Air emissions from ships - Abatement technologies ...

Intelligent Transportation Systems August, 26. - 30. 2013

Air emissions from ships - Abatement technologies state of the art and external costs estimation Guido Emilio ROSSI

Fabio BALLINI

Dept. of Electrical, Electronic, Telecommunications Engineering and Naval Architecture” (DITEN) University of Genoa Genoa, Italy [email protected] Abstract— The growth of seaborne transportation and the increasing attention to the protection of environment have increased the interest in pollution from ships. Pollutants such as SOx, NOx, particles, ozone and CO2 has an impact in public health. International regulations have been adopted in order to limit air pollutants and consequently brought to the necessity of measures and technologies aimed at reducing airborne emissions. This paper aims at considering the abatement technologies for air pollutants from ships, giving a technical description and an estimation about their efficiency in terms of emission reduction. The methodology for calculate the external costs of air emissions estimated by Clean Air For Europe - Cost Benefit Analysis (CAFE CBA) and Economic Valuation of Air pollution (EVA) Model are then presented. Keywords: air emissions, pollution, international regulations, abatement technologies, external costs, health costs

I.

INTRODUCTION

Sea transportation of people and goods has grown considerably over the last century and Shipping has gained essential role in the global transport system which from 1970 to 2008 increased more than threefold (Wijnolst et al. 1997; Asariotis et al. 2009). Today, almost 90% of the world goods are carried by sea and maritime transport account for over 90% of European Union external trade and 43% of its internal trade (UNCTAD, 2007). Apart from industrial activity and energy production, maritime transport is the largest contributors to air pollution and the increasing rate of trade make the problem even more a cause for concern as it origins a cumulative effect that contributes to the overall air quality problems encountered by populations in many areas, and also affects the natural environment, such as though acid rain. Air pollution from ships and the consequent environmental impacts have received increasing attention in recent decades. Due to combustion characteristics of typical marine engines and a wide-spread use of unrefined fuel, the global fleet emits significant amounts of SO2, NOX, particles, ozone and CO2. Pollution emissions from vessels have a significant impact on public health and global climate changes and it is an urgent matter to reduce it.

1st International Virtual Conference on ITS http://www.itransport.sk

Dept. of Electrical, Electronic, Telecommunications Engineering and Naval Architecture” (DITEN) University of Genoa Genoa, Italy II.

REGULATORY FRAMEWORK

A. International regulations International Maritime Organization (IMO) is an agency of the United Nations which has been formed to promote maritime safety. The main international convention covering prevention of pollution of the marine environment by ships from operational or accidental causes is the International Convention for the Prevention of Pollution from Ships (MARPOL). MARPOL Annex VI Prevention of Air Pollution from Ships (entered into force 19 May 2005), that was first adopted in 1997, limits the main air pollutants contained in ships exhaust gas, including sulphur oxides (SOx) and nitrous oxides (NOx), and prohibits deliberate emissions of ozone depleting substances. MARPOL Annex VI also regulates shipboard incineration, and the emissions of volatile organic compounds from tankers1. MARPOL Annex VI undertake a revision which began in 2005 by the Marine Environment Protection Committee (MEPC). Emission limits were significantly reduced taking in account the technological improvements and the experience gained. The revised Annex VI and the associated NOx Technical Code 2008, entered into force on 1 July 2010: it was therefore envisaged a gradual reduction in global emissions of SOx, NOx and particulates, and the introduction of Emission Control Areas (ECAs) to further reduce emissions of these pollutants in marine areas designated. An ECA can cover NOx, SO2 or PM or all three types of emissions. MARPOL Annex VI also defines Sulphur Emission Control Areas (SECAs) and Nitrogen Oxide Emissions Control Area (NECAs) as sea areas where there are stricter requirements for sulphur and NOx emissions.

1

http://www.imo.org/OurWork/Environment/PollutionPrevention/Air Pollu-tion /Pages/Air-Pollution.aspx

SECTION 1. Intelligent Transportation Systems

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policies. The Council Directive 97/68/EC 3 was adopted with the objective of reducing health and environmental effects from NOx, HC and PM emissions from ships.

Figure 1. Existing and potential Emission Control Areas worldwid. Source: Baltic Ports Organization Secretariat.

