Reducing Ship Air Pollution: Strategies For Cleaner Oceans

Air pollution from ships is a serious issue that contributes to overall air quality problems and affects the natural environment. While it may not have the direct cause and effect associated with an oil spill, for example, it has a cumulative effect on the air quality in many areas. To address this issue, the International Maritime Organization (IMO), a United Nations agency, developed MARPOL, the main international agreement covering all types of pollution from ships. Annex VI of the MARPOL treaty specifically addresses air pollution from ships, including requirements for the manufacture, certification, and operation of vessels and engines, as well as fuel quality. To reduce sulphur oxide (SOx) emissions, scrubbers can be used to clean the exhaust from marine engines, removing most of the direct sulphate particulate matter (PM). Additionally, ships operating near U.S. shores must meet advanced standards for NOx emissions and use fuel with lower sulphur content.

Scrubbers can be used to clean exhaust from marine engines, removing sulphur and reducing SOx emissions

SOx scrubbers are an effective way to reduce sulphur emissions from ships, as they can remove most of the direct sulphate particulate matter (PM). Sulphates are a large portion of the PM from ships operating on high-sulphur fuels. By reducing the SOx emissions, the scrubber also controls much of the secondary PM that is formed in the atmosphere from these emissions.

The MARPOL treaty, developed through the International Maritime Organization (IMO), is the main international agreement covering all types of pollution from ships. Air pollution from ships is specifically addressed in Annex VI of the MARPOL treaty, which includes requirements applicable to the manufacture, certification, and operation of vessels and engines, as well as fuel quality.

Ships operating up to 200 nautical miles off of US shores must meet the most advanced standards for NOx emissions and use fuel with lower sulphur content. Each regulated diesel engine in US-flagged vessels must have an Engine International Air Pollution Prevention (EIAPP) certificate, issued by the EPA, to document that the engine meets Annex VI NOx standards.

Ships operating within 200 nautical miles of the US must meet advanced NOx emissions standards and use low-sulphur fuel

MARPOL Annex VI, first adopted in 1997, limits the main air pollutants contained in ships' exhaust gas, including sulphur oxides (SOx) and nitrous oxides (NOx). To comply with these regulations, ships can use scrubbers to clean the exhaust from marine engines using high-sulphur residual oil and diesel fuels. This method is more economical than switching to low-sulphur fuel, and SOx scrubbers are capable of removing up to 95% of SOx from ship exhaust.

In the US, each regulated diesel engine in US-flagged vessels must have an Engine International Air Pollution Prevention (EIAPP) certificate, issued by the EPA, to document that the engine meets Annex VI NOx standards. Ship operators must also maintain records on board regarding their compliance with the emission standards, fuel requirements and other provisions of Annex VI.

The MARPOL treaty, developed by the International Maritime Organisation, addresses air pollution prevention requirements from ships

Annex VI of the MARPOL treaty limits the main air pollutants contained in ships' exhaust gas, including sulphur oxides (SOx) and nitrous oxides (NOx), and prohibits deliberate emissions of ozone-depleting substances (ODS). The use of scrubbers to clean the exhaust from marine engines using high-sulphur residual oil and diesel fuels is a more economical option for reducing SOx air emissions. The scrubbers used today for sulphur control are commonly known as SOx scrubbers. In a wet scrubber, the exhaust gas is mixed with washwater, and the water-soluble components of the exhaust gas are removed by dissolution into the washwater. SOx scrubbers are capable of removing up to 95 per cent of SOx from ship exhaust.

Ships operating up to 200 nautical miles off US shores must meet the most advanced standards for NOx emissions and use fuel with lower sulphur content. Each regulated diesel engine in US-flagged vessels must have an Engine International Air Pollution Prevention (EIAPP) certificate, issued by the EPA, to document that the engine meets Annex VI NOx standards. Certain vessels are also required to have an International Air Pollution Prevention Certificate (IAPP), which is issued by the United States Coast Guard (USCG). Ship operators must also maintain records on board regarding their compliance with the emission standards, fuels requirements and other provisions of Annex VI.

The MARPOL treaty also regulates shipboard incineration and the emissions of volatile organic compounds (VOCs) from tankers

The MARPOL treaty, developed through the International Maritime Organization (IMO), a United Nations agency, is the main international agreement covering all types of pollution from ships. Air pollution from ships is specifically addressed in Annex VI of the MARPOL treaty, which includes requirements applicable to the manufacture, certification, and operation of vessels and engines, as well as fuel quality used in vessels in the waters of the United States.

Annex VI of the MARPOL treaty limits the main air pollutants contained in ships' exhaust gas, including sulphur oxides (SOx) and nitrous oxides (NOx), and prohibits deliberate emissions of ozone-depleting substances (ODS). To meet these requirements, ships can use scrubbers to clean the exhaust from marine engines using high-sulphur residual oil and diesel fuels. This method is capable of removing up to 95% of SOx from ship exhaust.

Ships operating up to 200 nautical miles off US shores must meet advanced standards for NOx emissions and use fuel with lower sulphur content. Each regulated diesel engine in US-flagged vessels must have an Engine International Air Pollution Prevention (EIAPP) certificate, documenting that the engine meets Annex VI NOx standards.

The scrubbers used to reduce SOx emissions also control much of the secondary PM that is formed in the atmosphere from these emissions

Scrubbers are used to clean the exhaust from marine engines using high-sulphur residual oil and diesel fuels. The scrubbers remove sulphur from the exhaust, which in turn removes most of the direct sulphate particulate matter (PM). This is important because sulphates make up a large portion of the PM from ships operating on high-sulphur fuels.

The scrubbers are also capable of removing up to 95% of SOx from ship exhaust. By reducing SOx emissions, scrubbers also control much of the secondary PM that is formed in the atmosphere from these emissions.

The EGCSs used today for sulphur control are commonly known as SOx scrubbers. In a wet scrubber, the exhaust gas is mixed with washwater, and the water-soluble components of the exhaust gas are removed by dissolution into the washwater.

The MARPOL International Convention for the Prevention of Pollution from Ships requires the use of scrubbers to reduce SOx air emissions. Ships operating up to 200 nautical miles off US shores must meet the most advanced standards for NOx emissions and use fuel with lower sulphur content.

Frequently asked questions