A Techno-Environmental and Energy Efficiency Investigation of Marine Dual-Fuel Engines

Abstract

The ship-based greenhouse gas emissions along with the volumetric growth in maritime transportation have increased significantly over the years. International Maritime Organization (IMO) has tightened the emission limits by putting new regulations into effect to overcome the environmental impacts and therefore, the maritime industry has focused on energy-efficient ship design and operation, recently. Regarding the latest developments, dual-fuel engines operated with different fuels have been installed and new technological developments in emission control have been implemented onboard ships. In this context, the selection of engine systems where there are many options available has been a substantial problem in the design process of a ship, recently. The latest marine engines are capable of operating with various types of fuels at different emission control modes, therefore, energy efficiency and emission performance of the prime movers should be analyzed in detail. In this study, VLSFO, methanol, LPG, LNG and MDO-fueled engines with the same power output are investigated and the NOX reduction device integrated engines’ technical specifications are compared. Then, the selected dual-fuel engines are thermodynamically analyzed and the environmental impacts are evaluated under different engine loads, Tier II, Tier III modes and ambient conditions. Moreover, EEDI calculations are conducted under the case study of powering a medium-range tanker and engine options are evaluated in terms of energy efficiency. Finally, a sensitivity analysis of engine performance is carried and the results are validated. According to the results, the energy efficiency of the ship can be increased by up to 20% by selecting the LNG-fueled engine as the prime mover while it requires more space and equipment compared to other engines.