Integrating Process simulation and Life Cycle Assessment: A Case study on Polyethylene Gasification for Hydrogen, Hydrocarbons, and Methanol Production

The process industry faces increasing pressure to adopt sustainable practices while overcoming challenges such as narrow profit margins and a conservative approach to innovation. One critical barrier is the difficulty in quantifying environmental impacts during the early stages of process design, often due to limited primary data and a lack of comprehensive life cycle assessment (LCA) frameworks tailored to industry-specific needs. This study presents an integrated workflow for evaluating the feasibility and environmental performance of polyethylene (PE) gasification. It combines mechanistic chemical simulations, process modeling, and environmental assessment to address these challenges effectively. The starting point was literature plant schemes optimized in the proposed configurations. Then, a detailed reactor gasification model was carried out with OpenSMOKE++. Indeed, OpenSMOKE++ was used to predict gasification product distributions based on validated chemical kinetic models, while process simulation in Aspen Plus® was adopted to quantify the plant performance. Eventually, material and energy flows generated in Aspen Plus® were linked to the LCA software Bright-way 2.5 through a Python-based framework, enabling direct computation of environmental impacts. The approach was applied to three scenarios targeting hydrogen, hydrocarbons via Fischer-Tropsch synthesis, and methanol production from waste PE, considering a functional unit of 1 ton of waste PE processed in Italy. Comparative analysis with a Waste-to-Energy (WtE) plant showed that hydrocarbon and methanol production outperform WtE in terms of Global Warming Potential (GWP100) when heat and electricity recovery are considered. Potential improvements, such as renewable energy integration and advanced heat recovery, could further reduce the environmental footprint of gasification-based systems. This work exemplifies the potential of integrating process simulation with advanced LCA tools to assess and optimize sustainable waste management technologies. By leveraging the flexibility of open-source LCA tools, the proposed framework promotes the development of environmentally conscious process design.