In particular, concerning sulphur emissions limits, outside of the areas SECAs has been established a reduction from 4.50% to 3.50% by weight of the sulphur content of all marine fuels in globally by January 1, 2012, this percentage will then gradually reduced until it reaches the threshold of 0.50%, with effect from 1 January 2020. As part of SECAs areas, in the same way it is 'established an overall reduction from' 1.50% to 1.00% by weight of the sulphur content of all marine fuels from 1 July 2010; the percentage will be further reduced to 0.10% by 1 January 2015. The amount of sulfur emissions after combustion is obviously related to the amount of sulfur in the fuel. The limits to the percentage of sulfur also considerably reduce particulate emissions. Progressive reductions in NOx emissions from marine diesel engines installed on ships are also included in the revision of MARPOL Annex VI, with a definition of emission from large marine engine standards, classified as “Tier I”, Tier II” and “Tier III”. The revision established “Tier II” emission limit for engines installed on or after 1 January 2011; then a more stringent "Tier III" emission limit for engines installed on or after 1 January 2016 operating in ECAs. Marine diesel engines installed on or after 1 January 1990 but prior to 1 January 2000 are required to comply with “Tier I” emission limits, if an approved method for that engine has been certified by an Administration.

The Council Directive 1999/32/EC 4 regulates sulphur emissions from ships by limiting the maximum sulphur content of marine fuel. This Directive was amended by Directive 2005/33/EC that designated the Baltic Sea, the North Sea and the English Channel as SECAs and limited the maximum sulphur content of the fuels used by ships operating in these sea areas to 1.5%. In addition, the directive requires all ships passing in European ports to use fuel with a sulphur content of 0.1 per cent or less while at berth. This fuel standard applies also to passenger ships operating on regular service outside SECAs. However, already at the time of adoption the SECA fuel standard was widely recognised as being insufficient to address observed environmental impacts from shipping. The EU directive and the MARPOL Annex VI requirements were not aligned. In July 2011, the Commission scheduled a proposal to revise and strengthen the directive 2005 by incorporating the new sulphur standards adopted by the IMO in 2008. The revised sulphur directive was adopted in October 2012. Provisions of MARPOL Annex VI on alternative compliance methods were largely taken over into EU law thus hopefully ensuring their proper and harmonised enforcement by all EU member states. According the revised directive the global sulphur limit is set of 0.50 per cent in all EU sea areas by 2020, the IMO limit for SECAs of 0.10 per cent as from 2015 is confirmed. Over the years, several consultancy studies for the Commission have shown the large benefits of designating more European sea areas as SECAs, but there has still not been any action to this effect.

The revised measures and the corresponding limits of air emissions are expected to have an important beneficial impact on the atmospheric environment and on human health, particularly for those people living in port cities and coastal communities. B. EU regulations Air pollutant emissions in particular of SO2 and NOx from ships are a serious worry, as they are expected to surpass those of all land-based sources in the EU by 20202.The European Union fixes objectives in order to reduce certain pollutants and reinforces the legislative framework for combating air pollution via two main routes: improving Community environmental legislation and integrating air quality concerns into related

2 SEC (2005) 1133: Commissions Staff Working Paper accompanying the Communication on Thematic Strategy on Air Pollution (COM(2005)446 final) and the Directive on Ambient Air Quality and Cleaner Air for Europe(COM(2005)447 final).


Figure 2. Sulphur Emissions Control Area (SECAs) - Baltic and North Sea SECAs. Source: http://www.atobviaconline.com/helpFiles/WebService/bp_ shipping_marine_distance_ta.htm

3 Directive 97/68/EC of the European Parliament and of the Council of 16 December 1997 on the approximation of the laws of the Member States relating to measures against the emission of gaseous and particulate pollutants from internal combustion engines to be installed in non-road mobile machinery. 4 COUNCIL DIRECTIVE 1999/32/EC of 26 April 1999 relating to a reduction in the sulphur content of certain liquid fuels and amending Directive 93/12/EEC.


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III.

TECHNOLOGIES AND MEASURES TO ABATE EMISSIONS FORM SHIPS

In order to comply with the limits imposed by regulations, different technologies can be applied to new and existing vessels. The most important reduction measures on ships can mainly be divided into NOx, SOx and CO2 abatement technologies. Three different path can be followed with the aim of reducing air pollution from ships: 

to reduce pollutants on fuels



to reduce emissions after combustion



to use fuel alternatives like liquefied natural gas (LNG).

Another alternative to reduce pollution in the port areas is the Shore Side Electricity or Cold Ironing. Table I. shows an estimation on the effects on emissions from the NOx reducing technologies. Some technologies that reduce NOx emissions rise the emission of other pollutants. TABLE I.

NOX REDUCING TECHNOLOGIES AND THEIR ASSOCIATED EFFECT ON OTHER EMISSIONS

WiFE Water in Fuel HAM SCR EGR, based on Tier I EGR, based on Tier II LNG (lean burn)

NOx

PM

SO2

CO

CO2

VOC

-50% -65% -90% -80% -80% -88%

2% 0% 0% -1% 2% -90%

2% 0% 0% -1% 2% -67%

2% 0% 0% -1% 2% -80%

2% 0% 0% -1% 2% -10%27

2% 0% 0% -1% 2% -80%

Reductions are given as negative figures. Increases are given as positive figures. Source: Jørgen Jordal-Jørgensen, (2012) Reducing Air Pollution from Ship, Danish Environmental Protection Agency; Environmental Project no. 1421, 2012, Denmark.

