New research exploring the potential impact of EEXI (The Energy Efficiency Index for Existing Ships) on the transportation capacity, total emissions and carbon intensity of the global bulker fleet has suggested that the new measure could lead to a 6.6% drop in vessel emissions, but only in certain circumstances.
Adopted by MARPOL in June 2021, EEXI measures and restricts CO2 emissions per transport work, purely considering the ship’s design parameters. Conducted by maritime software provider NAPA, the new study maps EEXI requirements and engine power limitation on to real-life operations, given that limiting engine power is expected to be one of the most common means of complying with EEXI.
The analysis included detailed weather data and records of real routes and speed profiles cross-referenced with the NAPA ship model database, which includes vessel-specific performance models, with the aim of comparing how the emissions from historical voyages might have been impacted had operators followed EEXI requirements.
The retro-optimisation study used real voyage data from 1500 bulkers over 12 months in 2019, examining the true operational profiles of the vessels in actual weather conditions while analysing how much the maximum engine power limitation would have impacted these operations.
The data shows that the engine power limitations required by vessels to comply with EEXI would only have come into effect at high-speed peaks, NAPA says. Therefore, for most of the year, if EEXI had been in effect, vessel operations would have remained largely similar. In addition, the speed reductions required by EEXI would have reduced the transportation capacity by an average of 2% for bulkers.
However, the impact on transportation capacity was strongly dependent on the year in which the vessel was built, ranging from under 2% for newer vessels and up to 6% for vessels built in 2012. This indicates that EEDI, which came into force more recently, helped align vessels towards the current standard.
The study also found that the implementation of EEXI would reduce CO2 emissions by an estimated 6.6% and carbon intensity by 4.6% on bulk carriers.
“While this is a good start, it shows the gap between what EEXI can achieve and how much more ground there is to make up. It shows why, at MEPC 77, to truly match the level of ambition that has come out of COP26, the IMO member states will need to prioritise efficiency,” said Teemu Manderbacka, Lead R&D Engineer at NAPA.
“We wanted to analyse the effect of EEXI on real-life operations, so we tried to answer the question, ‘what would have happened if EEXI was implemented in 2019?’. We discovered that it would be similar to limiting the top speeds of cars in Europe from 160kph to 130kph. For most users on most roads, it doesn’t really change anything; the only people it affects are those on the autobahn in Germany.”
“It does, however, demonstrate that EEXI can reduce carbon intensity and that the carbon savings outweigh the reductions in lost transport capacity. It’s one step on a much longer journey.”