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Meeting sulphur emissions standards


As the International Maritime Organization (IMO) continues its drive to reduce sulphur emissions from ships, John Smythe, global marine and large engine technical adviser at Infineum, comments on the effect of current and future measures on lubricants and fuels.

Today’s shipping industry transports about 90% of global trade and offers one of the greenest solutions for transporting goods. The IMO’s Marine Environment Protection Committee (MEPC) is tasked with introducing measures to prevent and control pollution caused by ships. The International Convention for the Prevention of Pollution from ships (MARPOL) Annex VI, which was first adopted in 1997, limits the main air pollutants contained in the exhaust gas, including sulphur oxides (SOx) – a hot topic in the maritime industry today.

Sulphur limits falling

Sulphur reduction has been high on the agenda for some time. Since 2008, sulphur limits in open waters have fallen from 4.5% to 3.5% m/m – a drop that did not preclude the use of heavy fuel oils (HFO). In the next decade, the sulphur level at sea is set to fall again from 3.5% to 0.5% m/m.

However, this change will require significant investment and, because there are some concerns about the availability of low sulphur fuels that will be required to help meet the new target, there is some uncertainty about the exact implementation date.

MEPC has agreed on the terms of reference for a review of the availability of fuel oils that meet the new sulphur target. A Steering Committee consisting of 13 member-states, one inter-governmental organisation and six international non-governmental organisations has been established to oversee the review. Depending on the outcome of this feasibility review, which is to be completed no later than 2018, the requirement to cut sulphur to 0.5% m/m outside emission control areas (ECAs) could be in place as of January 1, 2020, or postponed until January 1, 2025.

In coastal waters that have been designated as ECAs or sulphur emission control areas (SECAs), sulphur was cut by a factor of 10 in January 2015 to 0.1%, and at present there are no plans on the table to reduce this further. This huge change means ships entering these waters that burn HFO at sea must now either install scrubbing equipment or switch to low sulphur fuel or liquid natural gas inside ECAs.

The dual and single fuel approaches being adopted to meet these new limits present a number of challenges including cost, availability, reliability and handling.

Impact on fuels

Meeting sulphur emissions standards
Photo courtesy of Infineum.

The successful implementation of a cut from 1% to 0.10% sulphur fuel in ECAs was handled using standard diesel, low sulphur marine gas oil and hybrid fuels. While alternatives such as exhaust gas scrubbers are in use, the cost of retrofitting these for use in older vessels is uneconomical in many cases.

The forthcoming reduction of the global sulphur cap from 3.5% today to 0.50% in 2020 or 2025 means we can expect major adjustments in supply patterns and significantly increased demand on refinery conversion processes handling residual streams. Current estimates suggest that well over 100 million tonnes per year of residual fuel will need to be switched to distillate-type molecules to meet the requirements of the 0.50% global sulphur cap. That is a significantly bigger step than the introduction of the 0.10% sulphur ECA fuel.

The industry has a number of potential options, the use of low sulphur bunker fuel being one solution. However, we are now less than four years away from the earliest possible implementation date, which is a very short period of time for refiners to decide on and implement major refinery investments to meet changes in fuel quality and demand. This could result in real availability issues of low sulphur fuels.

Although diesel fuel could be redirected towards the marine market, it is unclear whether the marine fleet will be prepared to pay additional price premiums for low sulphur fuels. In our view, the costs associated with HFO will continue to be significant in the marine sector, although the balance with marine diesel oil (MDO) will shift over time. As such, scrubbers will be fitted to enable HFO use.

Impact on lubricant formulations

Meeting sulphur emissions standards
Photo courtesy of Infineum.

The new sulphur limits also impact lubricant formulations since the base number (BN) needs to match the fuel type. High BN is needed for use with high sulphur fuels to neutralise the acids that are produced, while in low sulphur fuels, OEMs are looking for lubricants with 40 BN or less.

Ship owners would value a single lubricant, which could provide sufficient protection whatever fuel the vessel is using. But, as sulphur levels continue to fall this will be increasingly difficult to achieve.

However, the wider mix of fuels being used to meet the sulphur limits impacts lubricant formulations beyond BN. In lubricants for use in high sulphur fuels it is important to balance BN and ash levels to neutralise combustion acids and maintain the cleanliness of the piston assembly. Engines running on low sulphur fuels need lubricants with lower total BN and improved wear control. Where dual or multi-fuel engines are used, lubricants also need to provide advanced corrosion and wear protection.

In our experience, the wide variety of fuel options means OEMs will typically recommend engine lubricants that are suitable for the most severe fuel in use.

Infineum is already involved in a number of projects with OEMs, ship operators and with fuel and lubricant producers to ensure that products meet the requirements of all stakeholders and are co-engineered in time to meet these regulatory challenges.