Electric auxiliary propulsion for improved fuel efficiency and reduced emissions

Auxiliary drives can provide an alternative propulsion system for marine vessels giving the potential to achieve improved environmental performance during low-speed sailing. In this work, two case vessels were considered for analysis, a Roll-On–Roll-Off ship and a harbour tug boat. Actual sailing operational profiles were used as the basis for energy considerations to assess the potential for lower emissions. An energy-centric simulation model was built to estimate the emission of various pollutants, considering different machinery set-ups. Results have shown that savings are possible, especially for vessels which run on residual fuels, where auxiliary drives provide a way of exploiting the advantages of cleaner sources for manoeuvring instances.