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

Abstract

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.

Environmental economic analysis of speed reduction measure onboard container ships

“…Thus, derivation of a direct relationship between fuel consumption (FC) and main engine’s output power, which can be obtained using the basic equations of power, and fuel, as displayed in Eq. ( 1 ) (Elkafas and Shouman 2021 ): …”

“…In this way, the yearly fuel saving amount resulted from speed reduction measure (∆ F total ) estimated in t/year can be evaluated as displayed in Eq. ( 2 ) depending on the expected number of round trips per year (NT) and the amount of fuel saving (Elkafas and Shouman 2021 ). …”

“…The fourth strategy demonstrates the use of exhaust gas treatment technologies, such as filters for P.M, seawater scrubber system for SOx and selective catalytic reduction (SCR) for NOx emissions (Winnes et al 2020 ). The latest strategy represents the optimal operation of the ship, and one of those ways is to reach the best operational speed for the ship (Elkafas and Shouman 2021 ). Among the abovementioned strategies, the present paper will highlight the optimal operation of the ship, with respect to ship speed reduction; to achieve the target of both IMO and ship operators.…”

Local ship speed reduction effect on black carbon emissions measured at remote marine station

“…As the resistance of the vessel moving through the water is known to be the largest contributing factor for fuel consumption (Hollenbach, 1998), it is then natural to assume that restricting speeds would directly lead to a reduction in air emissions (Yau et al, 2012). However, the problem is not simple: restricting speed could lead to an increase in the need for carriage and therefore, to an increase in total emissions (Elkafas and Shouman, 2021;Tan et al, 2022). Local speed limits have been introduced in many areas for a variety of reasons.…”

An expressway traffic congestion measurement under the influence of service areas

“…To measure traffic congestion more accurately, existing studies proposed different measurements based on the causes of congestion [7,8] and the influences of congestion on operations [9] under different scenarios. These measurements can be divided into the following categories: 1) speed-based methods, such as speed reduction index [10,11], speed performance index [12,13]; 2) travel time-based method, for example, travel time reliability [13]; 3) delaybased methods, including delay rate [14], delay ratio [14]; 4) level of service, such as V/C [15].…”