A new peer-reviewed study published in the Journal of Marine Science and Engineering has revealed promising findings about methane emissions and the reliability of measurement methods for LNG-powered marine engines. Conducted by VTT Technical Research Centre of Finland as part of the GREEN RAY project, the research evaluates methane slip measurement from dual-fuel engines under both laboratory and real-world cruise ship operating conditions.
Key Insights from the Study
Consistency Across Measurement Methods:
Four different methane detection methods, including FTIR, NDIR, GC, and FID, were tested in engine laboratory, while three devices were deployed during onboard studies aboard the MSC Euribia, a modern LNG-fuelled cruise ship. The results across most methods aligned closely, demonstrating strong reliability for methane quantification, even at low concentrations.
Methane Slip from Modern Engines:
In laboratory tests with the state-of-the-art Wärtsilä 25 DF engine, methane slip ranged from 2.2 g/kWh at full load to 6.8 g/kWh at 10% load, lower than levels reported in previous studies with comparable engines. On board the cruise ship, methane emissions from Wärtsilä 46 DF engines ranged between 1.9 g/kWh and 9.7 g/kWh , further confirming that higher engine loads are associated with reduced methane slip.
Validation Through Real-World Comparison:
Comparison with independent sea trials on the same vessel confirmed the consistency and accuracy of the study’s results. The findings underscore that the latest generation of dual-fuel engines not only emits less methane but also enables precise emissions monitoring across different measurement devices.
High-Efficiency Methane Abatement Catalyst:
The study also evaluated a methane abatement catalyst (MAC), comprising a sulphur guard bed and a methane oxidation catalyst. At optimal operating temperatures (370-400°C), the system achieved methane conversion efficiencies exceeding 95%. Downstream methane levels dropped to as low as 10 ppm, confirming the system’s effectiveness in reducing emissions.
The complete study, Measuring Methane Slip from LNG Engines with Different Devices, is available in the open-access journal Marine Science and Engineering.
