Development and Demonstration of Strategies for GHG and Methane Slip Reduction from Dual-Fuel Natural Gas Coastal Vessels

Low Pressure Dual Fuel (LPDF) marine engines fueled with natural gas (NG) provide a cost-effective means for minimizing fuel sulfur content, and NOx and PM emissions for marine vessels. In addition, the use of NG can provide significant GHG reductions, if CH4 slip is mitigated. Alternative fueling strategies such as LPDF, are commonly assessed by life-cycle analyses using exhaust emission rates from generalized engine test cycles (e.g. IMO E2). As CH4 slip from LPDF NG engines is particularly sensitive to engine load, a greenhouse gas emission inventory based on generalized engine cycles may not accurately represent real-world vessel operation and emissions. The objectives of this work are to: (i) quantify the GHG emissions reductions possible using the current best available LPDF technology and, (ii) evaluate the attained real-world emissions reduction as a result of improved vessel operating strategies and state of the art engine technology for coastal LPDF vessels.