Air emissions legislation reviewfor internal combustion engines

IntroductionGeneral

The reciprocating engine is the natural choice for the shipping

industry, while in the power plant sector stationary engine-

driven power plants are popular today (Fig. 1). Larger baseload

engine-driven power plants with outputs up to 300 MW

electricity and also smaller decentralized combined heat and

power (CHP) production plants are both common.

Reciprocating engines offer many advantages:

� High thermal efficiency (low fuel consumption)

� Optimal matching at different loads (fast load response and

good load-following characteristics)

� Flexible fuel choice

� Easy maintenance and robust design.

Engine-driven power plants also have a short construction time,

they are compact and water conserving (Fig. 2), and they can be

located close to the end user.

Different types of reciprocating engines exist on the market

and are operated according to various principles. The most

common engine types and fuel alternatives are:

� Diesel engines operating on diesel oil, heavy fuel oil, crude

2

Fig. 1 Wärtsilä 20V34SG and 6R32DF prime movers.

130 MW power plantse

Assumption: hardness ofraw water is max 5°dH

600

500

400

300

200

100

0

Die

sela

ndga

sen

gine

bas

edp

ower

pla

nt, r

adia

tor

cool

ed

Die

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nt,

cool

ing

tow

er

Ste

amb

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rp

ower

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cool

ing

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er

m3/h

Fig. 2 Raw water consumption in different power plantswith primary flue gas cleaning methods, for exampleappropriate fuel choice and dry nitrogen oxides (NOX)reduction such as Low-NOX burners for the boiler and aLow-NOX combustion diesel engine.

oil, natural gas (high-pressure gas 350...400 bar), biofuels (gas

and oils), and Orimulsion™

� Spark-ignited (SG) Otto-type engines operating on

low-pressure gas fuels

� Dual-fuel engines (DF) that run on low-pressure natural gas

(with liquid fuel as pilot fuel) or on liquid fuels such as diesel

oil (as a back-up fuel) and heavy fuel oil. These engines can

operate at full load in both fuel modes. In liquid mode they

work according to the diesel process, and in gas mode

according to the Otto process.

Energy efficiency (low specific CO2 emissions)

Reciprocating engines have the highest rate of energy conversion

to mechanical output among simple cycle prime movers, which

means the lowest fuel consumption and therefore the lowest

specific CO2 and SO2 (sulphur dioxide) emissions for a given

specific fuel quality. CO2 (“the most important greenhouse

gas”) emissions are in focus today due to the Kyoto Protocol.

These emissions can be reduced by increasing the efficiency of

the prime mover or by switching the plant’s fuel, or both. Other

measures of reducing CO2 emissions are increased combined

heat and power (CHP) production in efficient decentralized

power plants close to the end user and replacing old inefficient

power stations with efficient new ones.

Typical energy efficiencies (mechanical output) for simple

cycle applications are 40...49% (calculated at the lower heat

value of the fuel), where smaller units have lower and large

2-stroke engines have the highest efficiency. Figure 3 gives

typical specific CO2 emissions for different prime movers.

Reciprocating internal combustion engines run at high

efficiency over a broad load range, which is a significant

advantage in ships or other applications where engine loading

varies considerably.

The high efficiency at part load together with the consecutive

use of engines in a multi-engine installation enables power plant

turndown ratios to as low as 10%. Multi-engine installations

also increase operating safety and availability by providing a

redundant solution and giving the possibility to perform

corrective or preventive maintenance on part of the plant while

the rest continues to produce power and heat.

The energy efficiencies of Wärtsilä engines have increased

substantially in recent decades. This trend reflects both better

engine performances and bigger engine sizes. Engine efficiencies

have generally risen as a result of increased firing pressures,

higher compression ratios, shorter fuel injection duration,

optimized valve timings and improved combustion processes.

The improvement of efficiency of Wärtsilä engines has a

significant impact on the environment from the lifecycle point

of view, since the operative life of a reciprocating internal

combustion engine is normally between 25 and 50 years and in

some cases even longer.

The CHP plant can be situated in urban or industrial areas

close to the consumers of the heat and electricity it produces, so

the need for land and transmission lines, with their associated

energy losses, can be minimized. Reciprocating engines are well

suited for cogeneration, e.g. for hot water production, steam

generation (sometimes with an additional steam turbine for

enhanced electrical efficiency), sea water desalination, district

cooling systems and for heating air for industrial processes. The

heat-to-power ratios for the engine in CHP applications

typically range from 0.5 to 1.3. As an example, the specific CO2

emissions of a cogeneration (CHP) plant producing electricity

and useful heat are about 370 g/kWh (heat + electricity) when

operating on heavy fuel oil at a total plant efficiency of about

80%. The total efficiency will vary from case to case depending

on the plant configuration.

