Biodiesel from Waste Vegetable Oil: Step-by-Step Guide

Biodiesel is a renewable and sustainable form of energy. It can reduce greenhouse emissions by almost 30%, which means that although they do release carbon dioxide into the atmosphere, they do so in a very limited manner.

With the aim of building a green new world, and eliminating the need for fossil fuel and other traditional energy sources, people are now turning towards biofuels like bioethanol and biodiesel. Thus, we see biofuel being used for transportation in many countries. It’s also being used to generate electricity. The rural areas in many underdeveloped and developing countries are using biofuel for domestic cooking purposes as well.

We can produce biodiesel from waste vegetable oil through a series of steps. Below is a quick overview of the steps involved in biodiesel production process from used waste vegetable oil.

1. Filtration

The purpose of the filtration process is to get rid of the unnecessary particles from the waste vegetable oil. In this step, we take the used cooking oil and then heat it to a certain degree. Once the liquid has been heated, the waste particles will automatically separate themselves from the main mixture. Afterward, we just have to filter it with a regular filter paper.

2. Water removal

Next, we need to remove water from the residual gangue. If the water is allowed to stay in the mixture, it’ll end up delaying the overall process. By removing all the moisture, we can make the reaction move a lot faster. The easiest way to remove water from the mixture is by heating it steady at 212 degrees F for some time.

3. Titration

Titration is conducted on the mixture to determine the amount of chemical catalyst (like lye) that will be needed. The catalyst is a key component in any chemical reaction. It pretty much determines how fast and how much of a product we’re going to receive. Thus, this step is very important in the biofuel manufacturing process.

4. Sodium methoxide preparation

In this step, we take methanol (18-20% of the waste vegetable oil) and mix it with sodium hydroxide. This gives us sodium methoxide, which is also used as a catalyst in the reaction. It helps perform synthesis reactions on the reagents and facilitates the overall reaction process. Sodium methoxide is a key ingredient in this manufacturing process. It’s considered to be a standard substance used to accelerate the reaction, and yield better results.

5. Mixing and heating

Next, we heat the residue between 120-130 degrees F. Afterward, we mix it properly. This process aims to evenly distribute the mixture. This will help the mixture to settle down later on, and cool off, after which we can begin the extraction process. In a way, the mixing and heating stage can be seen as the final preparation before extraction.

6. Setting

Once the mixing is completed, the liquid is allowed to cool and settle down, after which we can extract the final product, i.e. the biofuel.

7. Separation

After the liquid has cooled, the biodiesel can be extracted from the top of the mixture. It’ll be found floating on top, like oil in water. To get the biodiesel, we’ll have to remove the glycerin underneath it. This can be done by simply draining it out from the bottom, and keeping the fuel afloat. The biodiesel is finally ready.

The whole process described above is for a small-scale operation. However, it can be scaled up as needed, given that you have the right tools, ingredients, and setup.

It should also be noted that chemical catalysts (such as lye) are used in the manufacturing process as well. Recently, however, scientists and researchers are looking into the use of ultrasonics as additional catalysts. According to recent observations, a combination of chemicals and ultrasonics can lead to a higher yield of fuel, and reduce the overall processing time. This also leads to better utilization of waste vegetable oil.

Companies are now using ultrasonic systems and technology in a wide variety of fields, one of which is the biomass energy industry. And while the technology’s use in other fields has gained more traction in recent times, it shouldn’t be long before it’s used in biodiesel production systems, as well as in other biomass energy sectors, in full swing.