The document summarizes the process of producing biodiesel via base catalyzed transesterification from a non-commercial perspective. It describes the process in three stages: chemical preparation which involves filtering, removing water from, and titrating the oil to determine catalyst amount. Chemical combination involves creating a methoxide and combining it with the oil. Product purification separates the glycerin and cleans the biodiesel, with steps like settling, decanting, washing, and testing the final product. The document provides details of the chemical reactions and offers specific guidelines for carrying out each stage of the process.

1. Abstract—Motivated by the newly emerging alternative fuel
sources, this paper looks into a specific method of producing one
alternative fuel source, biodiesel. Rather than taking a
commercial standpoint, this paper looks into the most frequently
used biodiesel production process from a non-commercial scale,
base (alkali) catalyzed transesterification. While identifying the
chemical process, the paper specialized on the development of
biodiesel. With the personally created division of the
development process into three segments, the paper identifies the
preparation, combination, and purification processes required to
develop a high yielding biodiesel reaction. A step-by-step
description of each process enables this paper to essential serve as
an introductory tutorial in the production of biodiesel.
Additionally, a production timeline and safety concerns for
readers who wish to utilize this article as in preliminary guide for
biodiesel production.
I. INTRODUCTION
HILE petrol and diesel remains the two most prominent
fuel sources, there are newly emerging alternatives that
should not be overlooked. For reasons more than one (foreign
oil dependence, atmospheric emissions, etc), individuals have
begun to investigate production of these alternative fuel
sources. One such fuel source is biodiesel, and just like
producing energy via the ocean, there is more than one method
to achieve this.
In comparison to our current fuel sources, biodiesel is an
alternative that has shown positive results to in a multitude of
viewpoints. Not only the production of a useful fuel source
from what was previously considered as waste, but
additionally the improved effects on the environmental impacts
and the reduced deterioration on the utilized devices (IC
engines) demonstrate why biodiesel can be viewed as such an
attractive fuel alternative.
Rather than providing a survey on the various methods of
producing biodiesel, this paper will describe the most
commonly used method, base catalyzed transesterification,
from a non-commercial viewpoint. This paper will briefly
look into the chemical processes undergone in the production
of biodiesel. With a separation of the process into three
categories, there will be more focus will be towards the
process of each.
Finally, as this article can be utilized as a ‘how to’ for
‘backyard biodiesel production’, a rough timeline produced
from an alternate source and safety concerns shall be included
to provide the reader with an understanding of the extent and
seriousness each stage of the process entails.
II. DESCRIPTION
Biodiesel is the combination of organically-derived oils with
the combination of an alcohol. The term biodiesel
incorporates a variety of chemical compounds known as Fatty
Acid Methyl Ester (FAME) [1]. These compounds can be
produced from a variety of processes with the incorporation of
diverse chemicals.
The production of biodiesel can be done with a combination
of just about any organic oil and alcohol one desires. Due to
this, the chemical structure of the end result will vary between
blends of biodiesel.
Before lunging into the development of bio-diesel, a
frequently occurring question must be addressed; why would
one go through the process of developing biodiesel rather than
skipping the process and use straight oil? The answer for this
question is the effects on the IC – internal combustion engine,
the emissions released, and the increased difficultly for use [1].
Straight vegetable oil will develop a scenario where the IC
engine is exposed to a more stressful environment. An
increased temperature on the fuel injection pumps and the
carbon buildup on fuel injectors are the major effects an
engine will experience. Straight vegetable oil will burn less
clean as well (resulting in worse emissions). The melting point
of biodiesel (fatty acid methyl esters) is lower to that of
vegetable oil (triglycerides). Therefore, vegetable is more
difficult to impossible to utilize in colder temperatures [1].
III. PRODUCTION METHODS
While there are multiple methods of achieving biodiesel,
there is one process most commonly seen, transesterification
[2]. Transesterification is the process in which an ester is
exchanged with an alcohol to form a new ester and a new
alcohol.
