TRANSPHORMdeliverable · PDF fileDeliverydatefromANNEXI:MONTH32* ......

1

TRANSPHORM deliverable

Report from analysis of traffic activity in selected cities

D1.2.1

Lead beneficiary: IVL

Person months: 12

Nature: REPORT (R)

Dissemination level: PUBLIC (PU)

Delivery date from ANNEX I: MONTH 32

Notes:

Table of contents

Deliverable overview.............................................................................. 1

Copy of deliverable………………………………………………………………………………. 2

TRANSPHORM

Transport related Air Pollution and Health impacts –

Integrated Methodologies for Assessing Particulate Matter

Collaborative Project, Large-scale Integrating Project

SEVENTH FRAMEWORK PROGRAMME

ENV.2009.1.2.2.1 Transport related air pollution and health impacts

Deliverable D1.2.1, type R

Report on shipping emission factors

Due date of deliverable: project month 12

Actual submission date: project month 13

Start date of project: 1 January 2010 Duration: 48 months

Organisation name of lead contractor for this deliverable: IVL

Scientist responsible for this deliverable: Jana Moldanová

Revision: [1]

D1.2.1 TRANSPHORM Deliverable

2 of 21

Contents

Report on shipping emission factors 3

Introduction 3

International legislation on emissions from shipping 6

Abatement techniques for reduction of air pollution 9

Emission factors for SO2 and CO2 10

Emission factors for VOC and CO 10

Emission factors for NOX 11

Emissions factors for PM mass 13

Emissions factors for PM number concentration 17

Emissions factors for PAH and benzo(a)pyrene 18

Conclusions 20

References 21

Deliverable TRANSPHORM D1.2.1

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Report on shipping emission factors

Jana Moldanová1, Erik Fridell

1, Andreas Petzold

2, Jukka-Pekka Jalkanen

3

1 IVL, Swedish Environmental Research Institute, Box 5302, 40014 Gothenburg, Sweden

2 Deutche Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, 82234 Wess-

ling, Germany 3 Finish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland

Introduction

The main focus of this report is on emissions of particulate matter (PM) expressed as mass, number

size-distribution as well as some characteristics of the particle emissions such as black carbon, or-

ganic carbon and PAH. However, emission factors for a number of other compounds will be de-

scribed briefly. In the following text the emission factors reported in a few papers with compiled

data will be used to present suggested emission factors.

Emissions from a fleet of ships are usually calculated by means of quantifying the fuel consump-

tion by power production first and then multiplying the consumption by emission factors. Some

inventories use the bunker sales statistics as a direct estimate of the fuel consumption together with

an assumption of a distribution of ship and engines types. Others, including the bottom-up invento-

ries, estimate the power production, and thus the fuel consumption of individual ships, from fleet

movement statistics. Emission factors (EF) used are then related either to the generated power EFp

(g(species)/kWh) or to the fuel consumed EFf (g(species)/kg(fuel)), where the first one multiplied by the

specific fuel consumption (SFC, unit g(fuel)/kWh) is equal to the second one.

Emissions from a marine engine will depend on the type of fuel used as well as on characteristics

of the engine. The most important fuel parameters are if the fuel is heavy fuel oil (residual fuel,

HFO) or marine distillates (marine gasoil, MGO or marine diesel, MDO) and the sulphur content

(FSC). The emissions likely depend on the viscosity and the aromatics content of the fuel but there

is not sufficient data to link emission factors to these parameters. There are some other fuels that are

much more uncommon such as biodiesel, coal and natural gas.

Emissions have been found to vary significantly between engines. Probably the maintenance and

age of the engine are important for certain emission factors. For calculating emissions one usually

considers the engine power, the engine speed and the emissions standard. The latter applies to ni-

trogen oxides only. However, one can suspect that the emissions standard also will influence the

emissions of, e.g. particles and hydrocarbons, although there is, for most cases, not enough data

available to draw conclusions about this.

The engines on ships are usually one or several main engines, used for propulsions and a number

of auxiliary engines, used for propulsion, electricity generation, pumps etc. The main engine is of-

ten equipped with a shaft generator that produces electricity when the main engine is in operation.

In addition there are usually a number of boilers for hot water production fuel heating etc. Dominat-

ing sources of emissions at open sea are the main engines. At berth these are usually turned off

while the auxiliary engines still are being used. For those engines on ships operating with a power

plant principle, main engines are used for electricity generation and electrical motors are used for

propulsion. In these cases main engines are used both for propulsion and all additional equipment

power needs thus obviating the need for separate auxiliary engines. Here, main engines are run also

during harbour visits.


4 of 21

The engines are usually divided by engine speed into slow speed (60 – 300 rpm), medium speed

(300 – 1000 rpm) and high speed (1000 – 3000 rpm). Most modern larger merchant ships use slow

speed, two stroke engines or medium speed, four stroke engines. Some smaller vessels may use

high speed, four stroke diesel engines. The specific fuel consumption (SFC), expressed as mass of

fuel per unit of work by the engine (g/kWh), depend on the engine type and on the type of fuel used.

Typical values can be found in Table 1. Note that the SFC varies between different engines and will

typically be lower for larger engines than for smaller.

