Shipping decarbonization refers to the process of reducing and ultimately eliminating greenhouse gas (GHG) emissions from the global maritime transport sector. As international shipping currently accounts for nearly 3% of global CO₂ emissions, decarbonizing this sector is essential to achieving the goals of the Paris Agreement and building a climate-resilient global economy.
The pathway to decarbonization involves a combination of low- and zero-emission fuels, energy efficiency measures, digital optimization, carbon pricing, and global regulatory frameworks, particularly those established by the International Maritime Organization (IMO).
Why is shipping decarbonization important?
The shipping industry moves around 90% of global trade, making it essential for global commerce and economic development. However, most vessels run on heavy fuel oil (HFO), a fossil fuel that emits significant amounts of carbon dioxide (CO₂), nitrogen oxides (NOₓ), sulfur oxides (SOₓ), and particulate matter.
Without intervention, emissions from shipping are projected to rise due to growing trade volumes. Decarbonizing this sector is vital for:
- Meeting global climate targets and limiting temperature rise to 1.5°C.
- Improving air quality and public health, especially in coastal and port communities.
- Ensuring long-term regulatory and financial stability for maritime stakeholders.
Key Strategies for Decarbonizing Shipping
- Alternative Fuels
Transitioning from fossil fuels to low- or zero-carbon fuels is central to decarbonization:- Green ammonia and green methanol: Produced from renewable hydrogen and captured CO₂ or nitrogen.
- Hydrogen: Used in fuel cells or combustion, depending on vessel type.
- e-Fuels: Synthetic fuels generated from green hydrogen and CO₂.
- Biofuels: Advanced biofuels made from waste or non-food biomass, with lower lifecycle emissions.
- Energy Efficiency Technologies
Improving the energy performance of ships through:- Hull design optimization
- Air lubrication systems
- Waste heat recovery
- Battery hybridization
- Wind-assisted propulsion (e.g., rotor sails)
- Operational Measures
Adjusting ship operations to reduce fuel use:- Slow steaming (reducing cruising speed)
- Voyage planning and weather routing
- Just-in-time arrival to minimize idle time at ports
- Digitalization and Smart Shipping
Using real-time data, AI, and IoT tools to optimize fuel use, maintenance, and routing decisions. - Carbon Pricing and Market-Based Measures (MBMs)
Instruments like emissions trading schemes (ETS) or carbon taxes aim to internalize the environmental cost of emissions and incentivize cleaner technologies.
Regulatory Frameworks
Decarbonization is being guided by global and regional policies:
- IMO’s Revised GHG Strategy (2023): Sets the target of net-zero GHG emissions by or around 2050, with intermediate checkpoints in 2030 and 2040.
- Energy Efficiency Design Index (EEDI) and Carbon Intensity Indicator (CII): Mandatory IMO measures for new and existing ships.
- FuelEU Maritime: An EU regulation that mandates reductions in the GHG intensity of maritime fuels starting in 2025.
- EU Emissions Trading System (EU ETS): Includes shipping emissions from 2024, applying a carbon price to emissions from voyages to, from, and within the EU.
Challenges and Barriers
Despite growing momentum, shipping decarbonization faces several obstacles:
- Fuel availability: Most alternative fuels are not yet available at the required scale or price competitiveness.
- Infrastructure gaps: Ports and bunkering facilities must be upgraded to support new fuels.
- High upfront costs: Retrofitting ships or building new low-emission vessels is capital intensive.
- Fragmented regulation: Global alignment is needed to avoid competitive distortions and enforcement loopholes.
- Technology readiness: Some solutions, especially for long-distance and high-power ships, are still in development.
