Real data based comparative emission analysis of slow steaming for a tanker ship

Decarbonization has become a central priority in the maritime industry, driving the adoption of operational measures aimed at mitigating fuel consumption and greenhouse gas (GHG) emissions. Among these measures, slow steaming has emerged as a highly viable strategy due to its low implementation cost and immediate operational impact. This study presents an empirical, comparative emission analysis of normal sailing versus slow steaming for a crude oil tanker. The analysis leverages high-fidelity operational voyage data collected under identical route and similar environmental conditions. Results indicate that an average speed reduction of 15% yields approximately a 7% decrease in fuel consumption, CO₂ emissions, and SO_x emissions, alongside a quantifiable improvement in the Energy Efficiency Operational Indicator (EEOI). The findings confirm that slow steaming constitutes a highly effective operational decarbonisation lever, providing substantial environmental and economic benefits without necessitating capital-intensive technological retrofits.