Second Generation Bioethanol Production Process Via Catalyzed Steam Explosion Pretreatment: A Computer-aided Exergy Analysis and Heat Integration

摘要

Background: Bioethanol is one of the most important biofuels because it has been produced from residual biomass such as corn stover, sugarcane bagasse, agricultural waste, among others. Bioethanol production from non-food biomass represents an opportunity for the biofuels industry to use raw materials in countries with high agricultural development, providing new alternatives for increasing the global production of biofuels. Therefore, process technologies have to be analyzed in order to guarantee the real energy gain in the biofuels industry through exergy analysis and computer-aided system engineering. Objectives: In this work, exergy analysis and heat integration methodologies were applied to evaluate hydrolysis and fermentation technologies when steam explosion pretreatment was used as pathway. Methods/Analysis: Bagasse from sugar industry was considered as raw material for bioethanol production. This residual lignocellulosic biomass was pretreated through catalyzed steam explosion and sent to different process configurations such as Separated Hydrolysis and Fermentation (SHF), Simultaneous Saccharification and Fermentation (SSF), and Simultaneous Saccharification and Co-Fermentation (SSCF). The three processes were analyzed using exergy analysis criteria and the best alternative was integrated to reduce heating and cooling utilities in the process and to improve the energy profile for the bioethanol process. Findings: It was found that the highest exergy efficient was obtained when SSCF technology was used after catalyzed steam explosion pretreatment in comparison with SHF and SSF alternatives. Application of heat integration methodologies reduced cooling utilities by 57.7% and heating utilities by 63.4%. Novelty/Improvement: Implementation of computer-aided process, heat integration and exergy analysis allowed to compare and evaluate bioethanol technologies in order to reduce the energy requirements for the biofuel process and increase the net energy gain.