The fuel consumptions in Table 1 are for typical design speeds which usually correspond to an

engine load of 80-85% of the maximum engine power. If the engine is used at lower or higher loads

the specific fuel consumption is typically higher. Figure 1a shows SFC variation with changing en-

gine load under typical marine engine operation regime for a Wärtsilä 45 engine and SFC variation

used in the STEAM model (Jalkanen et al., 2009, Jalkanen et al., 2011). It can be seen that the SFC

will increase sharply at low loads. Figure 1b shows an example of how the SFC can vary with en-

gine load at different engine speeds.

Table 1. Specific fuel consumption for marine engines (Cooper and Gustafsson, 2005)

Engine type Fuel type SFC (g/kWh)

Slow speed Residual oil 195

Marine distillates 185

Medium speed Residual oil 215


High speed Residual oil 215


Emissions of some species like SO2, CO2 and metals are directly proportional to the SFC and fuel composition, regardless the type of engine or its operation regime (abatement techniques not accounted). Others, like NOX, VOC, CO and PM are dependent on combustion regime and thus on type of engine, its power setting and on physical properties of the fuel.


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a)

b)

Figure 1. Specific fuel oil consumption (SFC) change as a function of engine load. a - SFC as a function of engine

load under typical marine engine operation regime for a Wärtsilä 45 engine and SFC variation used in the

STEAM model (Jalkanen et al., 2009, Jalkanen et al., 2011). b – SFC change at variable engine speed from

Wärtsilä 45 project guide (2007). The iso-lines show the increase in fuel consumption in g/kWh relative to the

stated SFC at design speed.

SFC

(g/

kWh

)

Engine load

Wärtsilä46


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International legislation on emissions from shipping

Legislation is in force to control the emissions from shipping through Annex VI of the Marine Pol-

lution Convention (MARPOL) that was adopted in 1997 by the Marine Environmental Protection

Committee (MEPC) of the International Maritime Organisation (IMO) and came into force in May

2005 (IMO, 2006). Annex VI with its amendment from October 2008 put limits on emissions of

SO2 and NOX globally and contains provisions allowing establishment of Emission Control Areas

(ECA) with more stringent reductions of fuel–sulphur content and of emissions of NOX, or both

(IMO, 2009). Emission Control Areas for PM are mentioned in Annex VI as well, however no regu-

lation for PM as such is given and the PM reduction is expected to come from the reduction of fuel-

sulphur.

Globally the average sulphur content in fuel is today around 2.7% while the IMO limit value is

4.5% which will be reduced to 3.5% after January 1, 2012. From the 1st of January 2020

1 the fuel

sulphur content will be below 0.5% which will effectively reduce the emissions of SO2 and of sul-

phate particles (Figure 2).

Figure 2. The maximum fuel sulphur content (FS, in mass %) for marine fuels allowed globally and in Emission

Control Areas (ECAs) given by IMO (years when different ECAs enter in force are shown) and the current av-

erage FS of HFO and MDO used by the global fleet (average fuel composition from Endresen et al., 2005)

For emissions of NOX all ships newly built or with installed engine manufactured after year 2000

and prior to 1st of January 2011 must meet the Tier I emission standard and after 1

st of January 2011

the Tier II standard (Figure 3). In addition, after the 1st of January 2016 the Tier III standard must

be met for ships operating in NOX-emission protection areas. The revised Annex VI expanded the

Tier I rules on engines built between 1st of January 1990 and 1

st of January 2000 for ships equipped

with engine with a power output of more than 5,000 kW and cylinder displacement at or above 90

litres provided that an approved and certified method for reduction of NOX emissions exists for the

engine.

1 This regulation may be postponed to 2025 if there is risk of fuel shortage

0 %

1 %

2 %

3 %

4 %

5 %

2005 2010 2015 2020

F S

IMO global limit

ECA limit

Global average HFO

Global average MDO

Baltic Sea ECA

North Sea & English Ch. ECA

North America’s coasts ECA


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Figure 3. The maximum emission factors for NOX (g/kWh) for marine diesel engines given by IMO

In Europe establishment of ECA for SOX in the Baltic Sea entered into force in May 2005, in the

North Sea and English Channel in November 2006 and both ECAs entered in effect 1 year later. In

these areas the allowed sulphur content has been reduced from the initial limit value of 1.5% to 1%

after 1st of July 2010 and will be further reduced to 0.1% 1

st of January 2015. In North America‟s

coastal waters the ECA for SOX and NOX will enter into effect 1st of August 2012 (see Figure 2).

Extension of the European ECAs to NOX emissions is under the discussion. In October 2010 pro-

posal of ECA for waters around Puerto Rico and the Virgin Islands was approved on the 61st ses-

sion of the Marine Environmental Protection Committee (MEPC 61). Establishment of this ECA

will enter into force in 2012 (www.imo.org).

Considering the long lifetime of ship engines, the NOX legislation will impact the NOX emis-

sions only with a large delay. Further, the expected increase in the volume of ship movements will

compensate for the environmental benefits of these measures and will lead to a continued growth in

ship emissions. So far the IMO does not specifically regulate particle emissions and there are stud-

ies showing that even with low-sulphur marine diesel, the PM emissions will still be significant

(Winnes and Fridell, 2009).

