Economical and Emissions Analysis of MAN 5S65ME-C Engine under Diesel and Dual-Fuel Operation

Abstract

Background: The transition of marine propulsion systems to dual-fuel operation has become a key approach for improving fuel efficiency and reducing greenhouse gas emissions in compliance with IMO regulations. The MAN 5S65ME-C low-speed two-stroke engine represents a typical modern marine engine that can be theoretically adapted to operate in dual-fuel (ME-GI-type) mode using methane with pilot diesel injection. Methods: The study is based on thermodynamic and engineering calculations using operational data at 60% engine load. The indicated thermal efficiency was determined from diesel operation parameters and applied to theoretical methane conversion. Fuel consumption for dual-fuel operation was calculated using lower heating values and energy balance equations. Economic analysis was performed based on comparative fuel prices, while environmental assessment was conducted using standard CO₂ emission factors. Results: The results show that dual-fuel operation reduces total fuel mass consumption compared to diesel mode due to the higher calorific value of methane. The economic analysis demonstrates a significant reduction in daily fuel costs, while CO₂ emissions are reduced by approximately 25% in dual-fuel mode compared to diesel-only operation. Conclusion: The application of dual-fuel (ME-GI-type) operation for the MAN 5S65ME-C engine provides both economic and environmental advantages under the considered conditions. The results confirm that methane-based operation with pilot injection is an effective solution for improving fuel efficiency and reducing CO₂ emissions in marine propulsion systems.