Why Biofuels?

Global energy crises in the 1970s have triggered public awareness of the limited supply of fossil-derived fuels and the search for an alternative fuel source. Moreover, rapidly increasing energy demand coupled with environmental concern, especially climate change, has pushed research towards in developing alternative renewable energy resources especially for transportation. Specifically in the US, the Energy Policy Act of 2005 (P.L. 110-58), establishing a Renewable Fuel Standard (RFS), coupled with the Energy Independence and Security Act (EISA) of 2007 (P.L. 110-140, H.R. 6) required that the use of biofuel increase to 36 billion gallons (136 billion liters) annually by 2022. Biofuels, such as bioethanol and biodiesel, are liquid fuels mainly used for transportation. These are the promising alternative fuels as they are derived from renewable feedstocks. The use of biofuels has several inherent merits (e.g., enhancing rural economy, providing energy security, reducing the emission of greenhouse gases as well as other air pollutants). Presently, the United States is one of the largest biofuel-producing nations followed by Brazil. The main feedstocks currently used for biofuels production are almost entirely from food crops, such as grain starch, sugarcane, and oil seeds. For example, ethanol is primarily produced from the fermentation of sugarcane-derived sugar/molasses and starch-derived sugar obtained from corn, cassava, and sorghum. In contrast, biodiesel is produced from oil seed crops (e.g., soybean, palm oil, rapeseed, sunflower, and canola), waste oils, or animal fat. Currently, there are considerable efforts to use non-food-based feedstocks such as Jatropha, and algae for biofuel production.

Fig. 1 Major feedstocks currently used for biofuel production: sugarcane, corn, soybean, and palm oil (from left to right)