Assessment of Energy Efficiency and Ship Emissions from Speed Reduction Measures on a Medium Sized Container Ship

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A G Elkafas
M R Shouman


Greenhouse gases and other emissions from vessels and related activities in maritime trade have caused significant environmental impacts especially global warming of the atmosphere. Consequently, the International Maritime Organization (IMO) concern significant care to the reduction of ship emissions and improvement of energy efficiency through operational and technical measures. The proposed short-term measure is ship speed reduction in which the ship speed is reduced below its designed value. Therefore, the present paper aims at evaluating the potential energy efficiency and environmental benefits from using speed reduction measure through energy efficiency design index (EEDI), energy efficiency operational indicator (EEOI) and ship emissions calculation models as recommended from IMO. As a case study, a medium sized Container Ship is investigated. The results show that, reducing ship speed by 12.6% will reduce CO2 emissions by about 36%. Moreover, the attained EEDI value will be improved by 31.7% and comply with not only the current IMO requirements but also with the future ones. Additionally, reducing ship speed by 12.6% will reduce EEOI value from its value at design speed by 26.5%. Furthermore, it is noticed that SOx emission will comply with IMO 2020 limit if ship speed is reduced by 6.8% and above.

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