Synthesis of sustainable circular economy in palm oil industry using graph-theoretic method

Huge generation of oil palm biomass has stimulated the development of biorefineries for synthesis of bioproducts. By targeting the palm oil industry and the biorefineries as the consumers of these products, a sustainable circular economy can be created by recycling the biomass wastes to the said consumers. To evaluate the techno-economic feasibility of the sustainable circular economy, a mathematical model demonstrating the biomass network with consideration of recycling is developed in this work. Besides, Process Graph (P-graph) is incorporated to perform the combinatorial optimization of the biomass network, which targets three common resources: fertilizer, steam, and electricity for regeneration and recycling. Although the result shows that the linear economy model is preferred in terms of profitability, the circular economy model shows potential in reducing 39.292% of the imported steam and 13.469% of the imported electricity, while being 0.642% lower in terms of the gross profit. Three scenarios are then proposed to identify the potential bottleneck that can hinder the implementation of the sustainable circular economy approach, with the aid of sensitivity analysis. This work is expected to benefit the biomass-based industry sectors and the policymakers on future development and transition to the sustainable circular economy.