Due to the world's crude oil reserves, which are expected to be depleted in about 40 years, and other factors such as oil price ambiguity, greenhouse gas emissions, and the need for increased energy security and diversity, biofuels have received increased public and scientific attention in recent years. Biofuels refer to a variety of fuels that are obtained in some form of renewable bioresources. From the late 1970s as a renewable energy source to global fossil fuel problems, the biofuel business has seen tremendous growth in the last several years. Over the next decade, the demand for biofuels will grow at a rate that will necessitate significant consideration of alternatives to the predominantly glucose/starch-based feedstock. Fast-growing grasses, halophytes grown on marginal land and aquatic macrophytes, algae, and other oil-accumulating microorganisms could all be used as biofuel feedstock in the future.