This method can be broken into three approaches; a base
(alkali) catalyzed transesterification of the oil, an acid
catalyzed transesterification of the oil, and a conversion of the
oil to its fatty acids and then to biodiesel [2]. For each of these
approaches, various catalysts and alcohols can be utilized to
yield biodiesel.
Biodiesel Production via Base Catalyzed
Transesterification
(November 2007)
STEVEN G. ERNST
W

2. The most commonly used method; however, is the base
catalyzed transesterification of the oil. The base catalyzed
reaction is most commonly used because of its relative ease. It
can be performed at lower temperatures and lower pressures,
its yield conversion is around 98%, the conversion is direct, no
intermediary processing, and the process does not require
exotic materials [3]. For the purposes of this paper, focus will
be given only to the most widely used approach, base (alkali)
catalyzed transesterification.
IV. BASE (ALKALI) CATALYZED TRANSESTERIFICATION
A. Chemical Process
Base catalyzed transesterification involves the combination
of organic oil with an alcohol via a base catalysis. A base
catalysis is a chemical with a PH scale which is greater than 7;
it has the ability to donate extra electrons. Due to ability and
cost of chemicals the combination most often utilized includes
triglycerides, (vegetable oil) and methanol (CH3OH) with the
assistance of a sodium hydroxide (NaOH) known as lye
“caustic soda” or potassium hydroxide (KOH).
The catalyst promotes hydrolysis of the triglycerides to
produce fatty acids and two by-products, glycerol and water
[4]. Methanol combines with the carbon chains, known as free
fatty acids, to create fatty acid methyl esters, known as
biodiesel.
This process is very similar to the production of soap. In
fact, if one were to improperly mix the quantities of methanol,
a catalyst, and oil, one of the key chemicals in soap will be
produced. In this case, the mixture produces a quantity of
water that when mixed with the oil and the remaining catalyst
will develop glycerol, known as glycerin soap [4].
Tables I and II identify two reactions that can independently
occur. With the techniques to be described in the following
section, these reactions can be combined in a manner to
minimize the undesired bi-products (water, glycerol, fatty
acids, and unprocessed triglycerides and methanol).
TABLE I
TRIGLYCERIDE AND WATER REACTION
H O H O
| || | ||
H-C-O-C-Ra H-C-O-H HO-C-Ra
| |
| O | O
| || | ||
H-C-O-C-Rb + 3 H2O H-C-O-H + HO-C-Rb
| |
| O | O
| || | ||
H-C-O-C-Rc H-C-O-H HO-C-Rc
| |
H H
Triglyceride Glycerol Fatty Acids
TABLE II
FATTY ACIDS AND METHANOL REACTION
RCOOH + CH3OH  3CH3OOCR + H20
Fatty Acids Methanol Fatty Acid Methyl Ester Water
B. Development Process
The process of producing biodiesel includes mixing
vegetable oil with lye and methanol to produce glycerin and
biodiesel. The production of biodiesel via alkali catalyzed
transesterification can be done in a variety of ways. One such
technique involves integrating the reaction process of the
alcohol and the catalyst before combining with the oil. This
process provides for a more complete chemical reaction,
therefore reducing the amount of free glycerol production [5].
Nevertheless, the production process can be organized into
three sections; chemical preparation, chemical combination,
and product purification. Within each of these three sections,
there are steps to undergo the process.
The steps that are taken for each section to undergo the
production process are listed in table III.
TABLE III
BIODIESEL DEVELOPMENT PROCESS
Chemical Preparation
1. Oil Filtration
2. Water Removal
3. Titration
4. Catalyst Calculation
Chemical Combination
5. Methoxide Development
6. Product Combination
Product Purification
7. Glycerin Separation
8. Cleaning
9. Quality Testing
(i). Chemical Preparation
1. Oil Filtration
This step is done to remove non oil particles from the oil.