It is not only the efficiency of the prime mover that affects

the resulting CO2 gas emissions; the choice of fuel also has an

impact, for example if oil is used instead of coal, or if natural gas

or gases from renewable sources are used instead of oil. The

modern reciprocating engine is fuel versatile; it can be run on

both a conventional liquid or bioliquid fuel and also gaseous

(natural or bio) fuels (depending on the engine type).

3

CO2 emissions in g/kWh (electricity)

Gas engine,

natural gas,

single cycle

450

Diesel engine,

fuel oil,

single cycle

600

Gas turbine,

natural gas,

single cycle

600

Gas turbine,

fuel oil,

single cycle

750

Coal-fired,

steam boiler

800

Fig 3 Typical CO2 emissions for different prime movers.

Reduction technologies

It is generally preferable to apply primary methods to reduce air

emissions at their source rather than attempting to remove them

from the exhaust gases. Wärtsilä is putting heavy emphasis on

developing new primary methods for its engines while closely

following the development of the secondary methods.

Primary methods

1. Nitrogen oxides (NOX)

Nitrogen oxides (NOX) are formed in the combustion process

by oxidation of nitrogen (from the atmosphere and fuel) to NO

and NO2. The NOX formation rate in a engine is largely

temperature driven and consequently a function of the local

high-temperature areas and their duration during combustion.

To be able to reduce NOX emissions it is necessary either to

prevent their formation in the cylinder (primary method) or to

remove the NOX from the exhaust gases in an after-treatment

system (secondary method).

There are two basic primary methods of reducing NOX

emissions in diesel engines, the first “dry” and the second “wet”:

� In-cylinder combustion control measures without water

introduction:

– Low-NOX combustion for diesel engines

– The lean-burn approach for gas-fired spark-ignited (SG) or

dual-fuel engines (DF)

� Introducing water into the combustion process by:

– Injecting water directly into the combustion chamber

(applicable only on liquid-fuel-fired diesel engines), or

– Humidifying the combustion air, or

– Water emulsion (e.g. a water/fuel oil emulsion)

Dry methods

Low-NOX combustion research is focusing on optimizing the

closing timing of the inlet valve (technology called “Miller valve

timing”); early inlet valve closing suppresses the in-cylinder

combustion temperatures, which reduces NOX formation. So

far this method has achieved a NOX reduction of about 35%

(reduction from the beginning of 1990) with unaffected or

slightly improved engine-specific fuel consumption. Further

efforts are being made to achieve higher reductions.

In the lean-burn approach natural gas and air are premixed

before introduction into the cylinders, which results in a lower

combustion temperature. This low fuel/air ratio, called

lean-burn, reduces NOX efficiently.

Water/steam introduction

It has long been known that water has a positive influence on

reducing NOX formation by cutting temperature peaks in the

combustion process. Various methods of introducing water have

been evaluated and tested such as water-in-fuel emulsions,

humidification of the combustion air by various methods, and

4

Fig. 4 In the engine laboratory in Vaasa (Finland) new innovative engine designs and primary emission reduction methodsare developed and tested.

direct water injection into the combustion space. Each

alternative has its own merits and drawbacks. The water must be

of good quality to prevent clogging of the system, and the fuel

consumption also increases slightly with most “water/steam

introduction” methods. Fuel consumption depends on the

method used and the NOX reduction rates; at high NOX

reduction rates the emissions of unburned CO, HC and

particulates tend to increase.

Direct Water Injection (DWI)

Injecting water into the cylinder (applicable on some

liquid-fuel-fired diesel engine types) reduces the temperature in

the cylinder and in this way prevents the formation of NOX.

Direct Water Injection can reduce the NOX level by up to

50…60% (depending on the engine type) without adversely

affecting power output or engine components. The method

requires the minimum of space, which makes it suitable for

retrofitting at low investment cost. NOX reduction will be most

efficient from loads of 40% and higher of nominal engine

output.

To reach the maximum NOX reduction, water consumption

is slightly over half of the fuel oil consumption, and the water

used can be evaporated or technical water. DWI is applicable for

bigger engine types such as the W32, W38, W46 and W64 in

marine applications. More than 50 marine engines with DWI

are already installed or on order.

