**1. Introduction**

[31] Howells, G. 1995. Acid rain and Acid water. 2nd Ed. Ellis Horwood Ltd.

3616- 3620. doi: 10.1021/es903722p

164 Current Air Quality Issues

[32] Pierson W.R, Brachaczek, W.W (1983) Emissions of ammonia and amines from vehi‐ cles on the road. Environ. Sci. Technol. 17: 757- 760. doi: 0013- 936X/83/0917- 0757 [33] Bishop, G.A; Peddle, A.M; Stedman, D.H. 2010. On- road emission measurements of reactive nitrogen compounds from three California cities. Environ, Sci. Technol, 44:

> The aim of this chapter is to provide an overview of the air pollution generated by diesel engines of the ocean-going ships and the technologies as well as methodologies available to reduce these emissions. This chapter begins with general significant information of the air pollutant emission from ships followed by a summary of the International Maritime Organi‐ zation (IMO) regulatory MARPOL Annex VI being developed to control marine shipping emissions as well as information on the various types of the ocean-going ships and their prime movers with particular emphasis on marine diesel engines as sources of air pollution from ships. For better understanding of the formation of air pollutants from marine diesel engines, authors gave a brief overview of the working principles of marine diesel engines as well as their combustion process and chemistry of the pollutant formation during that process. Finally, the chapter concludes with an analysis of several control methods that can effectively reduce harmful pollutant emissions from marine diesel engines.

> Climate change on Earth is one of the largest civilised problems at the beginning of the twentyfirst century. Anthropogenic impact on the Earth's climate became one of the crucial environ‐ mental issues of modern civilisation in the late twentieth century. Therefore, nowadays the ecology and preservation of human environment have become two of the very important human activities all over the world. Besides primary pollution from the land, nowadays attention is being paid to the pollution from the ships. In recent decades, shipping industry and maritime traffic have rapidly developed. From the economic point of view, this trend, which continues today, has a very positive impact on economic development but on the other hand, a very negative impact on the environment in terms of air pollution. Exhaust gases from marine diesel engines are the primary source of emissions from ships and contribute signifi‐ cantly to environmental pollution. Ocean-going ships are the major contributors to global emissions of several hazardous air pollutants such as nitrogen oxides (NOx), sulphur oxide

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

from ships:

labelling.

distances.

(SOx), fine particulate matter (PM), hydrocarbons (HCs), carbon monoxide (CO) and green‐ house gas carbon dioxide (CO2).

The presence of these pollutants has local and global impact. Impacts on local (or regional) air quality are mainly linked to pollutants such as PM, NOx and sulphur, while CO2 has a global impact on climate [1]. The amount of gases emitted from marine engines into the atmosphere is directly related to the total fuel oil consumption. While pollutant emissions from land-based sources are gradually decreasing, those from shipping show a continuous increase. It is estimated that by 2020, the emissions NOx and SOx from international shipping around Europe are expected to equal or even surpass the total emissions from all land-based mobile, stationary and other sources in the 25 EU member states combined (see Figure 1). It should be noted that these figures refer only to ships in the international trade and do not include emissions generated from shipping in countries' internal waterways or from ships plying harbours in the same country, which are given in the domestic statistics of each country [2].

Figure 1. Emissions NOx (a) and SOx (b) 1990–2030 from land-based sources and international

shipping **Figure 1.** Emissions NOx (a) and SOx (b) 1990–2030 from land-based sources and international shipping

It has been estimated that about 90 % of the total sulphur dioxide (SO2) and NOx emissions from ships in the North Sea, including the English Channel, originate from a zone of approximately 50 nautical miles from the coast line. International shipping was estimated to be a source of 97 % of the total SO2 and NOx emissions in the North Sea within a distance of 100 nautical miles from the seaboard, as in [3]. The emissions of sulphur dioxide (SO2), particulate matter (PM) and greenhouse gases (GHGs) from global shipping were increased from 585 to 1096 million tons between 1990 and 2007. The CO2 emissions from international shipping are estimated at 943.5 million tons for the year 2007 and CO2 emissions from global shipping are about 1 billion tons for the year 2006. International shipping is responsible for 3 % of global CO2 emissions as in [4]. **2. International regulation concerning air pollution from merchant shipping**  It has been estimated that about 90 % of the total sulphur dioxide (SO2) and NOx emissions from ships in the North Sea, including the English Channel, originate from a zone of approx‐ imately 50 nautical miles from the coast line. International shipping was estimated to be a source of 97 % of the total SO2 and NOx emissions in the North Sea within a distance of 100 nautical miles from the seaboard, as in [3]. The emissions of sulphur dioxide (SO2), particulate matter (PM) and greenhouse gases (GHGs) from global shipping were increased from 585 to 1096 million tons between 1990 and 2007. The CO2 emissions from international shipping are estimated at 943.5 million tons for the year 2007 and CO2 emissions from global shipping are about 1 billion tons for the year 2006. International shipping is responsible for 3 % of global CO2 emissions as in [4].

