Ethanol produced from the structural and non-edible fractions of plants is called second generation (2G) ethanol. The product ¾ ethanol ¾ is identical to the one obtained from first generation (1G) technology already consolidated in the Brazilian sugarcane industry. However, while the 1G technology utilizes only the sugars from cane juice, which represent about 1/3 of the energy available in sugarcane, the 2G technology harnesses the structural carbohydrates from bagasse and straw, each one of these fractions representing an additional 1/3 of the sugarcane biomass. Hence, by unlocking the potential of the whole sugarcane, 2G technology enables substantial gains in the production of ethanol, without necessarily expanding the quantity of sugarcane.
Main Steps of Second Generation Ethanol
Production of 2G ethanol requires three main process steps:
- Physicochemical pretreatment, which solubilizes part of biomass components and opens its compact structure.
- Enzymatic saccharification, which utilizes enzymes to convert structural carbohydrates (cellulose and hemicellulose) in simple sugars, mainly glucose (from cellulose) and xylose (from hemicellulose). An efficient enzymatic cocktail requires a diverse set of enzymes with complementary activities.
- Alcoholic fermentation, which employs microorganisms to ferment the simple sugars into ethanol. The fermentation of glucose takes place similarly to 1G fermentation, while the fermentation of xylose demands special conditions.
CTBE conducts technology development and optimization as well as scientific investigation aiming at improving these critical steps of the 2G ethanol production process. CTBE research and development takes place within projects, usually with partners from industry and academia, and funding from governments, foundations, and private organizations. Part of our results are published in peer-reviewed articles, describing, for instance, findings in pre-treatment [1,2], enzyme production [3,4], enzyme engineering , fermentation , and process scale-up . By advancing the science and technology of 2G ethanol, CTBE fosters this breakthrough technology to become cost-competitive in the Brazilian sugarcane industry.
Synergies with Other Research Areas
Our efforts in 2G ethanol shall benefit from the synergies with the other CTBE research areas. Therefore, we consider the integration between 1G and 2G ethanol processes, the production of renewable chemicals for additional valorization of 2G process streams, and the technology assessments conducted by the Virtual Biorefinery. Furthermore, our efforts in 2G ethanol shall consider the agricultural determinants of productivity, quality, and sustainability in sugarcane cultivation. With this perspective, CTBE research in agricultural mechanization, agricultural management, and plant biology provides further synergy for the advance of 2G ethanol from sugarcane.