Success case

Significant reductions on harmful sulphur emissions from ships

Wärtsilä Finland Oy and Metso Power Oy are developing a new technology for the cleaning of harmful emissions from ships.

The sulphur directive approved by the European Parliament is based on an emission limit, agreed by the International Maritime Organisation IMO, to reduce the acidification impact of exhaust gases from ships in the future. IMO’s new regulations on fuel sulphur contents will concern both new and old vessels. The maximum permitted sulphur content of fuels used in the Baltic Sea, the North Sea and the English Channel in 2015 may be 0.1% instead of the previous one per cent, and in other sea areas only 0.5% in 2020 or alternatively in 2025.

The emission requirements of the sulphur directive can be met by using either fuel oil with a lower sulphur content or natural gas, or by installing scrubbers in the ships. These scrubbers are used for capturing not only sulphur, but also some of the particulate matter from exhaust gases. The majority of high-power diesel engines in ships in current operation are driven by heavy fuel oil. The choice made by the shipping company with regard to emissions reduction can depend, for example, on the extent the vessel is operated in the Sulphur Emission Control Areas (SECA) each year. Another key factor is the future price difference between fuels with low and high sulphur content.

Wärtsilä launched the development of scrubbers used on vessels in 2009. The scrubbers can be divided into two different categories:

seawater scrubbers and freshwater scrubbers. The seawater scrubber is the first technology to be used on vessels and it is best suited for ocean-going ships. The freshwater scrubber is better suited in an environment such as the Baltic Sea. A conventional hybrid scrubber can be operated either with seawater or freshwater, but not with a combination of the two. With the new technology, scrubbing can be started with seawater, and the remaining sulphur oxides are removed in the freshwater section. The system automatically optimises and regulates itself according to the sea area. The user will not have to decide which mode or combination of modes is used. The closer the water properties are to the quality of the seawater, the fewer chemicals are needed.

Installation of a sulphur scrubber on a ship is a significant step in the application of the exhaust gas cleaning technology in shipping. Depending on the type of vessel, the savings gained by the owner or operator of the ship will be significant. The lifetime of the scrubber can be expected to be in the same region as that of the vessel, about 25 years. In the near future, the repayment period for the investment in a new ship could be between two to three years or even less, depending on a number of factors.

Significant reductions on harmful sulphur emissions from ships

For more information: FCEP Program Manager Matti Kytö (VTT), matti.kyto@cleen.fi