Kazuo Hiekata

The International Maritime Organization (IMO) is pursuing reductions in greenhouse gas (GHG) emissions from international maritime transport. This paper presents a comprehensive review of simulation studies on IMO’s GHG measures, summarizing their simulation models and key components used. Our analysis reveals that these studies frequently rely on diverse assumptions that are often insufficiently documented, making it challenging to compare simulation results across studies. To address this critical issue, we propose a harmonized framework for maritime simulation models based on the review and findings. This framework provides structured variables and normalized units across domains, including demand, port operations, vessel characteristics, and fuel types, which the reviewed articles often assumed. The proposed framework is validated by an application example showing comparable tables of assumptions adopted by two different simulation studies. We anticipate that this framework will enable researchers to clearly present structured assumptions in their manuscripts, thereby enhancing readers’ understanding of assumptions and facilitating more efficient comparisons of simulation results across the field.

This study explored how the GHG fuel standard (GFS) regulation affects international shipping quantitatively by simulating future fleet transformation, fuel consumption, and well-to-wake GHG emissions based on an inputted GHG fuel intensity pathway and scenario of transportation demand, fuel availability and costs, and technology availability. The method comprisesthree steps: calculating the amount of scrapped and built ships, allocating fuel type and mix, and calculating fuel consumption. We simulated how the regulation changes fleet composition and the mix of fuel consumption. From the perspective of feasibility and alternative fuels’ availability, some meaningful insights to implement the GFS regulation were delivered.

The maritime industry is trying to utilize new technology for enhancing its competitiveness to overcome today’s severe economic situation, and some interact effects, or potentially emergent effects, will emerge during the introduction of these technologies. In this study, various simulations that relate to marine logistics and shipping were performed. By contrast, a detailed method that can reproduce emergent effects is required to some extent. This study utilized a Monte Carlo simulation for uncertainties, such as market and failure uncertainties. To evaluate and explore the emergent effect correctly and accurately when multiple technologies are introduced, an evaluation methodology was developed, which can evaluate the interact effect from the perspective of profit improvement and CO₂ reduction during the transportation period. As a case study, decision making for introducing 28 technology combinations to the maritime industry was conducted, and the utility of the proposed methodology was assessed.