Long-Term Potential to Reduce Emissions from International Shipping by Adoption of Best Energy-Efficiency Practices

Maritime shipping is highly fuel-efficient, but its sheer volume and rapid growth make it a major source of carbon emissions. Industry and governments seek to reduce the energy use and carbon footprint of shipping. Yet the reasons for the variation in shipping efficiency observed in the world fleet's embrace of best technical and operational practices to increase efficiency remain unexplained. The research reported in this paper offers a novel analysis that connected 2011 in-use fleet characteristics, first-ever global satellite data on ship movement, and technical literature on ship efficiency technology to assess the long-term prospects of increased shipping efficiency. This study also investigated how each ship characteristic influenced the efficiency of the shipping fleet. A ship stock turnover model was developed to track technical and operational efficiency practices in ships independently. The findings indicated that industry-leading ships were about twice as efficient as industry laggards across major ship types. If the available technical and in-use practices of the low-carbon industry leaders of today were fully embraced, the potential would exist to reduce carbon dioxide in absolute terms by more than 300 million metric tonnes by 2040, even while business-as-usual freight movement doubled. On the basis of the data in this assessment, the potential exists to develop a tool for shippers to quantify, evaluate, and compare their supply chain carbon footprints in a manner that does not rely on more aggregated fleet-average simplifications. The methodology, data, and findings of this study should benefit industry as it looks for ways to reduce energy consumption; researchers, who are examining ship operation; and policy makers, who want to curb the climate impact of international shipping.