Vegetable oil will react very similarly to diesel fuel under the conditions
inside a diesel engine; i.e. when it is highly compressed, it will heat
up and ignite, causing the air in the cylinder to expand, and to push
the pistons, in time. If you burned straight unprocessed vegetable oil,
however, the fatty acids in the oil would start to congeal and harden
(coke up) on the inside of your engine as well as in your fuel injectors,
eventually leading to big, expensive engine problems.
Therefore, it is necessary to process your oil to remove the fatty
acids-- making the oil more similar to diesel compositionally, or to
otherwise devise a system to keep your engine clean of residues from
Following is our procedure for edible waste oil transesterification,
which we used on our cross country trip. Please always use extreme caution
when working with these ingredients.
WARNINGS AND DISCLAIMERS!!!!!!!!!!!
-We are not automotive engineers, chemists nor scientists of any type
so this information is still in a crude, explorative stage. Experiment
to find what works for you.
-This information was collected from various individuals and has been
used by us BUT by no means do we hold any responsibility for anyone
attempting to do this process. Essentially this is public information
to be used at your own discretion and risk. There is information available
regarding transesterification and biodiesel. It is highly recommended
to cross-reference and /or to contact someone in the organic chemistry
department at a local university.
-This information shall not be resold to any individual but given freely
to all who may inquire about this procedure.
-Methanol is toxic. It can be absorbed by the skin and cause nerve
deterioration with prolonged usage. If splashed in eyes it can cause
blindness and could be fatal if swallowed. Take necessary precautions
when using methanol! A good respirator and decent rubber gloves are
-Lye is also very toxic and burns the skin upon touch. It is also extremely
damaging if ingested. It is possible, however to set up a safe means
of being able to mix fuel. An outdoor area is preferable or a space
with plenty of ventilation. Access to electricity and water are both
necessary. Have lots of newspapers and detergent on hand.
-Always mix a small batch first in an old blender to test your ratios.
If successful the amounts can be multiplied directly.
NEVER EVER USE ANY OF THE UTENSILS, POTS NOR BLENDER FOR LIQUID
NOR FOOD CONSUMPTION AGAIN!!!
Production of Biodiesel for Diesel fuel use
You will need:
- Used or fresh vegetable oil (strained with a coffee filter or cloth)
- Red Devil Lye
- Methanol (dry gas methanol-- we found it at automotive racing stores)
- Isopropyl Alcohol (for tests-- use 99% IPA)
- eyedropper- or other type of 1 milliliter dropper
- PH paper-- available at drug stores-- to test for acidity
- an old blender
- plastic or glass measuring cups or beakers, with metric measures--
and/or a gram scale
- plastic, glass or stainless stirrers and spoons,
- plastic buckets
- rubber gloves, safety glasses, plastic apron
Titration Process to determine how much Lye to use
Free fatty acids will increase with the amount of time vegetable oil has
been heated-- oil which has been used for cooking will require more of
the reactive agents-- lye and methanol-- than fresh oil. The presence
of too many free fatty acids will retard or stop the reaction which produces
biodiesel, so it is necessary to detect the exact amount of LYE (Sodium
Hydroxide-- or NaOH) needed to neutralize the acids. Adding too much or
too little NaOH will just make excessive amounts of bi-product (soap).
- Dissolve 1 gram NaOH (Sodium Hydroxide- Red Devil Lye) in 1000 ml.
of water. This is your NaOH solution.
- Dissolve 1ml. of Wasted Vegetable Oil (WVO) in 10 ml. Isopropyl
Alcohol(IPA). This is your WVO solution.
- With an eyedropper, drop the diluted NaOH into WVO mixture a milliliter
at a time. Count the drops. After each ml drop check the ph level
of the WVO solution with standard ph paper-- you will see an eventual
rise in the ph level. Continue to add the NaOH solution into the WVO
solution, a drop at a time, until it reaches a ph of 8-9.