Humidification of the combustion air

Combustion air can be humidified in different ways including

injecting steam before the inlet to the turbocharger or in the

charge air cooler. A new technology under development is CASS

(Combustion Air Saturation System), which is being pilot tested

on a Wärtsilä 32 Low-NOX engine. CASS technology seems to

be more efficient than the DWI system but with the drawback

that the water consumption is higher.

Water emulsion

Tests with Orimulsion™ have given a NOX reduction typically

up to 30% compared to normal heavy fuel oils. Water/fuel oil

emulsion will normally reduce NOX by 20...30% compared to

the fuel oil case.

2. Sulphur dioxides and particulate

The primary method of reducing SOX and particulate emissions

is to use a low sulphur/ash fuel oil or natural gas, whenever

commercially available.

3. Unburned emissions (CO, NMHC, etc.)

Due to its high combustion temperature, a diesel engine

produces low levels of unburned gaseous components, and thus

meets most existing emissions legislation governing stationary

power plants. The primary methods of keeping emissions low

are normal maintenance and the power plant’s operating profile.

Gas-fired spark-ignited and dual-fuel engine types have higher

levels of unburned emissions compared to a diesel engine and,

depending on the stationary power plant legislation in question,

sometimes these installations must be equipped with a

secondary method (oxidation catalyst).

5

Fig. 5 The Samalpatti power plant (106 MWe) in India was installed with Low-NOX Wärtsilä 46 engines in order to complywith the Indian requirements.

4. The smokeless engine

The need for non-visible smoke operation in the marine market

has been boosted in recent years especially by the cruise ship

industry. Since most harbours visited and routes operated by

cruise ships are close to densely populated or environmentally

sensitive areas the demand for non-visible smoke operation is

considered to be increasingly important. Wärtsilä has responded

to these needs with the introduction of common rail fuel

injection technology.

The apparent darkness of a stack plume depends upon many

parameters such as concentration, size distribution and the

colour of the particulate matter in the effluent, the gas

temperature at the stack exit, the depth of the plume (i.e. the

duct diameter), natural lighting and background conditions.

To avoid visible smoke it is necessary to prevent fuel droplets

from coming into contact with metal surfaces around the

combustion space. High fuel injection pressures generate small

fuel droplet sizes. With conventional mechanical injection

systems the fuel injection pressure drops at low loads, resulting

in large fuel droplets. Some of these will survive as droplets until

they hit the combustion space surfaces, generating smoke

emissions. The common rail fuel injection system on the other

hand keeps the injection pressure high and constant over the

whole load range, thus enabling operation without visible smoke

over the entire operation field.

The smokeless engine concept is available for bigger 4-stroke

engine types and for 2-stroke engines. The 2-stroke smokeless

engine is called the RT-Flex engine (Fig. 7). The key feature of

the RT-Flex system is that it gives complete freedom in the

timing and operation of fuel injection and exhaust valve

actuation. This flexibility is employed to reduce engine running

costs and exhaust emissions, and to ensure steady operation at

very low speeds. This is made possible by the precise control of

injection, together with the higher injection pressures achieved

at low speed, and the sequential shut-off of the injector.

Consequently RT-Flex engines can run very steadily, and

without smoking, at 10…12% of nominal speed.

Secondary methods

NOX: Selective Catalytic Reduction (SCR)

Selective Catalytic Reduction is the only suitable secondary

method today for reducing NOX typically by 85…90%. A

reducing agent, such as an aqueous solution of ammonia or

urea, is injected into the exhaust gas at a temperature of

6

Fig. 6 The RoRo vessel Mistal powered with a Wärtsilä 16V46 main engine equipped with Direct Water Injection.

Fig. 7 The bulk carrier Gypsum Centennial is equipped witha Sulzer 6RT-Flex58T-B main engine.

290…450 °C. The urea reagent in the exhaust gas decays into

ammonia, which is then put through a catalyzing process that

converts the NOX into harmless nitrogen and water.

It is important to note that at high NOX reduction rates the

control system of the SCR is critical due to its operation within

a narrow window. At high reduction rates the size of the SCR

reactor increases and more complicated premixing and reagent

injection systems are needed, which raises the investment cost. A

high NH3/NOX ratio is needed at high NOX reduction rates,

i.e. more reagent is needed, which results in higher operating

costs. A high NH3/NOX ratio may also lead to increased

emission of ammonia (ammonia slip).

A typical SCR plant consists of a reactor containing several

catalyst layers, a dosing and storage system for the reagent, and a

control system. In marine vessels, where available space is

limited, the reactor is designed to incorporate the exhaust gas

silencer – a solution called Compact SCR. The size of the

reagent tank depends on the size of the engines, the load profile

and how often the tank can be refilled.

