Innovation in biorefineries I. Production of second generation ethanol from elephant grass (Pennisetum purpureum) and sugarcane bagasse (Saccharum officinarum)

Abstract

In this first part of our work about innovation in biorefineries, the biomass is previously treated to separate cellulose from other components of the vegetal biomass, followed by acid hydrolysis to produce glucose, which is then fermented to produce second generation (2G) ethanol. The unwanted biomass generated in this first stage will be submitted to pyrolysis to produce biochar, bio-oil, and biogas in a subsequent bio-refinery procedure. In this work, elephant grass (Pennisetum purpureum) and sugarcane bagasse (Saccharum officinarum) were subjected to acid hydrolysis, under atmospheric pressure, as an example of the initial part of the process. Higher cellulose yield was obtained for sugarcane bagasse than for elephant grass, with values of 45 % and 32 %, respectively. In evaluation of the sugar produced, the two grasses showed values of approximately 13 g/100 g of dry biomass. In terms of the 2G ethanol obtained, sugarcane bagasse presented a yield of 96 L.t-1 of dry biomass, while the elephant grass yielded 79 L.t-1. Despite the fact that sugarcane bagasse showed a higher 2G ethanol production potential, elephant grass is a good alternative, due to its adaptability and capacity to grow in various climates and under adverse soil conditions.