The rules governing the maximum permitted content of sulphur in fuels used for international

shipping as determined by Annex VI of the MARPOL73/78 have been transposed into EU law and

complemented by directive 2005/33/EC on the sulphur content of certain liquid fuels which in Au-

gust 2005 amended directive 1999/32/EC. Directives 1999/32/EC and 2005/33/EC (EC, 1999; EC,

2005) provide fuel sulphur content regulations for vessels operating in EU territorial seas as pre-

scribed in Annex VI (not its year-2008 amendment). In addition all passenger vessels on regular

services in EU territorial seas, also those operating outside the ECAs, must from 11 August 2006

comply with the 1.5% sulphur limit. These directives provide also sulphur limits for marine gas oils

(MGO) and marine diesel oils (MDO) sold in the EU member states. Until 10 August 2006 applied

the 0.2% sulphur limit to all marine distillates used in EU territory excluding ships in the territory

of Greece, the French DOM-TOM, Madeira, the Azores and the Canary Islands. Between August

2006 and December 2007, the 0.2% sulphur limit for lower grade marine diesel oils was dropped,

and a less stringent limit of 1.5% sulphur was introduced to allow use of the marine diesel oils in

order to comply with the SOX Emission Control Areas, in case supplies of 1.5% S heavy fuel oil

were insufficient. The exemption for Greece and the outermost regions continued to apply. Between

January 2008 and December 2009 a more stringent 0.1% sulphur limit applied to high grade marine

0

5

10

15

20

0 500 1000 1500 2000 2500

EF N

Ox

(g/k

Wh

)

Engine speed (rpm)

TIER I

TIER II

TIER III


8 of 21

gas oils used in EU territory while the 1.5% sulphur limit for the low grade marine gas and diesel

oils continued to apply. The exemption for Greece and the outermost regions continued to ap-

of marine gas oils in EU territory (described above) were deleted. Instead a 0.1% sulphur limit was

introduced for all marine gas oils placed on the market in EU Member States‟ territory. At the same

time a 0.1% sulphur limit started to apply to all types of marine fuel used by ships at berth in EU

ports and by inland waterway vessels. This applies to any use of the fuel e.g. in auxiliary engines,

main engines, boilers. This legislation goes beyond IMO‟s Annex VI. There are following exemp-

tions from this 0.1% limit: for ships which spend according to published timetables less than 2

hours at berth, for hybrid sea-river vessels while they are at sea, and for ships at berth which switch

off all engines and use shore-side electricity. The outermost EU regions continue to be exempt from

this provision, but Greece does not, apart from a 2-year derogation for 16 named Greek vessels until

2012. From July 1st 2010 the more stringent 1% FSC limit of IMO applies in European ECAs while

EC is preparing legislation that will transpose the 2008-amendment of Annex VI into EU law (to be

published in June 2011). Figure 4 shows development of the limits of the sulphur content of marine

fuels in EU.

Figure 4. The maximum fuel sulphur content (FS, in mass %) for marine fuels allowed in EU territorial waters

and EU inland waterways given by Directives 1999/32 and 2005/33/EC.

0.0%

0.5%

1.0%

1.5%

2.0%

2005 2007 2009 2011 2013 2015

F S

Marine fuels used in EU ECAs (as established)

Marine fuels used by passenger vessels in all territorial seas

Marine fuels used in EU ports by ships at berts& in inland waters

MGO sold in EU

lower grade MDO&MGO (transient)

MDO sold in EU


9 of 21

Abatement techniques for reduction of air pollution

Emission factors need to take into account effects of abatement techniques. Some reductions of emission factors are summarized in Table 2. Most abatement techniques focus on the emissions of NOX. The most effective technique is selective catalytic reduction (SCR) where NOX react with an added reducing agent (normally urea) over a catalyst to produce nitrogen gas. The process is very efficient and reduction factors of 95% can be reached. There is however a certain minimum exhaust temperature needed for the reaction to take place. Many SCR installations are equipped with an oxidation catalyst in order to minimise the ammonia slip. This will also lead to the oxidation of CO and hydrocarbons thus reducing those emissions. Further, an SCR will also influence the PM emis-sions although the details are not quite clear. Other techniques for NOX reduction includes exhaust gas recirculation (EGR), engine modifications and different techniques to introduce water into the engine (humid air motor, HAM, direct water injection, DWI, emulsifier).

Scrubber techniques can be used to reduce the emissions of sulphur oxides to the atmosphere. The scrubbers can operate either with seawater or with freshwater under the addition of an alkaline compound. The scrubbers will trap the SOX as sulphates in the water. The efficiency will depend on, among other things, the alkalinity of the water and the volumes. Scrubbers will also capture particles but the efficiency varies between different reports.

Table 2. The various abatement techniques and their evaluated emission reduction efficiencies.

Abatement technique EFNOx EFSOx EFCO EFVOC EFPM EFNH3

Low NOX engine technologies1 −20% ±0

* ±0

† ±0

†

Exhaust gas recirculation1 −30 - −40%

Direct Water Injection1 −50 - −60% ±0 ±0 ±0

Humid Air Motor1 −70 - −85% ±0 ±0 ±0

Selective Catalytic Reduction1 −91% ±0 ±0 ±0 +0.1 g/kWh

SCR + oxidation catalyst2 −90% −70% −80%

Sea Water Scrubber3 ±0 −95% ±0-80%

‡

Fuel Emulsifier3 −10%

Wetpac3 −50%

* Some increase possible

† Unconfirmed up to 50 % reduction

‡ Value from Jalkanen et al. (2011). According to Corbett (2010) reductions range from -98% to -45%, largest fractions

of PM are reduced more effectively than the small ones. 1 Lövblad and Fridell, 2006

2 Cooper and Gustafsson, 2004

3 Jalkanen et al., 2009


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Emission factors for SO2 and CO2

The emission of SO2 is proportional to the fuel consumption and the sulphur content in the fuel.

