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How to Make Your Own Biodiesel


biodiesel processorRegardless of what people say, biodiesel is definitely a much better alternative to any fossil fuel.

Not only that it is much more environmentally friendly, but it is also possible to make high quality biodiesel in your own kitchen or garage, saving you money on both petrol and on car repairs. Here is how.

The process is anything but complicated. In fact, everyone can do it, they just need to dedicate sufficient amount of time, have patience and follow the instructions step by step. There is a whole book on the subject, and I do recommend that you read it thoroughly, but before you start, give this tutorial a shot, it is a small scale test run.

It will help you make up your mind, and hopefully convince you that you don’t need to be an expert chemist or engineer. You do not need anyone’s help or example in order to produce a quality product. In fact, others might slow you down, or mislead you.

So, let’s begin. First come the materials and amounts that you need for your test run, then come the methods, and at the end of it, there will be some tips and tricks for those of you, who feel they are ready to scale up the process to the real deal.


  • 1 litre of vegetable or animal oils and fats, also known as triglycerides (if this is the first time you do this, opt for new, unused oil). You can go for any of the following for maximum success and best quality final product: rapeseed oil, canola oil, corn oil, soy oil, sunflower oil.
  • 200ml Methanol (99+%). This you can buy from large supermarkets, where it is usually labeled as stove fuel, or gas stations, where it is simply an antifreeze. Just make sure you get pure methanol- check the list of ingredients on the bottle.
  • 5.33 grams 92% pure Potassium hydroxide (KOH) – adjust the amount accordingly if the purity is different, or 3.5 grams 97% pure sodium hydroxide (NaOH). These act as lye catalysts, both readily available in stores. Although the latter is cheaper, the former is easier to use and better at the job. We leave the choice to you and your budget, but keep in mind that anything less than 85% strength of KOH, and 97% of NaOH will not work.
  • A blender (or a mini-processor). Opt for a cheap second hand one, but do make sure the seals are in order, and all parts are clean and dry.
  • Accurate scales (best accuracy is 0.01 grams, but anything below 0.1g will do)
  • Measuring jugs
  •  1/2 liter plastic (HDPE) container with a screw-on lid
  • 2 funnels that fit the container
  • 3 X 2 liter plastic bottles (these do not have to be brand new, any soda or mineral water bottles will serve the purpose). One bottle will be used for settling, the other two for washing
  • Duct tape
  • Thermometer


Now, before we move on to the step-by-step tutorial, there are a few safety and consideration measures that everyone should read and take into account.

All equipment should be clean and dry. All products should be the best quality you can find/afford, especially the methanol and lye that you will use for your test run. Each one of the chemical substances comes with caution signs that should not be ignored, especially the methanol. Additional information on safety of the process you can find here.

Step 1. Prepare the Lye

The crucial point here is speed. Because lye absorbs water from the atmosphere very fast, it is recommended that you measure the amounts by placing the lye in a plastic bag before putting it on the scales. For most accurate results, you can even place the container inside the bag, weigh everything out, and then close the container firmly and tie the bag. Do not forget take into account the weight of the bag.

Step 2. Prepare Methoxide

Measure out 200ml of methanol and using the funnel transfer it to the half-liter plastic container. Again, do it as quickly as possible to prevent it from absorbing moisture from the air. Methanol is not flammable and does not release toxic fumes at room temperature, so do not be scared of it.  Using the second funnel add the lye and then close the lid tightly. Shake and swirl the container a few times for about a minute to bring up the temperature. If you are using KOH, the lye will dissolve in the methanol in about 10 to 30 minutes, while the NaOH will take a good few hours, depending on how vigorously you shake and swirl the container.

Step 3. Blending, transfer, settling

Heat up the oil to 55 degrees, then pour it into the blender. Add carefully the methoxide to the oil and secure the lid of the blender tightly. Adjust the settings to low speed, and switch the blender on. Mix for a minimum of 20-30 minutes, but if you can let it run for a bit longer, it is better.

Once this is complete, transfer the mix into a 2-liter plastic bottle and screw the lid. Let it settle for about 12-24 hours. Keep in mind that the longer it stays, the better the quality. Do monitor the process, as the mixture might cause the bottle to contract as it cools. When that happens, you need to let some air in.

As the liquid settles, you will be able to observe the separation of dark glycerine on the bottom and the clear (or cloudy, depending on the type of oil) biodiesel on top. After the settling is complete, transfer the biodiesel into a clean jar or bottle, making sure no glycerine gets in. If that happens, allow to settle again and repeat.

Step 4. Quality Assessment

To assess the quality, you can perform either of the two tests- the wash-test (adding water to the biodiesel, and letting it separate) or the methanol test (add biodiesel to methanol, and let it dissolve). In both cases, the quality is assessed depending on the time it takes for the process to be completed.

In most cases, the tests fail because large amount of glycerine is still present in the mix. But do not be harsh on yourself if that happens, this is why it is a test run after all. If you were able to see the clear split between biodiesel and glycerine, you have already succeeded in the task. Other possible explanations for failure could be the different agitation and time required for blending, which differs between blenders. In addition, you might not have weighed out the measurements precisely.

Just keep practicing, I am sure you will get there!

Step 5. Washing

Once you pass the quality tests, you need to wash your biodiesel. Take the two remaining plastic bottles, and make small (2mm) hole in the bottom corners of each bottle, then stick duct tape over. Add half a litre of tap water in the first bottle, then add the biodiesel.

Start stirring, preferably with a stirrer. If you do not have one, place the lid on the bottle tightly, turn the bottle upside down and roll it. Mix until both water and oil appear homogenous, then let them settle for a minimum of three hours. Then remove the duct tape and let the water drain off.

Once all water is gone and you are left only with biodiesel in the bottle, block the whole and then stick new duct tape over. Pour the remaining biodiesel into the second bottle, add water. Repeat the procedure three times for best results, cleaning the empty bottle before using it again.

Step 6. Drying

Once the washing is complete, let the biodiesel ‘dry’. You know it is ready to use, once the liquid is clear and translucent. This could take a few days, but if you need it fast, then heat it up to 48 degress and then let it cool. This will evaporate any remaining water, so make sure that there is a gap for the air to escape.

Congratulations, you are done! Go out and test it. And if you are convinced you want to make the next step and start your own large scale production, here is some extra info.

Additional tips.

  • If you want to use waste oil to cut budget the process is slightly more complicated. The full tutorial you can find here, but in short, you need to check water content and remove it, and then do titration to check acid content.
  • Follow the test-process every time if you want to be precise and accurate every time
  • Remove water
  • No need to filter your WVO or your biodiesel before use (unlike what people might tell you)
  • But always wash the biodiesel to remove soaps, excess methanol, residual lye or other contaminants before use
  • Do not try to speed up the process by centrifuging , just be patient and allow proper settling and washing. This will guarantee best results and minimal waste.
  • You will need to make a few adjustments on your engine before using the biodiesel (read here).
  • Safety first! Always!

And that is it.

Image (c) Biodiesel Processor

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  1. Nice information here! At present it is also possible to manufacture methanol from the discarded glycerol. A good way to add value to it. Check the information from the Biodiesel Magazine. or in google about the BD4-MG process.


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