Typically, the process involves heating the temperature of the
oil above 95 degrees Fahrenheit to allow a smooth flow
through a filtering material. Common materials suggested for
filtering the oil are double layer cheesecloth, restaurant coffee
filters, and canteen-type filters. Commercialized biodiesel
production sites undergo a more detailed filtering process.
2. Water Removal
“Water is removed because its presence causes the
triglycerides to hydrolyze to give salts of the fatty acids instead
of undergoing transesterification to give biodiesel,” [6].
Prevention of hydrolysis can occur by stirring the crude oil
with a drying agent such as magnesium sulfate to remove the
water in the form of water of crystallization [6]. However, the
viscosity of the oil may not allow the drying agent to mix
thoroughly [6]. The drying agent can later be separated by
decanting or by filtration.
Another conventional method of removing water from the
oil takes into consideration the boiling points of the two
compounds. Water has a lower boiling point than oil;

3. therefore the two are heated to a temperature high enough to
boil off the water. Table IV identifies two approaches
commonly used to achieve this step.
TABLE IV
WATER REMOVAL PROCESS
Method One:
Heat the oil up to 212 degrees Fahrenheit and wait until
the water boils off; use a mixer, rotating between 500-
600rpm, to avoid steam pockets from forming; raise the
temperature to 265 degrees Fahrenheit for ten minutes
when the boil slows; wait until the oil returns to room
temperature.
Method Two:
Heat the oil up to 140 degrees Fahrenheit for fifteen
minutes; pour the oil into a settling tank to sit for twenty
four hours; extract the upper ninety percent of the settled
solution.
3. Titration
Titration refers to a common laboratory method of
quantitative/chemical analysis which can be used to establish
the concentration of a known reactant [6]. In the case of
biodiesel production, titration is essential to identify the proper
amount of catalyst (such as sodium hydroxide and potassium
hydroxide) necessary for transesterification. The titration
process consists of inserting a measured amount of lye/water
solution into a warm/thoroughly mixed sample of the oil [7].
Identifying the proper amount of catalyst/water solution can be
done with litmus paper, a digital PH tester, and/or insertion of
a chemical identifier such as phenolphthalein. Details to the
procedure are listed in table V.
TABLE V
TITRATION PROCESS
Mix 1 gram of catalyst with 1 liter of distilled water until
it is completely dissolved; Mix 10 milliliters of isopropyl
alcohol with 1 milliliter of warm and stirred oil and 2
drops of phenolphthalein; keep warm and consistently
stir the mixture; drop 0.1 milliliters of catalyst/water
solution in to the oil/isopropyl/phenolphthalein mix;
continue dropping the solution in the mix until the
solution turn pink (magenta) for 10 seconds.
*Note: This process usually takes 1.5 to 3 milliliters to obtain the desired
PH level of 8 to 9
Fig.4. Titration Process
4. Catalyst Calculation
The amount of catalyst required is linearly scalable to the
amount identified in the titration stage. Depending on the
catalyst type, a numeric value is included as a summation to
the catalyst. Next, the summation is linearly scaled by the
amount of oil in the batch. The calculation for identifying the
amount of sodium hydroxide is shown below, given by [3]:
Catalyst (g) = Oil (L) x [3.5 + titration (ml)] (1)
Furthermore, the calculation for identifying the amount of
potassium hydroxide is shown below, given by [3]:
Catalyst (g) = Oil (L) x [8 + titration (ml)] (2)
(ii) Chemical Combination
Besides the ratios of each chemical, the process to which the
chemicals are combined dictates the yield quantities of each.
Rather than combining the three products (oil, alcohol, and a
catalyst) in one setting, the alcohol and the catalyst are first
combined to minimize the yields of the bi-products (glycerol,
fatty acids, and water). This method of combination has found
to be an ideal way to combine the two chemical reactions
described earlier.
