| Front page | | Contents | | Previous | | Next |

Ship emissions and air pollution in Denmark

5 Pollution from ships in ports

• 5.1 Introduction
• 5.2 Available studies
• 5.3 Sulphur regulation
• 5.4 Methodology: Emission inventories for ports
  • 5.4.1 Activities: At dock, pumping and manoeuvring
  • 5.4.2 Emission factors
• 5.5 Results
• 5.6 Results for Copenhagen
• 5.7 Cruise ships and air quality
  • 5.7.1 Cruise ships: NOX
  • 5.7.2 Cruise ships: particles and SO2
• 5.8 High rise buildings
• 5.9 Results: The Port of Aarhus
• 5.10 Conclusions concerning ships in port

5.1 Introduction

A minor component of the present project concerns the contribution to local air pollution from ships at port.

The model calculations in the previous chapters are performed with the DEHM model which has a spatial resolution of 6 x 6 km. In order address the question of the contribution to local air pollution from ships at port such resolution is inadequate. Therefore, a different methodology must be used. The present chapter presents an overview, based on previous studies as well as updated information on the current situation and on the expected developments. Information is provided for the ports of Copenhagen and Aarhus, with most details for Copenhagen.

One particular previous study is unmatched in its degree of detail, namely a study on cruise ships calling the port of Copenhagen (Olesen and Berkowicz, 1005). That study is used to infer several useful conclusions (mainly in Section 5.7).

The chapter contains the following parts:

• Section 5.2 gives on overview of available studies. The discussion of pollution from ships in ports utilizes methodology and results from previous studies.
• Section 5.3 gives an overview of sulphur regulation in ports, which is more stringent than for ships at sea.
• Section 5.4 explains the methodology used in compiling emission inventories for the ports of Copenhagen and Aarhus.
• Section 5.6 presents results concerning emissions for the Port of Copenhagen.
• Section 5.7 focuses on cruise ships. Cruise ships in Copenhagen contribute substantially to emissions in the port, and therefore a discussion on pollution from cruise ships is given.
• Section 5.8 briefly discusses high rise buildings close to ports, which has been an issue of interest in Copenhagen.
• Section 5.9 presents results concerning emissions in Aarhus.
• Section 5.10 summarises conclusions from the chapter.

5.2 Available studies

A frame of reference for many of the estimates made in the present chapter is a report by Oxbøl and Wismann (2003). It provides an inventory of emissions from ships in three Danish ports (Copenhagen, Køge and Helsingør), and also gives a crude estimate of emissions for ports in the entire country. The methodology used by Oxbøl and Wismann has been used here to produce updated estimates for the ports of Copenhagen and Aarhus.

A detailed study of the contribution to air pollution by cruise ships in the Port of Copenhagen was prepared by Olesen and Berkowicz (2005). Pollution with NO₂ received particular attention in that study. As part of the study a detailed emission inventory of cruse ships calling at the Port of Copenhagen in 2004 was compiled by Force Technology; it is described in an appendix to the report by Olesen and Berkowicz. Based on this inventory, combined with data for the physical characteristics of the cruise ships, meteorology and background concentrations, the authors carried out atmospheric dispersion calculations for various pollutants. The Danish OML model was used for the computations. It was concluded that the increase of NO₂ concentrations resulting from the presence of cruise ships was not capable of increasing the level of NO₂ above the limit values, neither close to the ships nor far away from them. This conclusion concerns the contribution from cruise ships to the general pollution level; it does not preclude that there may be local violations of NO₂ limit values in very busy streets due to the traffic load. The discussion is elaborated in Section 5.7, taking into account updated information, the new emission inventory, and also considering other pollutants that NO₂.

A further study which provides background information for the present study is an environmental assessment of the air pollution level for a planned pair of high rise buildings at Marmormolen in Copenhagen (COWI, 2009). The buildings are close to several ferries in the port of Copenhagen, and the presence of nearby ferries could potentially constitute a problem for the air quality in the buildings. The environmental assessment shows that in this specific case there is no conflict with air quality limit values. However, the scenario of a high rise building close to a ship berth is a matter deserving consideration, and it is discussed in Section 5.8.

