Microscopic Approach to Evaluate Energy Consumption and Emissions from Ships: Application to Measures Assessment

Maritime transport plays a central role in the debate about the sustainability of the transport sector. Analyses suggest that air emissions from shipping account for a significant portion of total emissions, affect air quality, and contribute to climate change and human health problems. The existing trend suggests that the situation will worsen. These results, though affected by obvious uncertainties, highlight the urgent need to take action. Harmful environmental impacts are controlled primarily through legislation prohibiting the use of certain substances, setting limits on emissions, and enforcing certain technical standards. However, the basis for designing effective policy instruments to abate air emissions is finding reliable estimates of those emissions. For the shipping sector, a debate continues about the most appropriate way to achieve its air emissions estimate. This paper contributes to this debate by proposing a new methodology that applies some of the available theories from the naval design scientific field to derive a microscopic analytical formulation of the energy produced and consumed by a ship during its trips. The methodology proposed is applied to evaluations of potential savings in energy and emissions by adjusting the speed–acceleration profile of ships in port. Results achieved confirm the power of the methodology and open its application to other case studies. They also highlight an aspect usually neglected in the literature: the impact of ships' activities in port on the environment. The simple exercises performed show clearly the relevance of the issue. They are also able to show that better management of ships' movements in port may produce significant environmental benefits.