#### Because shipping is inherently international, it is vital that shipping is subjected to uniform regulations on issues such as air emissions from ships. The shipping industry is principally regulated by the International Maritime Organization (IMO), which is a UN agency based in London and **2. International regulation concerning air pollution from merchant shipping**

Annex I deals with regulations for the prevention of pollution by oil.

Annex IV contains requirements to control pollution of the sea by sewage.

liquid substances carried in bulk.

pollution rules are contained in the 'International Convention on the Prevention of Pollution from Ships' known as MARPOL 73/78, which represents the first set of regulations on marine exhaust Regulations concerning air pollution from merchant shipping are developed at the global level. Because shipping is inherently international, it is vital that shipping is subjected to uniform

Regulations concerning air pollution from merchant shipping are developed at the global level.

responsible for the safety of life at sea and the protection of the marine environment. IMO ship

emissions. The original MARPOL Convention was signed on 17 February 1973, but did not come into force. The current Convention is a combination of the 1973 Convention and the 1978 Protocol. MARPOL73/78 contains 6 annexes concerned with preventing different forms of marine pollution

Annex II details the discharge criteria and measures for the control of pollution by noxious

Annex III contains general requirements for issuing standards on packing, marking and

Annex V deals with different types of garbage, including plastics, and specifies the

 Annex VI deals with gaseous emissions of ship engines and installations: the Convention regulates sulphur oxide, nitrogen oxide and particulate matter emissions from ship exhausts and prohibits deliberate emissions of ozone-depleting substances. It also contains provisions allowing for the creation of special Emission Control Areas (ECA) with even more stringent controls on air pollutant emissions. Annex VI also forbids any (deliberate) regulations on issues such as air emissions from ships. The shipping industry is principally regulated by the International Maritime Organization (IMO), which is a UN agency based in London and responsible for the safety of life at sea and the protection of the marine environ‐ ment. IMO ship pollution rules are contained in the 'International Convention on the Preven‐ tion of Pollution from Ships' known as MARPOL 73/78, which represents the first set of regulations on marine exhaust emissions. The original MARPOL Convention was signed on 17 February 1973, but did not come into force. The current Convention is a combination of the 1973 Convention and the 1978 Protocol. MARPOL73/78 contains 6 annexes concerned with preventing different forms of marine pollution from ships:

**•** Annex I deals with regulations for the prevention of pollution by oil.

(SOx), fine particulate matter (PM), hydrocarbons (HCs), carbon monoxide (CO) and green‐

The presence of these pollutants has local and global impact. Impacts on local (or regional) air quality are mainly linked to pollutants such as PM, NOx and sulphur, while CO2 has a global impact on climate [1]. The amount of gases emitted from marine engines into the atmosphere is directly related to the total fuel oil consumption. While pollutant emissions from land-based sources are gradually decreasing, those from shipping show a continuous increase. It is estimated that by 2020, the emissions NOx and SOx from international shipping around Europe are expected to equal or even surpass the total emissions from all land-based mobile, stationary and other sources in the 25 EU member states combined (see Figure 1). It should be noted that these figures refer only to ships in the international trade and do not include emissions generated from shipping in countries' internal waterways or from ships plying harbours in the same country, which are given in the domestic statistics of each country [2].

 Figure 1. Emissions NOx (a) and SOx (b) 1990–2030 from land-based sources and international shipping

**Figure 1.** Emissions NOx (a) and SOx (b) 1990–2030 from land-based sources and international shipping

shipping is responsible for 3 % of global CO2 emissions as in [4].

liquid substances carried in bulk.

from ships:

**shipping**

labelling.

