In 2008, the UN International Maritime Organization (IMO) revised its standards on the sulphur content of marine fuels (contained in MARPOL Annex VI). The current limit for sulphur content in the fuel is 1.0% m/m (by weight), and from 2015 onwards vessels sailing in Sulphur Emission Control Areas (SECAs) will have to comply with emission levels equivalent to a sulphur content of 0.1% m/m. Outside SECA’s, the limits are 3.5% m/m and from 2020 onwards 0.5% m/m.
Marine sulphur emissions can be reduced in three different ways:
• by decreasing the sulphur content of the fuel used
• by removing sulphur from the exhaust gas
• by changing fuel, for example through the use of natural gas
Several methods can be used for de-sulphurising exhaust gases. Wet scrubbing is an obvious alternative for ships, as the scrubbing medium is readily available and the technology has been used for Inert Gas Systems onboard ships for 50 years. Development of a new, more space efficient design for the cruise and ferry segment has led to orders from several ferry companies. Wärtsilä has also invested further in increasing its engineering and installation capabilities, and can now offer additional services, including basic engineering and a complete turnkey Exhaust Gas Cleaning solution.