ABSTRACT
Bioethanol, a promising biofuel gasoline additive, was recently produced by a new technology using acetic acid derived from organic waste. This study develops a multiobjective mathematical model with two competing minimization objectives: economy and environmental impact. The formulation is based on a mixed integer linear programming approach. The configuration of the organic-waste (OW)-based bioethanol supply chain network is optimized in terms of the number and locations of bioethanol refineries. The flows of acetic acid and bioethanol between the geographical nodes must meet the bioethanol regional demand. The model is validated in three real-scenario case studies with different OW utilization rates (30%, 50%, and 70%) in South Korea in the near future (2030). The multiobjective problem is solved using the ε-constraint method and the selected Pareto solutions balance the trade-off between the economic and environmental objectives. At the "best-choice" solution points, increasing the OW utilization rate from 30% to 70% decreased the total annual cost from 904.2 to 707.3 million $/yr and the total greenhouse emissions from 1087.2 to -15.7 CO2 equiv./yr.
Subject(s)
Waste Management , Waste Management/methods , Environment , Models, Theoretical , Republic of KoreaABSTRACT
An integrated optimization model for an organic-waste-derived butyric acid-to-butanol supply-chain network (BABSCN) is proposed to minimize the total network cost by simultaneously optimizing both strategic biodiesel production and waste management planning decisions. This model is useful for ensuring effective organic-waste provision for large-scale biodiesel production and waste management. The proposed mixed-integer linear-programming model optimizes the activities ranging from organic-waste preprocessing to butyric acid (BA), transportation of BA to biorefinery, butanol (BuOH) production and mixing with diesel to the distribution of biodiesel. This model is useful for forecasting organic-waste management biodiesel supply chains in South Korea in 2030. The case study results show that a total network cost of $US 3.16/gallon of B3 contains 3% BuOH from organic waste products combined with diesel. The biorefinery-related cost accounts for 98.3% of the total network cost, followed by the organic waste procurement cost (1.1%) and biodiesel distribution cost (0.6%). A scenario-based analysis shows that a 7%-BuOH increase in biodiesel increases the total network cost by 18.8%.