ABSTRACT
Initially when the potential of plants to produce liquid fuels was realized, the immediate focus was to use food and feed crops such as sugarcane (sugar), maize (starch), or soybean (oil) for biofuel production. Sugar can be directly fermented by yeast to produce ethanol, and starch can be easily converted into fermentable sugars. Many types of fats and oils can be chemically converted into biodiesel. Collectively, these fuels are known as rst-generation biofuels. However, it was soon realized that these crops alone cannot meet the current demand for fuel because converting these crops into fuels is relatively inefcient with respect to the ratio energy output to input, mostly because only a fraction of the plant is utilized. Also, increased production of crops for fuel use has raised concerns about the environmental impacts of intensive agriculture and changing land usage. In addition, with the rapidly growing human population and increasing demand for animal
1.1 Introduction ..............................................................................................................................3 1.2 The Past and Present-Ethanol and Biodiesel: The First-Generation Biofuels .......................4
