Poultry Waste Valorization via Pyrolysis Technologies: Economic and Environmental Life Cycle Optimization for Sustainable Bioenergy Systems

This article addresses the life cycle optimization (LCO) of the poultry litter supply chain considering pyrolysis technologies that aim to sustainably convert poultry waste into biofuel and biochar. A multiobjective optimization framework integrated with a life cycle analysis methodology is developed. The economic objective is to maximize annualized profit per functional unit, and the environmental objective is to minimize the annual CO2-equivalent greenhouse gas (GHG) emissions per functional unit. The formulated multiobjective mixed-integer fractional programming problems are solved using an E-constraint method and parametric algorithm. To illustrate the applicability of the proposed framework, a case study on the State of Georgia is presented. The Pareto-optimal solutions illustrate a clear trade-off between the unit annualized profit and the unit annual CO2-eq GHG emission. The most economically profitable solution has an annualized profit of $91 /ton poultry litter dry matter (DM) and an annual sequestration of 0.04 kg CO2-eq/ton DM. The most environmentally sustainable solution has a profit of -$1.02/ton DM and annual emissions of -511 kg CO2-eq/ton DM. Through spatial analysis, a clear correlation between pyrolysis facility locations and poultry litter production amount is revealed. Sensitivity analyses reveal biochar price and storage periods of unpyrolyzed poultry manure to be the greatest factors that influence the economics and environmental objectives, respectively.