評估船舶降速對碳排放效率之研究：以海岬型散裝現成船降速為例

Evaluating the Impact of Ship Speed Reduction on Carbon Emission Efficiency: A Case Study of Existing Capesize Bulk Vessels

基於國際海事組織（IMO）於2023年1月1日強制執行「現成船能源效率指標（EEXI）」及「營運碳強度指標（CII）」規範現成船舶的能源效率標準，本研究使用模擬評估模型和海岬型現成散裝貨船的數據來評估降低航速對營業毛利的衝擊以及減少二氧化碳排放的效率。研究結果如下：（1）選擇降低航速是現成船低成本和高效率節能減碳的重要策略。（2）船舶選擇經濟減速可以減少碳排放量，減少經營毛利損失，亦會降低船舶運輸能力。因此，為滿足IMO對於EEXI和CII之要求，船舶營運者應根據市場現況來調整最佳的船舶經濟航速，除了有助於船舶營運燃油成本下降，更有利於航運公司的永續經營。

Based on the regulations of the Energy Efficiency Existing Ship Index (EEXI) and the Carbon Intensity Indicator (CII) launched by the International Maritime Organization (IMO) on January 1, 2023, this study conducts a simulation evaluation model to assess the impact of gross operating profit and the efficiency of CO2 emission reductions through speed reduction, using data collected from existing Capesize Bulk Vessels. The findings of the study are twofold. First, the choice of speed reduction, optimal fleet management, and proper hull maintenance is a cost-effective strategy for reducing carbon emissions in existing ships. Second, selecting an economical speed for vessels can reduce carbon emissions, minimize operational profit loss, and lower the shipping capacity of the vessels. Therefore, in order to meet the IMO requirements for EEXI and CII, ship operators should adjust the optimal economic speed of their vessels based on market conditions. This approach not only helps reduce fuel costs for ship operations but also contributes to the sustainable operation of shipping companies.