What are GHG reduction measures?

Answer

GHG reduction measures are the measures used to reduce fuel consumption, improve energy efficiency, and shift shipping toward low/zero-GHG energy sources.

These improve the inherent efficiency of the ship:

• EEDI for new ships.
• EEXI for existing ships.
• Engine or shaft power limitation — EPL / ShaPoLi.
• Efficient hull form and reduced resistance.
• High-efficiency propellers, ducts, fins, PBCF and other energy-saving devices.
• Waste heat recovery.
• Efficient turbochargers and engine tuning.
• Hybrid propulsion, batteries and fuel cells.
• Wind-assisted propulsion and solar auxiliary power.
• Air lubrication systems.

EEXI has been mandatory for applicable existing ships since 1 January 2023. 

These reduce emissions by operating the existing ship more efficiently:

• CII monitoring and improvement.
• SEEMP Parts I, II and III.
• Speed / RPM optimization and slow steaming.
• Weather routing and optimum voyage planning.
• Trim and ballast optimization.
• Just-in-time arrival.
• Hull and propeller cleaning.
• Proper engine maintenance and combustion optimization.
• Efficient generator loading and auxiliary machinery operation.
• Reduce unnecessary electrical and steam loads.

For ships of 5,000 GT and above, annual CII reporting and rating applies; ships are rated A–E, and an E rating or D for three consecutive years requires corrective action. 

The major long-term reduction will come from replacing conventional fossil fuels with fuels having lower life-cycle GHG intensity, for example:

• LNG as a transitional fuel, subject to control of methane slip.
• Sustainable biofuels.
• Green methanol.
• Green ammonia.
• Hydrogen.
• Synthetic/e-fuels produced using renewable energy.
• Renewable electricity, batteries and fuel cells.

The important concept is increasingly well-to-wake GHG emissions, not merely CO₂ emitted at the exhaust.

IMO also intends to use regulatory and economic incentives to accelerate the energy transition. The proposed IMO Net-Zero Framework contains:

• a marine fuel GHG-intensity standard, and
• a GHG emissions pricing mechanism.