There are plans to establish a new cruise terminal at Nordhavn in Copenhagen. The environmental assessment for this project (Grontmij/Carl Bro, 2009) provides additional information that enters into the current study.

Besides the publications mentioned above, much additional information has been compiled through personal contacts with Copenhagen Malmö Port (Gert Nørgaard), Port of Aarhus (Søren Tikjøb), the Danish Petroleum Association (i.e. Energi- og Olieforum: Michael Mücke Jensen), Tom Wismann, Torm Shipping (Troels Jørgensen), MAN Diesel (Sven Henningsen), TR shipping (Anders Nødskov), Douglas Clark, Mols-Linien (Flemming Kristensen), Wärtsila (Johanna Vestergaard) and Royal Carribean International (Thomas Stjernhav).

5.3 Sulphur regulation

An important change which has occurred since many of the previous studies were completed, is that a set of requirements have been introduced, addressing sulphur in the fuel used when ships are at port. EU directive 2005/33/EC defines requirements to the maximum sulphur content of marine fuels used by ships at berth in Community ports. It prescribes that by 1 January 2010, a ship at berth is not allowed to use marine fuel with a sulphur content exceeding 0.1%. There are slight exemptions; thus, if a ship according to timetables is due to be at berth for less than two hours, it does not have to change fuel.

The regulations were implemented in Denmark by Statutory Order No. 1663 of 14 December 2006. For gas oil, a requirement of 0.1 % sulphur has applied already since January 2008.

The emission inventories presented in Section 5.6 and 5.9 are based on the regulations that will be in place in 2010: 0.1% sulphur content for ships at dock, and 1% sulphur content for manoeuvring, as required by the SECA regulations by March 2010.

5.4 Methodology: Emission inventories for ports

The emission inventory presented here is meant to provide an estimate of emission from ships in the ports of Copenhagen and Aarhus. The estimate does not claim to be accurate, but is prepared to the same level of detail as the previous investigation by Oxbøl and Wismann (2003). Basically, it applies the same methodology. However, there are some exceptions, where updated information makes a change pertinent.

Inventories of ships calling at the ports of Copenhagen and Aarhus in 2008 have been provided by the respective port authorities (personal communication: Gert Nørgaard, CMP and Søren Tikjøb, Port of Aarhus). The inventory for Copenhagen is the most detailed with information on when and where each ship called, while the information from Aarhus contains summarised information for classes of ships.

The methodology in Oxbøl and Wismann (2003) has been used. This represents a simplified approach compared to the one followed in Chapter 2 on emissions from ships at sea. Thus, ships have been classified according to the following categories:

• Tankers
• Bulk carriers (including various special ships)
• Container ships
• Ro-Ro ships
• Passenger ferries
• Cruise ships

5.4.1 Activities: At dock, pumping and manoeuvring

Estimates of energy consumption have been based on the same principles and assumptions as Oxbøl and Wismann (2003) with a few exceptions. Oxbøl and Wismann consider emissions caused by the following activities:

• Manoeuvring (arrival and departure at the dock)
• Activities at dock (generating of electricity)
• For tankers only: oil pumping

A set of assumptions provides a link from the size of ships in gross tonnage to the size of the main and auxiliary engines, and further – considering the load of engines and the duration of the various activities – to an energy consumption for each activity and ship class.

Table 5.1 lists the assumptions that are used here. The table is based on table 3.3 in Oxbøl and Wismann (2003). There are a few differences, however.

Concerning cruise ships at dock, the detailed study by Olesen and Berkowicz (2005) provides a relationship between size and power consumption at dock, based on responses to a questionnaire to ship owners. This relationship is indicated in Table 5.1.