CO2 emissions as in [4].

distances.

**2. International regulation concerning air pollution from merchant shipping** 

**2. International regulation concerning air pollution from merchant**

Annex I deals with regulations for the prevention of pollution by oil.

Annex IV contains requirements to control pollution of the sea by sewage.

It has been estimated that about 90 % of the total sulphur dioxide (SO2) and NOx emissions from ships in the North Sea, including the English Channel, originate from a zone of approximately 50 nautical miles from the coast line. International shipping was estimated to be a source of 97 % of the total SO2 and NOx emissions in the North Sea within a distance of 100 nautical miles from the seaboard, as in [3]. The emissions of sulphur dioxide (SO2), particulate matter (PM) and greenhouse gases (GHGs) from global shipping were increased from 585 to 1096 million tons between 1990 and 2007. The CO2 emissions from international shipping are estimated at 943.5 million tons for the year 2007 and CO2 emissions from global shipping are about 1 billion tons for the year 2006. International

It has been estimated that about 90 % of the total sulphur dioxide (SO2) and NOx emissions from ships in the North Sea, including the English Channel, originate from a zone of approx‐ imately 50 nautical miles from the coast line. International shipping was estimated to be a source of 97 % of the total SO2 and NOx emissions in the North Sea within a distance of 100 nautical miles from the seaboard, as in [3]. The emissions of sulphur dioxide (SO2), particulate matter (PM) and greenhouse gases (GHGs) from global shipping were increased from 585 to 1096 million tons between 1990 and 2007. The CO2 emissions from international shipping are estimated at 943.5 million tons for the year 2007 and CO2 emissions from global shipping are about 1 billion tons for the year 2006. International shipping is responsible for 3 % of global

Regulations concerning air pollution from merchant shipping are developed at the global level. Because shipping is inherently international, it is vital that shipping is subjected to uniform regulations on issues such as air emissions from ships. The shipping industry is principally regulated by the International Maritime Organization (IMO), which is a UN agency based in London and responsible for the safety of life at sea and the protection of the marine environment. IMO ship pollution rules are contained in the 'International Convention on the Prevention of Pollution from Ships' known as MARPOL 73/78, which represents the first set of regulations on marine exhaust emissions. The original MARPOL Convention was signed on 17 February 1973, but did not come into force. The current Convention is a combination of the 1973 Convention and the 1978 Protocol. MARPOL73/78 contains 6 annexes concerned with preventing different forms of marine pollution

Regulations concerning air pollution from merchant shipping are developed at the global level. Because shipping is inherently international, it is vital that shipping is subjected to uniform

Annex II details the discharge criteria and measures for the control of pollution by noxious

Annex III contains general requirements for issuing standards on packing, marking and

Annex V deals with different types of garbage, including plastics, and specifies the

 Annex VI deals with gaseous emissions of ship engines and installations: the Convention regulates sulphur oxide, nitrogen oxide and particulate matter emissions from ship exhausts and prohibits deliberate emissions of ozone-depleting substances. It also contains provisions allowing for the creation of special Emission Control Areas (ECA) with even more stringent controls on air pollutant emissions. Annex VI also forbids any (deliberate)

house gas carbon dioxide (CO2).

166 Current Air Quality Issues


Three different levels (tiers) of NOx control apply based on the ship construction date as follows:


inside the ECA. The Tier 3 NOx emission level corresponds to an 80 % reduction from the Tier 1 standard. The NOx emission limits are expressed as dependent on engine speed (n) in revolution per minute (RPM). These are shown in Table 1 and Figure 2 [6,7].


**Table 1.** NOX limits according to MARPOL Annex VI

For engines with an engine speed lower than 130 RPM, the Tier III level is 3.4 g/kWh. When operating outside an ECA, the engine must meet the Tier II limit of 14.4 g/kWh. Engines with an engine speed higher than 130 RPM must meet even lower limits (see Table 1 and Figure 2). Any abatement technology reducing the NOx emission to the required level can be accepted.

