Holistically Green and Sustainable Pathway Prioritisation for Chemical Process Plant Systems via a FAHP-TOPSIS Framework

Multi-criteria Decision Making (MCDM) could be the key towards truly holistically green sustainability, within the context of chemical process plants (CPPs). ASPEN Plus v12.0 was utilised for two representative CPP cases: isopropanol (IPA) via isopropyl acetate, and green ammonia (NH3) production. An integrated Fuzzy Analytic Hierarchy Process (FAHP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was modelled in MATLAB, to prioritise the holistically green and sustainable pathways. Life cycle assessments (LCAs) were employed to select the pathways, and the most suitable sub-criteria per four criteria: social, economic, environmental, and technical. In descending order of optimality, the pathways were ranked as follows for green NH3 and IPA, respectively: Hydropower (HPEA) > Wind Turbine (WGEA) > Biomass Gasification (BGEA)/Solar Photovoltaic (PVEA) > Nuclear High Temperature (NTEA), and Propylene Indirect Hydration (IAH) > Direct Propylene Hydration (PH) > Acetone Hydrogenation (AH). Sensitivity analysis evaluated the FAHP-TOPSIS framework to be overall robust. However, there are potential uncertainties within and/or among sub-criteria, particularly in the social dimension, due to software and data limitations. Future research would seek to integrate FAHP with VIKOR, and Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE-II).