Advances in Key Technologies and Applications for Ship Carbon Emission Reduction

In alignment with the global net-zero emissions target by 2050, the International Maritime Organization (IMO) and its member states are advancing regulatory frameworks such as the Carbon Intensity Indicator (CII) and Energy Efficiency Existing Ship Index (EEXI) to reduce greenhouse gas emissions in maritime operations. These frameworks mandate a 40% reduction in carbon intensity by 2030 compared to 2008 levels, a crucial step toward the sector′s long-term decarbonization goals. Current research focuses on retrofitting existing fleets with energy-efficient propulsion systems, including waste-heat recovery technologies and hull optimization designs, which can reduce fuel consumption by 15%−20%. Simultaneously, the adoption of low-carbon fuels like liquefied natural gas (LNG) and green methanol is accelerating. This study evaluates the efficacy of maritime decarbonization policies and technologies, tracking the sector′s transition from high-carbon practices to zero-carbon operations. Key innovations include closed-loop carbon management systems achieving up to 80% onboard carbon capture, demonstrated in pilot projects integrating exhaust gas treatment with renewable energy sources. Sustainable decarbonization further depends on hybrid solutions that combine low-emission fossil fuels, renewable energy systems, and resilient carbon capture infrastructure, including port-based carbon dioxide storage hubs. Recent advancements have focused on optimizing vessel operations through propulsion upgrades and fuel flexibility, supported by compliance with the CII and EEXI frameworks. These policies incentivize energy efficiency and emissions transparency, seen in the widespread adoption of dual-fuel engines capable of switching between LNG and methanol. Lifecycle management of carbon sequestration infrastructure ensures long-term emissions reductions across the supply chain, from fuel production to end-use. By integrating energy-efficient retrofits such as air lubrication systems, fuel transition roadmaps blending LNG and methanol, and carbon capture solutions, the industry achieves cost-effective emission reductions while moving from fragmented measures to unified strategies. For example, digital twin modeling for hull design enables real-time vessel performance optimization, reducing drag by up to 10% in simulated environments. Additionally, ammonia-fueled engines offer promising zero-carbon propulsion for deep-sea vessels, though challenges related to fuel storage and safety protocols still need further standardization. Looking ahead, future advancements will prioritize holistic vessel optimization through renewable energy integration, such as wind-assisted propulsion. Resilient supply chains for alternative fuels, along with standardized carbon accounting frameworks, will guide the shipbuilding industry toward achieving IMO′s 2050 net-zero targets. For example, the EU′s inclusion of maritime emissions in its carbon market from 2024 incentivizes investment in green fuel production and carbon capture infrastructure. This integrated approach aligns with global decarbonization strategies, emphasizing the synergy between regulatory mandates-such as IMO′s revised GHG strategy-and technological breakthroughs in fuel flexibility, energy efficiency, and carbon management.