Multi-objective optimal design for integrated palm oil mill complex with consideration of effluent elimination

Abstract

To reduce greenhouse gas (GHG) impact while sustaining palm oil mill (POM) profitability, Malaysia has recognised POME-derived biogas as a renewable energy. Biogas utilisation for on-site fuel replacement and grid electricity contribution is encouraged by government schemes such as Feed-in-tariff (FiT). Nevertheless, adoption rate of biogas facility is still low among Malaysian POMs. An integrated palm-oil based complex (POBC) was proposed for GHG mitigation by integrating POM and refinery processes while addressing sustainability concerns. This study presented a multi-objective optimisation model-based approach to aid POBC planning at maximised economic potential and net energy, while minimising its GHG emission, water footprint (WFP) and land footprint (LFP) for environment protection. Trade-offs between biogas recovery and POME elimination strategies were considered. The developed fuzzy model was applied to case study and analysed under different multi-objective scenarios. In comparison with baseline study, the economic potential of sustainable POBC increase by 6.7% at USD 39.31 × 106 with 88%, 74% and 91% improvements in GHG footprint, WFP and LFP by compromising 76% net energy. Effect of FiT revenue towards POBC synthesis was investigated. Pareto front was generated to verify the fuzzy results and visualise the relationship between objective functions. The optimisation model and optimal results shall provide input to Malaysian POMs on the sustainability benefits of POBC.