Characterization of Methane Emissions from a Natural Gas-Fuelled Marine Vessel under Transient Operation University of British Columbia

Format:

Book

Conference/Event

Author/Creator:

Cohen Sacal, David, author.

Contributor:

Corbin, Joel

Gagné, Stéphanie

Kirchen, Patrick

Penner, Harly

Conference Name:

SAE WCX Digital Summit (2021-04-13 : Live Online, Pennsylvania, United States)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2021

Summary:

Natural gas is an increasingly attractive fuel for marine applications due to its abundance, lower cost, and reduced CO2, NOx, SOx, and particulate matter (PM) emissions relative to conventional fuels such as diesel. Methane in natural gas is a potent greenhouse gas (GHG) and must be monitored and controlled to minimize GHG emissions. In-use GHG emissions are commonly estimated from emission factors based on steady state engine operation, but these do not consider transient operation which has been noted to affect other pollutants including PM and NOx. This study compares methane emissions from a coastal marine vessel during transient operation to those expected based on steady state emission factors.The exhaust methane concentration from a diesel pilot-ignited, low pressure natural gas-fuelled engine was measured with a wavelength modulation spectroscopy system, during periods of increasing and decreasing engine load (between 3 and 90%). Methane concentration, methane emissions, and excess air ratio were compared to steady state conditions. Load increases resulted in similar exhaust methane concentrations relative to steady state values (within 8%). In contrast, decreasing engine load increased the exhaust methane concentration up to 1.9-times relative to equivalent steady-load values and showed total methane emissions up to 43% higher over the transient duration. However, the marine vessel considered here, operated at steady load approximately 91% of the time and the transient CH4 emissions will have only a negligible impact on the total in-use GHG emission (1.7% increase). This indicates that while transient operation does affect CH4 emissions, the uncertainty introduced in using steady state emissions factors for the considered load cycles is negligible for ships that mostly operate at steady load. Moreover, the load transitions during which CH4 concentration was measured were more aggressive than what is experienced routinely during sailings. The transient measurements indicated the need for CH4 emission reduction control strategies, particularly for transients with load reductions

Notes:

Vendor supplied data

Publisher Number:

2021-01-0631

Access Restriction:

Restricted for use by site license