The presentation will provide many technical details about two and four stroke engine technologies which currently operate on alternative fuels like methanol, ammonia and their engineering and commercial impact on owners. It will show the engineering challenges during the research phase by the OEM, implementing such technologies onboard and the relationship between the IMO regulations and the effects on the R&D effort by OEMs. Ammonia is expected to be the least costly energy dense e-fuel to produce. But getting positive seagoing experience with ammonia as a marine fuel will be a key prerequisite for the wide adoption of this fuel type. Methanol engine orders represented 30% of our 2 stroke newbuilding project pipeline in 2023/24. The methanol-ready concept for 4 stroke engines will be discussed. Operating a methanol engines on diesel has challenges. The presentation will briefly comment of the feasibility of onboard carbon capture technologies. The paper will also mention the two most practical decarbonization strategies available today:

- Liquid: Diesel – Biodiesel – Methanol

- Gaseous: LNG – LNG with reduced slip – BioLNG.

These paths are expensive and require investments, not only from ship owners but also from the OEMs. Depending on what technology the ship owner already has in the fleet, retrofit solutions instead of buying new equipment can be adopted as well. The examples shown (vessel examples will be provided) provide an estimate for the engineering effort to retrofit an existing engine to operate with any of these fuels and the financial costs which come with it, together with the environmental benefits.