How Biofuels are More Environmentally Friendly than Fossil Fuels

Biofuels may have lower environmental impacts than fossil fuels.

FREMONT, CA: The U.S. government considers the production and use of biofuels to have fewer or lower negative environmental impacts than fuels derived from fossil fuels. When biofuel use lessens the demand for imported petroleum fuels, potential economic and security benefits are also. Government programs that promote or mandate the use of biofuels, such as the U.S. Renewable Fuel Standard (RFS) and California's Low Carbon Fuel Standard (LCFS), define the types of biofuels and processes or low-carbon pathways by which biofuels can be produced to qualify for use under the programs. Biofuels have environmental benefits, but their production and use have ecological impacts.

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Pure ethanol and biodiesel (B100) are nontoxic, biodegradable, and harmless if spilled. Nonetheless, gasoline-ethanol contains denaturants that render it undrinkable. Like petroleum fuels, biofuels (mainly ethanol) are combustible and must be transported with care.

When burned, pure biofuels create fewer particulate matter, sulfur dioxide, and air toxics than their fossil fuel counterparts. In general, biofuel-petroleum mixes produce fewer emissions than fuels that do not contain biofuels. Biodiesel burning may produce somewhat more nitrogen oxides than petroleum diesel combustion.

Ethanol and ethanol-gasoline combinations burn cleaner and have better octane levels than gasoline that does not contain ethanol, but they emit more evaporative pollutants from fuel tanks and distribution equipment. These evaporative emissions lead to the development of ozone and smog at ground level. To prevent evaporative emissions, gasoline must undergo further processing before blending with ethanol.

The combustion of biofuels releases carbon dioxide (CO2), a greenhouse gas. According to international convention, however, CO2 emissions from biofuel burning are omitted from national greenhouse gas emission inventories since the cultivation of biomass feedstocks used for biofuel production may offset the CO2 created when biofuels are consumed.

Biofuel consumption on net CO2 emissions depends on how biofuels are produced and whether or not agricultural cultivation emissions are included in the calculations. Some feel that the land, fertilizers, and energy utilized to cultivate biofuel crops should instead be used to cultivate food crops. Large tracts of natural vegetation and forests have been removed or burned in some areas of the world to cultivate soybeans and palm oil plants to produce biodiesel. The production of ethanol, renewable diesel, renewable heating oil, and renewable aviation fuel requires a heat source, and the majority of producers of these biofuels currently utilize fossil fuels. Some U.S. ethanol producers use corn stocks to generate heat, while Brazilian ethanol producers use sugar cane stocks (bagasse) to create heat and electricity.

The U.S. government is sponsoring initiatives to make biofuels from cellulosic biomass, which requires less cultivation, fertilizer, and pesticides than either corn or sugar cane. The feedstock for cellulosic ethanol includes native prairie grasses, fast-growing trees, sawdust, and even waste paper. Due to technical and economic obstacles, there is currently no commercial cellulosic ethanol manufacturing in the United States.

Lipid feedstocks—waste or used cooking oil and animal fats/tallow and grease—have relatively low carbon intensities as feedstocks for biofuels production. They have been used to achieve the federal RFS program's requirements for advanced biofuels rather than cellulosic ethanol production. The total process (or life-cycle) emissions for lipid feedstocks are minimal because lipids were previously utilized for another purpose. The only emissions associated with transporting these biofuels feedstocks come after collecting the waste oil/grease. Some state governments provide more support for the development of biofuels from lipid feedstocks than they do for the production of biofuels from crude, unusable vegetable oil feedstocks. Most feedstocks for U.S. non-fuel ethanol biofuels production in California are lipids, as is the bulk of credits generated under California's LCFS. In contrast to cellulosic and other renewable fuels, the federal RFS does not yet differentiate between lipid and vegetable oil feedstocks. At scale, the manufacture of lipid-based biofuels necessitates a substantial amount of hydrogen, which may increase process emissions and, consequently, their carbon intensity if derived from fossil fuels.