Annex VI of the International Maritime Organizations Marine Pollution Convention has been described as probably the biggest thing to hit the maritime industry since steam superseded sail. Known as IMO 2020, it restricts atmospheric sulfur emissions by shipping, mostly from burning fuel. It also places greater economic burdens on shipowners and challenges marine lubricant suppliers.

Many major ports and almost every national port authority say they will severely punish ships not in compliance with the new law. This leaves shipowners, charterers and operators with three compliance options: switch to compressed or liquefied gas (or install dual-fuel engines); fit an exhaust gas scrubbing system; or buy compliant liquid fuel. The first two options are existing solutions, where both fuel composition and lubricant requirements are known. However, the majority of ship operators are heading down the route to low-sulfur fuels, which leads to potential challenges for lubricant formulators.

Scrub That

Ships fitted with scrubbers will still be allowed to burn fuel with sulfur content of more than 0.5 percent by weight after 2020. Since 2012, the maximum sulfur limit has been 3.5 percent in international waters away from designated emissions control areas around the northern European and North American coasts.

A scrubber for a newbuild crude carrier, for example, costs between U.S. $2.5 million and $3 million, while a retrofit unit is between $4 million and $4.5 million, according to Drewry Shipping Consultants. But this eye-popping expense is still attractive for some operators, as high-sulfur fuel is expected to be cheaper than low-sulfur fuel. Drewry predicts the outlay for newbuild scrubbers can be recovered in fuel savings in a year.

Oils for engines burning high-sulfur fuel oil are traditionally 70 base number marine cylinder lubricants and have been available for decades. They have been tweaked in the past 10 years, as slow steaming to lower fuel consumption has resulted in much more condensation of acids in the cylinders, known as cold corrosion. This has led to adoption of even higher base number oils of 100 BN or even 140 BN. A higher base number lubricant can neutralize more acid.

This market is relatively mature, and products and practices are well established. Similarly, products are in place for specialist vessels running on compressed or liquefied gas, methanol or other non-hydrocarbon fuels.

As well as using the correct lubricant, it is strongly recommended by [original equipment manufacturers] and many lubricant suppliers to ensure that ship engineers employ a robust monitoring system to ensure that the right product is used at the right feed rate to prevent over spending on lubricant or risking failure of the engine, Sara Lawrence, global technical manager for Shell Marine, told LubesnGreases.

Low-sulfur Uptake

In a February 2019 white paper, Chevron Marine Lubricants said more than 90 percent of vessels in the global fleet are expected to switch to compliant fuels, with the remaining continuing to burn high-sulfur fuel oil with a scrubber installed.

According to one industry source, around 2,800 vessels out of 70,000 had a scrubber or were pending installation at the end of June 2019. Generally, these are bigger vessels, so this covers around 25 percent of capacity.

Lawrence thinks a major challenge for ship operators and lubricants marketers will be the lack of experience with lubrication with low-sulfur fuels. Many refiners and bunker operators are only planning to introduce low-sulfur fuels toward the end of 2019.

Other players have expressed concerns around the varying specifications and quality of the low-sulfur fuels that will be available, particularly as a vessel travels between ports. Refiners facing the challenge of producing much more low-sulfur fuel from their crudes will produce more distillate fuels, which are much more aromatic than hydrotreated low-sulfur fuel oil and usually have a much lower viscosity. There are concerns about the compatibility of different fuels and their stability, as most low-sulfur fuel is likely to be blended. While this is mostly a fuels issue, it could bring challenges for lubrication due to the wide variation in fuels physical properties and chemistry.

Key concerns center around fuels with poor stability, failing to meet the [Safety of Life at Sea] flashpoint limit or containing chemical components with an adverse impact on machinery systems, wrote Unni Einemo, director of the International Bunker Industry Association, wrote in marine industry publication Safety4Seas.

Incompatible low-sulfur fuels could lead to sludge formation in tanks and lines. Asphaltene separation could lead to sludge inside engine filters and separators. Either occurrence could damage engines. The International Bunker Industry Association advises shipowners to avoid comingling fuels and to consider separate tanks for varying fuel qualities. Like all advice, this may not be feasible, meaning the lubricant has to cope with the consequences.

