How to convert vegetable oil to biodiesel – do it yourself

For newbie, I’ll recommend starting with a fresh oil and small quantities. Later on, you can try doing it in large scale and with recycled oil.

What is the process of making biodiesel?
Vegetable or animal oils are triglycerides, Which means that they contain glycerine and fatty acids. This process turns the oils and fats into fatty acids, separating out the glycerine. After the separation, the glycerine sinks to the bottom and the biodiesel floats on top and can be siphoned off.
This process is called transesterification, which technically, substitutes alcohol for the glycerine in a chemical reaction, using lye as a catalyst. See

What Chemicals do you need?
For beginners, the alcohol that is best suite for the process is methanol. Although most methanol comes from fossil fuels (while it can also be made from biomass, such as wood), but using other alcohols like ethanol is more difficult and require distillation.

Methanol is also called: “methyl alcohol”, “wood alcohol”, “wood naphtha”, “wood spirits”, “methyl hydrate” , "stove fuel", “carbinol”, “colonial spirits”, “Columbian spirits”, “Manhattan spirits”, “methylol”, “methyl hydroxide”, “hydroxymethane”, “monohydroxymethane”, “pyroxylic spirit”, or MeOH (CH3OH or CH4O) -- all the same thing.

You can usually get methanol from bulk liquid fuels distributors, in supermarkets and chain stores as "stove fuel" for barbecues and fondues, and more.

You will also need a lye catalyst, that can be either potassium hydroxide (KOH) or sodium hydroxide (caustic soda, NaOH). NaOH is often easier to get and it's cheaper to use. KOH is easier to use, and it does a better job.

Make the first trial batch:
Here is what you need for start:

One liter of new vegetable oil.
lye catalyst – see above – KOH or NaOH
200 ml of methanol, 99+% pure
measuring beakers for methanol and oil
scales accurate to 0.1 grams, or preferably less -- 0.01 grams if possible.
½ liter translucent white #2 plastic container with screw-on cap and bung
2 funnels to fit the container
2-liter bottle for settling
two 2-liter bottles for washing
duct tape

Making Lye for home-made biodiesel productionyou have to work rapidly when measuring out the lye because it very rapidly absorbs water from the atmosphere and water interferes with the biodiesel reaction.

Measure the lye into a handy-sized frivolous plastic bag on the scales (or even do the whole thing entirely inside a big plastic container), then close the lid of the container firmly and then close the plastic bag, winding it up so there's not much air in it, so no more air can get in. Have exactly the same kind of bag on the other side of the scale to balance the weight, or adjust the scale for the weight of the bag.

How much to use?
NaOH must be at least 97% pure, so use exactly 3.5 grams.
If you're using KOH it depends on the strength.

If it's 99% pure (rare) use 4.9 grams (4.90875). If it's 92% pure (more common) use 5.3 grams (5.33), with 90% pure use 5.5 grams (5.454), with 85% pure use 5.8 grams (5.775).
Notice that any strength of KOH from 85% or stronger will work.

How to Mix the methoxide:

Measure 200 ml of methanol and pour it into the half-liter container trough a funnel. Methanol can also absorbs water from the atmosphere so make sure you do it quickly and close the lid of the methanol container tightly.
Don't be frightened of methanol, if you're working at ordinary room temperature and you can keep it at arm's length you won't be exposed to dangerous fumes. See More about methanol.

Carefully add the lye to the container trough the second funnel. close the bung and the screw on the cap tightly.

Shake the container a few times - spin it round and do not shake it up and down. The mixture gets hot from the reaction. If you swirl it thoroughly for a minute or so, the lye will completely dissolve in the methanol, forming a methoxide. As soon as the liquid is clear with no floating particles you can start the process.

The more you swirl the container the faster the lye will dissolve. With NaOH it can take from overnight to a few hours to as little as half-an-hour with lots of swirling - don't be impatient!, wait for all the lye to dissolve. Mixing KOH is much faster, it dissolves in the methanol more easily than NaOH and can be ready for use in 10 minutes.

The reaction process – using a blender:

Use a spare blender you don't need or get a cheap second-hand one -- cheap because it might not last very long, but it will get you going until you build something better.
Make sure that the blender seals are in good order. Check that all parts of the blender are clean and dry and that the blender components are firmly fitted.

- heat the oil to 55 deg C (130 deg F) and then pour it into the blender.

-While the blender is still turned off, gently pour the prepared methoxide from the HDPE container into the oil.

Secure the blender lid tightly and turn on. Use lower speed.
Mix for about 20-30 minutes.

When the process is completed, decant the mix from the blender or the mini-processor into the 2-liter bottle for settling and screw on the lid tightly.

Allow the mixture to settle for 12-24 hours.

Dark-coloured glycerol by-product will precipitate in a distinct layer at the bottom of the bottle, and a clear line of separation from the pale liquid above will be visible, that is the biodiesel. The biodiesel can vary in color depending on the oil used. Usually it's pale and yellowish. The biodiesel could be clear or still cloudy, which is not a problem. It will clear eventually but there is no need to wait.

After clearing, carefully pour the top layer of biodiesel into a clean jar or bottle, taking care not to get any of the glycerine layer mixed up with the biodiesel. If you do, re-settle and try again.

For washing use the two 2-liter bottles in series, with 1/2 a liter of tap water added for each of the three or four washes required. Pierce a small 2 mm opening in the underneath corner of each of the two bottles and cover the hole securely with duct tape.
If you have a small paint stirrer and a variable-speed drill, cut the lids off the bottles as above for the stirrer. Stir until oil and water appear homogenous. Let it settle for 2 hours or more.
If you do not have a stirrer, do not cut the lids off the wash bottles.
Mix the biodiesel and the water as above. Screw the cap on very tightly. Turn the bottle on its side and roll it about manually until oil and water are well mixed and homogenous. Settle, let it drain.


When the solution become clear (translucent) it is dry and ready to use. It might clear quickly, or it can even take a few days. If you're in a hurry, heat it gently to 48 deg C (120 deg F) and allow to cool.

Congratulations! You have just produced high quality biodiesel fuel.

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