A rolling horizon heuristic for creating a liquefied natural gas annual delivery program

In this paper a maritime inventory routing problem for one of the world's largest producers of liquefied natural gas (LNG) is presented. The producer is responsible for the LNG inventories at the liquefaction plant, the loading port with a limited number of berths, and the routing and scheduling of a heterogeneous fleet of LNG ships. In addition, the producer has to fulfill a set of long-term contracts to customers all around the world. The goal is to create an annual delivery program (ADP) to fulfill the long-term contracts at minimum cost, while maximizing revenue from selling LNG in the spot market. An ADP is a complete schedule of every ship's sailing plan for the coming year. A mixed integer programming (MIP) formulation of the ADP planning problem is presented, and it is based on a priori generation of all possible scheduled voyages within the planning horizon. Due to the size and complexity of the problem, a rolling horizon heuristic (RHH) is proposed. The RHH solves the problem by iteratively solving sub-problems with shorter planning horizons. The RHH finds solutions to the problem within a reasonable amount of time, and creates very good ADPs according to the problem owner. (C) 2010 Elsevier Ltd. All rights reserved.