ABSTRACT
Biofuels of different forms, that is, gas, liquid, and solid, bear dramatically different properties. These physical, chemical, and thermal characteristics are largely dependent on the sources of feedstock, the processing conditions, and the means of postconversion treatments. If a biofuel is produced for use as a transportation fuel, its properties are even more important. To be qualified for use in engines, a biofuel has to meet the fuel specifications that are governed by national and international standards. Even when used in boilers or stoves, a biofuel needs to follow corresponding standards in order to meet the emission requirements. In this chapter, the physiochemical properties of various biofuels are discussed with the emphasis on biofuels of mixed chemical compositions.