To determine your proportions, figure:
The number of drops of NaOH needed for the WVO solution to reach a
ph of 8-9 1 ml. plus 3.5 g. NaOH to catalyze the oil
An example formula used with one particular batch of WVO-wasted vegetable
1 ml of oil was titrated with a 1g NaOH/1000 ml H2O solution.
It required 6.0 ml to raise the ph level to 8 = .006g
so 6.0g/1000ml to neutralize the free fatty acids
plus 3.5 g NaOH as catalyst
= 9.5 g per 1000ml oil or 9.5g/915g oil=103% by wt.
Transesterification For Wasted Vegetable Oil (WVO)
Vegetable Oil: Diesel has a chain of 11-13 carbons, and new vegetable
oil has a chain of about 18--but wasted vegetable oil-- which has been
heated--has chains of up to 32 carbons. To burn in an engine, the chain
needs to be broken down to be similar in length to diesel
Lye: (Sodium Hydroxide ((NaOH)-- or potassium hydroxide also
works) is the catalyst for transesterification. It works by "cracking"
the vegetable oil molecules, splitting the triglycerides from the hydrocarbons
and shortening the carbon chain. (3.5g or .35% is the standard amount
of lye necessary to create a reaction, when using fresh vegetable oil,
so you can figure that used vegetable oil will always use more.)
Methanol: The amount of methanol needed will also vary, but
the ideal is to use the least amount of methanol necessary in order
to get the highest yield. The yield is related to completion; so if
you get a 90% yield that means that 90% of the fatty acids have been
eliminated from the vegetable oil. We have found that the best is to
use 15% to 20% methanol, based upon the total weight of your batch of
*it is best to use dry gas methanol (we found methanol at an automotive
A hydrometer can also be used to check the amount of completion according
- Vegetable Oil has a specific density of .910
- Biodiesel has a specific density of .850-.870
Recipe for Colorado Gold example test
-- using WVO we got in Colorado
- Weigh 4kg of WVO heated in a stock pot on a hot plate up to 120F
- In separate container mix-15%of 4Kg=600g Methanol (MeOH)* (or 17.2%
by volume=750ml) with-
- 40g (1%) of NaOH until the NaOH dissolves. Add the NaOH slowly!
It will become extremely hot, and on a larger scale potentially dangerous.
This combined mixture makes Sodium Methoxide. Add this to the WVO and
mix for 40-60 minutes. We used a dry wall mixer bit attached to a 1/2
foot drill to do the mixing
NOW---Draw out samples every 5-10 minutes to check the rate of separation.
The cloudy looking free fatty acids, called glycerine, will sink to
the bottom and the methyl esters--a translucent liquid, will remain
on top. When the separation appears not to be advancing any more, stop
mixing. Let the mixture settle for at least 8 hours.
The liquid you have on top now is methyl ester, but before using it
you have to remove any remaining soaps or salts which could cause engine
damage . The glycerin which has sunk to the bottom should be disposed
at your local toxic waste disposal site.
RINSING METHYL ESTER: Pour off the methyl ester into a separate clean
container, so it can be washed free of any remaining soaps, salts or
free fatty acids.
Add water to the methyl ester. Stir slightly and then allow mix to
settle. When the water has cleanly separated from the methyl esters,
drain or pump the water out from the bottom. Repeat until the discarded
rinse water reaches ph level of 6-7 -- and no soap bubbles appear.
If the liquid is cloudy, there is water being retained in the fuel,
and it will need to be reheated slowly to evaporate out the water. Any
white substances forming at the bottom or any bubbles forming at the
surface is a sign of soaps and should be removed or the liquid should
be re-washed. The cleaned methyl esters are now a homemade version of
biodiesel and are ready to go into your diesel tank.
ONE MORE WARNING: To use 100% Biodiesel for longer than 4 weeks straight
will cause complications to any rubber components of the engine that
the fuel might come into contact with-fuel pump, hoses, o-rings, etc.
These can either be replaced with steel or heavy duty rubber or.. it
is recommended to use a percentage of diesel with your homemade fuel-
at least 20%.