Meeting IMO Requirements

The most viable solution – exhaust gas cleaning systems

As the strict IMO regulations are being implemented step by step, time is slowly running out for ship owners around the world. It is high time to choose the right solution to the SOx and NOx emission challenge.

Even though there are other ways to go about the problem, installing exhaust gas cleaning systems has, however, proven to be the most viable solution.

How to comply with IMO SOx requirements?

  • Use Marine Gas Oil only
    • The expensive MGO fuel meets the Sulphur limits required in the emission control areas.
    • Drawbacks: Significantly increased fuel costs
  • Switch between fuels
    • Meet the emission limits by switching to low Sulphur fuel when entering an emission control area.
    • Drawbacks: Increased fuel costs
    • Complicated procedures when switching between fuels
  • Install an exhaust gas cleaning system
    • Exhaust gas cleaning systems from ME Production reduce emissions in accordance with IMO regulations
    • Drawbacks: None

International Legislation

Reducing emissions of air pollutants and greenhouse gases

In 2007, international shipping was estimated to have contributed about 2.7 % to the global emissions of carbon dioxide (CO2). In order to minimize airborne emissions from ships and their contribution to the climate change challenge, IMO – the International Maritime Organization – has adopted mandatory energy efficiency measures.

The mandatory treaty provisions – Annex VI of the MARPOL Convention – to reduce emissions of air pollutants and greenhouse gases from international shipping were first adopted at IMO in 1997. Later followed revisions significantly strengthening the emission limits and in July 2010 the revised MARPOL Annex VI and the associated NOx Technical Code 2008 entered into force.

The revised Annex VI aims for a progressive reduction globally of SOx and NOx emissions and introduces so-called emission control areas (ECAs) to reduce emissions even further in specific sea areas. The revised measures are expected to have a positive impact on the environment including local and global air pollution.

Air pollution and fuel quality

The International Maritime Organization (IMO) has adopted mandatory energy efficiency measures to reduce the amount of CO2 emissions from international shipping. The international air pollution and fuel quality requirements are found in MARPOL Annex VI.


  • Sets limits on Sulphur oxide (SOx) and nitrogen oxide (NOx) emissions from ship exhausts.
  • Prohibits deliberate emissions of ozone depleting substances.
  • Limits the Sulphur content of fuel oil. The global Sulphur cap is reduced initially to 3.50% (from the current 4.50%), effective from 1 January 2012; then progressively to 0.50 %, effective from 1 January 2020.
  • Allows special SOx and NOx emission control areas (SECAs and NECAs) to be established. The Baltic Sea, the North Sea, the English Channel, the American and Canadian coasts and inland waters are emission control areas.
  • In the SECAs more stringent limits on Sulphur emissions apply. The limits are reduced from the original 1.50% to 1.00% beginning on 1 July 2010 and will be even further reduced to 0.10 %, effective from 1 January 2015.
  • In the NECAs, all ships are required to drastically reduce their NOx emissions. The Tier II emission limit applies to engines installed on or after 1 January 2011. Tier III emission limit applies to engines installed on or after 1 January 2016 operating in NECAs. Tier III levels are 80% lower than the current levels.

IMO sets 2020 as implementation date for 0.5% sulphur cap

Under the new global cap, ships will have to use fuel oil on board with a sulphur content of no more than 0.50% m/m, against the current limit of 3.50%, which has been in effect since 1 January 2012. The interpretation of “fuel oil used on board” includes use in main and auxiliary engines and boilers. Exemptions are provided for situations involving the safety of the ship or saving life at sea, or if a ship or its equipment is damaged.

Ships can meet the requirement by using low-sulphur compliant fuel oil. An increasing number of ships are also using gas as a fuel as when ignited it leads to negligible sulphur oxide emissions. This has been recognised in the development by IMO of the International Code for Ships using Gases and other Low Flashpoint Fuels (the IGF Code), which was adopted in 2015. Another alternative fuel is methanol which is being used on some short sea services.

Ships may also meet the SOx emission requirements by using approved equivalent methods, such as exhaust gas cleaning systems or “scrubbers”, which “clean” the emissions before they are released into the atmosphere. In this case, the equivalent arrangement must be approved by the ship’s Administration (the flag State).

The new global cap will not change the limits in SOx Emission Control Areas (ECAS) established by IMO, which since 1 January 2015 has been 0.10% m/m. The ECAs established under MARPOL Annex VI for SOx are: the Baltic Sea area; the North Sea area; the North American area (covering designated coastal areas off the United States and Canada); and the United States Caribbean Sea area (around Puerto Rico and the United States Virgin Islands).

Nitrogen oxide (NOx)

The purpose of NOx regulations is to reduce the emission of nitrogen oxide (NOx) from ships since it contributes to air pollution ashore and to algal bloom in the sea. Read more about the regulations on NOx emissions.

When the chapter on air pollution from ships (chapter VI) of the MARPOL Convention was revised in 2008, new sulphur requirements were introduced and, at the same time, the NOx requirements were amended. This means that, from 2016, new ships must meet requirements that will result in an 80 per cent reduction of NOx emissions from ships, but only in NECAs (NOx Emission Control Areas).

Right now, there are NECAs only along the coasts of the USA and Canada and around a few American areas in the Caribbean. In the longer term the North Sea and the Baltic Sea are also expected to become NECAs.

At its recent session, the Marine Environment Protection Committee (MEPC) of the IMO approved the North Sea, the Baltic Sea and the English Channel as NECAs from 2021.

NOx regulations in detail

The regulations on the discharge of nitrogen oxides (NOx) are laid down in MARPOL Annex VI and the technical NOx Code.

The regulations, which apply to engines with an output of more than 130 kW, are as follows:

TIER I (Global regulations)

  • The use of marine diesel engines installed on ships constructed between 1 January 2000 and 1 January 2011 is prohibited unless the emission of nitrogen oxide from the engine follows the upper curve on the graph (see below).

TIER II (Global regulations)

  • The use of marine diesel engines installed on ships constructed on or after 1 January 2011 is prohibited unless the emission of nitrogen oxide follows the TIER II curve on the graph (see below). This corresponds to approx. a 15-20 per cent reduction compared to TIER I.

TIER III (NECA regulations)

  • The use of marine diesel engines installed on board ships constructed on or after 1 January 2016 and operating in a NECA must reduce NOx emissions by approx. 80 per cent compared to TIER I. See the lower curve on the graph (see below).

In addition, regulations apply to engines installed between 1 January 1990 and 1 January 2000 if they have an output of more than 5,000 kW. They must meet the TIER I requirements.

We run our own test center

ME Production runs its own test center for full-scale testing of new products and solutions. At the test center we are capable of simulating our customers’ operating environments and thus, design customized systems that fit the individual vessel’s actual layout and operational profile.