This is because virtually all the sulphur in the fuel will be oxidised into SO2 in the engine. The

emission factor expressed as mass of SO2 emitted per mass of fuel consumed is therefore

EFSO2 (g/kg fuel) = fS(%) * 20, (E 1)

where fS is the mass fraction of S in the fuel (in weight per cent) and factor 20 (19.97) comes from

recalculation of the molar weight from S to SO2 and from % to g/kg. To express the emission in

mass per engine work the specific fuel consumption must be used. In a more detailed analysis one

should consider that some sulphur is oxidised further into SO3 and may form sulphate particles.

This is typically on the order of 1-5 per cent of the S-content in the fuel, depending on the engine

load (Petzold et al., 2010).

In a corresponding way the emissions of CO2 will be dependent on the carbon content in the fuel

and the fuel consumption. This then neglect the small fraction of the carbon that will be emitted as

carbon monoxide, organic compounds and soot. The sum of these will typically be two to three or-

ders of magnitude lower than the CO2-emissions. The carbon content in marine fuels can vary

somewhat but is normally around 87%. Table 3 shows the emission factors for SO2 and CO2 for

different engine types expressed in mass of emission per engine work and mass of emission per

mass of fuel consumed.

Table 3 Emission factors for CO2 and SO2 from Cooper and Gustafsson (2004)

Engine type Fuel type FSC EFCO2

(g/kWh)

EFCO2

(g/kgfuel)

EFSO2

(g/kWh)

EFSO2

(g/kgfuel)

Slow speed Residual oil 2.7% 620 3 179 10.5 54.0

Residual oil 1% 620 3 179 3.90 20.0

Marine distillates 0.5% 588 3 179 1.85 10.0

Marine gas oil 0.1% 588 3 179 0.37 2.0

Medium Residual oil 2.7% 683 3 179 10.6 54.0

speed Residual oil 1% 683 3 179 4.30 20.0


Marine gas oil 0.1% 652 3 179 0.41 2.0

High speed Residual oil 2.7% 683 3 179 10.6 54.0

Residual oil 1% 683 3 179 4.30 20.0


Marine gas oil 0.1% 652 3 179 0.41 2.0

Emission factors for VOC and CO

The emissions of hydrocarbons and carbon monoxide represent incomplete combustion of the fuel.

These emissions from marine diesel engines are typically small due to the lean burning conditions

and stable engine loads, but sharp increases may occur during rapid load changes of engines (accel-

eration/deceleration phases) because of incomplete combustion of fuel. Typical emission factors can

be found in Table 4. Note that the emission of CO and HC will increase at lower load (manoeuvring

in Table 4). The details in the emissions at lower loads will depend on the operation and on the in-

dividual engine. Sarvi et al (2008) investigated the effect of engine load on emission factors of CO

and HC on a four-stroke MSD engine using HFO (Figure 5).


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Figure 5. Effect of engine load on emission factors (in g/kWh) for CO and HC. The engine is a four-stroke MSD

in propulsion mode using HFO (from Sarvi et al., 2008, their Figs 4 and 5).

Table 4. Emission factors for CO (EFCO) and HC (EFHC) from Cooper and Gustafsson (2004).

Engine type Fuel type Operational

mode

EFCO

(g/kWh)

EFCO

(g/kgfuel)

EFHC

(g/kWh)

EFHC

(g/kgfuel)

Slow speed Residual oil At sea 0.5 2.5 0.3 1.6

Manoeuvring 1.0 4.6 0.6 2.8

Marine distillates At sea 0.5 2.7 0.3 1.5


Medium speed Residual oil At sea 1.1 5.1 0.2 0.9




High speed Residual oil At sea 1.1 5.1 0.2 0.9




Emission factors for NOX

The larger part (~90%) of the nitrogen oxides emitted from marine engines is formed from nitrogen

in the air at the high temperatures prevailing in the combustion zones in the cylinders. The emis-

sions of nitrogen oxides is as mentioned earlier regulated for engines manufactured after the year

2000 and for engines with a power output of more than 5,000 kW and cylinder displacement at or

above 90 litres after 1990. The emission standards define the maximum allowed NOx emission fac-

tor (in g/kWh) determined by the year of installation of the ship engine and by its rated speed n.

This NOx emission factor is a weighted emission factor for a certain driving cycle at standard en-

gine inlet air humidity (10.71 g/kg) and temperature (25ºC). The driving cycle depends on type of

0

0.5

1

1.5

2

2.5

3

25 50 75 100

EF (

g/k

Wh

)

Engine load, % of max

CO

HC x 10


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engine (cycles C1 for variable-speed, variable-load auxiliary engine, D2 for constant-speed auxilia-

ry engine, E2 for “Constant-speed main propulsion” application including diesel-electric drive and

all controllable-pitch propeller installations, E3 for propeller-law-operated main and auxiliary en-

gines) and the measured emission factor is corrected to the standard conditions. Determination of

the NOx emission factors is in detail described in the NOx Technical Code (Annex 14 i.e. revised

Annex VI of MARPOL from 2008, for Tier I is until 2011 possible to use Annex VI from 1997).

