What can the shipowners trade?

Shipowners can trade any NOx and SOx reductions achieved below the IMO or EU baselines that is, any reductions below the 1,5% sulphur fuel content for the SECA and any reductions below the NOx curve (12-14 g NOx/kWhr for medium speed diesels).

For example in the case of NOx, this is about 90% of the reductions achieved through an SCR system. The emission of sulphur dioxide is directly proportional to the content of sulphur in the bunker fuel or LNG.