A THIRD of all greenhouse gas emissions linked to shipping engaged in oceangoing cargo trades are the result of just 2,000 vessels — all of them containerships, according to a new academic study.

It found that boxships also accounted for “the vast majority” of the 5,000 most energy-intensive ships that collectively cause about 53% of the total GHG emissions.

The research, from the Laboratory for Maritime Transport of the National Technical University of Athens, considered the world fleet of dry bulk carriers, tankers, containerships and liquid petroleum gas carriers above 10,000 dwt, numbering more than 24,000 vessels.

While data gathering on actual emissions in operation is the goal of the EU Monitoring, Reporting, Verification process and International Maritime Organization Data Collection System, the university’s ‘quantitative analysis’ set out to provide a carbon profile of the global fleet through projections based on already available design and technical characteristics.

As with the IMO’s Energy Efficiency Index, the study sought to measure efficiency by calculating emissions per unit of transport work.

Larger ships generally produced higher emissions, but the larger cargo carrying capacity was factored in to capture economies of scale.

The results showed bulkers were the “optimum performers,” achieving a design efficiency almost three times higher than containerships.

Even the least efficient class of bulk carrier, the handymaxes, performed better than any class of containerships including post-panamaxes.

Tankers also outperformed container vessels with 2.5 times less the carbon intensity, though this was said to be primarily due to the dominant position of very large crude carriers.

LPG carriers, which accounted for less than 1.7% of emissions, were 50% more efficient than boxships.

With only 20% of the number of vessels and 18.4% of the capacity, containerships nevertheless produced a huge 38% of all emissions, the study projected.

This was ahead of the 35% of emissions caused by bulkers, although they represented half the total surveyed fleet in number of ships and 47% of all capacity.

Destabilising shipping

Dimitrios Lyridis, associate professor of maritime transport at the university, said ambitious IMO targets for reduction of emissions by 2030 and 2050 could prove “potentially destabilising” for shipping, the “most environmentally friendly” mode of transport for global trade.

“Such a development should be avoided and this means that research and analysis of the measures that can achieve these objectives should be intensified so as to ensure the sustainability of the shipping industry,” he said in an introduction to the study.

Bulk shipping sectors offered much less room for improvement than did containerships in terms of energy efficiency and carbon profile, the study stated.

The researchers argued that it is imperative to start the decarbonisation effort as early as possible and the analysis offered supporting data to determine where to focus efforts.

The study suggested “targeted interventions in ports and trades where it matters the most” in terms of volumes of GHG produced.

“For example, east to west containership corridors could become low-carbon corridors based, for example, on a limited number of supply points of biofuel or other carbon neutral fuels,” it said.

Scale of port operations, with access for larger vessels, should be “high on the agenda”.

But, as alternative fuels generally and shore-side infrastructure might take longer to establish, the study concluded that focusing on ‘low-hanging fruits’ related to size and speed was “imperative”.

The study also offered a snapshot of the fleet’s energy efficiency by country of management, flag, country of build and even by class society.

Norway, with only 32 containerships included in the survey, and Japan and Greece, both strong in bulkers and tankers, were “practically equal” as the top three fleet management domiciles in terms of emissions performance.

Greece also emerged as “the most environmentally friendly” of the major flags in terms of the ratio of emissions to dwt.

In Europe, Germany, Portugal and Denmark had the most carbon-intensive fleets, largely due to the structure of their fleets and a dominant presence of containerships.

The NTUA’s emissions intensity index quantified CO2 emissions for each vessel per deadweight ton and nautical mile, based on key factors including main engine power, service speed and the vessel’s age group.