Produção de etanol de segunda geração

Abstract

In relation to sustainability, increasing challenges are faced by actual society and due to the scarcity of the oil reserves and climate changes, the renewable energy sources have presented themselves as an alternative to the future of the planet. Among the renewable energy sources, it can mention biofuels, which have been quite used. In the case of Brazil, the most prominent is ethanol, since the country is worldwide acknowledged for the production of this fuel. However, the sugar production and of first generation ethanol uses only about onethird of the total energy of the sugarcane, because approximately two-thirds are in the straw and bagasse, fact that has aroused the interest of the sugar and energy sector in using such biomass in the second generation ethanol production. Once the 2G ethanol obtention is consolidated in Brazil, it will have potential to increase the productivity in up to 50% in relation to the current production. However, some factors still represent challenges to be overcome, so the second generation ethanol production is commercially implemented and gains market share. It can cite, for example, the existence of other applications for the lignocellulosic waste and the fact that the productive process requires some steps that are not present in the 1G ethanol production (pretreatment and hydrolysis of the raw material) and which need the domain of technologies that are not yet completely developed and which are currently complex, which results in low yield in the conversion of the raw material, negative energy balance and high production cost. Considering the use of sugarcane, the difference between the production cost of the 2G and 1G ethanol can reach R$ 0.30 per liter. Thus, in order to break the existing barriers to the second generation ethanol production, researches have been carried out, aiming at both the development of production technologies and the improvement of the raw material used. For these and other factors, the general objective of this work is to make a bibliographic review about the second generation ethanol productive process. The specific objectives are: to present the raw materials used, to describe the main pretreatment methods in use, to talk about the hydrolysis step and to describe the fermentation of the hydrolyzate.