All You Need to Know About Biofuel

Using biofuels efficiently reduces reliance on foreign oil, minimizes greenhouse gas emissions, and ensures sustainability.

FREMONT, CA: Unlike other renewable energy sources, biomass can be directly converted into liquid fuels, called "biofuels," for transportation. Biodiesel and ethanol are the most common types of biofuels in use today, representing the first generation of biofuels.

Using wastes, cellulosic biomass, and algae-based resources, the Bioenergy Technologies Office (BETO) is developing next-generation biofuels. A major focus of BETO is the production of hydrocarbon biofuels, also known as "drop-in" fuels, which can be used in existing refineries, tanks, pipelines, pumps, vehicles, and engines to replace petroleum. 

Biodiesel: A cleaner-burning alternative to petroleum-based diesel fuel, biodiesel fuel is produced from renewable sources, such as vegetable oils and animal fats. A cleaner-burning alternative to petroleum-based diesel fuel, biodiesel fuel is produced from renewable sources, such as vegetable oils and animal fats. Alcohol is combined with vegetable oil, animal fat, or recycled cooking grease to produce biodiesel, which is non-toxic and biodegradable.

Ethanol: In addition to being a renewable fuel, ethanol is also used as a blending agent with gasoline in order to increase octane and minimize emissions of carbon monoxide and other pollutants that cause smog.

The most frequent blend of ethanol is E10 (10 percent ethanol, 90 percent gasoline) and can be used in most gasoline-powered vehicles up to E15 (15 percent ethanol, 85 percent gasoline). Fuel-efficient flex-fuel vehicles run on E85 (a gasoline-ethanol blend containing 51 percent–83 percent ethanol, depending on geography and season), an alternative fuel that contains much more ethanol than regular gasoline. Approximately 97 percent of gasoline in the United States contains some ethanol.

Plant starches and sugars are commonly used to make ethanol, especially corn starch, in the United States. However, scientists are now developing technologies that would allow the use of non-edible fibrous materials such as cellulose and hemicellulose, which make up most plant matter.

Here are some examples of biofuel conversion processes:

Deconstruction: Advanced biofuels, e.g., cellulosic ethanol and renewable hydrocarbon fuels, are typically produced in a multistep process. Plant cell walls, which consist of the biological molecules cellulose, hemicellulose, and lignin bound tightly together, must first be broken down. High-temperature deconstruction or low-temperature deconstruction can be used to accomplish this.

Upgrading: In order to produce a finished product, intermediates such as crude bio-oils, syngas, sugars, and other chemical building blocks need to be upgraded. Chemical or biological processing can be involved in this step.

Bacteria, yeast, and cyanobacteria can ferment sugar or gaseous intermediates into fuel blendstocks and chemicals. In addition, sugars and other intermediate streams, such as bio-oil and syngas, can be processed using a catalyst to remove any unwanted or reactive compounds.