Carbon Dioxide Mitigation:
Biofuels

The most commonly known biofuels are ethanol and biodiesel. Both are derived from biomass which can be converted into liquid fuels otherwise called biofuels. Until recently biofuels were thought of, by some, as the answer to reducing greenhouse gas (GHG) emissions and foreign energy dependence. As of late, new studies have unearthed problems associated with biofuels in a well-to-wheel scenario, stemming from land use changes to the negative pricing effects of food to fuel. When analyzing the GHG balance of biofuels, one must take into account the feedstock selection (i.e. corn vs. sugar cane, or soy vs. algae), agricultural methods practiced, associated land use changes, and the type of production technology implemented. Depending on the site-specific parameters of a biofuel project , it is possible to produce biofuels in a sustainable manner.

Ethanol fuel is used as an alternative to gasoline. In the U.S., anhydrous ethanol is blended with petroleum based gasoline as E10 (10% ethanol, 90% petrol) or E85 (85% ethanol, 15% petrol). Corn is mostly used in the U.S. while sugarcane is the principle feedstock in Brazil. Corn-based ethanol is very energy/carbon intensive and only returns about 1.34 units of fuel energy for each unit of energy expended. Sugarcane-based ethanol can reap better yields of energy (up to 8 units in Brazil). Recent research and development have now made available cellulosic ethanol technology. This technology allows virtually any plant matter to be utilized for the production of ethanol by unlocking sugars bound in cellulose and hemicellulose. Cellulosic-based ethanol also supports efforts towards producing alternative fuels in a sustainable manner.

Biodiesel can be made from plant or vegetable oil, animal fat, or recycled cooking grease by combining any one of these feedstocks with an alcohol, generally methanol, through a process known as transesterfication. In the U.S., biodiesel is mostly used as a blend with petroleum diesel for automotive transportation. Blends of B10 (10% biodiesel, 90% petrol diesel) and B20 (20% biodiesel, 80% petrol diesel) are sold publicly at various gas stations across the nation. Biodiesel uses are not limited to just automotive transportation, but also include operation of commercial trucks, tractor trailers, farm equipment, diesel aircraft, diesel generators, and heating. Most biodiesel found in the U.S. is produced from soybean oil or imported palm oil. Biodiesel can be created from an assortment of other more sustainable oilseed feedstocks such as algae. The benefits of algae are expansive, to name a few: it does not compete with agriculture, requires less water than the traditional crop-based biodiesel, and growth and productivity can be 30 to 100 times higher than other oil crops.