BioDiesel Generation

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In 2005 syrenew began using a Bio Diesel blend within the company car. This is proving to be both economical and beneficial to the environment, as well as being quite simple to do. Below is the method in use and some comments on how it can be done in Victoria. Enjoy!

Method

For every one liter of used vegetable oil you will need 3.5 grams of KOH, and 200ml of methanol. With safety gear on, measure 200ml of methanol into a glass blender. Then weigh 3.5 grams of KOH and carefully tip into the blender. (NaOH was used but the results were not as reliable) Place the lid on the blender and mix until the KOH has dissolved. (some heat may be generated by this process – exothermic reaction). You have made potassium methoxide. Be carefull as this is a very dangerous and toxic chemical.

I have found the best method to be 20 litres of oil, 4 litres of methanol and 180 grams of KOH.

You then carefully pour the methoxide into the oil in a large container. Mix for 10 minutes and then let stand overnight. During this time you will see a dark layer on the bottom (glycerine) with a clear layer of biodiesel on the top (methyl ester).

The glycerine, having a higher specific gravity, will settle to the bottom and the biodiesel will be on top of the mixture. Decant as much glycerol as possible from the mix.

Washing

You will first need to wash your biodiesel before using it. Even though it won't look like it, you will have soaps and particulates suspended in your biodiesel. The easiest way to get rid of soap is to add water and turn it into an emulsion. There is a lot of debate about the best way to wash biodiesel, but the simplest way is to wash with an equal volume of water by gently spraying a mist onto the top of the biodiesel. Leave it to settle and again the biodiesel will be on the top of the mixture, with soapy water and some glycerol on the bottom. Test the pH of your biodiesel and continue to wash it until the pH is close to 7.5.

I normally wash the biodiesel three times and let it settle between washes.

Drying

To remove the water in your biodiesel, either heat it up to 100 degrees and evaporate any water or leave it in open capped containers (preferably in the sun) for a few days.

Filter and then add to your diesel tank. (10% to 20% in winter, up to 50% in summer)

Currently I am running at close to 50% during winter, however am finding problems with water in the line. It has been close to 100% over summer without problems.

Mixing Chart

Used Oil	Methanol	KOH
Litres	Litres	Grams
9	1.8	81
10	2	90
11	2.2	99
12	2.4	108
13	2.6	117
14	2.8	126
15	3	135
16	3.2	144
17	3.4	153
18	3.6	162
19	3.8	171
20	4	180
21	4.2	189
22	4.4	198
23	4.6	207
24	4.8	216
25	5	225