Cleaner, cheaper fuel from orange peels and newspaper
By Darren Quick
February 18, 2010
While it may not quite be the Mr. Fusion energy reactor Doc Brown uses to convert household scraps into power for his time-traveling DeLorean, scientists have found a way to turn discarded fruit peels, newspapers and other waste products into cheap fuel to power the world’s vehicles. Its developer says the new approach is greener and less expensive than the current methods available to run vehicles on cleaner fuel and is part of his goal to relegate gasoline to a secondary fuel.
University of Central Florida professor Henry Daniell developed a technique with the U.S. Department of Agriculture that uses plant-derived enzyme cocktails to break down orange peels and other waste materials into sugar, which is then fermented into ethanol. The breakthrough can also be applied to several non-food products including sugarcane, switchgrass and straw.
Currently cornstarch is fermented and converted into ethanol, but ethanol derived from corn produces more greenhouse gas emissions than gasoline does. Daniell says ethanol created using his approach produces much lower greenhouse gas emissions than gasoline or electricity.
There’s also an abundance of waste products that could be used without reducing the world’s food supply or driving up food prices – a common concern for deriving fuel from biomass. In Florida alone, discarded orange peels could create about 200 million gallons of ethanol each year, Daniell said. According to Daniell no company in the world can produce cellulosic ethanol – ethanol that comes from wood or the non-edible parts of plants.
Depending on the waste product used, a specific combination or "cocktail" of more than 10 enzymes is needed to change the biomass into sugar and eventually ethanol. Orange peels need more of the pectinase enzyme, while wood waste requires more of the xylanase enzyme. All of the enzymes Daniell's team uses are found in nature, created by a range of microbial species, including bacteria and fungi.
Daniell's team cloned genes from wood-rotting fungi or bacteria and produced enzymes in tobacco plants. Tobacco was chosen as an ideal system for enzyme production because it is not a food crop and it produces large amounts of energy per acre. Producing these enzymes in tobacco instead of manufacturing synthetic versions could reduce the cost of production by a thousand times, which should significantly reduce the cost of making ethanol, Daniell said.