De-rating engines the first choice in meeting EEXI requirements

In November 2020, the IMO approved amendments to MARPOL Annex VI, introducing an Energy Efficiency Design Index for existing ships (EEXI).

Subject to adoption at MEPC 76 in June 2021, the requirements will enter into force in 2023. The EEXI will be applicable for all vessels above 400 GT falling under MARPOL Annex VI.

This means that Energy Efficiency Design Index (EEDI) limits would be implemented to existing ships and a rating mechanism to mandate improvements to the operational carbon efficiency of ships.

With only two years to go, shipowners are looking at the easiest and cost-efficient ways of meeting these requirements as they plan drydocks for their ships after 2023.

This was one of the key topics of today’s conference session titled Short-term solutions to pressing regulatory challenges, held as part of the Global Maritime Environmental Congress (GMEC), a premium event at SMM Fair in Hamburg.

The simplest way for the shipping community to make sure its tonnage meets the EEXI requirements is to de-rate their engines, one of the conclusions said.

De-rating an engine means lowering the vessel’s maximum speed, specified maximum continuous rating (MCR), and thereby optimizing the actual load point with the design load point.

As a result, a vessel can achieve higher efficiency by cutting fuel oil consumption.

According to the panel, despite the rise of LNG as fuel in the newbuildings sector, with gas accounting for almost 30 percent of the orderbook, it is not likely that LNG will be the option for retrofitting existing ships as this would be an extremely expensive choice.

“LNG is more of a mid-term measure. Basically, if you’re dealing with a newbuild today then LNG is a viable option and then you just need to decide on your operating profile. But, when you have an asset of 11 -12 or 15 years then you still have to comply with the EEXI requirements, in that case, you need to do the paperwork, assess where you are and the calculation of the EEXI follows the EEDI systematics. For those ships today, and if the gap is large, then engine power limitation is the first choice because it gives you the largest benefit,” said Rasmus Stute, Vice President – Area Business Development Manager at DNV GL – Maritime.

DNV GL remains a strong supporter of LNG as a bridging solution since it is a fuel with high energy content, fit for long-distance shipping.

“LNG is without any alternative, at least for the next one or two ship generations,” Stute added, explaining that the industry has come a long way when it comes to dealing with the methane slip.

Another reason for such a decision is that many solutions on the market like wind or propulsion systems using air bubble concepts offer a rather low carbon reduction improvements, the session has heard.

As a result, they are not considered to be an attractive investment as they don’t offer an attractive return on investments.

The first wave of future-proofing of vessels to meet stricter energy efficiency requirements will see around 100,000 ships that are currently in operation being retrofitted with different solutions, as explained by Marting Stopford, CEO of Clarksons Research.

The second wave will see the construction of new diesel ships or dual-fuel ships for quite a few years before the industry moves to the construction of gas, hybrid ships in the third wave, and finally, zero-carbon ships in the fourth wave.