Assessing the air pollution co-impacts of hybridizing coastal ferry powertrains on ports and coastal communities.

Diesel-electric large passenger ferries play a crucial role in connecting coastal communities. Their current diesel-electric powertrain configuration makes them prime candidates for hybridization, providing a cost-effective and accessible route to decarbonization. While reductions in fuel consumption and CO₂ emissions are well-established benefits of hybrid systems, the primary aim of this study is to quantify and evaluate the associated air pollution co-benefits, particularly in and around ferry terminals where population exposure is high and nearby coastal communities are most affected. The study assesses the impact of emissions from British Columbia (BC) Ferry Corporation's Coastal class ferries, equipped with baseline diesel-electric powertrains, and when operating with plug-in hybrid propulsion systems, on local air quality in Tsawwassen Port, BC, Canada. A GT-SUITE™ engine model was developed for the marine diesel engines used in Coastal class ferries to estimate fuel consumption and nitrogen oxide (NOx) emissions. Using ferry traffic data and emission factors for cruising, maneuvering, and berth modes, annual NOx emissions were calculated through a fleet activity-based method. Calculated NOx, local meteorology, and coastal land use data were utilized in the AERMOD model. The model evaluated pollutant concentrations, assessed concentration in both marine and residential zones, and quantified the air quality benefits associated with hybrid powertrains. The results show that hybridizing coastal ferry powertrains may reduce NOₓ concentrations by up to 45 %, offering substantial air quality improvements alongside decarbonization benefits, particularly in densely populated and environmentally sensitive coastal zones.