Comparative life cycle assessment of byproducts from sugarcane industry in Pakistan based on biorefinery concept

A comparative life cycle assessment of the sugarcane biorefinery in different conceptual arrangements was conducted considering four different alternatives with increasing utilization of byproducts. The first alternative with the least use of byproducts was taken as the base case and the fourth alternative was a completely integrated plant with gradually enhanced and efficient use of byproducts. The functional unit was defined as the production of 1 t of sugar in the biorefinery complex. The calculations were performed for the eight most relevant impact categories including global warming, freshwater eutrophication, terrestrial acidification, terrestrial ecotoxicity, freshwater ecotoxicity, human carcinogenic toxicity, mineral resource scarcity, and fossil resource scarcity. Overall, it was observed that for most of the impact categories, the values were progressively reduced with an increased use of byproducts (i.e., prevention of cane burning and its recovery; filter cake, ash, wastewater, and sludge as fertilizer; bagasse and cane trash for high-pressure cogeneration; ethanol as biofuel and recovery of CO₂; biogas for waste to energy production). In general, it could be concluded that an enhanced and efficient use of byproducts would significantly improve the environmental performance of the biorefinery complex.