10 Best Methods to Control Marine Emissions from Ships

How to Control Marine Emissions from Ships


Marine emissions are a big problem for the environment. They are created when ships produce large amounts of pollution. Marine emissions are a major ecological issue. As our planet becomes increasingly polluted, it is more important than ever for people to understand HOW TO CONTROLMARINE EMISSIONS.

Marine emissions are a big issue for many people. The spread of marine pollution is a huge issue that we are facing on a global level. Maritime emissions can cause a great deal of damage to the environment, including the health of humans. 

This blog post will cover the basics of marine emissions, how to control them, and how you can help to solve the ecological crisis. We will also provide the readers with the latest information on marine emissions and how to control them.

1.   How to protect the marine environment,

2.    Prevent air pollution from ships,

3.    Regulate air emissions from ships,

4.   Reduce air pollution in the shipping industry.

Why should air pollution from ships be regulated ?

Despite the fact, there is no natural origin and enact correlated with pollution of air from ships. Spill-over oil will induct accumulative bad effects, which add to the comprehensive air quality complications confronted by people in many areas and influence the natural surroundings in severe acid rain.

International Convention for the prevention of pollution from Ships (MAPROL) are stringent. Universally continuous minimization in emissions of SOx, NOx, and particulate elements and the addition of emission control areas (ECAS) to minimize emissions of these toxic wastes additionally in nominated sea spaces.

With the revised MAPROL regulations, the universal sulfur cap has been decreased from 3.5% to 0.5% effective from January 2020.

How to protect Marine Environment

Main Types of pollutants from ships

  1. Oils used onboard ships.
  2. Chemicals
  3. Sewage
  4. Garbage
  5. Ballast Tank water
  6. Paints-Antifouling
  7. Air Pollution

Oils used onboard ships

Oil spills will be the reason for the severe and prolonged standing impacts. Spilled oil creates severe hazards to fresh water and a marine climate, affecting surface assets and extensive area of under surface species associated with humankind’s food resources.

Spilled oil will harm the surroundings in the following ways.

  • Physical harm to wildlife (birds and mammals).
  • Poison unprotected creatures. 


Chemicals and many other toxic aqua materials will be a threat to the marine environment. Following the type of pollutants are also included a variety of commodities such

  1.  Vegetable oil, 
  2. Raw substances from the production,
  3.  Effluent from the factory. 


Marine release of SewageWill harms the environment and human beings by polluting seafood, spreading disease to water users, generating unsuited surroundings for marine life.

The severe accumulative effects will be caused by Sewage discharge from ships.


Garbage will be especially present in the sea, with some natural plastics greenhouse effect. Particles of plastics will enter the seafood, and other debris in the marine surroundings will also suffocate the seafloor and unite around mammals. 

Ballast Tank water

Ballast water is carried in the blast water tanks for maintaining the ship’s stability; This water is pumped into the ballast water tanks before assuming the sailing. Unfortunately, some marine organisms are also carried in the blast water. These organisms become pests pest and will cause a threat to the sea and fisheries once pumped out of the sea.

Paints-Anti fouling

Anti fouling paints are used to reduce the growth of the leech at the hull of the ship. However, these paints scraped off while cleaning will be poisonous to the sea environment.

Air Pollution

Greenhouse gases like Carbon dioxide, Sulphur, and nitrous oxide are contained in the engine exhaust gases. Exhaust gases also have un-burnt fuel and soot particles. These pollutants contained in the exhaust gases will are health hazards to Human beings.

Essential reasons to pay more attention to MARINE EMISSIONS

With the shipping industry’s growth, the ship’s harmful impingement on air quality continues to expand. 

Land-based industrial emissions –Sox and NOx and other particulates have drastically minimized at a higher rate. 

Sox and NOx, and other particulates from shipping industries need to pay more attention to ship emissions.

Many premature deaths are caused by the emissions of hazardous quality of air by international shipping.

 SO2 and NOx get transformed into minute particles, sulphates, and nitrates aerosols due to the chemical reaction in the air.

Ships also emit black carbons increases the health hazards on the shipping surroundings. These tiny particles get into the lungs and blood, causing heart and lungs failure with chronic respiratory ailments.

Marine emissions will also include carcinogenic particles that contribute to cancer diseases in human beings.

Acid rain


It refers to SO2 and SO3. Even though SO2 is noticed as gas or molecules, SO3 is detected as PM. In combustion processes, sulfur in fuel leads to the formation of SOx. SOx is an unwelcome by-product because it is considered an air pollutant along with NOx. SOx is the leading cause of smog.

How to prevent Air pollution from ships? 

Fuel regulations for MARINE EMISSIONS

  • Combustion enhancement: – An Important Benefit of combustion enhancement is that no additional device is required outside of the engine.

Bio Fuels

Bio fuels, which usually are liquid or gas, are made from plants instead of fossil fuels. Diesel Engines use the specified bio diesel fuel. In this process of producing BDF, glycerol is extracted from vegetable oil of animal fats.

