A country-level Pareto-optimal palm waste utilisation network for economic and environmental sustainability

Abstract

Despite their enormous potential as biofuel for downstream industries, palm wastes are underutilised. Traditional palm waste disposal methods are ineffective and harmful to the environment. The augmented ε-constraint method is applied to optimise Malaysia's palm waste utilisation pathway in a multi-objective model, attempting to maximise profit while minimising greenhouse gas emissions. The net greenhouse gas emissions from the optimal palm waste utilisation pathway are compared with the baseline case to investigate the net greenhouse gas emissions reduce if the stakeholders utilise palm waste accordingly. There are eleven Pareto-optimal solutions generated from the model. The 5th Pareto-optimal solution (composting: 79.31%; anaerobic digestion: 10.05%; biomass combined heat and power: 9.47%; dried long fibre production: 0.42%; briquetting: 0.37%; pelletizing: 0.35%; carbonisation: 0.02%) satisfies both objective functions with a 0.75° of satisfaction. It generates 4.89 × 109 MYR/y of net profit and −1.62 × 107 tCO2-e/y net greenhouse gas emissions. The 1st, 2nd, 9th, 10th, and 11th Pareto-optimal solutions meet Malaysia's biomass renewable energy target. The results are sensitive to the market prices of pellets, DLF, and biomass-derived electricity. This study provides quantitative information for stakeholders to design an efficient palm waste utilisation strategy that is environmentally and economically feasible.