Concerning pumping, the report by Oxbøl and Wismann (2003) assumed the pumping of 1 ton oil would require 0.7 kg fuel. This value was quoted from a single reference in literature, but Oxbøl and Wismann were not able to verify it.

The present estimate is based on information from the Danish Petroleum Association (pers. communication Michael Mücke Jensen) and from TORM Shipping (Troels Jørgensen). Ship-based pumps, driven by auxiliary engines, are used for unloading oil. For loading, land-based pumps driven by ordinary power supply are used. On ships, different types of machinery are used for pumping, and the energy consumption depends on local conditions at the port (the pumping distance, the height to which the oil should be pumped etc.). However, in the Port of Copenhagen pumping does not require much energy. The estimate from the Danish Petroleum Association is that pumping of 1000 m³ oil per hour requires a power supply of 50-60 kW. This value has been used for the calculations here, and is indicated in the table. It leads to substantially lower estimates for power consumption for pumping than the estimate by Oxbøl and Wismann.

The assumed duration of the various activities is indicated in Table 5.1. The energy consumption for dock and manoeuvring is computed as the product of the power, the engine load and an estimated duration of the activity. The estimated times is indicated in the table. For manoeuvring it follows Oxbøl and Wismann (2003). For time at dock the values are based on the ship list for Copenhagen 2008. Tankers are at port on average 11.2 hours, container ships 11.7, cruise ships 12.5, while the group labelled 'bulk carriers' is assumed to be at dock for 19 hours; the latter group is mixed and includes various types of special ships. The average of 19 hours is based on bulk carriers. An exception is made for the RoRo ferry Tor Corona in Copenhagen, for which more detailed information is available from COWI (2009).

Concerning ferries, in the port of Copenhagen information is taken from the environmental assessment for Marmormolen by COWI (2009). It contains detailed information on emissions for the ferries to Oslo (Crown of Scandinavia and Pearl of Scandinavia), the ferry to Poland (Pomerania) and for the Ro-Ro freight line to Klaipeda (Tor Corona). Where available, this detailed information has replaced the general rough estimates.

For the port of Aarhus, information on emission for ferries is from Mols-Linien (personal communication, Flemming Kristensen).

Table 5.1 Overview of assumptions and calculation procedures

5.4.2 Emission factors

In general, the emission factors listed in Table 5.2 have been used. However, for ferries, more detailed information is available and forms the basis for the computations. A few comments on the emission factors in Table 5.2 are appropriate.

Table 5.2 Emission factors used in the inventory for ships in port.

For NO_X, the emission factors are those applied by Oxbøl and Wismann (2003). The more detailed approach that is applied in Chapter 2 of the present report is not used, because the ship data are not sufficiently detailed. It should be mentioned that use of the NO_X emission factor from the table will result in a substantial overestimate of NO_X emissions from gas turbines (around a factor of three). Gas turbines are used as auxiliary engines for some ships – e.g., some cruise ships.

Concerning the ferries, more accurate estimates for NO_X emission factors than those shown in the table are used. This makes a large difference for the Oslo ferries, which use SCR (selective catalytic reduction) technology to reduce NO_X emissions, and for the ferries Mai Mols and Mie Mols, which are equipped with gas turbines.

For SO₂ an emission factor based on expression (8) in Chapter 2 is used. Further, for the results shown in the subsequent sections, a sulphur content has been assumed of, respectively, 0.1 for ships at dock and 1.0 % for manoeuvring. This corresponds to the situation in 2010 after the strengthening of the SECA requirements. It is lower than that used by Oxbøl and Wismann (2003).

The particle emission factors in Table 5.2 are based on equation (10) in Chapter 2.

It should be noted that all computations use emission factors for ship engines meant to represent conditions averaged over time. When engines are started there may be a burst of pollution, which is not accounted for. To the extent that such emissions take place, they may be a cause of nuisance, although they don't have much influence on average conditions.

