This article is written with the dual aim of educating and preparing Yacht Engineers, their Captains, Operators, Owners and Management Companies to best plan and comply with the increasing demand to reduce exhaust gas emissions created by fuel and engine selection. It is not intended to replace or amend any statutory regulations.
“We” and by that I include: marine engineers, ship operators, management companies, owners and commercial operators of fossil fuel burning processes are contributing to atmospheric pollution in a magnitude and effect which could only be considered ridiculous a few years ago. Here are some interesting figures published by the Guardian.
- The world's biggest container ships have 109,000 horsepower engines which weigh 2,300 tons
- Each ship expects to operate 24hrs a day for about 280 days a year
- There are 90,000 ocean-going cargo ships
- Shipping is responsible for 18-30% of all the world's nitrogen oxide (NOx) pollution and over 9% of the global sulphur oxide (SOx) pollution
- One large ship can generate about 5,000 tonnes of sulphur oxide (SOx) pollution in a year
- 70% of all ship emissions are within 400km of land
- 85% of all ship pollution is in the northern hemisphere
Revised MARPOL Annex VI
There are well over one hundred Yachts over 85m and diesel engines are becoming more powerful for their size. The main changes to MARPOL Annex VI are a progressive reduction globally in emissions of SOx, NOx and particulate matter (PM) and the introduction of emission control areas (ECAs) to reduce emissions of those air pollutants further in designated sea areas.
Under the revised MARPOL Annex VI, the global Sulphur cap will be reduced from current 3.50% to 0.50%, effective from 1 January 2020, subject to a feasibility review to be completed no later than 2018. The limits applicable in Emission Control Areas (ECA’s) for SOx and particulate matter were reduced to 0.10%, from 1 January 2015.
For Yacht engines which are mainly diesel powered (so as to comply with SOLAS storage regulations with a flash point of greater than 60°C) are widely regarded as “an efficient means of propulsive power” but produce 3 main atmospheric pollutants. Apart from Water and Carbon Dioxide, Oxides of Sulphur (SOx) and Oxides of Nitrogen (NOx) form during the combustion process.
Burning diesel fuel in the presence of air produces SOx through “chemical bond splitting” at higher temperatures and NOx through something called endothermic reaction. The former can be substantially reduced by using low sulphur fuel and the latter by engine design, effective combustion, correct maintenance procedures and operating at the right temperatures. In simple terms the more Sulphur in the fuel and the faster you run your engines the hotter the combustion process - the worse it gets.
The Oxides of Nitrogen (NOx)
For the Chemists amongst you 78% of the atmosphere is made up of Nitrogen, 21% is Oxygen and 1% others. Nitrogen is harmless until pressurised or heated. This is bad news for the vital factors which create the conditions for effective combustion in a diesel engine. If you can control the amount of Nitrogen in the atmosphere at sea level, please come with me to Norway and we will try for a share the Nobel Prize.
Tier I: For engines fitted in vessels with a keel laid on or after 1st Jan 2000 the NOx limits fall under something called Tier 1, which limit emissions to 9.8 grams of NOx per kilowatt hour of engine running if the engine is capable of 2000 RPM and of 130kW rating or above.
Tier II: The limits were further reduced by the International Maritime Organisation (IMO) Marine Environmental Protection Committee (MEPC) to 7.7 grams per kW hour for engines fitted to vessels with a keel date of 1st Jan 2011 or later, entitled Tier 2.
Tier III: The Tier III controls will apply only to the specified ships while operating in Emission Control Areas (ECA’s) established to limit NOx emissions. Next year (2016) the amendments provide for the Tier III NOx standards to be applied to a marine diesel engine that is installed on a ship constructed on or after 1 January 2016 and which operates in the North American Emission Control Area or the U.S. Caribbean Sea Emission Control Area that are designated for the control of NOx emissions. Here there is a substantial reduction to 2.0 grams per kW hour. Outside these areas the Tier II controls apply.
Note* the Tier III requirements do not apply to a marine diesel engine installed on a ship constructed prior to 1 January 2021 of less than 500 gross tonnage, of 24 m or over in length, which has been specifically designed and is used solely, for recreational purposes. The NOx control requirements of Annex VI apply to installed marine diesel engine of over 130 kW output power irrespective of the tonnage or Flag of the ship onto which such engines are installed. NOx ECA’s are currently the North American Emission Control Area and the U.S. Caribbean Sea Emission Control Area).
The amendments are expected to enter into force on 1 September 2015.
The Oxides of Sulphur SOx
Most Hydrocarbon fuels contain some Sulphur as this occurs naturally in crude oil. It can be chemically removed during the refining process by methods such as “hydro-treating” but has been retained at various levels to aid lubrication and avoid blockages. Sulphur and water when added together can form Sulphuric acid which can cause cold corrosion of engine parts especially cylinder liners and of course produce acid rain in the atmosphere.