Furthermore, MARPOL Annex VI has set a maximum global fuel sulphur limit of currently 3,5 % in weight (from 1 January 2012) for any fuel used on board a ship. Annex VI also contains provisions allowing for special SOx Emission Control Areas (ECA) to be established with more stringent controls on sulphur emissions. In an ECA, the sulphur content of fuel oil used on board a ship must currently not exceed 1 % in weight. The MARPOL Annex VI has undertaken a review with the intention to further reduce emissions from ships. The current and upcoming limits for future fuel oil sulphur contents are presented in Table 2 and Figure 2 [6,7].


**Table 2.** Sulphur limits in fuel according to MARPOL Annex VI

The rules of SOx apply to all ships, no matter the date of ship construction. Although the SOx requirements can be met by using a low-sulphur fuel, the regulation allows alternative methods to reduce the emissions of SOx to an equivalent level.

<sup>1</sup> Designated Emission Control Areas (ECA) that are defined by the IMO currently comprise the Baltic Sea, the North Sea, the English Channel, the US Caribbean Sea and the area outside North America (200 nautical miles – see Figure 3) The first sulphur Emission Control Area (ECA) was established in the Baltic and came into force internationally on 19 May 2005, and all ships were required to either use the 1.5 % low-sulphur fuel or fit an exhaust gas cleaning system as required by regulation 14 of Annex VI 12 months from this date which was 19 May 2006.

**Figure 2.** Reduction of NOx and sulphur in fuel on the global and ECA limit

inside the ECA. The Tier 3 NOx emission level corresponds to an 80 % reduction from the Tier 1 standard. The NOx emission limits are expressed as dependent on engine speed (n)

For engines with an engine speed lower than 130 RPM, the Tier III level is 3.4 g/kWh. When operating outside an ECA, the engine must meet the Tier II limit of 14.4 g/kWh. Engines with an engine speed higher than 130 RPM must meet even lower limits (see Table 1 and Figure 2). Any abatement technology reducing the NOx emission to the required level can be accepted.

Furthermore, MARPOL Annex VI has set a maximum global fuel sulphur limit of currently 3,5 % in weight (from 1 January 2012) for any fuel used on board a ship. Annex VI also contains provisions allowing for special SOx Emission Control Areas (ECA) to be established with more stringent controls on sulphur emissions. In an ECA, the sulphur content of fuel oil used on board a ship must currently not exceed 1 % in weight. The MARPOL Annex VI has undertaken a review with the intention to further reduce emissions from ships. The current and upcoming

The rules of SOx apply to all ships, no matter the date of ship construction. Although the SOx requirements can be met by using a low-sulphur fuel, the regulation allows alternative

1 Designated Emission Control Areas (ECA) that are defined by the IMO currently comprise the Baltic Sea, the North Sea, the English Channel, the US Caribbean Sea and the area outside North America (200 nautical miles – see Figure 3) The first sulphur Emission Control Area (ECA) was established in the Baltic and came into force internationally on 19 May 2005, and all ships were required to either use the 1.5 % low-sulphur fuel or fit an exhaust gas cleaning system as

limits for future fuel oil sulphur contents are presented in Table 2 and Figure 2 [6,7].

**Fuel sulphur cap Area Date of implementation**

Max. 1 % S in fuel ECA 1 July 2010 Max. 3,5 % S in fuel Globally outside ECA 1 January 2012 Max. 0,1 % S in fuel ECA 1 January 2015 Max. 0,5 % S in fuel Globally outside ECA 1 January 2020

**Table 2.** Sulphur limits in fuel according to MARPOL Annex VI

methods to reduce the emissions of SOx to an equivalent level.

required by regulation 14 of Annex VI 12 months from this date which was 19 May 2006.

n < 130 130 < n < 2000 n > 2000

in revolution per minute (RPM). These are shown in Table 1 and Figure 2 [6,7].

Tier I 2000 17 45 n-0,2 9,8 Tier II 2011 14,4 44 n-0,2 7.7 Tier III 2016 3,4 9 n-0,2 1,96

**Tier Effective date NOx limit (g/kWh)**

168 Current Air Quality Issues

**Table 1.** NOX limits according to MARPOL Annex VI

**Figure 3.** Existing Emission Control Areas as per MARPOL Annex VI (source: www.marlink.com)

The sulphur ECA limit which entered into force in 1 January 2015 can be met using a lowsulphur fuel with sulphur below 0.1 %. The global limit, outside sulphur ECA, can be met using fuel with sulphur content below 0.5 %, which will be required from 2020. The date of the global limit reduction may be changed to 2025 as a result of a feasibility review to be conducted no later than 2018 (see Figure 2).

