Recent technical advancements in first, second and third generation ethanol production

Ethanol is an alternative biofuel produced by a biotechnological process from sucrose-rich crops (e.g., sugarcane, beet, and sweet sorghum). In order to increase the productivity of this alcohol without increasing the cultivated crop area, efforts have been focused on the use of alternative raw materials, such as lignocellulosic residues and microbial sources, called second-generation (2G) and third-generation (3G) ethanol, respectively. However, 2G and 3G production processes are not consolidated, with a lot of bottlenecks. Aiming to overcome them, recent studies have shown that it is possible to reduce the process cost by optimizing and evaluating different alternatives for the critical steps of pretreatment, hydrolysis, and fermentation. In this chapter, after a short introduction about ethanol and its production around the world, the main characteristics, drawbacks, challenges, and perspectives are discussed for the 1G, 2G, and 3G ethanol production processes.