Emission factors in Tier I standard represents engine standard of year 2000, for older vessels an

engine upgrade may be needed but that is obligatory only provided that an approved and certified

method for reduction of NOX emissions exists. Tier II standard represents c.a. 20% emission reduc-

tion from Tier I and is expected to be met by internal engine combustion optimization measures.

The parameters examined by engine manufacturers include fuel injection timing, pressure, and rate

(rate shaping), fuel nozzle flow area, exhaust valve timing, and cylinder compression volume. Tier

III standard represents c.a. 80% reduction and requires dedicated NOx emission control technolo-

gies such as various forms of water induction into the combustion process (with fuel, scavenging

air, or in-cylinder), exhaust gas recirculation, or selective catalytic reduction. Typical emission fac-

tors for the different Tiers and engines speeds can be found in Table 5.

Table 5. Emission factors for NOX from Cooper and Gustafsson (2004) (no Tier) and IMO regulations. The emis-

sion factors in g/kgfuel assume that the SFC will not change between the Tiers.

Engine type Fuel type Emission

class

EFNOx

(g/kWh)

EFNOx

(g/kgfuel)

Slow speed Residual oil No Tier 18.1 87.4

Tier 1 17.0 82.1

Tier 2 14.4 69.5

Tier 3 3.4 16.4

Marine distillates No Tier 17.0 91.6

Tier 1 17.0 91.6

Tier 2 14.4 77.6

Tier 3 3.4 18.3

Medium speed Residual oil No Tier 14.0 61.7

Tier 1* 11.3 49.8

Tier 2† 8.98 39.6

Tier 3‡ 2.26 10.0


Tier 1* 11.3 54.9

Tier 2† 8.98 43.7

Tier 3‡ 2.26 11.0

High speed Residual oil No Tier 12.7 58.9

Tier 1 9.8 45.5

Tier 2 7.7 35.7

Tier 3 1.96 9.1


Tier 1 9.8 47.6

Tier 2 7.7 37.4

Tier 3 1.96 9.5 * EF for engine speed n = 1000 to 2000 rpm, EF = 45 · n

(-0.2) in Tier I.

† EF for engine speed n = 1000 to 2000 rpm, EF = 44 · n

(-0.23) in Tier II.

‡ EF for engine speed n = 1000 to 2000 rpm, EF = 9 · n

(-0.2) in Tier III.


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Emissions factors for PM mass

Particles emitted by marine engines consist of a volatile and non-volatile fraction. Volatiles are mainly sulphate with associated water and organic compounds. Non-volatiles consist of elemental carbon (soot, char) and of ash and mineral compounds containing Ca, V, Ni and other elements. Because of the high content of condensable matter in the exhaust the methodology of sampling im-pacts the PM mass found. Sampling directly in the hot exhaust captures to a large extend only the non-volatile part of PM while sampling in the diluted and cooled exhaust captures also some of the volatiles. The amount, however, depends on the dilution and temperature program of the sampling. Figure 6 shows the difference between PM sampled in the hot and diluted exhaust from a slow-speed diesel engine running on HFO with 1.9% sulphur.

Figure 6 Composition of PM (as mg/m3 exhaust gas) collected on filters in the diluted and hot exhaust gas (Mol-

danová et al., 2009).

Emissions of PM varies with fuel type, fuel sulphur content and engine operation mode. Table 6

shows EFPM for cruise conditions published by Cooper and Gustafsson (2004) for different marine

engines for HFO and MDO fuels together with EFPM from the Lloyds emission database (European

Commission, 2002). These emission factors are based on larger number of measurements (c.a. 45

measurements at IVL database and 25 in Lloyd‟s database). The mean FSC in Cooper and Gus-

tafsson (2004) was 2.3% and in EC (2002) 2.7%. The PM measurements reviewed in these reports

were performed using the partial dilution equipment, i.e. corresponding to the PM in „diluted‟ ex-

haust in Figure 6.

0

50

100

150

200

dilluted hot

mg/m

3

unidentified

sulph. assoc. water

sulphate

OC

EC

ash


14 of 21

Table 6. Emission factors for PM mass (EFPM) for cruise and manoeuvring conditions from Cooper and Gus-

tafsson (2004) for different marine engines for residual oil (RO) and marine distillates (MD). The mean FSC is

2.3 wt.% for RO and 0.4 wt.% for MDO. EFPM for cruise conditions from the Lloyds emission database (Euro-

pean Commission, 2002) for the global fleet, these EFPM are weighted for fuels used by the engine category. The

global FSC in this study is 2.7 wt.%.

Cooper & Gustafsson (2004) EC (2002)

Engine type Fuel type EFPM at sea EFPM manoeuvring EFPM at sea

g/kWh g/kgfuel g/kWh g/kgfuel g/kg fuel

SSD MD 0.2 1.08 0.4 1.97 7.6*

SSD RO 1.3 6.67 2.6 12.12

MSD MD 0.2 0.98 0.4 1.77 1.2*

MSD RO 0.5 2.33 1.0 4.23

HSD MD 0.2 0.98 0.4 1.77

HSD RO 0.5 2.33 1.0 4.23 * Mixture of MD and RO

When more recent data from individual engines are added, one can see a span of EFPM for en-gines using RO between 1 and 13 g/kg fuel with the mean around 7, and for engines using MD be-tween 0.2 and 1 g/kg fuel. Figure 7 shows a plot of the available data on EFPM at cruise conditions (engine load 75-90%) against the fuel-sulphur content (FSC). We can see a clear linear relation be-tween emission factor for PM and the FSC for data measured on engines using RO. Emission factor for MSD engines from Cooper and Gustafsson (2004) are lower comparing to other data, however there are only few more individual measurements for this engine and fuel category available. The Lloyds EF for SSD engines are included (EC, 2002) assuming FSC 2.7% which is Lloyd‟s estimate of the global mean FSC for RO.

