Reducing emissions to air and water

The International Maritime Organization (IMO) revised its standards on the sulphur content of marine fuels in 2008. These were included in Annex VI to the International Convention for the prevention of Pollution from ships (MARPOL Convention). Since 2012, the current global limit for the sulphur content of the fuel oil used by ships has been 3.5% m/m (by weight), and from 2020 onwards the limit will be 0.5% m/m. For vessels sailing in Sulphur Emission Control Areas (SECAs), the sulphur limit has been 0.1% m/m since 1 January 2015. 

Marine sulphur emissions can be reduced by:
• reducing the sulphur content of the fuel used
• removing sulphur from the exhaust gas
• operating on cleaner fuel such as liquefied natural gas (LNG)

One primary method for reducing emissions from a marine engine is to run on cleaner fuel. Operating with LNG is an effective way to comply with current exhaust emission legislation, since LNG is one of the few fuels pure enough to meet even the strictest regulations. In addition to enabling compliance with NO_x and SO_x restrictions, particulate matter (PM) is minimized. Wärtsilä provides a range of gas solutions, including the Wärtsilä dual-fuel engines and the Wärtsilä LNGPac™ fuel gas handling system.

Wärtsilä scrubber systems have been developed to efficiently remove SO_x from the exhaust gas, but additionally they also remove significant levels of particulate matter. Low sulphur fuel, on the other hand, doesn’t automatically mean fewer particles. In fact, running on marine gas oil (MGO) will mean releasing small particles (also called black carbon) into the air, which are especially harmful to people. Wärtsilä has developed a full wet scrubber portfolio that can cover a wide range of specific needs for our customer’s installations. Great effort has also been put into reducing the environmental impact of our scrubbers. This includes not only cleaning the exhaust gas, but also the wash water from the scrubber system. All Wärtsilä scrubbers have been tested and certified according to the IMO guidelines, thus ensuring safe operation and compliance with MARPOL Annex VI , Regulation 4.







 
 
 

In addition to improving the efficiency of its solutions, Wärtsilä continuously develops technologies for reducing greenhouse gas linked emissions from both diesel and gas engines. For gas engines, Wärtsilä is developing technologies such as Ultra Low THC (Total Hydro Carbons) emission reduction, which reduces the THC levels by 30-90%.

The long-term investments in research and the strive for more environmental sound solutions have resulted in materialisation of many benefits and success especially at low load where the methane slip has reduced by as much as 75%. Many of the engine optimisations can also be retrofitted on existing older engines. These measures can include optimising combustion space, updating the software that is controlling the combustion, and a general optimisation of the machinery power management.

GHG emissions from Wärtsilä engines have been decreasing for decades. Wärtsilä's target is to further reduce the GHG emissions of its gas engines by 15% from 2015 to 2020. 



 

All Wärtsilä engine portfolio products are IMO NO_x Tier II compliant. A marine diesel engine installed on a ship constructed on or after 1 January 2016, and operating in the North American ECA and the United States Caribbean Sea ECA, must comply with the Tier III NO_x standards. The same rule applies in the North Sea and Baltic Sea for ships with keel laying on or after 1 January 2021. This demands for further reduction of 75% in NO_x levels from Tier II requirement. NO_x reduction to Tier III level requires a step change in terms of engine technology and product offerings.

Wärtsilä solutions for IMO NO_x Tier III are: 

• Selective Catalytic Reduction (SCR): Wärtsilä’s SCR solution is applicable for low and high sulphur applications and compatible with scrubbers.
• Gas engine (Dual fuel (DF) in gas mode): Operating with LNG is an effective way to comply with current exhaust emission legislation, since LNG is one of the few fuels pure enough to meet even the strictest regulations. In addition to enabling compliance with NO_x and SO_x restrictions, particulate matter (PM) is minimized. 

Wärtsilä as a company has long been offering technologies for enhanced environmental performance. As one of the marine industry’s leading equipment suppliers, we have a responsibility to supply efficient environmental solutions that can comply with regulations and protect the quality of our seas. 

Ballast water management systems
The BWMC entered into force 8^th September 2017. Ships are required to manage their ballast tanks to remove or render harmless the ballast water discharge of invasive species. Wärtsilä’s Aquarius range of IMO approved Ballast Water Management Systems (BWMS) offer solutions to limit the spread of ballast water-related invasive species and prevent their introduction to aquatic ecosystems. The Aquarius BWMS range also has USCG AMS status. Read more »

Wastewater treatment
Wärtsilä is the world’s leading manufacturer of marine sewage treatment systems. For over four decades the Wärtsilä Hamworthy Super Trident sewage treatment plant has been widely regarded as standard specification on all types of vessels. Wärtsilä solutions facilitate the management and treatment of both grey and black wastewater, in accordance with the most stringent legislation applicable, including the removal of Phosphates and Nitrates, as for example required for Alaska. Read more »

Oily water systems
The Wärtsilä Oily Water Separator (OWS) processes bilge water with a separating process, removing oil traces to a level greatly exceeding the minimum standards required by the IMO. The amount of oil in water after treatment is less than 5 ppm. Read more »