Sustainable strategies to reduce GHG emissions for shipping

The International Convention for the Prevention of Pollution from Ships (MARPOL) is the leading international agreement to prevent maritime environment pollution caused by ships when operating or because of weather or accidental factors.

Sustainable strategies to reduce GHG emissions for shipping
Photo by Chelsea on Unsplash

The International Maritime Organization (IMO) is a specialised agency of the United Nations, promoting cooperation among States and the Transport industry to upgrade maritime safety and prevent marine pollution.

It is estimated that the emission of pollutants, such as greenhouse gases, caused by the combustion of hydrocarbons derived from petroleum is equivalent to 1.7% of the global total, including passenger and cargo ships. 

The Environmental Sustainability Strategy reduces Greenhouse Gas Emissions (GHE) from shipping and sets strategic objectives; its primary purpose is to reduce annual GHG emissions from international cargo by 2050 and develop mechanisms and workable alternatives to cope with GHG emissions shipping.

Since the strategy’s adoption, IMO has approved a Programme of Follow-up Actions to the Initial Strategy until 2023 and has made significant progress in considering and implementing some of the short-term GHG reduction measures included in the candidate list. The IMO Member States have committed to review the strategy by 2023.

A fundamental part of this initiative foresees a reduction in carbon generation from international maritime transports to reduce by at least 40% CO2 tons emissions generated by ships throughout international waters by 2030, continuing efforts towards 70% by 2050, taking as a baseline what was caused by the shipping operations during 2008.

The initial GHE strategy includes several short-medium- and long-term measures based on mandatory energy efficiency requirements already adopted by many ships, such as safety, regulations, prices, infrastructure availability, GHG emissions from the life cycle, supply chain limitations, obstacles to adoption. Decarbonising shipping will require low- or zero-carbon fuels.

It is vital to single out priority areas to develop guidelines that pinpoint sustainability criteria, appropriate fuel certification schemes and approaches for IMO’s periodic review of emission values.

These must be mandatory measures under Annex VI of the MARPOL Convention. To this end, members designed an energy efficiency index achieved from existing ships (EEXI). It should be calculated for 400 gigatons or more vessels, following different values established according to ship types and size categories. It indicates the energy efficiency of the ship compared to a baseline.

Ships are required to comply with a specific Existing Vessel Energy Efficiency Index (EEXI), which is based on a needed reduction factor (expressed as a percentage relative to the EEDI baseline). A boat can improve its rating through various measures, such as cleaning the hull to reduce drag, speed optimisation; installation of energy-saving light bulbs; installation of extrasolar/wind energy for accommodation services.

In simple terms, the short-term measure aims to achieve the carbon intensity reduction targets of the IMO initial GHG strategy. It is achieved by instructing all ships to calculate their Existing Ship Energy Efficiency Index (EEXI) and establishing their annual operational carbon intensity indicator (IIC) and IIC classification. In other words, ships get a ranking for energy efficiency (A, B, C, D, E, where A is the best). A boat that runs on a low-carbon fuel gets a higher rating than one that runs on fossil fuel.

Finally, it should be noted that IMO work on climate change stretches out beyond maritime transport. As the secretariat of the London Convention and the London Protocol, IMO regulates carbon capture and storage (CCS) below the seabed to mitigate the impact of rising concentrations of carbon dioxide CO2 in the atmosphere and ocean fertilisation and other marine geoengineering activities. CCS is a technology that aims at permanent isolation and underground storage (sequestration) of CO2.

Where would you like to be in the ranking for energy efficiency?

Dave Food

M: +44 7775 861863


Photo by Chelsea on Unsplash

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