An overview of integration opportunities for sustainable bioethanol production from first- and second-generation sugar-based feedstocks

The production of bioethanol from second generation feedstocks which are mainly lignocellulosic biomass provides the opportunities for a cleaner, and low carbon biofuel that can serve as an alternative to fossil fuel. However, one major constrain is the high cost of production due to expensive pre-treatment technologies. On the other hand, bioethanol production using first generation feedstock is a proven and well-established technology with high bioethanol productivity and yield, but the process is identified with the issues of food-to-fuel debate and high environmental impact from land use charge. Integrating second generation bioethanol production process with the well proven first generation bioethanol production facilities has the potential of harnessing the synergistic effect that could maximize the technical, economic and environmental benefits of the integrated first and second generation process. This study examined literature on studies related to first generation bioethanol production, second generation bioethanol production and the integrated first and second generation processes with the aim of identifying the extent of integration opportunities for first and second generation bioethanol production from different sugar-based feedstocks. The review put into consideration the different process scenarios available in terms of the technical, economic and environmental benefits of the bioethanol production processes. The benefits of the different integration scenarios for bioethanol production were considered in comparison with the standalone first generation and second generation bioethanol production scenarios. Based on the consideration of the different integration scenarios, some recommendations were proposed for attention in future research on the integration of first and second generation bioethanol production from sugar-based feedstocks. (C) 2019 Elsevier Ltd. All rights reserved.