5.5 Results

Based on the assumptions indicated in the previous sections, inventories have been compiled for Copenhagen and Aarhus. They will be discussed in the subsequent sections. The discussion for Copenhagen is most exhaustive, and it is supplemented by discussions on cruise ships and high rise buildings.

5.6 Results for Copenhagen

In the case of Copenhagen, two previous inventories exist that can be used for comparison and reference:

1. The one by Oxbøl and Wismann (2003) which is based on traffic data for 2001. In the subsequent graphs these results are labelled '2001'.
2. The one focusing exclusively on cruise ships which was compiled by Force Technology and used by Olesen and Berkowicz (2005). It uses traffic data from 2004. In the following figures it is referred to as '2004'.

Table 5.3 Port of Copenhagen. Energy consumption and emission of various components in 2008. These values are displayed en Figure 5.1 and Figure 5.2.

The current, updated, estimate is labelled '2010', because it represents the situation in 2010 concerning sulphur content in fuel (although it is based on traffic data from 2008). The results of the inventory are tabulated in Table 5.3.

Figure 5.1 shows a key parameter for the inventory: Energy consumption during a year. The left panel of the figure shows values referring to activities at dock ("docking"), including pumping. Ro-Ro ships were not treated separately for Copenhagen in Oxbøl and Wismann (2003); these ships are therefore also here included among "Other bulk ships".

The right panel shows energy consumption during manoeuvring, based on the assumption that a total time of 0.5 hours is required to enter and leave the port.

Click here to see: Figure 5.1 Copenhagen: Energy consumption according to old inventory by Oxbøl and Wismann (labelled 2001) and the updated inventory (2010). Left panel is for activities at dock, including pumping by tankers. Right panel for manoeuvring in port.

Some noticeable features stand out from the left panel ('Docking'). For tankers, there is a considerable decrease from '2001' to '2010'. This is due to the previous assumption that pumping from tankers is very energy consuming – an assumption which is not in agreement with recent information from the Danish Petroleum Association.

There is a notable decrease in energy consumption for ferries. There are now only two passenger ferry lines in Copenhagen: to Oslo and to Poland. In 2001, there was also a line for Bornholm.

For bulk ships and container ships there are differences which reflect the combined effect of a different number of ships, their size distribution, and the time spent at dock, which is used for energy consumption computation. The duration was previously estimated as 8.8 hours for tankers, bulk ships and container ships. This was based on data from one month. According to the list of ships from 2008, the duration is longer than 8.8 hours (see Table 5.1). In computing the average duration of a stay, outliers have been removed, due to the assumption that a ship does not use its auxiliary engine all of the time during a very long stay. It must be recognized that for these ship types the methodology is suitable to provide an overview, but that the accuracy can be questioned. When comparing the left and right panel, it appears that energy consumption during docking dominates over energy consumption during manoeuvring.

The number of cruise ships calling at Copenhagen has increased gradually: From 201 calls in 2001 to 259 in 2004, and further to 295 in 2008. Accordingly, there is an increase in energy consumption for cruise ships.

Click here to see: Figure 5.2 Copenhagen. Emission of NO_X, SO₂ and PM (primary particles). The left column of figure refers to activities at dock (including pumping by tankers), while the right column refers to manoeuvring in port.

Figure 5.2 shows the situation for emission of the pollutants NO_X, SO₂ and PM. The figure for NO_X reflects the same pattern as the graph for energy consumption. Note that for cruise liners a column has been added, referring to the study based on 2004 data. The total NO_X emission for ships was 523 t in 2001, and has decreased to 373 t for the 2010 inventory. The reduction is caused partly by the change of the assumption concerning pumping, and partly because the contribution from ferries has decreased even more than the decrease in energy consumption justify. The reason is the use of SCR technology on the Oslo ferries, which reduces their NO_X emissions by around 85 percent.

