalyst process. The
acid catalyst is mixed with methanol and then this
mixture is added to the free fatty acids or a feedstock
that contains high levels of free fatty acids. The free
fatty acids convert into biodiesel. The acids will need
neutralization when this process is complete, but this
can be done as base catalyst is added to convert any
remaining triglycerides.

23.  There is continuing interest in using lipases as
enzymatic catalysts for the production of alkyl fatty acid
esters. Some enzymes work on the triglyceride,
converting them to methyl esters; and some work on the
fatty acids. The commercial use of enzymes is currently
limited to countries like Japan, where energy costs are
high, or for the production of specialty chemicals from
specific types of fatty acids. The commercial use of
enzymes is limited because costs are high, the rate of
reaction is slow, and yields to methyl esters are typically
less than the 99.7% required for fuel-grade biodiesel.
Enzymes are being considered for fatty acid conversion
to biodiesel as a pretreatment step, but this system is
not commercial at this time.

24.  Neutralizers are used to remove the base or acid
catalyst from the product biodiesel and glycerol. If you
are using a base catalyst, the neutralizer is typically an
acid, and visa versa. If the biodiesel is being washed,
the neutralizer can be added to the wash water. While
hydrochloric acid is a common choice to neutralize base
catalysts, as mentioned earlier, if phosphoric acid is
used, the resulting salt has value as a chemical
fertilizer.

25. Thank You