Sugarcane as a Bioenergy Source: History, Performance, and Perspectives for Second-Generation Bioethanol

For hundreds of years, sugarcane has been a main source of sugar, used as a sweetener, and alcohol, fermented from the plant juice. The high cost of petroleum towards the end of the twentieth century stimulated the development of new fermentation technologies for producing economically viable bioethanol from sugarcane as an alternative to importing petroleum. More recently, awareness of the effects of greenhouse gas emissions due to the global climate changes propelled bioethanol as a viable renewable fuel. Consequently, sugarcane gained importance as a bioenergy feedstock. However, the lack of knowledge about sugarcane physiology, notably on aspects of photosynthesis and source-sink relationship, has slowed the advance of this expanding bioenergy-producing system. Besides the changes in source-sink relationship, another option to increase bioethanol production even more would be to use a greater fraction of the total biomass of plants, i.e., not only the soluble sugars but also the sugars present in the cell wall fractions. Here, we review the history of sugarcane as a bioenergy crop and discuss some of the relevant routes that could be adopted in the near future to make sugarcane an even better feedstock for producing biofuels.