Liquid biological fuels are made from biomass and offer an alternative to gasoline and diesel produced from petroleum. The main liquid biological fuels in use today are ethanol and biodiesel. Ethanol is produced primarily from corn and sugar cane while biodiesel can be made from vegetable oils, animal fats, or recycled cooking greases. Both ethanol and biodiesel can be used as gasoline substitutes or blended with gasoline or diesel to reduce dependency on petroleum.

Ethanol Production from Corn and Sugar Cane

In the United States and Brazil, ethanol is mainly produced from corn and sugar cane through fermentation processes. Corn ethanol production involves milling corn kernels to break them down, followed by fermentation of corn mash using yeast. This converts the starch in the corn into sugar and then into alcohol. The alcohol is separated and distilled into fuel-grade ethanol. Brazil is the world’s second largest ethanol producer after the US, with sugar cane as the primary feedstock. Sugar cane has a higher sugar content than corn, making it more efficient for ethanol production. However, concerns have been raised about the impact of diverting agricultural land for biofuel crops on global food supplies and prices.

Biodiesel from Vegetable Oils, Animal Fats, and Waste Grease

Biodiesel can be made from new or used vegetable oils, animal fats, and recycled waste greases through a process called transesterification. In this process, the feedstock is heated and chemically reacted with an alcohol like methanol or ethanol in the presence of a catalyst. This separates the fatty acid chains within the feedstock from the glycerin they are attached to, producing fatty acid esters (biodiesel) and glycerin as co-products. Common vegetable oil feedstocks used for Liquid Biofuels production include soybean oil, canola oil, palm oil, and corn oil. Animal fats from beef and pork processing are also sometimes used.

Blending Options and Engine Performance

Both ethanol and biodiesel can be used in pure forms or blended with petroleum fuels. Vehicles can use these blends with no engine modifications in most cases. E85, which is 85% ethanol and 15% gasoline, is used in flex-fuel vehicles specially designed for it. Biodiesel blends have similar energy contents as petroleum diesel and can be used interchangeably. Ethanol has less energy content than gasoline, so vehicles may see slightly reduced fuel economy on E85. However, careful engine tuning can help offset this.

Production Trends and Infrastructure Needs

Biodiesel production has also grown significantly worldwide and the European Union, United States, Argentina and Brazil are major producers. Global production capacities of biodiesel and ethanol are projected to continue expanding as countries aim to increase the use of renewable fuels. However, greater fuel infrastructure investment in storage terminals and retail pumps is still needed, especially for higher ethanol blends. The number of such compatible fueling stations also needs to grow to boost broader consumer acceptance.