NOx emissions
All Wartsila engines comply with IMO MARPOL 73/78 Annex VI for NOx emissions. Other tuning options to meet lower emissions are possible upon demand.
Sulphur content in fuel
A host of new regulations related to the sulphur content in fuel are currently at the implementation phase. The special IMO and EU requirements for SECA areas (Sulphur Emissions Control Area) specifying 1.5% maximum sulphur in marine fuel content, entered into force in the Baltic Sea in May 2006 and in the North Sea and English Channel in autumn 2007.
In 2006, the fuel sulphur content was restricted to 1.5 % for all passenger ships operating in regular service to or from EU ports, and within EU territorial seas. From 2010 the sulphur content of all marine fuels used in EU ports and inland vessels by all ships, will be restricted to a maximum of 0.1%.
The California Air Resource Board (CARB) has issued reduced sulphur in fuel regulations applying to auxiliary engines (including diesel-electric) on ocean-going vessels operating within 24 nautical miles of the California coastline. The maximum permitted sulphur content is 0.5% from January 2007, and will be 0.1% from January 2010.
Additionally, several voluntary regimes have been established alongside the mandatory regulations. For example, in Sweden new sulphur-related fairway dues have been differentiated with the following specified limits:
• 0.2 and 0.5% for passenger vessels
• 0.2, 0.5 and 1.0% for other vessels.
Due to the new regulations, the shipping community is faced with new challenges on a large scale, especially those ships that will operate both inside and outside restricted areas, switching over from one fuel to another, in some cases to a distillate fuel. Wärtsilä has issued guidelines, and can offer technology for design and modification of the fuel system onboard to meet compliance. However, the Wärtsilä engine itself (old and new) can cope with any fuel sulphur content.
For new-builds expected to operate purely within fuel sulphur restricted areas, fuel and lubricating oil filling, storage, transfer, separation, and supply systems can in principle be arranged as per a traditional HFO ship. However, to enhance the flexibility and second-hand value of the ship, consideration could also be given to designing these systems to operate alternatively inside and outside the SECA areas.
Onboard exhaust gas cleaning of SOx by using a scrubber system is an alternative to the use of high-cost, low-sulphur fuel qualities. Wärtsilä has initiated a project aiming at developing and testing marine scrubber technology. The project will investigate the effect of scrubber design on performance, lifetime and economy, installation requirements, discharge water criteria, ecological impact, risk of acid rain droplets, and white smoke, etc. Through this project Wärtsilä is developing unique knowledge and expertise about scrubbing technology, both for new buildings and retrofit installations.
Smoke
Alaska enforces regulations governing the permitted smoke levels from ships. Wärtsilä has demonstrated its compliance with these regulations.
Emission reduction technologies
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Area of concern
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Technology
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Principle
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Benefit
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Smoke
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Wärtsilä common-rail engines
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The injection pressure is kept high and stable throughout the load range. Optimal engine operation is achieved at all speeds and loads.
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Smokeless operation
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Wärtsilä RT-flex engines
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Precise control of the injection process, plus high injection pressures at low engine speeds and the sequential shut-off of the injectors, combine to give steady running at low running speeds, down to 10 –12% of nominal speed.
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Smokeless operation
Reduced operating costs
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NOx
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WETPAC H
(Humidification)
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Pressurized water is added to the intake air after the turbocharger compressor. The water evaporates instantly and enters the cylinders as steam, reducing the combustion temperature and thus NOx formation.
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Reduction typically 40 %
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WETPAC DWI
(Direct Water Injection)
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A DWI valve, through which the water and fuel is injected into the cylinder
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Reduction typically 50 %
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SCR
(Selective Catalytic Reduction)
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A reducing agent, such as an aqueous solution of urea is injected into the exhaust gas. The urea in the exhaust gas decays into ammonia, which is then put through a catalysing process that converts the NOx into harmless nitrogen and water
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Reduction
85-95 %
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