Annex VI of MARPOL 73/78 and the NOx Technical Code enter force on May 18, applying to every ship over 400gt and every fixed and floating drilling rig and other platform.
Marine pollution was first addressed by the IMO in its International Convention for the Prevention of Pollution from Ships (MARPOL) in 1973, later modified by a Protocol of 1978. A new Annex VI, Regulations for the Prevention of Air Pollution from Ships, was added in September 1997, to enter force several years later in order for fuel and engine manufacturers to have time to introduce cleaner technology.
Under the new rules, limits are set on sulphur oxide (SOx) and nitrogen oxide (NOx) emissions from ship exhausts. Deliberate emissions of ozone depleting substances are also prohibited.
The problem of SOx emissions was tackled by introducing a global cap of 4.5% m/m on the sulphur content of fuel oils, with observance to be monitored by the IMO. In addition, provision was made for creating special ‘SOx Emission Control Areas’ in environmentally sensitive areas (starting with the Baltic Sea) with even more stringent rules: i.e. fuel with sulphur content no higher than 1.5% m/m or the fitting of exhaust gas cleaning technology.
NOx emissions present a more complex problem since they are formed as by-products of fuel combustion in diesel engines. Whereas in the past all engines were optimised for minimal fuel consumption, the new Annex VI rules mean that performance must be trimmed to reduce those emissions. A mandatory NOx Technical Code, developed by IMO, defines how this is done.
The Code applies to all engines >130kW installed on ships built after January 1, 2000 and all engines that undergo a major conversion (i.e. potentially causing the emission standards to be exceeded) after that date. Specific NOx emission limits vary according to engine speed.
But according to Martek Marine director Steve Coulson, “there’s a large amount of misinterpretation within the industry as to what a NOx-compliant engine is.” Tested in the factory, levels may comply with the limits – e.g. less than 17.0g/kW h for engines with a speed < 130rpm – he says, but the Code requires the engine to be surveyed every year, in order for the Flag Administration (or class on their behalf) to issue an International Air Pollution Prevention (IAPP) Certificate.
There are basically two ways to achieve this, he continues: the Engine Parameter Check Method or Direct Measurement and Monitoring Method.
The first method involves a surveyor coming onboard and carrying out a check of record books covering engine parameters and an actual inspection of NOx influencing engine components and adjustable features (which involves stripping the engine), However, the downside is that incurs an inspection fee, is disruptive and necessitates the installation of manufacturers’ original NOx-related components (not cheaper ‘after market’ spares), says Coulsen.
The second method works by having a NOx analyser fitted onboard the vessel, which takes readings once every 30 days, with data stored on a CD or mini-disk and handed to the Administration. The annual survey is then reduced to an inspection of the monitoring system and data alone, probably only half an hour’s exercise, in order for them to issue an IAPP. However, here the challenge is to ensure that the system is secure and tamper-proof.
A third option, the so-called ‘Simplified Method’, in theory exists but in practice combines the most onerous aspects of the previous two and has been unofficially dubbed the ‘Bankruptcy Method’, adds Coulsen.)
Martek itself has spent three years perfecting its new MariNOx Engine Emissions Monitoring System, which it claims offers the simplest solution for compliance with Annex VI and The NOx Technical Code. Constant monitoring of emissions also allows optimisation of engine performance, allowing fuel savings of up to 4%, says Martek, therefore providing rapid payback of the system’s cost of around $100,000. Testing has already taken place aboard a tanker of over 100,000dwt at different engine loads, and both the owner and Martek are reported to be ‘delighted’ with results.
Reprinted by permission from the April 2005 issue of Seatrade magazine.
Date: 2005-06-06