|Title||Ship Emissions Assessment (SEA)|
|Collaborators||James J. Corbett (CMU), Paul S. Fischbeck (CMU), Spyros Pandis (CMU)|
|Keywords||ship, emissions, air pollution, nitrogen, NOx, sulfur, SO2, SOx, global, inventory, trade|
The Ship Emissions Assessment (SEA) produced the first geographically resolved, global inventory of emissions from commercial ship engines operating internationally. This inventory shows that ship engine combustion is an important source for several air pollutants, including oxides of nitrogen (NOx), and oxides of sulfur (SOx). For example, we estimated annual NOx and SOx emissions from ships to be 3.08 Tg (1012 grams) as N, and 4.24 Tg as S, respectively [Corbett and Fischbeck, 1997; Corbett et al., 1998b]. In other words, international ship emissions represent more than 14 percent of nitrogen emissions from global fuel combustion sources and more than 16 percent of sulfur emissions from world petroleum use [Corbett and Fischbeck, 1997]. Using the SEA inventory, we showed that nearly 70% of ship emissions occur within 400 km of land regions, that 85% occur north of the equator, and that ship air pollution can be of regional importance where they may be of the same order or greater than adjacent land-based emissions. We also showed that globally ship sulfur emissions equal about 20-25% of the global ocean dimethylsulfide (DMS) emissions, but can equal or exceed DMS flux in the mid-latitudes of the Northern Hemisphere and other regions where shipping is intense[Corbett et al., 1998b]. By including our work in global chemical transport models, we showed that sulfur emissions from ships account for 70-100% of the SO2 concentration and 10-30% of the SO4 concentration in the remote marine boundary layer [Capaldo et al., in preparation; Corbett et al., 1998a]. Near land regions, our model predictions showed that ship emissions contribute 5-30% to the ambient sulfur concentrations near many populated land regions [Capaldo et al., in preparation]. (Similar global modeling analyses are underway to quantify the contribution of nitrogen emissions to NOx and ozone concentrations in both remote ocean and coastal regions.) Other air pollutants and carbon dioxide were estimated in the SEA, which has contributed to the fundamental understanding of the remote ocean atmosphere, and to the applied science of regional air pollution.
On a regional level, our research also produced the first
comprehensive national inventory of commercial ship emissions
for the United States [Corbett and Fischbeck, 1998a; Corbett
and Fischbeck, in preparation], improving upon earlier attempts
[Davis, 1995; EPA, 1991]. By combining an engineering
analysis of ship engine operations with trade data describing
the tons of cargo moved over the nation's navigable waterways,
we estimated ship emissions in U.S. waters to be more than three
times as great as earlier calculations. For example, our estimates
for NOx emissions from ships (foreign and domestic) in U.S. waters
is 747 thousand metric tons [Corbett and Fischbeck, 1998a;
Corbett and Fischbeck, in preparation], compared to the
236 thousand metric tons reported in the Transportation Energy
Data Book: Edition 15 [Davis, 1995]. Moreover, our results
indicate that emissions from ships on U.S. inland rivers equal
about 70% of the emissions from ships on all three U.S. coastlines
combined despite the fact that three times as many miles
of the U.S. navigable waterways extend along coastal borders
[Corbett and Fischbeck, 1998a]. Because of this work,
ship emissions in U.S. waters can be more accurately included
in nationwide and regional air quality studies.
|References||Capaldo, K.P., J.J. Corbett, P. Kasibhatla, and
S.N. Pandis, A Global
Sulfur Emissions Inventory For Oceangoing Ships And Its Impact In Global Chemical Transport Models, in preparation.
Corbett, J.J., K.P. Capaldo, P. Kasibhatla, and S.N. Pandis, A Global Sulfur Emissions Inventory For Oceangoing Ships And Its Impact In Global Chemical Transport Models, in International Aerosol Conference, edited by International Aerosol Society, Elvesier, Edinburgh, Scotland, 1998a.
Corbett, J.J., and P.S. Fischbeck, Emissions From Ships, Science, 278 (5339), 823-824, 1997.
Corbett, J.J., and P.S. Fischbeck, Commercial Marine Emissions Inventory for EPA Category 2 and 3 Compression Ignition Marine Engines in United States Continental and Inland Waterways, Carnegie Mellon University, Pittsburgh, PA, 1998a.
Corbett, J.J., and P.S. Fischbeck, Letter to U.S. EPA Office of International Activities: CO2 emissions from international shipping, Carnegie Mellon University, Pittsburgh, PA, 1998b.
Corbett, J.J., and P.S. Fischbeck, Commercial Marine Emissions Inventory and Analysis for United States Continental and Inland Waterways, in preparation.
Corbett, J.J., P.S. Fischbeck, and S.N. Pandis, Global Nitrogen and Sulfur Emissions Inventories for Oceangoing Ships, Journal of Geophysical Research, accepted, 1998b.
Davis, S.C., Transportation Energy Data Book: Edition 15, U.S. Department of Energy, Oak Ridge Tennessee, 1995.
EPA, Non-road Engine and Vehicle Emission Study - Report, United States Environmental Protection Agency, Washington, DC, 1991.