The lifetime of the catalyst elements is typically 3…5 years

for liquid fuels and longer if the engine is operating on gas. The

high running costs of the catalyst result from the consumption

and price of the reagent and from replacement of the catalyst

layers. The reagent consumption depends on the stipulated

NOX limit.

SCR technology can be applied on all Wärtsilä engines,

2-stroke as well as 4-stroke. Experience in the application of

SCR in diesel engine plants has highlighted the following

points:

� SCR is a sensitive method: a certain minimum temperature is

needed to avoid salt formation (“SOX” sensitivity) on the SCR

elements.

� Some trace metals which might be present in the fuel oil act

as “catalyst poisons” and deactivate the catalyst

� A soot blowing system should be installed in the reactor

containing the catalyst elements (especially when operating

on liquid fuels).

SCR technology is used on many ferries in the Baltic Sea and

currently about 60 marine engines are fitted or have been

ordered with SCR. Around the world about 1000 MWe of

stationary power plants equipped with Wärtsilä engines are

equipped with SCR.

SO2 and particulates

The emissions of sulphur dioxide and particulates are mainly

fuel related. If a low-sulphur/ash fuel or natural gas is not

commercially available and the stipulated emission limit is strict,

a secondary exhaust gas cleaning method should be used. A wet

flue gas desulphurization (FGD) unit is used mainly for SO2

removal and an electrostatic precipitator (ESP) for particulate

removal. A semi-dry FGD removes SO2 and particulates

simultaneously.

Several types of FGD are available in the power plant market

and the choice of method depends on many factors such as

plant size, the availability and quality of water resources and

reagent, and legislation (concerning SO2 , particulates, the

minimum outstack exhaust gas temperature, and end product

disposal requirements, etc.). At the moment FGD is installed in

about 1000 MWe of stationary power plants equipped with

Wärtsilä engines around the world. The most used FGD

methods are NaOH in smaller plants and CaCO3 scrubbers in

bigger plants.

Due to the different temperature and composition of the

diesel engine flue gas, the electrical properties of the diesel

particles are different compared to particles from a boiler’s flue

gas. Wärtsilä therefore extensively tested the ESP (Electrostatic

Precipitator) performance in a diesel engine power plant during

1999 - 2001. Based on this experience Wärtsilä is currently

building the first commercial diesel engine power plant (capacity

about 150 MWe) to be equipped with ESP.

Secondary exhaust gas cleaning equipment is bulky and its

investment cost is high. Operational costs will vary a lot

depending on the electricity need, the byproduct disposal cost

(ESP and FGD) and, for FGD, the additional reagent and water

costs.

Unburned emissions (CO, NMHC(NonMethaneHydroCarbon), etc.)

Bigger diesel engines fulfil most existing stationary power plant

legislation on unburned gaseous emissions such as CO through

good engine maintenance. The use of oxidation catalysts is not

recommended in the case of fuels containing sulphur as the

oxidation catalyst might oxidize a large amount of the SO2 to

SO3, which will form sulphate (a submicron particulate), and

the catalyst might get deactivated by the flue gas. Diesel engines

(mainly high-speed) operating on good quality brands of light

fuel oil are occasionally equipped with oxidation catalysts.

Gas-fired spark-ignited and dual-fuel engines are sometimes

equipped with oxidation catalysts depending on the stationary

power plant legislation in force. The performance of the

oxidation catalyst depends considerably on the flue gas

temperature. Wärtsilä engine power plants with outputs of

about 800 MWe are equipped with oxidation catalysts.

7

Emission standards: Marine

Wärtsilä’s minimum development standard for Wärtsilä and

Sulzer engines for marine use is that these engines comply with

the requirements of the International Maritime Organization

(IMO). Wärtsilä has developed, and is developing, NOX

reducing technologies that comply with even more stringent

national or regional legislation expected in the future.

1. MARPOL Annex VI

After a ratification process lasting several years, the IMO

MARPOL 73/78 Annex VI legislation seems to have gained the

necessary support of the member states in 2003 to become

ratified and enter into force internationally one year later.

The IMO MARPOL 73/78 Annex VI sets limits on NOX

and SOX emissions from ships and also on “other air emissions”

like VOC and ozone-depleting substances. These “other air

emission” limits do not, however, concern ship machinery (Fig.

8).

