Efficient Production of Biogas and Biofuel

How to Make Biodiesel from Vegetable or Seed Oil

Diesel engines were originally designed to run on peanut oil—this was before the discovery of efficient methods for producing diesel from petroleum. Because of this, diesel engines still retain the capability to operate on vegetable and seed oils.
Biodiesel is a refined derivative of these oils. It serves as a middle ground between using petroleum-based diesel and running engines on pure vegetable oil

Overview:

This procedure outlines the steps to produce biodiesel from vegetable or seed oil through transesterification using methanol and sodium hydroxide.

Materials:

Vegetable or seed oil (500 mL assumed for example)

Methanol (100 mL, 1/5th the oil volume)

Sodium hydroxide (NaOH, 5 g, oil volume ÷ 100)

Heat source (able to maintain 60–80°C)

Stirring apparatus

Thermometer

Filtration setup (e.g., fine mesh or filter paper)

Separation containers (2+)

Water for washing

Ventilated area for drying

Procedure:

1. Measure Inputs:

• Measure 500 mL of vegetable or seed oil.

• Add 100 mL of methanol (1/5 of oil volume).

• Add 5 g of sodium hydroxide (1 g per 100 mL oil).

2. Heat and Stir:

• Heat the mixture to 60–80°C.

• Stir continuously.

• Maintain stirring until sodium hydroxide has visibly stopped dissolving.

• Continue stirring for an additional 20 minutes.

3. Filter the Mixture:

• Filter the mixture to remove any remaining solid sodium hydroxide.

• The liquid should now be free of visible solids.

4. Settle and Separate Glycerine:

• Pour the filtered mixture into a container.

• Allow it to settle and cool for 24 hours.

• After settling, glycerine will form a layer at the bottom.

• Carefully decant the upper biodiesel layer, leaving glycerine behind.

5. Wash the Biodiesel:

• Add clean water to the biodiesel and shake.

• Allow the mixture to settle, separating water from biodiesel.

• Decant the biodiesel, discarding the water (now containing soap).

• Repeat the wash cycle until the wash water runs clear.

6. Dry the Biodiesel:

• Leave the washed biodiesel in a well-ventilated area to evaporate residual water.

• Once the biodiesel is dry (no visible water droplets or cloudiness), it is ready for use.