A Step-by-Step Guide to Biodiesel from Used Cooking Oil

Biodiesel is a fuel that can be made from various organic materials, such as used cooking oil. The article below will show how to make biodiesel from used cooking oil for your car or truck from recycled cooking oil. All you need to get started is some cooking oil and methanol, which can both be purchased at most hardware stores in the form of two separate products: methylated spirits and methanol (wood alcohol).

Why is Biodiesel Significant?

Biodiesel production in the US has increased by more than 50% since 2003. Biodiesel is produced both domestically and internationally, with China leading in biodiesel production (about two-thirds of global biodiesel) followed by Europe. The European Union passed a directive in 2017 to increase its use of renewable energy sources to 20 percent of total energy use by 2020. The biodiesel industry has expanded rapidly in Europe; for example, Germany produces roughly half of the world’s supply of biodiesel and is a major exporter to other European countries as well as the US.

Biodiesel production from used cooking oil can be accomplished using either an acid or base catalyst method, although this article will demonstrate how to make biodiesel using the base catalyst method.

When converting cooking oil into biodiesel, it is important that only oils with a high percentage of ‘free fatty acids’ (FFAs) are used for this process. A free fatty acid value below 0.25% indicates that oil cannot be readily converted by either non-catalytic or catalytic means.

Free fatty acids are the result of an incomplete reaction during transesterification and indicate that there is still some glycerin left in the oil. However, free fatty acid values between 0.25% to 0.75%, which can typically be found for most used cooking oils, should not pose any significant problems.

There are a number of biodiesel producers in the US, with many located along the West Coast and in Hawaii because these areas have high concentrations of restaurants that use cooking oil. One company is Baker Commodities, which collects used vegetable oil from commercial kitchens across California to produce biodiesel for fueling transportation fleets throughout Southern California.

Biodiesel can be used in any diesel engine without modification. Used cooking oil is a readily available resource for biodiesel production, and restaurants that use this type of oil are familiar with how to store it properly until pick up.

How Can You Make it?

In order to produce biodiesel from recycled cooking oil, the first thing you will need is some methanol (wood alcohol) and methylated spirits (also known as denatured ethanol). Both of these chemicals are available at your local hardware store. The next thing you’ll need is a container to mix the oil, methanol, and other ingredients in that will hold approximately 20 liters.

The final step before starting production involves heating up two parts of oil with one part methanol. Once the mixture has cooled, it will have a jelly-like consistency that can then be stirred to produce biodiesel.

The process for making biodiesel from used cooking oil using base catalysis is as follows: 

Step One – Heat up 20L of vegetable oil with five liters of methanol in a 44-liter (11 gallons) drum to 100 degrees Celsius for 30 minutes.

Step Two – Allow the mixture of oil and methanol to cool down overnight to room temperature. This should produce biodiesel that is ready for use after settling has occurred or can be used right away without waiting or additional processing steps if desired.

Base-catalyzed biodiesel production is a relatively straightforward process that does not require any special equipment or extensive knowledge of how to produce this alternative fuel. However, it is important to remember that the end product must be checked for free fatty acids (FFAs) prior to use in order to ensure proper conversion during base catalysis has occurred.

How to Make Biodiesel at Home On Your Own: 

You will need a container that holds about 20 liters, vegetable oil (canola or soybean), methanol, and an electric drill with a paint mixer attached. There are a couple of steps that will explain how to make biodiesel from used cooking oil. The steps are as follows: 

Step One – Pour five gallons of oil into the container and attach a drill to it.

Step Two – Slowly pour in three gallons of methanol while stirring at about one rotation per second using your electric drill with a paint mixer attachment. This should be done for 30 minutes until you’ve added all five gallons of methanol. 

Step Three – When your biodiesel has stopped stirring, allow it to settle for 24 hours. The biodiesel will separate from the glycerol and water that has been produced during the reaction.

Step Four – Drain off your biodiesel into another container through a heated coffee filter using hot tap water until you’ve decanted as much liquid as possible out of this other container without disturbing the biodiesel at the bottom of it.

Step Five – Repeat this process until you have filtered out all your biodiesel through coffee filters in hot water. When done, pour your purified biodiesel into a container to store for use when needed. 


How Much Biodiesel is Produced from Vegetable Oil? 

The amount of biodiesel produced from cooking oil depends on how the vegetable oil is processed and how much methanol you add during this process. The more methanol that’s added, the higher your yield will be in terms of how many liters of biodiesel can be made with one liter or gallon of used cooking oil. 

Is Biodiesel Cheaper than Diesel?

Biodiesel is cheaper than conventional diesel and can be used in the same way despite how it’s made. However, if you make biodiesel yourself at home using one of these two processes for making this alternative fuel, then it will likely cost more to produce your own biodiesel unless you’re able to get methanol for free from your local gas station.

What Engine Can Run on Vegetable Oil?

An engine must be converted to run on vegetable oil before it can use this alternative fuel. However, how much of the original components of your vehicle will need to be replaced depends on how well you want biodiesel made using either one of these two processes for making biodiesel from used cooking oil.

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