New regulations on marine pollution

Caring for the environment is among the most important issues discussed around the world. Improvements in machinery largely focus on reducing or completely eliminating its negative effects on the environment.

The changes apply to machines operating on land, in the air and, of course, at sea. One common gaseous pollutant from vessels is nitrogen oxide (NOx). The reduction of pollution from this gas is subject to international regulations.

In accordance with the International Convention for the Prevention of Pollution from Ships (MARPOL – precisely, with Rule 13 of Annex VI to the Convention), nOx emission limits are set for diesel engines above 130KW (IMO I, IMO II and IMO III). They depend on the rated speed of the motor. The current global limit is IMO II. In turn, The IMO III limit applies to ships built after 1 January 2016 and in NOx emission control areas. Until the end of last year, the NOx Emission Control Convention applied to North American areas and the US Caribbean Sea.

The year 2021 brought big changes because, from 1 January, the Baltic Sea and the North Sea emission areas also became NOx emission control areas.

NOx emission control aresa

Strefy Kontroli Emisji NOx ( ECA NOx) 

 źródło: www.egcsa.com

NOx Emission Control Areas ( ECA NOx)

Source: www.egcsa.com

Consequences of introducing the Baltic and North Sea into NOx emission control areas

The introduction of the North Sea and Baltic Sea – where Europe’s largest ports are located – into the NOx emission control area means that all new ships operating globally will have to be equipped with IMO III-compliant engines. IMO III NOx emissions, which are about 5 times lower compared to IMO I, require internal combustion engine manufacturers to implement additional emission reduction technologies.

IMO Standard III – who is not affected?

It should be noted that the emission level requirement does not apply to vessels less than 24 meters in length used and designed for recreational purposes and also vessels with a total power of less than 750 KW. Such ships cannot meet the standard due to design or construction constraints.

Caterpillar – elimination of nitrogen oxides in exhaust gases

One of the technologies used is Selective Catalytic Reduction (SCR). This is the most effective method of eliminating nitrogen oxides in the exhaust gas. The agent that reduces nitrogen oxides is an aqueous urea solution ( Diesel Exhaust Fluid – DEF). It is sprayed directly into the exhaust stream before the reactor, where it breaks down into ammonia and carbon dioxide. Ammonia reacts with nitrogen oxides to form free nitrogen and water vapour.
According to IMO regulations, each engine on a marine vessel subject to IMO regulations should have technical documentation identifying critical engine components affecting NOx emissions. Such critical elements are:

• injectors,
• injection pump,
• camshaft,
• cylinder head,
• piston, connecting rod,
• charge air cooler,
• turbocharger,
• SCR system.

Thus, the SCR system becomes an integral part of the engine. Therefore, the entire system must be designed, manufactured and tested by the engine manufacturer, especially since the correct operation of the system on the ship is under the supervision of inspectors from classification associations. Caterpillar, a leader in 4-stroke marine engines, offers only factory-prepared IMO III engines with SCR system. Designing the engine to work with the SCR system allows it to work optimally and reliably and, most importantly, ensures a constant reduction in harmful nitrogen oxides. The CAT engine computer continuously adjusts the engine’s operating parameters to ensure the best conditions for reaction in the catalytic converter. If necessary, it shuts down part of the cylinders so that the remaining cylinders, being more loaded, cause a faster increase in the exhaust gas temperature allowing the catalytic reaction to be initiated.
Such an option is not available in marine engines from other manufacturers offered with third-party SCR systems. In fact, they are IMO II engines with “add-ons” that limit emissions to IMO III levels. Such systems purify exhaust gases only when conditions are right. The engine computer in no way “knows” that it is working with the SCR system so its software does not influence the optimisation of the process.

Zalety silników okrętowych Caterpillar IMO III

Advantages of Caterpillar IMO III marine engines

Other advantages of a factory-supplied system are worth mentioning here. Of course, expanding the technology with additional components comes at a slightly higher cost of purchasing the engine. However, by optimising fuel injection and setting camshaft with the utmost precision in CAT engines, a 5-7% reduction in fuel consumption can be achieved compared to standard engines. Thus, the cost of purchasing an SCR system pays for itself during the engine life cycle. SRC service intervals coincide with the engine’s regular maintenance schedule, so no additional maintenance is required throughout the life of both the engine and the SCR system.

Caterpillar offers a complete IMO III-compliant engine programme. All IMO III engine models offer the option to switch to the IMO II operating regime. This saves DEF in areas where it is not necessary to meet IMO III emissions.
Larger models use a system of assisted DEF spraying with compressed air (Air Assisted Dosing) which allows better mixing and a more complete chemical reaction with lower DEF consumption.

For compactness, the airless dosing system is used in smaller models.

IMO III engine main propulsion programme

IMO III auxiliary engine and power generator programme

IMO III auxiliary engine and power generator programme

Invest wisely by reaching out to professionals

Buying a product featuring the latest solutions guarantees quality and reliability. The engines belong to the premium class, so you will always find comprehensive solutions tailored to the latest requirements.

CAT^® Marine Engines

mail: mhoffman@eneria.pl

Written by: Maciej Hoffman

Marine Department Director

Marine Market Expert