For reference, the emission of NO_X from ship activity can be compared to other large NO_X sources:

• The sum of NO_X emissions from ships is estimated at 373 t in 2010;
• Cruise ships are responsible for 200 t of these;
• The power plant Amagerværket 568 t emitted in 2008;
• Emission by ships in Øresund according to Chapter 3: 7760 t in 2007;
• Emissions by all road traffic in the region of Copenhagen: 19000 t.

In Figure 5.2, the graph for SO₂ at dock for cruise ships displays an awkward development with very low values for the 2001 inventory, a much higher value in 2004, and a moderate value for 2010. The reason is an unrealistic assumption in the 2001 inventory: It was assumed that cruise ships used fuel with a sulphur content as low as 0.05 percent. The study in 2005 involved use of a questionnaire to the shipping companies, and it was revealed that the actual sulphur content used by cruise ships while at berth in Copenhagen ranged from 0.2 to 3.2% with a mean around 1.6%. In 2010 the maximum allowed sulphur content while at quay is 0.1 %; this reduces sulphur emission by a factor of 16 compared to the 2004 case.

For PM (primary particles, all sizes), the total decreases from 13 to 8 t. Particle emission depends somewhat on sulphur content in the fuel, so a decrease is to be expected. The largest single contribution to the decrease is, however, correction of the assumptions concerning pumping.

The distribution of NOx emission by district is shown in Figure 5.3. The figure includes activities at dock and pumping, but not manoeuvring. It is appears from the figure that Frihavnen has the largest load. Of the 145 t NO_X emitted in Frihavnen, 88 are due to cruise ships.

Figure 5.3 Distribution of NOx emission in various districts in the Port of Copenhagen.

5.7 Cruise ships and air quality

According to the inventory, cruise liners are responsible for a substantial part of NO_X emission - 200 t compared to the total of 373 t (including all activities). The present section focuses on cruise ships.

It is interesting to examine how the emission load for cruise ships is distributed geographically. Figure 5.4 shows the NO_X emission load according to the study using 2004 data, as well as the new inventory.

Figure 5.4 Geographical distribution of NOx emission load from cruise ships at berth in 2004 (top) and 2008 (bottom).

In 2008, cruise ship emission predominantly took place at three berths: no. 192 at Langelinie, and no. 245 and 254 in Frihavnen. However, the situation with a heavy emission load at these berths is not permanent, because there are plans to establish a new cruise terminal from 2012 North of the present, as indicated in Figure 5.5.

Figure 5.5 Plans for new terminal for cruise ships.

Carl Bro/Grontmij (2009) has carried out an environmental assessment in preparation to the construction of the new terminal. The assessment report does not include any details on the influence of cruise ships on the air quality after the establishment of the terminal, but notes that the issue is one of an existing pollution source that is moved. Further, the report indicates that there are plans to establish land-based power supply, which can be put to use in a long term perspective.

Within the present study we have not carried out atmospheric dispersion calculations, because a new estimate that matches the previous study by Olesen and Berkowicz (2005) in degree of detail is outside the scope of the current work. Also, Olesen and Berkowicz (2005) provide sufficient evidence to draw useful conclusions.

In the next section we will recapitulate some important conclusions from the previous report, while adding new information.

5.7.1 Cruise ships: NO_X

The exhaust gas from combustion engines – such as the engines in cruise ships – contains a mixture of nitrogen oxides (NO_X). NO_X is the sum of NO and NO₂. In terms of health effects and limit values, NO₂ is the substance of interest. When emitted from a ship engine, NO is much more abundant than NO₂. Only 5-10% is emitted directly as NO₂. NO can be gradually converted to NO₂ by reactions in the atmosphere. Fast conversion is possible if ozone is available.

When evaluating concentrations of NO₂ it is important to be aware that there is not a one-to-one correspondence between NO_X and NO₂; close to sources of pollution, concentrations of NO_X can be much higher than those of NO₂.

