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PortuguêsHow will the hardening of emissions regulations be affected?
SINCE THE 1ST OF JANUARY, 2015, COMMERCIAL VESSELS THAT NAVIGATE THROUGH EMISSIONS-CONTROLLED AREAS (ECAS) ESTABLISHED IN APPENDIX VI OF THE INTERNATIONAL CONVENTION FOR THE PREVENTION OF POLLUTION FROM SHIPS (MARPOL), THAT IS, INCLUDING THE BALTIC SEA AREA, THE NORTH SEA AREA, NORTH AMERICA, AND THE CARIBBEAN SEA OF THE UNITED STATES, ARE RESTRICTED IN THEIR USE OF FUEL OIL TO MAXIMUM SULPHUR CONTENT OF 0.1% WITH THE AIM OF MEETING LIMITS ON EMISSIONS OF SULPHUR OXIDE (SOX) AND HEAVY PARTICULATES INTO THE ATMOSPHERE, ESTABLISHING A LIMIT ON THE CONTENT OF SULPHUR ON VESSELS THAT NAVIGATE OUTSIDE THESE EMISSIONS-CONTROLLED AREAS OF 3.6%.
By: Fernando Díaz Pernas, an industrial engineer and expert in manufacturing processes from UPM and commercial director of Olipes High Quality Lubricants.
If these restrictions are already causing shipowners to perform continuous combinations of fuels of varying quality to feed the engines on their vessels (which is not without its risk, if the lubricant is not correctly selected according to the type of fuel used), the situation is about to get even more complicated from the 1st of January, 2020*, when the sulphur content limit is reduced from 3.5 to 0.5% in these exclusion areas.
When the moment arrives, the shipowner will have to decide whether or not to change to fuel with a low sulphur content or even continue using heavy fuel oil (HFO) with a high sulphur content and install an exhaust gas purifier device on the vessel to comply with the SOx limits (which entails a major investment in equipment and a higher cost of maintenance), regardless of the waters being navigated or, on the contrary, opt for the use of fuels with a low sulphur content, ;liquefied natural gas (LNG), or any of the new ‘hybrid’ fuel oils in emissions-controlled areas (ECAs), and residual foil with a high sulphur content in international waters.
The key factors when taking these decisions will be the high cost and low availability of marine fuels with a low sulphur content, the lack of investment in LNG infrastructure, and the significant improvements achieved in exhaust gas purification technology with respect to the reduction of SOx, Nitrous Oxides (NOx), and particulates (PM).
Effects on the formulation of lubricants
If, as seems likely, shipowners decide to continue using HFO with exhaust gas purifiers (scrubbers), they will also require lubricants with a high alkaline content (TBN) in order to ensure that the acids produced during combustion are neutralised effectively by the lubricating oil, in order to thus protect the motor against corrosion; although admittedly lubricants with a high TBN generate more ash, meaning that they cause more scratching and deterioration to sleeves. Therefore, the main challenge for lubricant manufacturers is to offer the shipowner a motor oil with a balanced formulation that offers a sufficient and stable TBN, in order to ensure against corrosion, and at the same time maintain the cleanliness of the piston assembly in order to avoid deterioration and premature wear.
If large cargo and container vessels opt for the use of two fuels, the need could arise to use different motor oils to cope with the conditions inside and outside the ECA. On the high seas, oils with a high TBN (TBN 100 to TBN 140) would still be necessary, to be used with HFO, and oils with a lower TBN (TBN 40 or lower) when the boats switch fuel in the ECAs, with special attention being paid to the necessary cleanliness and protection when using LNG, since the continued use of an oil with a high TBN with these fuels could give rise to the formation of residue on the piston assembly, which would lead to very high wear in the cylinder. In short, we would have to change the lubricant on board each time the fuel being used is switched over.
Cold corrosion, another key factor to be taken into account
In the face of increasingly restrictive environmental restrictions and the pressing need to reduce operating costs, shipowners are considering options such as investing in new motors with longer piston strokes or modifying existing motors to allow them to operate at low loads (also known as slow steaming).
Although these strategies reduce the fuel consumption, they are also prone to suffering from so-called ‘cold corrosion’, caused by water condensation in the coldest areas of the cylinder walls. This water reacts with the sulphur dioxide in the combustion gases to form sulphuric acid, therefore increasing wear due to corrosion of the cast iron liners. This cold corrosion occurs even when exclusively low-sulphur fuels are used and although to prevent its effects, the only current solution is to use lubricants with a high TBN, manufacturers of additives, such as Infineum or of lubricants, such as Olipes, are now working on new ways to prevent it, with innovative formulations with TBNs lower than 100. However, these advances in lubricant formulations will have to go hand in hand with motor operating loads closer to the optimum design point and the installation of additional equipment, such as suppressors for turbo compressors.
In spite of the advances that are being made with these formulations, there is currently no universal solution, with a single lubricant for all types of fuels and operating conditions. The smartest solution, and the one we recommend at Olipes, is to pair each type of fuel to the most appropriate lubricant.
Although it is probable that original equipment manufacturers (OEMs) choose to recommend engine lubricants suitable for the most problematic fuel (HFO with a high sulphur content), we must not discard the possibility that in the future they will include this fuel-lubricant pairing in their recommendations.