1.1. NOX

All Wärtsilä standard engines can meet the NOX limits set by

Annex VI. To show compliance, Wärtsilä has tested selected

“parent engines” on the test bed since 2000 and subsequent,

approved engines are delivered with an EIAPP (Engine

International Air Pollution Prevention) Statement of

Compliance.

1.2. SOX

The Baltic Sea and the North Sea have been declared emission

control areas; the sulphur content in fuel used on board ships in

a SOX emission control area is not permitted to exceed 1.5%.

IMO/MEPC is further studying the application of a

voluntary Greenhouse Gas Emission index for ships. A working

group is preparing an IMO greenhouse gas strategy resolution

for adoption by the IMO Assembly in 2003.

2. EPA

The US Environmental Protection Agency (EPA) issued new

legislation concerning air emission legislation for US coastal

shipping in early 2003 (Table 1). Existing legislation already

covers engines from 2.5 litres/cylinder upwards. This new

legislation covers C3 category engines, i.e. new marine

compression-ignition engines at or above 30 litres/cylinder, and

the limit on NOX emissions is the same as the IMO’s limit.

However, the EPA has announced that they will review and

tighten the legislation in 2007.

8

SP

EC

IFIC

NO

EM

ISS

ION

S(g

/kW

h)

x

4

6

8

10

12

14

16

0 200 400 600 800 1000 1200 1400 1600 1800 2000

2

rpm

18

20

0

IMO limit

Direct water injection

Low-NOx combustion

Direct water

injection

SCR

W64 W46/ZA40 W38 W32 W26/W20 W200RTA

x

Fig. 8 The NOX limit in the Annex VI of MARPOL, as adopted by the MARPOL 1997Conference.

3. EU

The European Union is also active in imposing legislation

related to NOX and SO2 emissions in certain sensitive sea areas

and inland waterways. However, this is still under development.

4. Local regulations

River Rhine

Limits on air emissions from ships on the River Rhine have been

in force since 2003. These limits apply to NOX, CO, THC and

particles.

Alaska

Alaska operates limits on the smoke emitted by ships.

Other

Economic instruments for reducing emissions have been

adopted in some countries. A system of environmentally

differentiated fairway dues was introduced in Sweden in 1998

and an environmental differentiation of tonnage tax in Norway

2001. Complementary reductions in port dues are offered by

many Swedish ports, and also by the port of Mariehamn in the

Åland Islands and by the port of Hamburg. Vessels with the

Green Award certificate are entitled to a rebate on port fees in

50 ports around the world.

9

New EPA regulations from January 2003.

CylinderdisplacementLitres/cylinder

HC + NOx

g/kWhPM

g/kWhCO

g/kWhImplemen -tation date Engines

displ. < 0.9 7.5 0.40 5.0 2005

0.9 < displ. < 1.2 7.2 0.30 5.0 20041.2 < displ. < 2.5 7.2 0.20 5.0 2004

2.5 < displ. < 5.0 7.2 0.20 5.0 2007

5.0 < displ. < 15.0 7.8 0.27 5.0 2007 W20

15 < displ. < 20.0power < 3300 kW

8.7 0.50 5.0 2007 W26

15 < displ. < 20power > 3300 kW

9.8 0.50 5.0 2007 W26

20.0 < displ. < 25.0 9.8 0.50 5.0 2007

25.0 < displ. < 30.0 11.0 0.50 5.0 2007 WV32LN

displ. > 30.0 IMO 2004 W32, W38, W46,W64, RTA, ZA40

EPA has not finalized Tier 2 standards for engines with a displacement exceeding30 litres/cylinder.

EPA will announce final Tier 2 standards for these engines by April 2007

(NO )X

Table 1. Environmental Protection Agency (EPA) Tier 1Emission Standards for Marine Engines, 40 CFR Parts 9 and94.

Fig. 9 Carnival Spirit was the first vessel to be equippedwith a Wärtsilä 46 common rail engine.

Emission standards: Power plants

Wärtsilä’s product development strategy for diesel power plants

is to fulfil the World Bank’s stack emission guidelines “Thermal

Power - Guidelines for New Plants 1998" for installations

located in a non-degraded airshed by using primary methods.

This includes a suitable choice of fuel, and the use of the

Low-NOX combustion method on the engine. Secondary flue

gas treatment methods such as FGD, SCR and ESP are available

for installations located in a degraded airshed or subject to more

strict national limits or when poor, low-cost fuel qualities are the

only economical fuel choice, see Figure 10 (NOX limit), Figure

11 (particulate limit) and Figure 12 (SO2 limit).

