1 Introduction

1.1 Regulation 14 of Annex VI requires ships to use fuel oil with a sulphur content not exceeding that stipulated in regulations 14.1 or 14.4. Regulation 4 allows, with the approval of the Administration, the use of an alternative compliance method at least as effective in terms of emission reductions as that required by the Annex, including the standards set forth in regulation 14. The Administration of a Party should take into account any relevant guidelines developed by the Organization pertaining to alternatives provided for in regulation 4.

1.2 Similar to a NO_X emission reduction system, an exhaust gas cleaning (EGC) unit may be approved subject to periodic parameter and emission checks or the system may be equipped with a continuous emission monitoring system. These guidelines have been developed with the intention of being objective and performance oriented. Furthermore, use of the SO₂(ppm)/CO₂(%) ratio method will simplify the monitoring of SO_X emission and facilitate approval of an EGC unit. See appendix 2 for the rationale explaining the use of SO₂(ppm)/CO₂(%) as the basis for system monitoring.

1.3 Compliance should be demonstrated on the basis of the SO₂(ppm)/CO₂(% v/v) ratio values.

Table 1: Fuel oil sulphur limits recorded in regulations 14.1 and 14.4 and corresponding emissions values

Note: The use of the ratio emissions limits is only applicable when using petroleum based distillate or residual fuel oils. See appendix 2 for application of the ratio method.

1.4 These guidelines are recommendatory in nature, however, Administrations are invited to base the implementation of the relevant requirements of regulation 4 of MARPOL Annex VI on them.