Technological advances will inevitably improve the method. For example, scientists in Australia and the U.S. have substituted a genetically engineered bacterium for yeast in the fermentation process. The process has vastly increased the efficiency by which waste paper and other forms of wood fiber is fermented into ethanol. Biofuels: Biomass is converted into transportation fuels such as ethanol, methanol, biodiesel and additives for reformulated gasoline. Biofuels are used in pure form or blended with gasoline. Ethanol: Ethanol, the most widely used biofuel, is made by fermenting biomass in a process similar to brewing beer. Currently, most of the 1.5 billion gallons of ethanol used in the U.S. each year is made from corn and blended with gasoline to improve vehicle performance and reduce air pollution. Methanol: Biomass-derived methanol is produced through gasification