How Is Biodiesel Made?

With climate change and global warming increasingly pressing issues facing the human race, there has been a growing trend towards the use of more environmentally friendly forms of fuel. Hydrogen is driving ahead as a green energy source in Germany, for example, while biodiesel is increasing in popularity all over the world, including in the UK.

An alternative fuel source to petrol or diesel, biodiesel is created from natural resources such as animal and vegetable fats, soybean, palm or rapeseed oils or waste cooking oil from restaurants. As such, it’s a renewable and clean method of powering our vehicles – but how is it made? This article will delve a little deeper into the process behind manufacturing biodiesel.

Step 1 – Harvesting the oil

Oil is the principal ingredient in biodiesel and is usually gathered from a variety of different sources. Used cooking oil which would otherwise be discarded by the hospitality industry is an inexpensive source, while crops such as canola, palm, soybean or rapeseed can also be processed to produce the oil. Vegetable fats and animal fats are two more alternatives which work well, too.

Step 2 – Cleaning the oil

Before the oil (or fat) can be used to manufacture biodiesel, it must first be cleansed of its contaminants and impurities. This is achieved by filtering out any solid particles found in the substance, as well as removing any water present in its makeup. There are a number of other physical and chemical processes which may be employed at this time in order to improve the quality of the oil even further.

Step 3 – Titration

In order for the oil to be suitable for biodiesel production, it’s necessary to adjust its pH levels to the desired concentration. Using the method of titration, manufacturers can determine the specific quantities of methanol and an oxidised catalyst that are required to convert all of the triglycerides in the substance to convert into biodiesel.

Step 4 – Transesterificaction

During this process, the triglycerides in the oil are separated into fatty acid ethers and glycerol via the injection of an alcohol such as ethanol. The methoxide is mixed in with the oil and circulated at a temperature of approximately 49°C for two hours, after which the glycerol is removed from the bottom of the tank and used to make soap or other products, or else discarded.

Step 5 – Cleansing

The remaining substance is then cleansed using water, which helps to remove any lingering remnants of methanol and the catalyst. The biodiesel is mixed with water and circulated at around 32°C for between one and two hours, or until all the water has evaporated. Sawdust and other dry substances can also be used to achieve the same effect, but must be filtered out before the biodiesel can be used commercially.

Step 6 – Finessing

The final step in the biodiesel production process is ensuring that it meets all relevant quality standards, especially if it is intended for commercial use. This involves the use of sophisticated technology which can analyse the characteristics of the substance and determine whether any water is left over and confirm that the oil has been thoroughly converted into biodiesel. And voila! It is ready to use.