In the previous lesson, we discussed how substitutes for gasoline in the form of ethanol can be derived from sugar. However, if you want to replace diesel fuel with alternatives that have similar properties, oil- and fat-based fuels can be used.

While it is theoretically possible to run diesel engines directly on extracted vegetable oils and animal fats, these have much higher viscosity than diesel fuel and, due to their reactive groups, can lead to unwanted reactions in the tank and incomplete combustion.

Converting these feedstocks into biodiesel solves many of these issues. The conversion can generally occur through one of three processes:

• Transesertification
• Hydroprocessing
• Iso-Conversion Process