Figure 7. Emission factors for particle mass EFPM as a function of FSC. EFPM for RO is plotted in blue, data for

MSD engines are with white cross, filled blue are for SSD. EFPM for MD is plotted in green, all for MSD engines.

The blue line is linear regression for the data measured on engines using residual oil (RO) (EFPM = 4.43 x FSC –

3.29, R2 = 0.63).

0

2

4

6

8

10

12

14

0 1 2 3 4

EFP

M [

g/kg

fu

el]

FSC [wt.%]

RO

RO MSD

MD

EC (2002)

Cooper (2004)

Cooper (2004)


15 of 21

PM mass emission factors change with the engine load. In the stack typically between 1 and 5%

of sulphur is oxidized to SO3 (Moldanová et al., 2009; Petzold et al., 2010) and contributes to the

exhaust PM. Petzold et al. (2010) showed a positive correlation between the SO2 in-stack oxidation

and the engine load for engines using HFO with similar fuel sulphur content (between 2 – 2.5%)

(Figure 8a). While EF for sulphate is positively correlated to the engine power, i.e. contributes most

to the PM emissions at high engine loads, emissions of black or elemental carbon and of organic

carbon are higher at low engine loads and have their minima at loads around 50% and increases

somewhat at cruise conditions (Figure 8b, Petzold et al., 2010,). The resulting dependence of EFPM

on engine load thus varies with fuel sulphur content and potentially also with fuel type. One should

also remember that the fuel consumption of course also varies with the engine load making the

emissions (in g/hour) higher at cruising that at low loads.

In the STEAM2 model Jalkanen et al. (2011) use EFPM (emission factor for total particulate mat-

ter mass) and emission factors for 5 different PM components: EC, OC, sulphate, ash and the sul-

phate-associated water as a function of engine load and the FSC. The FSC dependence is built on

data from the 2nd IMO GHG study (IMO, 2009) and the dependence on engine load on data from

Agrawal et al. (2008a), Petzold et al. (2008) and Moldanova et al. (2009). Table 7 and Table 8 show

emission factors from STEAM2 for a span of FSC and engine loads.

a)

b)

Figure 8. a - Efficiency for converting fuel sulphur to particulate-matter sulphate at various engine loads and for

fuels with different sulphur contents given in wt-%; the dashed line represents a linear relationship between part

of sulphur in exhaust converted to sulphate and engine load. (Ref (1): Kasper et al., 2007; Ref (2): Agrawal et al.,

2008a; Ref (3): Agrawal et al., 2008b; Ref (4): Moldanová et al., 2009; other data: Petzold et al., 2010) (from

Petzold et al., 2010, their Fig. 4). b - Mass emission factor for carbon-containing compounds, sulphate and PM in

the raw exhaust gas, FSC 2.40wt-% (EC - elemental carbon, OM – organic matter, both analysed by multi-step

combustion method) (from Petzold et al., data in their Table 1).

0 20 40 60 80 100 1200.0

1.0

2.0

3.0

4.0

5.0

6.0

test, 2.40 wt-%

serial, 2.32 wt-%

Ref (1), 0.16 wt-%

Ref (2), 2.05 wt-%

Ref (3), 2.85 wt-%

Ref (4), 1.95 wt-%

Kurok, unpublished

su

lfu

r co

nve

rsio

n ,

%

engine load , % of max


16 of 21

Table 7. Total PM2.5 emission factors (g/kWh) at selected engine loads and fuel sulphur content (wt-%)

Load 0.1% S 1.0% S 1.5% S 2.7% S 3.5% S

20% 0.41 0.99 1.31 2.08 2.60

40% 0.38 0.91 1.21 1.92 2.40

60% 0.36 0.87 1.15 1.83 2.28

80% 0.35 0.86 1.14 1.80 2.25

100% 0.36 0.88 1.16 1.84 2.30

Table 8. The emission factors of PM2.5 subcomponents (g/kWh) as a function of engine load. The fuel sulphur

content is 1.5 wt-%

Load EC OC Ash SO4= H2O Total PM

20% 0.06 0.23 0.06 0.54 0.42 1.31

40% 0.05 0.21 0.05 0.50 0.39 1.21

60% 0.05 0.20 0.05 0.48 0.37 1.15

80% 0.05 0.20 0.05 0.47 0.37 1.14

100% 0.05 0.20 0.05 0.48 0.37 1.16

In the atmosphere the oxidation of the emitted SO2 proceeds and in ship plumes sulphate be-

comes the dominant component of the PM. If all sulphur corresponding to 1% FSC would be oxi-

dised into H2SO4 and this H2SO4 would condense on particles in the ship plume, one would get an

emission factor for particulate H2SO4 of 30.6 g/kg fuel and, further, if also the water associated to

sulphate is accounted for an emission factor of 67 g/kg fuel is obtained. This numbers can be com-

pared to the typical EFPM that are a few grams per kg fuel.

