The term third generation biofuel has only recently enter the mainstream it refers to biofuel derived from algae. Previously, algae were lumped in with second generation biofuels. However, when it became apparent that algae are capable of much higher yields with lower resource inputs than other feedstock, many suggested that they be moved to their own category.
Second generation biofuels are also known as advanced biofuels. What separates them from first generation biofuels the fact that feedstock used in producing second generation biofuels are generally not food crops. The only time the food crops can act as second generation biofuels is if they have already fulfilled their food purpose. For instance, waste vegetable