Pull out your lab goggles, we’re
There is a growing segment of Americans who
are becoming increasingly frustrated with rising fuel prices.
As a result, many are turning to alternative sources of fuel.
One of the most popular is biodiesel. The number of people who
home-brew their own fuel is rising, and recipes for biodiesel
may be found on any number of websites. So grab your lab goggles
and chemistry kits, we’re going to show you how to make
biodiesel for fun and profit.
Actually, there is very little chemistry in
the process of making biodiesel. However, before we begin, you
will need to gather several things. The main and most important
ingredient is waste vegetable oil (WVO). This may be obtained
from many restaurants in your area. Call them and ask for their
old oil. Most will be happy to let you pick it up from them
The next ingredient in the mixture is methanol
(CH3OH). It is important that it be 99% pure. Methanol can be
found at chemical supply stores, or at the local racetrack.
Methanol is toxic, and may cause blindness or even death, so
use caution when you handle it. It is absorbed through the skin,
so wear protective gloves and eyewear whenever you are handling
it. Also be careful to avoid breathing in fumes if you work
in an enclosed area.
The final ingredient for the mixture itself
is sodium hydroxide (NaOH, also known as caustic soda or lye).
This must be kept as dry as possible in an airtight container.
All instruments used to measure and stir lye should also be
kept as dry as possible
You will need a very accurate scale to measure
the amount of lye to add to within a hundredth of a gram. This
is also a dangerous chemical that you need to be cautious handling.
Wear gloves and eye protection to reduce the chance of accidents.
You cannot just throw all of the above ingredients
together and run a truck on the result. There is another step
in the process called titration that needs to be performed on
the WVO to determine the quantity of lye you’ll need to
Titration is the most crucial step, and it
should be taken slowly and all measurements should be as accurate
as possible. For this you will need 99% pure isopropyl alcohol,
distilled water, phenolphthalein solution (not more than a year
old, and kept away from strong sunlight). Phenol or phenol red
from pool supply stores may not be the same substance. Be sure
to get your phenolphthalein from a reputable chemical store.
The final step is called washing, and for
this you will need water and vinegar.
For the entire process, you will need several
largish containers (size depends on how large a batch you plan
on making) to hold and mix ingredients in, and they will get
messy. Containers used for biodiesel should never be used for
any other purpose afterwards.
Step 1- Filtering
You will need to filter the WVO to remove any food
particles in it. If it is too thick, you may have to heat it
up to run it through a filter. 95°F (35°C) should work.
Once it is warm, pour the WVO through a funnel lined with a
double layer of cheese cloth.
Step 2- Removing water
WVO will sometimes contain water content. This is
undesirable since any water left in the oil will form soap when
reacted with lye. Heat the WVO to about 212°F (100°C).
Allow the water to boil off, but be careful that steam pockets
do not splash hot oil out of the heating vessel. When the boiling
slows, raise the temperature to 265°F (130°C) for 10
minutes. Then remove the heat and allow the WVO to cool.
Step 3- Titration
Make a solution of one gram of lye to one liter of
distilled water. Make sure the lye is completely dissolved.
In a separate small container, mix 10 milliliters of isopropyl
alcohol with 1 milliliter of your WVO.
Add two drops of phenolphthalein to the alcohol/oil
mix. Using a graduated eye dropper, or some other instrument
marked in tenths of milliliters, vigorously stir in several
tenths of a milliliter of your lye/water solution to your oil/alcohol
mix at a time. Keep careful track of how many milliliters of
solution you have to add until the mixture turns pink for 10
Step 4- The Calculation
Take the number of milliliters you added in the titration
step and multiply by the number of liters of WVO you will be
processing. Also, for each liter of WVO, you will need to add
an additional 3.5 grams of lye. So for example, if you used
2.4 milliliters in titration and you have 150 liters of WVO,
then 2.4 x 150 = 360 grams plus 3.5 x 150 = 525 grams. So 360
+ 525 = 885 total grams of lye to be added.
Step 5- Preparing the Sodium Methoxide
The amount of methanol you’ll need is about
20% of the volume of WVO you are processing. So for our example
of 150 liters of WVO, you would need 20% of 150 liters, or 30
liters of methanol.
Mix the methanol with the amount of lye that
you calculated in a glass, enamel, or stainless steel container.
Tin, aluminum or zinc containers will all react with the lye,
producing undesirable results. The methanol will react with
the lye to form sodium methoxide.
Sodium methoxide is a dangerous chemical.
If it gets on your skin, it will burn you without you feeling
it, so if it gets on you, use large amounts of water to flush
the skin immediately. Try to have a hose running wherever you
are working with this and other dangerous chemicals. Always
follow standard safety procedure by wearing goggles, gloves
and apron while handling the chemicals.
Step 6- Heating and Mixing
Pre-heat the WVO to 120-130?°F (48-54°C).
A paint stirrer on an electric drill will serve as a mixer.
Add the sodium methoxide to the WVO while stirring. You should
stir the mixture for about an hour. If this is too long to hold
a drill, you may want to assemble a rig to hold it in place
over your mixing vat/bucket. Adjust the speed of the drill so
that there is no splashing. You want a vortex to just appear
on the surface.
Step 7- Separation
Allow the newly mixed solution to settle for a minimum
of eight hours. The biodiesel will float on top while a denser
product called glycerine will have congealed on the bottom.
Suspended in the biodiesel will also be soapy residues. Neither
the gylcerine nor the soap is wanted in the finished product,
so washing is required.
Step 8- Washing
Siphon the biodiesel out of the container into one
without the glycerine mess at the bottom. The glycerine has
many uses, and you may find people locally that would like to
take it from you. Look for a local materials exchange program.
Otherwise it may be composted after letting it vent for three
weeks to allow methanol to evaporate off.
Now that the glycerine has been removed, you
will need to get the soapy residues out of the biodiesel. It
is a good idea to add a little vinegar to the solution to remove
any left over lye and bring the pH level closer to seven (neutral).
Next you’ll need to get a container
to use for the washing. Try to find a container that is translucent.
Then you’ll need to install two valves, one as near to
the bottom as possible, and one that is just high enough to
sit above the level of the water you will be using to wash your
Fill the container with water to a little
below your upper valve. Then put your biodiesel in the rest
of the container. Gently stir the water and oil together. Be
careful to not agitate the soaps with hard stirring. After a
thorough mixing, allow the solution to sit for 12-24 hours.
The denser soapy water will settle to the bottom allowing you
to decant off the cleaned biodiesel through your upper valve.
Once the fuel has been decanted out, you can drain and dispose
of the water.
Repeat this process two or three times to
clean as much soap as possible from the fuel. For these additional
cleanings, it is not necessary to add vinegar.
Step 9- Drying
After a third washing, you will want to remove any
leftover water in the biodiesel. Slowly reheat the oil, and
the water and impurities will sink to the bottom. The finished
biodiesel should have a pH of seven as confirmed by litmus paper
or a digital pH tester.
Congratulations! You’re on your way
to fuel self-sufficiency.
Bear in mind that this is a rough guide to
the fine art of biodiesel creation. Additional research is strongly
encouraged on the subject if you truly wish to run machinery
on the results.
An online resource for aspiring biodiesel
home-brewers can be visited at
Please remember to be safe when experimenting
and follow all recommended safety tips. American Recycler intends
this to be informative, not a set of comprehensive instructions,
and as such, will not accept liability for any damages to persons
or machinery resulting from information contained in this article.