Biofuels that are produced from non-food feedstocks (second generation) are commonly known as advanced biofuels. They can be classified into four groups (generations) based on their production process and type of feedstock (Table 1). As summarized in Table 1, it is evident that each generation has its own advantages and disadvantages and it is difficult to choose one among them for large-scale produc­tion and application. For example, fourth-generation biofuels seem to be very attrac­tive and carry several advantages from carbon emission and environmental pollution point of view; however, its process of production is cumbersome and technically not proved and established as of now to make it commercially viable.