5. Methoxide Development
Sodium methoxide and potassium methoxide is the
combination of methanol and a catalyst. While the amount of
catalyst to be mixed is known from the titration stage, the
amount of alcohol (methanol), however, has yet to be
determined. The preferred combination of methanol to the
final product includes 20% methanol by mass [7]. In other
words, for about every 100 grams of oil, there should be
around 20 grams of methanol included in the mixture. Take
caution in this process as the vapors from methanol can be
dangerous. It is recommended that proper PPE-personal
protective equipment is worn and proper safety procedures are
taken during this stage of the process. Shown in the following
formula is the numerical method of identifying the proper
methanol/oil rate [8].
0.2
Methanol (L) = ( ) x [Oil (kg)]
0.915
(3)
The alcohol and catalyst combination is an exothermic
reaction which should occur in a well ventilated/isolated
chamber. Mixing of the combination will ensure a complete
reaction with the oil and will take between 5 to 20 minutes.
The process can be identified as complete when the
combination has returned to room temperature.
6. Product Combination
This stage of biodiesel production is commonly referred to
as the reaction process. It is where the majority of the
chemical reactions, described earlier, occur. The process
simply involves mixing the heated oil with the methoxide until
the two have completely merged. From previous experience
with the production of biodiesel, table VI identifies the
recommended mixing procedure.
TABLE VI
VEGETABLE OIL AND METHOXIDE COMBINATION
Preheat the oil to 120 – 130 degrees Fahrenheit; mix the oil
during the process at a rate to develop a small vortex in the
center; add sodium/potassium methoxide to the oil while
stirring; continue stirring for 50 – 60 minutes.
*Note: This process usually takes 1.5 to 3 milliliters to obtain the desired
PH level of 8 to 9

4. (iii) Product Purification
The desired product from the reaction is the fatty acid
methyl esters. Therefore, the end result from the product
combination includes impurities which require filtration. The
most common impurities are; glycerin, free glycerin, and water
[7]. For commercial applications, the final product requires
stringent testing to verify the properties of biodiesel adhere to
the requirements of the National Renewable Energy
Laboratory [7]. For non-commercial applications, the quality
testing is far less significant.
7. Glycerin Separation
Glycerol, known as glycerin, is a bi-product from the
reaction. Free glycerin refers to the glycerin that remains
bound to the fatty acid methyl esters. Proper titration
techniques can reduce but not eliminate this bi-product from
forming. Both glycerin and free glycerin can be separated
from biodiesel with relative ease [7]. Proper heating and
mixing of the final solution during the combination stage will
reduce the amount of free glycerin formed.
The density of glycerin is greater to that of the fatty acid
methyl esters. With proper time, the glycerin settles to the
bottom of the storage device allowing the biodiesel to be
decanted out of the top or side of the settling container. This
process can occur by following the subsequent steps [7].
After the combination stage is complete and the final
solution has reduced to room temperature, let the solution
settle in a settling container for at least 8 hours [7].
Afterwards, decant the biodiesel into a separate storage
container. An alternative approach is to heat the temperature
of the final solution above 100o
F and decant after 1 hour. The
increased temperature acts as a catalyst in the separation
process [7].
8. Cleaning
Cleaning, commonly referred to as washing, is done
primarily to remove the glycerol remains from the biodiesel.
Regardless of which method of cleaning is chosen, a
combination of cleaning methods will yield the best results.
The washing solutions, listed below, are commonly
implemented in a series of three or four sessions [5]. In
addition to the cleaning solution, the solution goes through a
drying and a final filtering. In this filtering session, the
solution is slowly reheated, filtered through one of the media
previously listed. The solution is then decanted out of a side
value and is ready for quality testing [5].
During the second stage of the development process,
extraction of water from the vegetable oil was necessary to
eliminate the opportunity for bi-products to form. In this
stage, it is the opposite. Water is incorporated into the
biodiesel to separate the incomplete glycerol compound from
the fatty acid methyl esters (biodiesel). As what is mixed with
biodiesel, bonding occurs between the water and the remaining
bi-products.