It is also important to note that the amount of available ozone in the background air sets a "ceiling", which limits the amount of NO that can be converted to NO₂. The concept of a "ceiling" set by ozone applies to dispersion at a local scale, not to long-range transport. Thus, if we consider the effect that cruise ships have on the level of NO₂ pollution in Copenhagen, the mechanism of limiting by ozone is important. Accordingly, the emission of NO_X from cruise ships is reflected by only a small increase in NO₂ concentrations in the streets of Copenhagen. The calculations that were carried out in the detailed study by Olesen and Berkowicz (2005) used the Danish OML model in 'chemistry mode', which takes account of the ozone limiting mechanism.

For NO₂, there are some parameters of key interest, because they refer to the EU directive on air quality from 2008 (2008/50/EC). The directive sets a limit for NO₂ which is based on hourly concentrations. The hourly concentration of NO₂ is allowed to exceed a limit of 200 μg/m³ no more than 18 times a year (this limit must be complied with in 2010).

Another limit value for NO₂ refers to the annual average, which must not exceed 40 μg/m³ (from 2010).

In the 2005 study, the OML dispersion model was run several times, based on various sets of assumptions, e.g. concerning the base year for meteorology, for background concentrations etc. The so-called Basic Run is representative for the results.

Some main results from the Basic Run are presented in Figure 5.6. These results can be compared to the first limit value mentioned above. The map shows the 19th highest NO₂ concentration during one year concentrations, resulting from the combined effect of cruise ships and the urban background pollution in the city of Copenhagen. The background pollution is assumed constant throughout the area. The values in Figure 5.6 are all in the interval between 98 and 101 μg/m³; according to the directive they are required to be less than 200 μg/m³. If the cruise ships had not been present, Figure 5.6 would have shown a constant value of 98 μg/m³, corresponding to the contribution from the urban background pollution.

The results presented above are meant to illustrate the contribution to NO₂ concentration level, by comparing a reference situation where there is only background pollution with a situation where cruise ships have been superimposed on this reference situation. It is clear from the results that the 19th highest NO₂ concentration value is not increased much by the presence of the cruise ships. In a busy street, NO₂ concentration levels will be higher, and here the contribution from cruise ships will be even less able to affect the 19th highest concentration than in the situation depicted in Figure 5.6.

Click here to see: Figure 5.6 The left panel shows a map, while the right shows a corresponding schematic "map" of concentrations. The two maps cover the same area (1800 m x 4800 m). Each of the small squares on the right is 200 x 200 m.The white rings on the schematic map represent quays.
For each calculation point (receptor) the schematic map shows the nineteenth highest hourly concentration of NO2 during one year, according to the Basic Run.
The values displayed should be compared to the limit value of 200 μg/m³. Please note that the scale is limited to the interval 98 to 101 μg/m³. Throughout the black area there is a constant value of 98 μg/m³, and this value remains 98, irrespective of whether the cruise ships are present or not.

In the study by Olesen and Berkowicz (2005), the conclusion as to NO₂ average concentrations was that concerning the annual average concentration of NO₂, the Basic Run results in a level of around 23 μg/m³, almost unaffected by the presence of cruise ships. Their maximum contribution is 0.8 μg/m³ at the location where the impact is greatest (600 m east of Langelinie, in the Øresund). These numbers should be compared to a limit value of 40 μg/m³

NO_X emissions are 29% higher for cruise ships in the '2010' situation (based on traffic data from 2008) than they were according to the inventory based on 2004 data. A new set of detailed calculations must thus be expected to lead to slightly increased values compared to the previous study. If all other factors were equal, NO₂ concentrations would be increased, but with substantially less than 29%, because of the limiting effect of ozone. As noted before, a study as detailed as Olesen and Berkowicz (2005) is outside the scope of the present work.

There is one assumption which might be changed if a new, detailed study were conducted. To some extent gas turbines are used by cruise ships while at berth, whereas the emission factor for NO_X that was used for the computations is representative of diesel engines. Compared to a diesel engine, a gas turbine emits only around one third of the NO_X amount per kWh. With a detailed inventory the emitted NO_X amount would be smaller than assumed here.

