Decarbonisation and retrofitting tanker main engines

A key point raised during the discussion was the challenges faced by tanker owners in adhering to emissions regulations due to conventional two-stroke engines. In this context, Wärtsilä specialises in retrofit solutions to mitigate these challenges.

To provide tanker owners with tailored retrofitting strategies, Mr Lamaris proposed a case-by-case approach, considering factors such as the age of the vessels and drydock constraints. By aligning the retrofit plans with the future goals and strategies of the tanker owners, Lamaris emphasised the importance of variable investment targets. This approach ensures the retrofitting process is optimised, accounting for the individual characteristics of each fleet.

The utilisation of ammonia as a retrofit fuel was also discussed with Mr Lamaris drawing attention to the challenges associated with handling ammonia as both a cargo and a fuel, which are very different. He provided insights into an ongoing project in which a vessel is being converted to burn ammonia. The project aims to assess the feasibility and viability of using ammonia as a retrofit fuel. Although concrete results are yet to be obtained, this initiative signifies an important step towards exploring alternative fuel options and reducing environmental impact.

Mr Lamaris gave some insights into an alternative and promising long-term solution, “The basic idea is to take out the two-stroke main engine or replace it with not one, but two or three, four-stroke engines,” he said. The replacement four-stroke engines might individually be capable of utilising LNG or methanol in dual-fuel mode, and operate in a hybrid mode in conjunction with batteries.

This transition offers increased efficiency and flexibility in tanker operations but he noted further research and development are required to validate and implement these solutions effectively.

But the potential is there to have a single engine replaced with a multiple engine set up with a final electric drive, allowing a much wider range of propulsion thrust generated by a wider range of fuels, throughout the different stages of the voyage. This set-up is beginning to find interest within the container ship sector.

The tanker sector has produced a different reaction, with owners reporting that as the charterer pays for the fuel (in certain contracts) then there is less impetus to save fuel. But all the shipping sectors are governed by shipping cycles outside their control. While in the current phase of the cycle, the emphasis is on lower emissions and fuel savings, in another phase, higher freights and earnings may be available to those vessels that can steam faster and produce more voyages. Having access to a wider, less restricted speed range, is one rationale for focusing on future proofing earnings.

Another consideration, noted Mr Lamaris, was the increasing efficiency of four-stroke engines, which is now laying aside the accepted wisdom that the two-stroke engine burns less fuel per gramme of fuel.

On the financial side, extending the life of a tanker through engine retrofit installation will also extend the period over which a loan can be amortised, allowing the vessel to extend across shipping cycles.

Therefore, retrofit solutions, as exemplified by the successful project discussed above by Mr Lamaris, are not restricted to retrofit installation of better, but conventional components, but the potential to not only ensure compliance but also improve vessel efficiency and reduce fuel consumption. The case-specific approach advocated by Mr Lamaris emphasises the importance of tailoring retrofit plans to account for the unique characteristics and constraints associated with mixed-age tanker fleets. Additionally, the exploration of alternative fuels such as ammonia, coupled with advancements in engine technology, presents promising options for reducing emissions and promoting sustainability in the industry.

The conclusion from the discussion on engine retrofitting in the tanker industry shed some light on the importance of complying with emissions regulations while enhancing operational efficiency. The insights shared by Mr Lamaris demonstrated the viability of retrofit solutions in achieving these objectives.

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