A mathematical model for liquid natural gas supply chain optimization with consideration of middle tankers

Energy plays an important role in production and service systems. Among energies, in today’s world, natural gas has become as one of the effective ones. The optimal relation between different echelons of chains and goods transfers is among important challenges of supply chains. Maritime transportation and cargo ships routing is one of the common methods for freight transportation in fossil fuels supply chain such as gas. In this regard, a mathematical model is presented for a three-echelon supply chain consisting of origin and destination of intermediate tankers. In order to design the optimum routes in a LNG supply chain, a transportation system is considered with intermediate tankers Also, in this model the optimal values of transported gases to tankers and destinations are determined so as to minimize storage cost while satisfying demands.
Since the proposed model is NP-hard, Simulated Annealing and Differential Evolution algorithms are employed to solve the model. To demonstrate the efficiency of the proposed algorithms, the results are compared with the results of GAMS software for small-size problems. Then, the two meta-heuristics are compared for large-sized problems. The results show that DE obtains better solution in reasonable times.