German TA-LUFT regulations have been widely applied to

gas engines in the European market. Wärtsilä´s strategy for

lean-burn engines, including the spark-ignited engine and

dual-fuel engine in gas mode, is to comply with the German

TA-LUFT regulation using primary techniques as far as

practicable. Compliance with the German TA-LUFT regulation

today normally requires a CO oxidation catalyst, see Figure 13

(NOX limit).

In modern environmental legislation, emission norms are

technology-specific, i.e. each prime mover type (boilers, gas

turbines and reciprocating engines) has its own limits. National

legislation or guidelines on specific emission limits for

reciprocating engines can be found in Japan, South Korea,

Taiwan, India, UK, France, Germany, Italy, Portugal, Ecuador,

and Finland. Internationally, the World Bank’s guideline

Thermal Power Guidelines for New Plants 1998 is widely used

as the minimum norm if the host country does not have its own

specific legislation for engine-driven power plants (see examples

in Figures 14 and 15). Technology-specific flue gas emission

concentration limits must closely correspond to actual

conditions as these best describe the performance of secondary

cleaning equipment, if needed. For bigger reciprocating engines

this means 15 %-vol O2. In the World Bank Guidelines, India,

Ecuador and the UK, for example, a reference oxygen

concentration of 15 %-vol O2 for emissions is used for

reciprocating engines.

The most cost-effective emissions norm is one based on the

environmental quality need approach (taking into account both

environmental aspects and cost). Examples include the World

Bank’s Thermal Power Guidelines for New Plants 1998 and the

Japanese diesel engine norm.

The most important stack emissions are NOX, particulates

and SO2. In some countries national legislation also regulates

CO and NMHC emissions. Some legislation takes into account

the existing infrastructure when determining SO2 and

particulate limits and thus expensive secondary cleaning

equipment, such as FGD that produces a byproduct and

consumes valuable water resources, can be avoided. Plant size

and location (urban/rural) also sometimes affect the limits.

10

Fig. 10 NOX limit (WB Thermal Power- Guidelines for NewPlants 1998)

Fig. 11 Particulate limit (WB Thermal Power- Guidelines forNew Plants 1998)

Fig. 12 SO2 limit (WB Thermal Power- Guidelines for NewPlants 1998)

References:

� UK:

– “The Environmental Protection Act 1990, part 1 (1995

Revision), (PG1/5(95): Secretary of State´s

Guidance-Compression Ignition Engines, 20 - 50 MW

Net rated Thermal Input"

– “Achievable Releases to Air; HM Inspectorate of Pollution;

Processes Subject to Integrated Pollution Control, Chief

Inspector´s Guidance Note, Series 2 (S2), S2 1.03

Combustion Processes: Compression Ignition Engines

50 MWth and Over (September 1995)"

� Germany:

– Technische Anleitung zur Reinhaltung der Luft - TA-Luft

October 2002.

� India:

– “Environment (Protection) Third Amendment Rules,

2002"

� Japan:

– “Nationwide general limits”

� Ecuador:

– “Standard for Emissions to the Air from Stationary

Combustion Sources", December 2002

� Portugal:

– Resolutions 286/93 and 1058/94

� World Bank:

– World Bank Guidelines “Thermal Power - Guidelines For

New Plants" 1998;

– http://lnweb18.worldbank.org/essd/envext.nsf/51ByDocN

ame/ThermalPowerGuidelinesforNewPlants/$FILE/Hand

bookThermalPowerGuidelinesForNewPlants.pdf

� Annex VI of MARPOL 73/78, Regulations for the

– Prevention of Air Pollution from Ships

� International Maritime Organisation

– www.imo.org ttp://www.imo.org

� Environmental Protection Agency

– www.epa.gov/ http://www.epa.gov/

11

Fig. 13 NOX limit for gas engines (TA-LUFT 2002)

Fig. 14 Some HFO diesel engine particulate norms.

Fig. 15 Some HFO diesel engine NOX norms.

W-P

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Wärtsilä Finland OyP.O.Box 252,FIN-65101 Vaasa, Finland

Tel: +358 10 709 0000Fax: +358 6 356 9133

Wärtsilä Corporation is the leading global ship power supplier and a

major provider of solutions for decentralized power generation and of

supporting services.

In addition Wärtsilä operates a Nordic engineering steel company

Imatra Steel and manages a substantial shareholding to support the

development of its core business.

For more information visit www.wartsila.com

WÄRTSILÄ ® is a registered trademark. Copyright © 2003 Wärtsilä Corporation.