Contribuições da engenharia de sistemas em bioprocessos à transição para a economia neutra em carbono: análise tecno-econômica-ambiental de biorrefinarias

Abstract

R&D of (bio)chemical processes should include economic analysis and environmental assessment since the early stages of research, to improve the chance of successful industrial implementation. Process Systems Engineering tools (PSE) allied with technical-economic analysis (TEA) and life-cycle assessment (LCA) can be used to identify possible bottlenecks, providing targets for R&D teams. Thus, the objective of this work was to expand the retro-techno-economic analysis (RTEA) through the LCA inclusion, methodology refinement with the addition of the global sensitivity analysis (GSA) and heat integration through the Pinch methodology. The processes were simulated in the EMSO software. Pinch analysis occurs at each convergence loop. The tool has been evaluated in several case studies, providing a maximum deviation of 10.7% compared to optimization techniques. When applied to the 1G and 1G-2G ethanol biorefinery, a system with more than 27 thousand variables, there was a reduction in utility consumption of up to 12,8%, increasing plant productivity. In addition, energy integration increased the robustness of the simulation by creating a “virtual heat exchangers network”. This network deals, in simulation time, with convergence problems due to structural changes in the process, which can occur during the analysis. The expansion of RTEA incorporating LCA, called retro-techno-economic-environmental analysis (RTEEA), combine life cycle analysis (LCA) metrics with economic ones, in order to delimit regions of operation of the process, which simultaneously meet the desired economic and environmental performance. In this methodology, instead of assessing the economic and environmental feasibility of a specific operational condition, TEA and LCA are used to provide target values for the main process metrics. RTEEA is composed by four stages: base case construction, incorporation of TEA and LCA in the process simulation, selection of key variables through GSA and delimitation of the feasible space. RTEEA was applied in two case studies: 1G and 1G-2G ethanol biorefinery from sugar cane and the production of cellulases enzymes through solid state fermentation of sugarcane bagasse in an integrated process to 1G-2G biorefinery. The selection of key variables through the process GSA was carried out in two stages. The first, using the Morris method, aims to determine which variables can have their values fixed, thus being excluded from the next step. The second part, using the Sobol method, aims to list, in order of priority, which variables most contribute to the variation of the values of the model outputs. In the first case study, RTEEA identified that any feasible 1G-2G ethanol production process will always have a lower greenhouse gas emission than the 1G ethanol process. In the second case study, GSA demonstrated that enzyme activity is the variable that most affects the metrics. In addition, the RTEEA showed that if the economic viability of the process is attended, the environmental constraint will also be encountered.