基於動態海況之船舶碳排及能耗數值模型開發

Abstract

為應對氣候變遷，航運業面臨減少能源浪費和溫室氣體排放的挑戰。為了實現節能減碳的目標，國際海事組織在2023年修訂的減少船舶溫室氣體排放戰略提出兩大要點分別為：基於目標船用燃料分階段降低溫室氣體強度的技術要點，及以海上溫室氣體排放定價機制為基礎的經濟要點。而本研究根據此兩項要點為基礎，透過建立計算船舶能耗的模型提供減少船舶溫室氣體排放的方法。 本研究旨在開發一種基於靜水阻力和波浪附加阻力的船舶能耗模型。該模型透過船舶阻力及推進效率之經驗公式與船舶水動力計算，能夠預測航程中船舶的能耗和二氧化碳排放，並推算出航程中的低能耗航速及碳稅。 本研究提出船舶能耗數值模型，以雙殼油輪KVLCC2及貨櫃輪KCS為案例，發展數值模型來模擬船舶的各種物理子系統，包括靜水阻力、波浪附加阻力、推進和引擎系統，並利用MATLAB-Simulink開發之模型進行航行模擬；利用Wasim計算任意波浪入射角及週期之波浪附加阻力，並建立於MATLAB-Simulink其資料庫，透過整合靜水阻力及波浪附加阻力，我們能夠快速計算船舶在不同海況下的能耗。 結果表明，本研究在MATLAB-Simulink中開發的船舶能耗模型透過與其他文獻的驗證可以針對給定航程產生合理的結果；在即時環境中，所需的計算量也相對較低。本研究以新加坡到臺灣之航線為例，輸入既有航程之預測海況，包含波浪週期、波浪入射角及波浪高度，計算航程之低能耗航速，並進行航程燃油消耗量及二氧化碳排放之比較，提供減少能源浪費和二氧化碳排放的解決方法，以本研究案例來說，船速的優化將可減少因阻力產生的能量消耗及二氧化碳排放約13%至20%，對於達到減少船舶溫室氣體排放戰略的目標具有實際的正向效益。

To tackling climate change, the shipping industry faces the challenge of reducing energy waste and greenhouse gas (GHG) emissions. In order to achieve the goal, the International Maritime Organization (IMO) revised strategy for reducing GHG emissions from ships in 2023 and proposed two major points, including a technical point to reduce GHG intensity in stages based on target marine fuels, and an economic point based on the maritime GHG emissions pricing mechanism. Based on these two points, the study provides methods to reduce ship GHG emissions by establishing a model to calculate ship energy consumption. The objective of the study is to develop a ship energy consumption model based on calm water resistance and wave added resistance. This model uses empirical formulas of ship resistance and propulsion efficiency and ship hydrodynamic calculations to predict the ship's energy consumption and carbon dioxide (CO2) emissions during a voyage, and calculate the low-energy consumption speeds and carbon tax during the voyage. The study proposed a numerical model that takes the double-hulled oil tanker, KVLCC2, and the container ship, KCS, as cases, a numerical model was developed to simulate various physical subsystems of a ship, including calm water resistance, wave added resistance, propulsion and engine systems. And the model developed by MATLAB-Simulink was used for navigation simulation. The model further uses Wasim to calculate the wave added resistance of any wave direction and period, and establishs them in the MATLAB-Simulink database. By integrating the calm water resistance and the wave added resistance, we can quickly evaluate the energy consumption of ships under different sea conditions. The results show that the ship energy consumption model developed in MATLAB-Simulink in the study can produce reasonable results for a given voyage through verification with other literature; the required computational effort is also relatively low to be used in a real-time environment. The study takes the route between Singapore and Taiwan as an example and inputs the sea conditions of the specified voyage to the numerical model, including wave period, wave direction and wave height. The model calculates the speed leading to low-energy consumption of the voyage, predicts the fuel consumption and CO2 emissions of the voyage, and provides solutions to reduce energy waste and CO2 emissions. Taking this study case as an example, optimizing ship speed will reduce energy consumption by resistance and CO2 emissions by about 13% to 20%. It has positive benefits for achieving the strategic goal of reducing ship GHG emissions.