Incorporating Environmental Perspective in Integrated Strategic-Tactical Economic Optimization Model of Biomass-to-Biofuel Supply Chain—A Real Case Study in Ethiopia

Several optimization models, which consider economic and environmental perspectives, have been developed recently to support the sustainable biomass-to-biofuel supply chain (BBSC) design. All of the economic-environmental optimization models rely on solving long-term planning problems with a conventional hierarchical approach, where tactical decisions are made based on the optimal strategic decisions from the strategic-level model, despite it arousing non-optimal solutions. Moreover, almost all of them have used non-monetary-based environmental indicators, which result in difficulties with clarity when comparing with economic objectives. Therefore, in this work, an effort is made to develop a more reliable planning strategy that offers optimal strategic and tactical decisions simultaneously and maximizes the economic and environmental benefits. Furthermore, the environmental performance of the BBSC has been assessed in terms of monetary value by adopting an ecocost approach after performing an LCA on the system. The integrated model is applied in the real biofuel sector of Ethiopia to optimize the country’s bioethanol and biodiesel supply chain over a 20-year horizon. Despite the abrupt rise in the model size, with it being a real countrywide case with many variables and large quantities of data, an alternative semi-heuristic method that offers a feasible solution to the multi-objective problem is provided.

Biodiesel Supply Chain Network Design Under Hybrid Uncertainties: A Novel Multi-objective Robust Fuzzy Stochastic Approach

In the biofuel supply chain, there may be various and hybrid uncertainties that, if ignored, can lead to inefficient network design. In this study, a multi-objective robust fuzzy stochastic programming (MORFSP) model is proposed for designing biodiesel supply chain network (BSCN) under different and hybrid uncertainties. This model simultaneously minimizes total cost of the BSCN and total environmental impacts of activities of the network. Fixed costs and environmental impact of opening facilities are described as fuzzy variables. Demands, supplies, other costs and environmental impacts are considered as fuzzy scenario based variables. The proposed MORFSP model considers different risks, including possibilistic variability and scenario variability related to economic and environmental objective functions, and unsatisfied demand costs. This model is applied in a real case study to design a BSCN in Iran. Waste cooking oil (WCO), and some non-edible plants like Salvia lerifolia (SL) and Jatropha Curcas L. (JCL) are considered as sources of producing biodiesel. The proposed approach used for designing a four-echelon, multi-period, and multi-product, of BSCN. The results show the effectiveness of the proposed model for designing the BSCN under hybrid uncertainties.