Exhaust emissions from high speed passenger ferries

Exhaust emission measurements have been carried out on-board three high-speed passenger ferries (A, B and C) during normal service routes. Ship A was powered by conventional, medium-speed, marine diesel engines, Ship B by gas turbine engines and Ship C conventional, medium-speed, marine diesel engines equipped with selective catalytic reduction (SCR) systems for NOx abatement. All ships had similar auxiliary engines (marine diesels) for generating electric power on-board. Real-world emission factors of NOx, SO2, CO, CO2, NMVOC, CH4, N2O, NH3, PM and PAH at steady-state engine loads and for complete voyages were determined together with an estimate of annual emissions. In general, Ship B using gas turbines showed favourable NOx, PM and PAH emissions but at the expense of higher fuel consumption and CO2 emissions. Ship C with the SCR had the lowest NOx emissions but highest NH3 emissions especially during harbour approaches and stops. The greatest PM and PAH specific emissions were measured from auxiliary engines operating at low engine loads during harbour stops. Since all ships used a low-sulphur gas oil, SO2 emissions were relatively low in all cases.