Fuel governance and specifications for marine diesel engines (MARINE EMISSIONS

commonly, high-grade fuels are climate-friendly but are expensive.


 The Natural evaporated gas known as boil-off gas of LNG is used as fuel for the engines. Use of LNG is to reduce mainly   SOx, NOx, and CO2 emissions. SOx emission is almost zero, while NOx and CO2 could be minimized by nearly 80% and 25%, respectively. Nonetheless, a demerit is that a substantial special tank is required to store LNG, which causes problems in terms of expenditure and stock capacity in a ship.


This regulation caps the mass of NOx emissions per engine output power for specified engine rotating speed n as shown by the horizontal axis below.

Marine Emissions from Ships

NOx reduction by Urea selective catalytic reduction method (HOW TO CONTROL EMISSIONS IN MARINE AND LAND)

SCR method-nox reduction
  • For the removal of NOx, Urea selective catalytic reduction method is a safer method than the Ammonia Injection Method.

Pollution Control by Marine Diesel Engines (MARINE EMISSIONS)

Better fuel efficiency and compact size of the Diesel Engines have the benefit of lower carbon dioxide and helps in reducing the MARINE EMISSIONS . In spite of these facts harmful particulate matter and NOx contained in the Diesel Engines emissions, control technology is needed.

Marine Diesel emits high NOx concentration which emissions are relatively high (500e1000 ppm). Moreover Marine diesel emissions consists of sulphur oxides (SOx) and PM

Due to the low RPM of Diesel engines incepts emissions at slow rate and are easy to control.

From the viewpoint of environmental safety, Fuel injection system is the main technology for the reduction of emissions in addition to the improvement of efficiency in Diesel Engine, since it is concerned with the combustion enhancement.

Impulsive Valve timing system is the automated regulation mechanism. Closing of intake valve before the bottom dead centre will lower the combustion temperature and minimize the effective compression ratio. This will result in emission reduction.

Fuel is injected with an abundance ratio of surface area to the volume by greater number of smallest particles. This form of injected fuel produces enhanced vaporization from the area of the fuel globules. This complete process results in perfect and cleaner combustion with reduced NOx and Particulates emissions.

An ignition delay is created by injecting a small amount of fuel into the pre-ignition chamber. NOx is minimized by preventing rapid ignition by the ignition delay method.  A common-rail fuel injection system is installed for the new technologies of emission control.

Common Rail Injection

10 Best Methods to Control Marine Emissions from Ships

Humid Air Method

The Humid Air Method is one of the solutions that can be used to reduce ships’ emissions effectively. This method works by introducing water vapor into the exhaust gas stream of a vessel, which reduces the overall combustion temperature and helps reduce emissions. This technique has been proven to significantly reduce hydrocarbon and nitrogen oxide (NOx) emissions from ships.
The Humid Air Method is relatively cheap, easy to implement, and does not require significant changes or modifications to ship engines or systems. In addition to reducing air pollution, this method also provides other benefits, such as improved engine efficiency and reduced fuel consumption. It allows ship owners and operators to meet emission requirements while remaining competitive in cost and performance.

Exhaust Gas Re circulation (EGR)

Exhaust Gas Recirculation (EGR) is a technology that controls marine emissions from ships and other vessels. It works by rerouting some of the exhaust gas from the engine back into the scavenge space, mixing it with air during combustion, and reducing harmful pollutants. As a result, EGR helps reduce nitrogen oxide (NOx) emissions, which can cause environmental degradation and global warming.

The International Maritime Organization (IMO) has issued strict regulations to limit NOx emissions from sea-going ships. EGR has proved to be an effective way to reduce NOx levels to meet these standards while still providing efficient operation of the engines. This technology also helps reduce carbon dioxide levels, further improving air quality and contributing towards global efforts at reducing climate change.

Water Injection and Water emulsion

Water injection and emulsion are two of the most widely used methods for controlling marine emissions from ships. As engines become more powerful, exhaust gases, such as nitrogen oxides (NOx), contain higher pollutants. By injecting water or creating a fuel/water emulsion, combustion temperatures can be reduced, leading to lower NOx emissions.

This method has become increasingly important in recent years as governments worldwide introduce stringent emission regulations to protect our environment. This method adds water directly into the engine cylinder through an injector or mixed with the fuel before injection.
Water emulsion also helps reduce smoke visibility, enhancing air quality in ports and coastal areas.
This method has the disadvantage of increasing the combustion of certain fuel oils while reducing NOx by only 20-45%.

 Two Stage Turbocharger

To address this marine emissions problem, ABB has developed a modern two-stage turbocharger. Two-stage turbocharger helps reduce the exhaust gas temperature in the charge air cooler and the NOx content of the exiting exhaust gas. This turbocharger is designed to provide maximum fuel efficiency and reduce emissions from ships by up to 40%.