(a) Mist Washing
Mist washing, also known as agitation washing, involves
applying water to the biodiesel in the form of a mist. Similar
to that found in the produce section as a local grocery store,
water is misted down upon the biodiesel for a period of time.
The misting effect creates a gentle integration of the water into
the biodiesel [1]. The misting occurs until multiple gallons of
milky water have formed in the bottom of the settling tank, and
then the milky water is drained off [1].
(b) Bubble Washing
Rather than incorporating the water from top of the
biodiesel and having it settle to the bottom, bubble washing is
a process of bubbling both air and water (created by an aerator
commonly used in aquariums) from bottom of the biodiesel to
rise to the top and fall again to the bottom of the settling tank
[1]. This method creates twice the exposed area per molecule
of water to the biodiesel (increased agitation), therefore
resulting in a more effective process [1].
(c) Settling
Settling occurs during both the mist and bubble washing
stages. This will allow excess sediments, the water/fatty acid
compounds, to settle to the bottom of the storage tank. Once
this is complete, the biodiesel can be extracted from the upper
portion of the storage tank.
(d) Drying
Once three or four sessions of the washing series has taken
place, the next stage of the cleaning process is to extract the
excess water. Simply store the biodiesel in an air exposed
container for a period of a week. The greater the exposure to
air, the quicker the evaporation process of water becomes. As
shown below in the production timeline, this is the lengthiest
section of the biodiesel production process.
(e) Re-Filtration
Similar to that of the first step in the development process,
the final product is run through a media to filter any salutatory
particles that may remain. Once this stage is complete, the
biodiesel production is ready for quality testing to occur.
9. Quality Testing
Regardless towards the steps you take to purify your final
product, the resultant combination will include impurities.
Testing on the quality of the final product is a process that
ensures the biodiesel has acceptable properties. While
commercially distributed biodiesel contain stringent
regulations on the characteristics of biodiesel, most non-
commercially based productions contain minimal testing.
Ensuring the pH level is neutral (7), visually identifying no
solids particles are present, identifying the product has no
cloudiness, and ensuring no soapy residue remains are the
minimal testing that occurs [7].
For commercial distributions, other factors such as flash
point, kinematic viscosity, cetane number, carbon residue,
sulfur residue, acid number, and free glycerin count are a few
of the properties which require testing [7]. The National
Renewable Energy Laboratory Requirements place limitations
on such properties for all commercially distributed alternative
fuels.
V. PRODUCTION TIMELINE
Included in the figure below is a rough guide for a timeline
of each process. The information listed below was developed
by [8].

5. TABLE VII
PRODUCT TIMELINE ESTIMATES
START
Collecting Oil - 1-2 hours
Filtering Oil - 1-2 hours (depends on amount of oil)
Titration Of Oil - 10-15 minutes
Transferring Oil To Processor - 10-20 minutes
Heating Oil - 1-4 hours (depends on amount of oil,
voltage & wattage of element)
Making Methoxide - 5-20 minutes (depends on
amount of methanol and catalyst used)
Mixing Methoxide Into Oil - 20-30 minutes
Mixing Oil & Methoxide - 2-3 hours
Settling Oil - 8-10 hours (usually overnight)
Draining Glycerin - 5-10 minutes
Transferring Biodiesel To Wash Tank - 10-20 minutes
First Mist Wash - 2-3 hours
Second Mist Wash - 2-3 hours
First Bubble Wash - 6-8 hours (usually overnight)
Second Bubble Wash - 6-8 hours (usually overnight)
Transferring Biodiesel To Drying Containers - 10-20
minutes (depends on amount)
Drying Biodiesel - 2 hours to 1 week (depends heavily
on weather and amount made)
Transferring To Storage Containers - 10-20 minutes
(depends on amount)
FINISH
VI. SAFETY CONCERNS
There are safety concerns that must be considered
throughout the production of biodiesel. Chemicals of concern
are methanol, ethanol, sodium hydroxide (NaOH), potassium
hydroxide (KOH), and sulphuric acid (H2SO4), and methoxide
[10]. These chemicals have safety procedures which much be
thoroughly reviewed before handling. “The most dangerous
part of making biodiesel is from the time the methanol is
purchased to the time the methoxide is completely introduced
into the oil,” [10]. Safety must be the key factor in the design
of the reactor. Proper ventilation, emergency fluids, and
protective clothing are only a few elements to be considered in
the production of biodiesel.