In order to comply with the requirements of Regulation 14 of MARPOL, the burning of lowsulphur fuel oils (LSFOs) was introduced. There is also an EU regulative about the sulphur content in marine gas oil. Namely, in accordance with EU's marine fuel sulphur directive (1999/32/EG, Article 4 with amendment as per directive 2005/33/EC), the sulphur content in marine gas oil within the territorial waters of an EU member state may not exceed 0.1 % by weight. This applies to all ships regardless of flag. As of 1 January 2010, the sulphur content of any marine fuels may never exceed 0.1 % by weight for ships in port with the exception of short stays in port (up to 2 h).

For ships continuously operating on low-sulphur fuel oil and for those that may be fitted with an exhaust cleaning system, there is no issue. However, for ships which burn heavy fuel oil with 3.5 % sulphur content and are not equipped with scrubbing equipment, the problem of compliance is much greater as large quantities of fuel are being mixed during the oil change‐ over to low-sulphur fuel oil. MARPOL Annex VI Regulation 14 requires those ships using separate low-sulphur fuel to comply with this regulation and in entering or leaving an Emission Control Area, shall carry a written procedure showing how the fuel oil changeover is to be done, allowing sufficient time for the fuel oil service system to fully flushed out all fuel oils exceeding the applicable sulphur content prior to entry into a sulphur Emission Control Area. The volume of low-sulphur fuel oils in each tank as well as the date, time and position of the ship when any fuel oil changeover operation is completed prior to the entry into an ECA or commenced after exit from such an area shall be recorded in such logbook as prescribed by the Annex VI Regulation.

Furthermore, ships are also an important source of greenhouse gas (GHG) pollutants. According to the Green House Gas study by the IMO consensus, international shipping emitted 843 million metric tonnes of carbon dioxide, 2.7 % of the global CO2 emissions in 2007. Including domestic shipping and fishing ships larger than 100 gross tonnes (GT),2 the amount would increase to 1.019 billion tonnes, i.e. 3.3 % of the global CO2 emissions. At the present trend, this percentage could go two or three times higher from the present by 2050 emissions [8, 9].

In order to control this CO2 emission from shipping, the first formal CO2 control regulations were adopted by the IMO at the 62nd session of the Marine Environment Protection Committee (MEPC) in July 2011. The amendments to MARPOL Annex VI included the addition of Chapter 4 on regulations on energy efficiency for ships to make mandatory the Energy Efficiency Design Index (EEDI) for new ships and the Ship Energy Efficiency Management Plan (SEEMP)

<sup>2</sup> Gross tonnage (GT) determined under the IMO 1969 Tonnage Convention represent the total volume of of ship's enclosed spaces measured in register tonne (RT) where 1RT=100 f3 or 2,83 m3, conversely. Net tonnage (NT) determined under the IMO 1969 Tonnage Convention represents the volume of cargo spaces (cargo holds and cabins) in register tonne (RT).

for all ships. The regulations apply to all ships of 400 GT and above and are entered into force in 1 January 2013.

The basic formulation of EEDI is based on the ratio of total CO2 emission per tonne mile. As CO2 depends upon fuel consumption and fuel consumption depends upon the total power requirements, eventually this EEDI formulation has certain impact on ship design parameters and hydrodynamics. The SEEMP establishes a mechanism for a shipping company and a ship to improve the energy efficiency of ship operations. The SEEMP provides an approach for monitoring ship and fleet efficiency performance over time using. The results from the study that IMO ordered from Lloyd's Register and Det Norske Veritas to estimate the impact of the new requirements show that the EEDI will, as new ships are built, gradually reduce the emissions from the world fleet with 3 % in 2020, 13 % in 2030 and 30 % in 2050. The SEEMP will not directly mandate an emission reduction, but by increased awareness of costs and reduction potentials, the study estimated the reduction to be between 5 and 10 % from 2015 onwards [9,10].
