Thermochemical Power Group (TPG), DIME, University of Genoa, Via Montallegro 1, 16145, Genoa, Italy.
Department of Naval Architecture and Marine Engineering, Faculty of Engineering, Alexandria University, 21544, Alexandria, Egypt.
Environ Sci Pollut Res Int. 2023 May;30(21):59645-59659. doi: 10.1007/s11356-023-26745-4. Epub 2023 Apr 4.
The International Maritime Organization (IMO) has concerned significant care to the reduction of ship emissions and improvement of energy efficiency through operational measures. One of those measures is ship speed reduction, which is classified as a short-term measure; in which the speed is reduced below its designed value. The present paper aims at evaluating the potential energy efficiency, and environmental and economic benefits because of applying speed reduction measures. The research methodology depends on establishing a simple mathematical model for technical, environmental, and economical aspects because of this concept. As a case study, container ships from different categories in a range of 2500-15,000 twenty-foot equivalent units (TEU) are investigated. The results show that a 2500 TEU ship can comply with the energy efficiency existing ship index (EEXI) by reducing the service speed to 19 knots. While for the bigger ships, the service speed must be 21.5 knots or below. Furthermore, the operational carbon intensity indicator (CII) has been evaluated for the case studies and found that the CII rating will keep its score between A and C levels if the service speed is equal to or below 19.5 knots. Moreover, the annual profit margin of the ship will be calculated based on applying speed reduction measures. Based on the economical results, the annual profit margin value, and its corresponding optimum speed change with the size of the vessel and the applicable status of carbon taxes.
国际海事组织（IMO）通过运营措施，非常关注船舶排放的减少和能源效率的提高。其中一项措施是减速，这被归类为短期措施；即降低船舶速度至低于其设计值。本文旨在评估因减速措施而带来的潜在节能、环保和经济效益。研究方法依赖于建立一个简单的数学模型，用于技术、环境和经济方面的概念。作为一个案例研究，研究了不同类别、载箱量在 2500-15000 标准箱（TEU）范围内的集装箱船。结果表明，2500TEU 船可以通过将服务速度降低到 19 节来满足能效现有船舶指数（EEXI）。而对于更大的船舶，服务速度必须低于 21.5 节。此外，还评估了案例研究中的营运碳强度指标（CII），发现如果服务速度等于或低于 19.5 节，CII 评级将保持在 A 级和 C 级之间。此外，还将根据减速措施的应用计算船舶的年利润率。基于经济结果，年利润率及其对应的最佳速度随着船舶的大小和碳税的适用情况而变化。