SOx Sulphur Limits
The current worldwide maximum Sulphur content in Diesel fuel is 3.5% m/m by weight (mass for mass). This to be reduced to 0.5% outside of an ECA subject to review to be completed by 2018. The limit in an ECA was reduced on the 1st January 2015 from 1% to 0.1%.The diesel fuel available at many ports falls well below this value – depending upon the type you buy. Be careful what type and grade of fuel you buy and consider next bunkers in your voyage planning to make sure you comply with the law wherever you go. ISO 8217 standard DMA may not comply with the new ECA regulations.
Check the fuel specification sheet. Low Sulphur Marine Gas Oil (LSMGO) <0.1% is required for ECA’s or running engines alongside in an EU port for more than 2hrs (EU directive 2005/33/EC article 4b). “This regulation applies to all vessels irrespective of flag, ship type, age or tonnage”. Diesel fuel available for the automotive industry in the EU is <0.001% commonly called Ultra Low Sulphur Diesel.
There is a great deal of research and development underway especially by fuel and engine manufacturers to reduce emissions. Commercially available additives can be mixed with the fuel in which encouraging results have proven to substantially reduce both SOx and NOx values. These were until recently the great hope for the future until data suggested that some additives actually cause engine and component damage and the choice of lubricant critical. The use of Bio Fuel has also allegedly damaged some engines and components especially fuel pumps and injectors.
For the Yacht Industry the message is clear – educate and prepare. Your engine technical file should state your engine emissions and whether the engine is IMO compliant by a manufacturer’s declaration – does yours? and how could you demonstrate compliance to an inspector?
Emission Control Areas (ECA’s)
The ECAs established are:
1) Baltic Sea area – as defined in Annex I of MARPOL (SOx only)
2) North Sea area – as defined in Annex V of MARPOL (SOx only)
3) North American area (entered into effect 1 August 2012) – as defined in Appendix VII of Annex VI of MARPOL (SOx, NOx and PM)
4) United States Caribbean Sea area (entered into effect 1 January 2014) – as defined in Appendix VII of Annex VI of MARPOL (SOx, NOx and PM)
What should I do?
If you are “in Class” your surveyor will confirm your engine applicability and compliance. The engines will have an Engine International Air Pollution Prevention Certificate (EIAPPC) or IMO “Type Approval Certificate” to demonstrate compliance with MARPOL Annex 6 if you are over 400 gross tonnage.
If you are in an “ISM” or mini ISM then your Management Company DPA should help you prepare documentary evidence to show compliance.
For SOx compliance – buy the right fuel for your area of operation and keep your engines running to original specifications, also careful selection of lubricants used is essential to protect cylinder liners.
For NOx compliance, if in doubt consult your engine manufacturer and ship builder. Check your engine manufacturer’s emission characteristics and vessel build date – especially if you will be operating in an ECA. Either way you must be in possession of written evidence of compliance.
If you do not comply or predict non - compliance in the future because of these changes, consideration should be given to exhaust gas cleaning or the use of emission reducing fuel additives, but this should be done in consultation with the engine manufacturers. Regular maintenance to ensure the engine is running to its “design intent” will also play a major part in reducing emissions.
There are other means by which equivalent levels of SOx NOx and particulate matter emission control, both outside and inside ECA, could be achieved.
These may be divided into methods termed primary (in which the formation of the pollutant is avoided) or secondary (in which the pollutant is formed but subsequently removed to some degree prior to discharge of the exhaust gas stream to the atmosphere).
There are some fairly unusual techniques such as passing the hot exhaust gas through human urine which has shown to reduce NOx levels along-with current techniques such as injecting water into the turbo chargers and injectors to keep endothermic temperatures down but still maintain a satisfactory Net Specific Energy (NSE). Other commonly accepted in service emission reducers include, after burners, exhaust coolers, scrubbers and catalytic converters.
On an operational note (and for your MCA Oral exam) – keep records and serial numbers of replacement parts (especially injectors and fuel pumps) and ensure they are genuine Original Equipment Manufacturer (OEM) items.
Also keep records of bunker receipts for 3 years, and continuous drip samples for one year with all of the details where and when you obtained your fuel from. The inclusion of Date, Time, Location, Name of Supplier, Signatures, Type and Grade, Sulphur Content, Cetane Value, Density, Viscosity, Wax Point and Water Content will go a long way to keeping you out of trouble and maintain the life expectancy of engines and components. Remember Flag and Port State
Inspectors are waiting at your next port of call to catch you out. A Yacht recently bunkered DMX instead of DMA do you know what that means?
Tim Moss MBE, MSc, CEng, CMarEng, FIMarEST, FIET, Head of Engineering Bluewateryachting and Member of the International Association of Maritime Institutes (IAMI).