Early environmental sustainability guidance on supercritical water gasification technologies for sugarcane bagasse management

Abstract

The sugar industry is considered a high-energy-demand and wasteful industrial sector in many developing countries. Such a high energy demand can undermine the sugar industry's economic and environmental aspects. Shifting from a linear economy model to a circular economy (CE) can help this industrial sector solve the current economic and environmental crises, decrease dependencies on fossil-based energies, increase circularity, and save considerable resources. However, such a transition necessitates comprehensive pre-feasibility studies to avoid problem shifts. Herein, we compared some novel waste-to-energy (WtE) technologies from a life cycle assessment (LCA) point of view; (a) integrated supercritical water gasification (SCWG) at 700 °C with solid oxide fuel cell (SOFC), (b) integrated SCWG at 700 °C with combined cycle gas turbine (CCGT), (c) cogeneration (Boiler), (d) integrated fixed-bed gasification combined cycle (IFXBGCC), and (e) integrated fluidized-bed gasification combined cycle (IFLBGCC). Iran, as a developing country with high dependencies on fossil resources and less CE implementation, was selected as a case study. Scenarios were compared using a functional unit (FU) of thermal management of 1 tonne of bagasse. SCWG is found to be an environmentally superior approach when hydrogen production is the primary function of the system. Otherwise, using boiler and steam turbine is is still the best approach to generate heat and electricity from bagasse. Direct combustion in the boiler showed considerable savings in climate change, i.e., 469 kg CO2 eq saving/FU. The LCA results showed that bagasse to energy throughout direct combustion is a promising pathway to generating clean energy; in addition to helping industries earn more income, and contribute to sustainable development.