While some measurements indicate that about 50 - 70% of the total suspended particles (TSP)

could be as PM2.5 and the remainder as PM10 (Cooper, 2003) other studies show that as for other

diesel engines the emissions are dominated by particles with diameters less than 1 µm (i.e. TSP =

PM10 = PM2.5). There are also studies that show the presence of larger (tar-like and reentrained) par-

ticles in the exhaust from slow speed engines using heavy fuel oil (Lyyränen et al., 1999; Fridell et

al., 2008; Moldanova et al., 2009) indicating that TSP may be larger than PM10. One can anticipate

that the particle size distribution will be dependent on fuel type, engine type, operation and age of

the gas plume.


17 of 21

Emissions factors for PM number concentration

Emission factors for particle number concentrations are in the order of magnitude of 1016

/kg fuel.

Measurements, presented by Petzold et al. (2010), on a 4-stroke MSD burning RO show emission

factors for total particle number, EFN, between 1 and 4.5 x 1016

/kg fuel, with a positive correlation

between EFN and the engine load (Figure 9a). Airborne measurements in ship plumes have shown

EFN of the same order of magnitude but a factor of 2-3 lower (Lack et al., 2009; Petzold et al.,

2008; Murphy et al, 2009) (Figure 9a). Petzold et al. (2010) investigated the volatility of the emitted

particles in exhaust from a 4-stroke MSD test engine using a thermo denuder. They found that 2/3

of the particles at high load and 1/3 at low load were volatile and that the number of non-volatile

particles did not change for loads >20%. The increase in total particle emissions with load by a fac-

tor of 3 was almost entirely attributed to sulphuric acid-water droplets. Figure 9b shows the number

concentrations of particles in the accumulation mode, i.e. those with diameters in the range 0.1-3

µm, measured on test engines and in ship plumes.

a) b)

Figure 9. Emission factors for particle numbers measured on test engine burning RO with FSC 2.21 and in air-

borne measurements in ship plumes. a – total and non-volatile particles, b – particles in accumulation mode.

(from Petzold et al., 2010, data in Table 1)


18 of 21

Emissions factors for PAH and benzo(a)pyrene

Polycyclic aromatic hydrocarbons (PAH) are compounds that consist of fused aromatic rings and do not contain heteroatoms or carry substituents. PAH cover a large group where naphthalene is the simplest species. There are several different groupings of PAH compounds defined for criteria pol-lutant critical levels. Widely used are EPA‟s 16 priority PAH “PAH-16” and EPA‟s 7 carcinogenic “PAH-7‟. In Europe “Total PAH-6” and “Total PAH-4” are defined for emission reporting to the European Commission (EC, 2000). Species included in these groups are shown in Table 9.

Table 9. PAH compounds and groups as defined by EPA and EC.

PAH species

Naphthalene

EP

A‟s

PA

H-1

6

Acenaphthylene

Acenaphthene

Fluorene

Phenanthrene

Anthracene

Pyrene

Benzo(a)anthracene

EP

A‟s

PA

H-7

Chrysene

Dibenzo(ah)anthracene

Benzo(a)pyrene

EC

‟s

Tota

l P

AH

-6

EC

‟s

Tota

l P

AH

-4

Benzo(b)fluoranthene Benzo(k)flouranthene Indeno(1,2,3-cd)pyrene

Benzo(ghi)perylene

Fluoranthene

There are only few data on emissions of PAHs from shipping. Publications of Lloyds (1995),

Cooper et al. (1996), Cooper (2001; 2003) and Agrawal et al. (2008; 2010) present a limited set of

Emission Factors of PAHs for a range of marine engines covering the most commonly used marine

fuels. Publications of Cooper et al. and Agrawal et al. are in agreement in that napthalenes and phe-

nanthrenes account for 80-90% of the measured PAH species. Cooper and Gustafsson (2004) pre-

sented, based on the first 4 publications, EFPAH for the EC‟s “Total PAH-4” for different engines

and fuels. The data used, however, do not cover the whole presented emission matrix. Comparing

these EFs with data from individual measurements found in literature one can observe that 1) the

measured EFs are largely variable with fuel and engine operation mode but relatively large variabil-

ity is present also for data obtained at similar conditions, 2) agreement between different EF esti-

mates for marine engines at full load operation using marine distillate fuels seems fairly good and

the EF is ~1x10-6

g/kWh, 3) different EF estimates for engines using heavy fuel oil differ for PAH-4

by factor 100 at most, Cooper and Gustafsson (2004) being lower than Agrawal et al. (2008b,

2010). Measurements of Agrawal et al. indicate that emission factors of these species for engines

running on HFO are much higher than those for engines running on distillate fuel. Emission factors

for PAH (Total-4) benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene and indeno[1,2,3-

cd]pyrene are summarised in Table 10. Measurements reported by Agrawal et al. (2008b, 2010)

show that PAH emissions at low engine loads tend to be substantially higher than emissions at op-

timum load. Figure 10 shows differences between EFs of several PAH species and groups at differ-

ent engine loads and the same EFs at optimum engine load expressed relatively to the EF at opti-


19 of 21

mum load. We can see that large increase in EFs is in the 15% load mode. However, large variabil-

ity in the data exists as can be seen on difference between data points at 50% engine load.

Table 10. Emission factors for PAH (Total PAH-4, EC, 2000), benzo(a)pyrene. benzo(b)fluoranthene, ben-

zo(k)fluoranthene and indeno[1,2,3-cd]pyrene; st.dev. is standard deviation of the data.