Further it can be noted that some issues which were questioned during the previous study have been clarified. In the previous study, four sets of assumptions concerning the fraction of directly emitted NO₂ were used. The exhaust gas from combustion is a mixture of NO and NO₂. The 'Basic Run' was conducted under the assumption that 10% of NO_X is emitted directly as NO₂. It has been confirmed that this is reasonable as an upper estimate. MAN Diesel (personal communication, Svend Henningsen) indicates that the percentage of directly emitted NO₂ is 5-10%, and closer to 5 than 10.

The previous study assumed that SCR (selective catalytic reduction) technology for reduction of NO_X emissions was not applied by cruise ships. Recent information confirms that this assumption is reasonable for the time being. However, it will change, especially after 2016.

In year 2011 the IMO Tier II NO_X standard will enter into force. This means that all new installations have to meet a 20% reduced NO_X emission level compared to now. The 20% NO_X reduction can be achieved by engine internal methods. No exhaust gas after-treatment system will be needed (pers. communication from Johanna Vestergaard, Wärtsilä).

However, in 2016 the IMO Tier III NO_X standard will enter into force in the so-called NECA areas. The Danish Marine waters are expected to be appointed NECA's. In these areas an 80% NO_X reduction from today’s Tier I level will be required for new ships. For achieving an 80% NO_X reduction, an SCR exhaust gas after-treatment system is a likely option.

5.7.2 Cruise ships: particles and SO₂

Besides NO_X pollution, the previous study by Olesen and Berkowicz (2005) considered pollution with SO₂ and particles. It was found that the largest increase in particle pollution level (primary particles on an annual basis) was 0.035 μg/m³. This can be compared to the forthcoming annual limit value of 25 μg/m³ for PM_2.5, and to the levels indicated in Chapter 5.

For SO₂, the contribution in the most exposed area (in the water West of Langelinie) was 1.5 μg/m³ in 2004. The SO₂ contribution from the previous study will be reduced by a factor 16 after 2010 when the regulations concerning sulphur content in fuel for ships at port come into effect.

5.8 High rise buildings

The study by Olesen and Berkowicz (2005) considered pollution levels mainly at a height of 1.5 meters, but with some additional calculations for a height of 7 meters. For the current study, some additional calculations have been carried out based on the data for the 2005 study, but for greater heights than 1.5 and 7 meters. They show that a height of around 50 meters is most critical in respect to compliance with the NO₂ limit value, and that at this height there may be problems with compliance within a distance of around 100 m from the ships.

When planning high rise buildings close to berths, it is recommended to conduct studies of sufficient detail to verify whether there is a potential problem.

A study by COWI (2009) presents such computations for the case of a two planned buildings at Marmormolen that are situated close to the Oslo ferry. These ferries are equipped with SCR gas cleaning technology, and it is demonstrated that the ferries are no cause of concern in respect to NO₂ levels.

5.9 Results: The Port of Aarhus

The Port of Aarhus is Denmark's largest container port and public bulk terminal. Figure 5.7 is a map of the Port of Aarhus. It indicates the current positions where the various types of ships pertain, and also plans for future developments (the map should be considered a draft only).

Click here to see: Figure 5.7 Draft map of the Port of Aarhus, indicating positions where the various types of ships pertain. A planned Omni-terminal (expected in 2011) and a planned area for containers and ferries (expected in 2015) are indicated.

For the port of Aarhus, an emission inventory similar to the one for Copenhagen has been prepared. It is based on summarised information on ship traffic received from Søren Tikjøb (Port of Aarhus) as well as information on the ferries of Mols-Linien (Flemming Kristensen). Key information is listed in Table 5.4.

The information for Aarhus concerning the duration of stay differs somewhat from that of Copenhagen. In particular, one may note the long duration of stay for bulk carriers (48 hours as opposed to 19 hours for Copenhagen). As to manoeuvring, the same assumptions as for Copenhagen are used in general (a duration of 0.5 hour per call). For ferries, the duration is shorter with a lighter load (5 minutes, 15% load, according to information from Mols-Linien.).

