Retrofitting Marine Internal Combustion (IC) Engines for Methanol Fuel Integration

The maritime sector is undergoing a significant transformation as it seeks to meet increasingly stringent environmental regulations imposed by international bodies such as the International Maritime Organization (IMO). Among the various alternative fuels being explored, methanol has emerged as a strong candidate due to its low emissions, ease of storage, and potential for carbon neutrality when produced from renewable sources. This paper investigates the feasibility and methodology of retrofitting conventional marine internal combustion (IC) engines for methanol usage, providing a comprehensive analysis of both low-pressure and high-pressure methanol fuel supply systems. The study delves into the working principles, components, advantages, and disadvantages of these systems, focusing on performance, safety, cost, and environmental impact. Furthermore, it examines dual-fuel strategies involving methanol and pilot diesel, particularly in the context of single-point injection (SPI) and multi-point injection (MPI) systems. The retrofitting process is explored in detail, including engine design modifications, injector configurations, and combustion behaviour with methanol's distinct physical and chemical properties. Comparative evaluations are provided to highlight the trade-offs between simpler low-pressure systems and more efficient but complex high-pressure configurations. Emphasis is placed on emissions reduction, engine efficiency, and the practicality of implementation in existing vessels. The paper concludes that while technical challenges remain—such as methanol’s lower energy density and corrosiveness—appropriate retrofitting solutions can effectively bridge the transition toward cleaner and more sustainable marine propulsion systems.