VII. CONCLUSION
While there are multiple methods of producing biodiesel,
this paper demonstrates the general process taken for one
method. There are other methods which have quite similar
processes but different compounds. It can be seen that there
are three divisions of biodiesel production process via alkali
(base) catalyzed transesterification. These divisions, chemical
preparation, chemical combination, and product purification,
describe the development process in a sequential order. From
the combination division, the mixing order and quantities of
each compound is critical in obtaining a maximum yield
process. Additionally, this paper notes there are safety
concerns to be taken when developing biodiesel and that safety
procedures must be taken into consideration depending on the
selected materials and process.
ACKNOWLEDGMENTS
The paper is primarily based upon the references listed
below in the references section. All other information used
throughout the paper was taken from general knowledge
obtained by the author thorough out his educational career,
industrial career, and hobbyist projects.
REFERENCES
[1] Gerhard Knothe, Robert O. Dunn, Marvin O. Bagby. The Use of
Vegetable Oils and Their Derivates as Alternative Fuels. Peoria, IL. Oil
Chemical Research, National Center for Agricultural Utilization
Research, Agricultural Research Service, US Department of Agriculture.
[2] Soya.be (November 2007). Biodiesel Production. 2006.
http://www.soya.be/biodiesel-production.php
[3] National Biodiesel Board. Biodiesel Fact Sheets. Jefferson City, MO.
2007.
[4] Utah Biodiesel Supply. (November 2007). How Biodiesel is Made.
MGBJ Enterprises, LLC. 2007.
http://www.utahbiodieselsupply.com/makingbiodiesel.php
[5] Jon Van Gerpen. Biodiesel Production and Fuel Quality. Moscow, ID:
University of Idaho. 2005.
[6] Wikipedia. (November 2007). Biodiesel.
http://en.wikipedia.org/wiki/Biodiesel
[7] David Ryan. Biodiesel – A Primer. Fayetteville, AR. ATTRA
Publication: December 2004.
[8] Wales Environment Trust. (November 2007). Biodiesel Production
from Waste Cooking Oil. Sustainable Energy.
http://www.walesenvtrust.org.uk/uploaded_documents/104/Biodiesel%2
0
[9] Graydon Blair. The Basics of Biodiesel Production. Utah Biodiesel
Supply. Biodiesel Now: January 27, 2007.
[10] Rick DaTech, Biodiesel Safety. Collaborative Biodiesel Tutorial: 2005.
Steven G. Ernst Born in Salem, Oregon in
1984. He became a member of IEEE in 2007.
Currently pursuing a master’s of science degree
in Electrical Engineering at Oregon State
University in Corvallis, Oregon. The anticipated
date of graduation is June 2009. He received his
bachelor’s of science degree in Electrical
Engineering at Oregon State University in
Corvallis, Oregon in March of 2007. His
interests include Power Electronics, Power
Systems, and Renewable Energy Systems. His
research focuses towards Renewable Energy
Systems.
He has worked for Intel Corporation as a
JUNIOR DESIGN ENGINEER in 2006 – 2007.
He has worked for Siltronic Corporation as a FACILITIES ENGINEER in
2005. He currently is working for the Army Corps of Engineers as a
STUDENT ENGINEER in Portland, Oregon since 2007.
Mr. Ernst has received the Ritter Scholarship Achievement for Electrical
Engineering as well as the McDougall Scholarship Award for Electrical
Engineering. Mr. Ernst regularly attends the IEEE meetings held at Oregon
State and provides thoughtful in-site to the congregations.