Inventory and forecasting of maritime emissions in the Belgian sea territory, an activity-based emission model

Air quality policy has focussed on land-based emissions for decades. In recent years, it has become increasingly clear that emissions from sea-going vessels can no longer be ignored. There is a growing need for detailed emission inventories to evaluate the impact of this transport mode on air quality and health. In this paper we present MOPSEA, an activity-based emission model to determine emissions from sea-going vessels. The model considers shipping activities of sea-going vessels on Belgian territory, combined with individual vessel characteristics. We apply this model to study the effects of recent international efforts to reduce emissions from sea-going vessels in Belgian territorial waters for the current fleet and for two scenarios up to 2010. The emission model for Belgium, based on different vessel operating areas, reveals that most maritime emissions from the main engines will increase. CO2 emissions will increase by 2–9% over the 2004–2010 period due to an increase in shipping activity. NOX emissions are projected to rise between 1% and 8% because the increase in activity offsets the reductions from the international maritime organisation (IMO) and European regulations. In contrast, SO2 emissions will decrease by at least 50% in 6 years time. The switch of auxiliaries from heavy fuel oil to diesel oil at berth results in a large emission reduction (33%) for PM and small reductions for CO2, NOX, CO and HC (4–5%). The choice between a bottom-up versus top-down approach can have important implications for the allocation of maritime emissions. The MOPSEA bottom-up model allocates only 0.7 Mton CO2 to Belgium, compared to 24.2 Mton CO2 based on bunker fuel inventories.