The two-stage turbocharger works on a two-step process where the first step involves exhausting air from inside a ship’s engine compressor and recycling it through its intercoolers. The two-stage turbocharger helps cool down the air before it enters the combustion chamber, helping reduce noise levels and particulate matter and Nitrogen Oxides (NOx). The second step involves re-compressing this cooled air into an even higher pressure, providing more power output than any other type of single-stage turbocharger.
This latest development from ABB not only reduces emissions but also cuts fuel costs for

Modification Engine components

To reduce NOx formation during combustion process, it is better to design an engine which has higher efficiency and lower fuel consumption. Modification of engine components such as air intake, fuel injection system and exhaust system are some of the strategies used for controlling marine emissions from ships. In addition, use of alternative fuels such as biofuels or liquefied natural gas (LNG) will help in reducing the emission levels significantly.

High Scavenge Pressure and Compression Ratio

The increasing emissions from ships due to their large combustion engines is a major environmental problem. Introducing high scavenge pressure and compression ratio is an effective solution to tackle it. High scavenge pressure and compression ratio can ensure that a large amount of air is introduced inside the cylinder, reducing the combustions’ harmful exhausts.

High scavenge pressure and compression ratio will reduce the number of pollutants released into the atmosphere and help limit global warming. It also helps make ships more fuel-efficient and reduces operational costs for ship owners.

High scavenge pressure and compression ratio can be achieved through advanced engineering solutions such as turbochargers, intercoolers, fuel injection systems, and exhaust gas recirculation systems. Many countries are adopting these measures on their vessels to reduce marine emissions as part of their green policies.

As such, it is clear that with high scavenge pressure and compression ratio, we can have considerable control over the marine emissions released from ships to protect our environment.

Selective Catalytic Reduction

Selective Catalytic Reduction (SCR) is a promising technology for reducing Nitrogen Oxide (NOx) emissions from ships. It is the most efficient method for controlling marine emissions, potentially reducing up to 90-95% of NOx pollution. The SCR works by injecting a low-sulfur fuel known as Diesel Exhaust Fluid (DEF) into the exhaust gas stream of engines and converting nitrogen oxides into harmless nitrogen and water vapor. This method can be applied both in new vessels and in existing fleets, providing an effective solution for reducing air pollution from ships.

Scrubber Technology for Exhaust Gas

Scrubber technology is being used to clean exhaust gas from ships, To address the issue of Marine emissions.
The process involves passing the exhaust gas from the engine through a scrubber tower where a liquid is showered. This liquid can be either freshwater or seawater blended with chemicals such as caustic soda and acetic acid. The chemical reaction between these chemicals and pollutants in the exhaust gas results in clean emissions released into the atmosphere.

In addition to reducing emissions, scrubber technology helps ships meet international standards for air pollution control set by regulatory bodies like IMO and EPA. This technology can thus play an essential role in reducing marine pollution caused by ships and help protect our environment in the future.

Cylinder Lubrication

To counter the Marine emissions from ships, good quality cylinder lubrication along with efficient control systems such as Pulse or Alpha lubrication systems can neutralize the problem and help reduce marine emissions.

Cylinder lubrication plays a vital role in controlling marine emissions as it reduces friction and wears between moving parts, thereby reducing fuel consumption and harmful exhaust gases. It also helps improve engine efficiency and reliability, extend engine life, reduce maintenance costs, and increase safety on the ship. The Pulse or Alpha lubrication systems are advanced control systems that help monitor and regulate the oil supply to each cylinder accurately at all times.

In conclusion, high-quality cylinder lubrication, along with efficient control systems such as Pulse or Alpha lubrication systems, can be used to reduce marine emissions from ships effectively. Such solutions are environment-friendly and cost-effective in the long run.

Use of Low sulphur fuel oil

Low Sulphur Fuel Oil is one of the most commonly used methods to comply with Annex VI of the MARPOL Convention while entering an Emission Control Area (ECA). This method is proven effective in reducing ships’ emissions and helps maintain a healthy environment.

It is also an expensive option but offers greater control over pollutants and can help reduce the risk of fines for entering an ECA without complying with emission standards. LSFO has become increasingly popular due to its effectiveness in controlling harmful pollutants from ships, making it one of the most reliable methods for ship owners and operators to comply with MARPOL regulations.

FAQ on Marine emissions

Degrades air quality, affects human health, and contributes to the far-reaching effects of climate change

More than three percent of global carbon dioxide emissions can be attributed to ocean-going ships

Areas where stricter controls have been introduced to minimize emissions from ships to the atmosphere

Actively participate in efficient ship operation and waste reduction

Blog Conclusion

We hope you enjoyed our article on Marine Emissions from Ships.While the ocean is a beautiful and important part of our lives, we also need to realize that it’s a natural habitat. And through research, we have discovered some of the harmful things that don’t quite make sense in the ocean’s ecosystem. For example, the use of harmful chemicals in the ocean that disrupt the basic marine life and how these chemicals can affect the human population. Thank you for reading, we would love to hear from you!

Hi, I’m Sham, Founder of marinediesel.co.in. A web site that provides authentic information regarding Marine Diesel Engines, and learn marine Engineering free with us

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