Table 5.4 Key information on ship traffic to the port of Aarhus

Figure 5.8 presents results for emissions at the Port of Aarhus. The underlying numbers are tabulated in Table 5.5.

As Aarhus is Denmark's largest container port and public bulk terminal, the energy consumption and emission connected with bulk carriers and container ships are larger than those of Copenhagen (the duration of stay also plays a role, but is also stipulated as being longer for Aarhus).

The emission loads are somewhat smaller than those of Copenhagen. Figure 5.9 gives a comparison of various totals for the two ports. The energy consumption, NO_X emission load, etc. are compared in a relative sense. All emission loads are smaller for Aarhus than for Copenhagen, and amount to 45-75% of the Copenhagen values.

Table 5.5 Port of Aarhus. Energy consumption and emission of various components in 2008. Corresponds to Figure 5.8.

Click here to see: Figure 5.8 Port of Aarhus. Emission of NO_X, SO₂ and PM (primary particles). The left column of figure refers to activities at dock (including pumping by tankers), while the right column refers to manoeuvring in port.

Figure 5.9 Comparison of various totals for Aarhus relative to Copenhagen.

5.10 Conclusions concerning ships in port

The following conclusions can be inferred from previous studies on concentration levels, combined with updated emission information:

• Cruise ships are a considerable source of NO_X pollution in Copenhagen. Cruise ships are responsible for around 55% of NO_X emissions from ships at port in Copenhagen. The NO_X emission from cruise ships is estimated to be 30% larger in 2008 than it was in a previous, detailed study referring to 2004. In Aarhus, cruise ships are only responsible for around 3% of NO_X emissions.
• It is important to note that there is not a one-to-one correspondence between NO_X and NO₂. For instance, a 30% increase of NO_X emissions will lead to an increase of concentration levels of NO₂ which are smaller than 30% when we consider local scale (such as Copenhagen).
• The local NO₂ levels, at ground close to cruise ships (within the nearest 500 m or so) are well below EU limit values - unless cases can be found where heavy car traffic bring the NO₂ concentrations at such locations to a critical level. Thus, on an annual basis the increase of NO₂ concentrations due to cruise ships was found in the 2004 study to be 0.8 μg/m³ at the location where the impact was greatest (600 m from the ships, in the Øresund). This should be seen in the context of an urban background level on the order of 20 μg/m³ and a limit value of 40 μg/m³.
• When considering conditions at high rise buildings close to berths with very heavy ship traffic, there may potentially be problems with NO₂ exceedances very close to the berth (within the nearest hundred or few hundred meters). In such cases it can be wise to conduct detailed studies. As an example, it has been demonstrated that for planned high rise buildings (ca. 100 m tall ) at Marmormolen in Copenhagen located approximately 250 m from the berth of the Oslo ferries the presence of the Oslo ferries will not lead to violations of the NO₂ limit values.
• The increase in yearly averaged concentration levels for primary particles due to the presence of cruise ships at quay in Copenhagen was found in the 2005 study to be small: 0.035 μg/m³at the most critical location 200 m from the ships. This can be seen in the context of the limit value of 25 μg/m³ for PM_2.5 and the contribution of all ships in general, which is slightly less than 1 μg/m³ according to section 4.9. It should be noted, however, that this estimate is based on emission factors representing time-averaged values for engines in ordinary operation. When engines change operating conditions there may be bursts of smoke which are not accounted for in the present estimates, but may be a cause of nuisance.
• For the port of Aarhus, the total energy consumption and the total of emissions for all substances is smaller than it is for Copenhagen. However, for certain ship types (container ship, other bulk carriers) the load at the port of Aarhus is larger than for Copenhagen.

| Front page | | Contents | | Previous | | Next | | Top |

Version 1.0 October 2009, © Danish Environmental Protection Agency