The North Sea: a case study on the reduction of sulphur levels in marine fuels
Paula J. SPREUTELS*
During the March 2000 meeting of MEPC 44, the application made by the EU, its Member States and Norway, for the status of SOx Emission Control Area for the whole of the North Sea, has been accepted. This means that on the same date that Annex VI to Marpol 73/78 will enter into force, the sulphur content of the marine fuel which may be used by shipping in the North Sea will be limited to 1.50% m/m max; there is only a one year waiver for ships entering the SECA. In clear, the SECA makes it necessary for ships to carry low sulphur bunker fuel on board, or to use marine diesel when entering the Area.
To the East, the North Sea SECA is prolonged by the Baltic Sea SECA.
This paper, based on a Concawe study, discusses immissions from shipping in the busiest part of the North Sea and the Channel.
Key words: North Sea, SECA, sulphur, marine fuels, emission
EU: European Union
IMO: International Maritime Organisation
kt: kilo tonnes
MARPOL: International Convention for the Prevention of Pollution from Ships
MEPC: Marine Environment Protection Committee
m/s: meter per second
Mt/y: million tonnes per year
SECA: SOx Emission Control Area
SO2: sulphur dioxide
SOx: sulphur oxides
UK: United Kingdom
UN-ECE: United Nations Economic Commission for Europe
% m/m: mass percent
The concept of introducing special areas for SOx emission control has been debated extensively within IMO. When Annex VI  to the Marpol 73/78 convention was published, criteria and procedures for designating SO Emission Control Areas (SECAs) were included in Appendix III. The Baltic Sea was a priori granted the status of SECA.
Annex VI defines an SOx Emission Control Area as an area where the adoption of special mandatory measures for SOx emissions from ships is required to prevent, reduce and control air pollution from SOx and its attendant adverse impacts on land and sea areas.
It was clear from an early stage that because of the acidification problems in N.W. Europe the European Union and the North Sea Member States would be inclined to make a SECA submission for the North Sea, or at least for part of the North Sea. Concawe, the Oil Companies' European Organization for Environmental and Health Protection, made a detailed analysis of the impact of sulphur emissions from ships within the heavily trafficked southern North Sea and Channel as a contribution to the debate on the need to limit the sulphur content of bunker fuels.
This study  (published in 1994) is the basis for this review.
The computerised immission modelling results are based on a very comprehensive inventory of ship emissions and on calculations of sulphur dispersion and deposition on a fine spatial scale.
Fig.1 illustrates the approach to the development of the emission inventory.
The area under consideration is represented in fig. 2, which also represents the emissions from shipping (1992 data), mapped onto shipping lanes and ports.
The amount of fuel consumed by ships in the area (1992 data) is approximately 4 Mt/y. Consumption in port is 29% of this total.
The corresponding SO2 emission is approximately 206 kt, of which around 55 kt in ports.
* Texaco Technology Ghent, Heavy fuel Technology
Technologiepark-Zwijnaarde 2, 9052 Ghent, Belgium
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