AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Impacts of Switching from Diesel to Liquefied Natural Gas (LNG) for A Marine Vessel
WEIHAN PENG, Jiacheng Yang, Joel Corbin, Qi Li, Una Trivanovic, Steven Rogak, Prem Lobo, Patrick Kirchen, Stephanie Gagne, David R. Cocker III, Wayne Miller, University of California, Riverside
Abstract Number: 742 Working Group: Combustion
Abstract Ship owners are challenged to meet ever more stringent standards for criteria pollutants and greenhouse gases (GHG). To meet those goals, the manufacturers of trucks, buses and cars have shown that operating on natural gas reduced both criteria pollutants and greenhouse gases; however, little is known about switching from diesel to natural gas in marine vessels. In this project, the emissions from a modern large ferry’s dual-fuel engine operating on natural gas in the Tier 3 mode and operating on diesel in the Tier 2 mode were compared.
We measured particle size distributions and black carbon (BC) emissions, and found that the emitted particles were associated with the lubrication oil (the majority of mass) or the diesel pilot fuel (majority of BC) for both fuels. We also measured emissions of criteria pollutants (PM2.5, CO, SOx, NOx), EC/OC, carbonyls, CH4, and CO2 from the vessel for various engine loads. Switching from diesel to LNG reduced PM2.5 mass by 93%, BC by 97%, CO2 by 18%, and NOx by 93%, however, emissions increased for incomplete combustion products(CO and HCHO) and unburned CH4. A health risk assessment showed that diesel was more harmful when considering carcinogenic and chronic health effects from both PM and HCHO. An analysis of the GHG and BC emissions was performed and found that, on 100-year basis, LNG’s GWP per kWh was higher than diesel’s at lower loads, but that it was similar at 75% engine load and better at higher loads. Since CH4 emissions may be reduced by technological advances, LNG has the potential to be a lower-GWP fuel than diesel in the future, in addition to its health benefits. Mitigation strategies for further reducing pollutants from LNG exhaust were discussed, with emphasis on reducing the increased pollutants i.e. CO, HCHO and CH4.