Inge Norstad

Reducing fuel emissions by optimizing speed on shipping routes

Fuel consumption and emissions on a shipping route are typically a cubic function of speed. Given a shipping route consisting of a sequence of ports with a time window for the start of service, substantial savings can be achieved by optimizing the speed of each leg. This problem is cast as a non-linear continuous program, which can be solved by a non-linear programming solver. We propose an alternative solution methodology, in which the arrival times are discretized and the problem is solved as a shortest path problem on a directed acyclic graph. Extensive computational results confirm the superiority of the shortest path approach and the potential for fuel savings on shipping routes.

Analysis of an exact algorithm for the vessel speed optimization problem

Increased fuel costs together with environmental concerns have led shipping companies to consider the optimization of vessel speeds. Given a fixed sequence of port calls, each with a time window, and fuel cost as a convex function of vessel speed, we show that optimal speeds can be found in quadratic time.

Optimization, risk assessment and resilience in LNG transportation systems

Purpose – This paper aims to address how to systematically address vulnerability in a maritime transportation system using a formal vulnerability assessment approach, create quantitative measures of disruption risk and test the effect of mitigating measures. These quantitative data are prerequisites for cost efficiency calculations, and may be obtained without requiring excessive resources.Design/methodology/approach – Supply chain simulation using heuristics‐based planning tools offers an approach to quantify the impact of disruption scenarios and mitigating measures. This is used to enrich a risk‐based approach to maritime supply chain vulnerability assessment. Monte Carlo simulation is used to simulate a stochastic nature of disruptions.Findings – The exemplary assessment of a maritime liquefied natural gas (LNG) transportation system illustrates the potential for providing quantitative data about the cost of disruptions and the effects of mitigating measures, which are foundations for more precise cos...

Benchmark Suite for Industrial and Tramp Ship Routing and Scheduling Problems

Abstract This paper considers a class of cargo ship routing and scheduling problems from industrial and tramp shipping and presents a wide range of benchmark instances that have been created to represent realistic planning problems for various shipping segments. Initial results for the benchmark instances are provided both through exact and heuristic methods. Optimal solutions to smaller problem instances are provided by a commercial mixed-integer programming solver, and high-quality solutions to larger problem instances are provided by a state-of-the-art adaptive large neighborhood search heuristic. The provided benchmark instances, as well as an instance generator, intend to stimulate future development of solution algorithms for this important planning problem, and to provide a basis for modelling and solving various real-life problem extensions that go beyond what is included in the benchmark instances.

Risk-Based Design of Maritime Transport Systems

This chapter provides an approach to modelling and analysis of supply chain vulnerabilities due to physical and functional interdependencies in maritime transport systems. The results of the analysis are risk of supply breaches of the commodities transported by the system. The risk analysis is set into the context of development of infrastructure for maritime transport systems, where industrial shipping systems are used as an example. The risk analysis is used to balance the scale of the system’s infrastructure against an assessment of the requirements and vulnerabilities of the system’s dependents. The maritime transport system is here regarded as a critical infrastructure for supply of required commodities into a region.

Risk of Supply Breaches in Maritime LNG Transport

This chapter presents a case study based on the approach described in Chap. 11. The case is a maritime transport system for distribution of liquefied natural gas, liquefied natural gas (LNG), from a producer to a set of receiving terminals in different geographical regions. The objective is to provide an example of modelling and analysis of interdependency risk in maritime transport infrastructure and potential-related vulnerabilities, where the transport system is part of a tightly coupled energy supply system. The main focus is given to the interdependency risk assessment of supply breaches of LNG based on detailed inventory routing–based simulations. Interdependency modelling and assessment based on the cascade model presented in Chap. 4 is discussed at the end.