A. NOx Abatement technologies Lowering the temperature in the combustion chamber abates the formation of NOx. Water can be used to lower the combustion temperature, adding water in fuel prior to injection (WiFE) or by charging the cylinder with humidified air (HAM). The reduction of NOx emissions using WiFE and HAM technologies vary from 50%-90%. Some other technologies reach an emissions abatement by treating the exhaust gas produced after the combustion. The treatment of exhaust gasses post-combustion by the technologies of Scrubber, Selective Catalytic Reduction (SCR), Exhaust gas recirculation (EGR), can reduce the NOx emissions up to 85-99%. 1) Humid Air Motor The abatement technology of Humid Air Motor system (HAM), uses seawater to lower the temperature in the combustion chamber. Water vapour is injected to humidify the combustion air and lower the temperature peaks during the combustion process thereby reducing the NOx emissions. The


NOx reduction potential is estimated to be up to approx. 7080% (Eyring et al., 2005b)5 . 2) WiFE – Water in Fuel Emulsion Water in Fuel Emission (WiFE) is a technique for preventing NOX formation during combustion by emulsifying water to the fuel. The temperature in the combustion chamber is lowered by the fuel water emulsion, because of evaporation of the water thereby reducing NOX emissions. Studies6 show that 1% NOx reduction is obtained per 1% of added water. A water-to-fuel-ratio of 30% can reduce NOx emissions by 30% and PM by 60-90%. The maximum amount of water that can be added to fuel depends on the engine load, but the maximum water-to-fuel-ratio is 50%, (= NOx reduction of 50%). A water content of 50% increases the fuel consumption by approx. 2%. 3) Scrubber Scrubber system is an air pollution control device that can be used to remove some particulates and/or gases from exhaust streams. The scrubber cleans the exhaust gas and removes SO2, particles and acid gasses by the use of alkaline compounds. Seawater (or freshwater mixed with caustic soda (NaOH)) are used as a “scrubbing” agent. The sludge resulting of the process is filtered and the water is spilled back into the sea. Scrubbers can reduce SOx by 99% and NOx 7 and PM by 85% without increasing CO2 emissions. 4) SCR - Selective Catalytic Reduction Using ammonia (NH3) or urea as a catalyst, the SCR convert NOx into nitrogen and water thus abating emissions. The catalyst is injected into the hot exhaust gas to react with nitrogen oxides, producing harmless nitrogen (N2) and water. The SCR is a well known and widely used technology for abating NOx from exhaust gases. Reduction of NOx emissions may reach 90-95%. However, to reach a 90% NOx reduction, approx. 15g of urea is needed per kWh energy from the engine. Most common SCR applications reduce NOx emissions slightly below the maximum capacity (i.e. 85-90%) in order to limit ammonia emissions. The high percentage of reduction achievable with SCR technology has to cope with the problem of the relatively large space requirement and storage of ammonia or urea especially in connection with a retrofit solution. 5) EGR - Exhaust Gas Recirculation Exhaust Gas Recirculation (EGR) lower combustion temperatures and therefore lower NOx emissions by recirculating filtered and cooled exhaust gas into the charge air. The oxygen content in the cylinder is reduced and the specific

5 Eyring, V., Kohler, H., Lauer, A., Lemper, B. (2005b). Emissions from international shipping: 2. Impact of future technologies on scenarios until 2050. Journal of Geophysical Research, 110. 6 MAN Diesel and Turbo (2010): “two-stroke engine emission reduction technology: state-of-the-art”, cimac paper: 85. Apollonia Miola, Biagio Ciuffo, Emiliano Giovine, Marleen Marra; “Regulating air emissions from ships: the state of the art on methodologies, technologies and policy options”; page 57; European Commission Joint Research Centre, Institute for Environment and Sustainability. November 2010. 7 A. Miola et al, 2010


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heat capacity temperatures.

increased

causing

lower

combustion

The EGR technology reduces NOx emissions by 35%, but combining EGR with WiFE - water in fuel emission, the abatement can reach a percentage of about 70-80%. B. Alternative fuel: Liquefied Natural Gas (LNG) Liquefied Natural Gas (LNG) is natural gas in a liquid form that is clear, colorless, odorless, non-corrosive, and non-toxic. LNG is produced when natural gas is cooled to minus 259 degrees Fahrenheit through a process known as liquefaction. During this process, the natural gas, which is primarily methane, is cooled below its boiling point, whereby certain concentrations of hydrocarbons, water, carbon dioxide, oxygen, and some sulfur compounds are either reduced or removed. LNG is also less than half the weight of water, so it will float if spilled on water. LNG offers the ability to reduce sulfur oxide and nitrogen oxide emissions significantly (SOx