Engine

type

Fuel

type

Cooper and Gustafsson (2004)

Agrawal et al., 2008

75-85% load

Agrawal et al., 2010

75-90% load

at sea manoeuvring

g/kgfuel g/kWh g/kWh g/kWh st.dev g/kWh st.dev

Total PAH-4

SSD MD 3.2×10-5

5.92×10-6

5.37×10-6

SSD RO 3.1×10-5

6.05×10-6

5.46×10-6

1.5×10-4

1.4×10-4

1.3×10-3

3.8×10-4

MSD&SSD MD 2.9×10-5

5.95×10-6

5.54×10-6

5.3×10-6

7.9×10-7

MSD&SSD RO 2.8×10-5

6.02×10-6

5.38×10-6

GT&ST MD 2.0×10-5

6.00×10-6

5.94×10-6

GT&ST RO 2.0×10-5

6.10×10-6

6.05×10-6

Benzo(a)pyrene

SSD MD 5.4×10-6

9.99×10-7

9.07×10-7

SSD RO 5.1×10-6

9.90×10-7

9.17×10-7

1.2×10-4

1.2×10-4

2.0×10-4

1.2×10-4


1.00×10-6

9.02×10-7


1.01×10-6

9.03×10-7

1.7×10-6

2.5×10-7

GT&ST MD 3.3×10-6

9.90×10-7

9.90×10-7

GT&ST RO 3.3×10-6

1.01×10-6

1.01×10-6

Benzo(b)fluoranthene

SSD MD 1.1×10-5

2.00×10-6

1.81×10-6

SSD RO 1.0×10-5

2.01×10-6

1.81×10-6

3.9×10-6

2.3×10-6

2.1×10-5

6.1×10-6


2.01×10-6

1.82×10-6

6.9×10-7

1.0×10-7


2.00×10-6

1.83×10-6

GT&ST MD 6.7×10-6

2.01×10-6

1.83×10-6

GT&ST RO 6.6×10-6

2.01×10-6

1.83×10-6

Benzo(k)fluoranthene

SSD MD 5.4×10-6

9.99×10-7

9.07×10-7

SSD RO 5.1×10-6

9.95×10-7

9.17×10-7

5.9×10-6

1.9×10-6

6.5×10-5

1.3×10-5


1.00×10-6

9.02×10-7

1.4×10-6

2.1×10-7


1.01×10-6

9.03×10-7

GT&ST MD 3.3×10-6

9.90×10-7

9.00×10-7

GT&ST RO 3.3×10-6

1.01×10-6

9.15×10-7

Indeno[1,2,3-cd]pyrene

SSD MD 1.1×10-5

2.00×10-6

1.81×10-6

SSD RO 1.0×10-5

2.01×10-6

1.81×10-6

2.3×10-5

2.2×10-5

9.9×10-4

2.4×10-4


2.01×10-6

1.82×10-6

1.5×10-6

2.2×10-7


2.00×10-6

1.83×10-6

GT&ST MD 6.7×10-6

2.01×10-6

1.83×10-6

GT&ST RO 6.6×10-6

2.01×10-6

1.83×10-6


20 of 21

Figure 10. Difference between emission factors of various PAH species and groups and emission factors of the

same PAH species/groups at optimum engine load of 75-85% expressed relatively to the EF at optimum engine

load (i.e. 1 means EF 100% higher than at optimum load) (data from Agrawal et al., 2008b and 2010).

All findings on EFs for PAHs are quite consistent with how PAHs are formed, which is during incomplete combustion of organic matter including the petroleum products. The EFs are then ex-pected to be higher from combustion of fuel with higher PAH concentration and at low load condi-tions. In publications dealing with PAH emissions from shipping only Cooper et al. (2001) analysed fuels for PAH content. They found PAH content of 1% in MGO and 6.6% in MDO (0.5%S).

Conclusions

This report summarizes emission factors of gaseous and particulate species from shipping. It shows a rather complex picture where emission factors for CO2 and SO2 are directly proportional to the C and S content in fuel burned, NOx and directly emitted particulate sulphate are more efficient-ly produced in efficient combustion meaning high engine loads while CO, VOCs, particulate BC, OC and PAHs are more efficiently produced in incomplete combustion meaning low engine loads. Emission factors are thus function of fuel type, fuel sulphur content, type of engine and load of en-gine used. The activity data needed for calculation of emission inventory is than fuel used (at least MGO+MDO and HFO) in different types of engines, including engines equipped with different clean technologies, information on fuel sulphur content plus part of fuel used under different engine loads. Considering that the changes of EF against the engine load mostly deviate for very low loads (15-25%), separation on cruise and manoeuvring would be sufficient.

Emission factors for CO2, NOx, SO2 CO and HC presented here are based on a large number of measurements in Lloyd‟s and IVL‟s databases. These emission factors are widely used, however many other data and compiled emission factors exist. We have not performed a complete review of data for these species as focus of this report is on PM. Data on emission factors for PM mass, num-ber and composition for shipping are very limited. The existing emission inventories of PM mass emissions from shipping use ENTEC data on PM mass emission factors (EC and ENTEC, 2002). The existing data on PM number and composition are reviewed here.


21 of 21

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http://europa.eu/legislation_summaries/environment/air_pollution/l21050_en.htm

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