Vessel Speed Reduction for Ocean-going Vessels

This page last reviewed September 9, 2014


Greenhouse Gas and Criteria Emission Benefits through Reduction of Vessel Speed at Sea

M. Yusuf Khan,†,‡ Harshit Agrawal,†,‡, Sindhuja Ranganathan,‡ William A. Welch,‡ J. Wayne Miller,†,‡ and David R. Cocker III*,†,‡

†Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California, Riverside, California 92521, United States
‡College of Engineering-Center for Environmental Research & Technology, University of California, Riverside, 1084 Columbia Avenue, Riverside, California 92507, United States

Reducing emissions from ocean-going vessels (OGVs) as they sail near populated areas is a widely recognized goal, and Vessel Speed Reduction (VSR) is one of several strategies that is being adopted by regulators and port authorities. The goal of this research was to measure the emission benefits associated with greenhouse gas and criteria pollutants by operating OGVs at reduced speed. Emissions were measured from one Panamax and one post-Panamax class container vessels as their vessel speed was reduced from cruise to 15 knots or below. VSR to 12 knots yielded carbon dioxide (CO2) and nitrogen oxides (NOx) emissions reductions (in kg/nautical mile (kg/nmi)) of approximately 61% and 56%, respectively, as compared to vessel cruise speed. The mass emission rate (kg/nmi) of PM2.5 was reduced by 69%with VSR to 12 knots alone and by ∼97% when coupled with the use of the marine gas oil (MGO) with 0.00065% sulfur content. Emissions data from vessels while operating at sea are scarce and measurements from this research demonstrated that tidal current is a significant parameter affecting emission factors (EFs) at lower engine loads.  Emissions factors at ≤20% loads calculated by methodology adopted by regulatory agencies were found to underestimate PM2.5 and NOx by 72% and 51%, respectively, when compared to EFs measured in this study. Total pollutant emitted (TPE) in the emission control area (ECA) was calculated, and emission benefits were estimated as the VSR zone increased from 24 to 200 nmi.  TPECO2 and TPEPM2.5  estimated for large container vessels showed benefits for CO2  (2−26%) and PM2.5  (4−57%) on reducing speeds from 15 to 12 knots, whereas TPECO2 and TPEPM2.5 for small and medium container vessels were similar at 15 and 12 knots.

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