Maritime software services provider Napa has released preliminary results of research showing engine power limitations required by the Energy Efficiency Index for Existing Ships (EEXI) would only come into effect for bulkers at high-speed peaks.

Its retro-optimisation study used real voyage data from 1,500 vessels over 12 months in 2019 to explore the potential effect of EEXI on the transport capacity, emissions and carbon intensity of the global bulker fleet.

"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," said the Finnish analyst.

"For most of the year, if EEXI had been in effect, vessel operations would have remained largely similar."

Adopted in June 2021 by the International Mari­time Organization, EEXI measures aim to restrict CO2 emissions by considering a ship's design parameters, with one of the most common means of complying likely to be through limiting engine power.

The study was unique, the firm said, as it mapped EEXI requirements and engine power limitation on to real-life operations, including detailed weather data and records of real routes and speed profiles, cross-referenced with the Napa ship model database, which has vessel-specific performance models for the global fleet.

True operational profiles of vessels in actual weather conditions were analysed to discover how much maximum engine power limitation would affect these operations.

Ossi Mettala. Photo: NAPA

Speed reductions required by EEXI would have reduced the bulker fleet's transportation capacity by an average of 2%, but the impact was heavier on older vessels. It ranged from less than 2% for newer vessels and up to 6% for vessels built in 2012.

The study also showed that implementation of EEXI would reduce CO2 emissions by an estimated 6.6% and carbon intensity by 4.6% on bulk carriers.

Teemu Manderbacka, lead R&D engineer at Napa, said the impact of EEXI would be similar to reducing the top speeds for cars in Europe from 160km per hour to 130km/h.

"For most users on most roads, it doesn't really change anything; the only people it affects are those on the autobahn in Germany."

Manderbacka added that while EEXI has made a good start, there is much more ground to make up and IMO member states will need to prioritise efficiency at this week's Mari­time Environmen­tal Pro­tec­tion Committee — MEPC77 — meeting.

"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," he said.

Napa senior customer success manager Ossi Mettala said it was important to simulate the regulation with real life operations "to get an accurate picture of just how far we have to go to reach the IMO's targets — or the more ambitious targets of net zero by 2050".

The tools used would enable vessels to operate more efficiently and provide greater insight into misaligned incentives and practices — such as rushing to port just to wait, he said.