Detergency Test

When transitioning to low-sulfur fuels, OEMs recommend that operators of two-stroke marine engines begin with a 40 BN lubricant and then monitor the outcome. This is partly because base number is not a suitable surrogate for detergency, said Infineums Pui Fun Cheong at the ICIS Asian Base Oils & Lubricants Conference in Singapore.

The majority of the base number in a crankcase lubricant, for example, comes from the detergent, which is usually a metal carbonate (almost always calcium) surrounded by a sheath of surfactant, otherwise called a detergent. Measuring the base number of a detergent is a measure of calcium carbonate, not detergent content.

However, cost-consciousness in the industry is such that there is little opportunity for lubricants marketers or additive suppliers to differentiate a lubricant on detergent type. OEMs often only issue pass or fail letters with no differentiation on performance, which discourages investment in lubricant research and development. This leads the industry to regard base number as a proxy for detergent content while users want the cheapest possible base number source in their oil.

Operators usually adjust their lubricants detergency to address issues such as sludge and varnish. However, according to Chevron Marine Lubricants, too much alkalinity (due to a feed rate that is too high) can lead to excessive deposits. Too low of a detergent content could see the sludge become varnish in hot spots.

German diesel engine company Man Energy Solutions, which has supplied around 70 percent of the two-stroke marine cylinder engines in use today, created a system for blending varying base number lubricants on board from two lubricants of differing base numbers. However, industry feedback is that this system is often not used.

Maersk developed a system called Blend on Board that uses the system oil as a diluent. However, the system oil is usually an SAE 30 viscosity grade, whereas the cylinder lubricant is SAE 50. Too much dilution drives the lubricant viscosity too low for safe operation.

Four-stroke Challenge

The biggest challenge may be for operators of vessels with four-stroke engines using low-sulfur fuel. As these engines have a sump, any changes to fuel quality and type can pose more challenges for lubricants. In a two-stroke engine with total loss lubrication, the lubricant feed rate can be varied or the lubricant switched to cope with changes to combustion conditions.

Many lube marketers offer different lubricants for use in four-stroke engines with distillate fuels and (high-sulfur) residual fuels, but few operators have experience of managing switches between low-sulfur fuel oil and distillate fuels.

The usual advice to operators is to manage this via lubricants top-up, but this should be informed by analysis of used oil.

No one has experience of operating extensively on 0.5 percent sulfur fuel, said Lawrence. Challenges can come if you switch between residual and distillate fuels. Typically, products that are recommended for distillate use cannot handle large quantities of asphaltenes, and topping up could cause asphaltenes to drop out. This is not new, but what will be different is the variability and availability of the different fuel types.

Beyond 2020

Open-loop scrubbers usually used on the open seas contribute to about 4 percent fuel economy loss, so their use will not be long term. The IMO has committed the industry to a 40 percent reduction in CO2 emissions by 2030 and 70 percent of all greenhouse gases by 2050.

Leading lubricants marketers and additive suppliers say they are keen to be facilitators of this change but that the landscape will probably have to change significantly. The decline of the commercial shipping market after the global economic crisis in 2007-08 means that almost all operators are now focused on cost, and they bemoan what they view as the commoditization of supplies, including lubricants. Total cost of ownership or the possible long-term benefits of different formulations are only considered important by a minority of operators, they say.

On the other hand, tension between products that compete on quality and those that compete on price is present in many markets. Some may argue that overall this is healthy.

It is also worth mentioning that marine lube suppliers enjoy high barriers to entry, one of them being that ship operators prefer to procure from companies that can supply them in any port where they stop. A global network is a large advantage. Several new players and alliances have tried to build such networks in recent years so they can enter the market.

Another barrier is obtaining approvals for new products, which OEM engine builders give only after field trials and that can be long and expensive. This is a challenge to new entrants, but for existing suppliers it also limits opportunity to differentiate products on performance, according to one insider who asked not to be named. This compounds the issue of commoditized products and discourages investment in lube research and development.

Lubricant marketers and additives suppliers say they are ready to help ship owners and operators meet the next set of targets. In other industries, co-development of fluids – for example, to address energy efficiency – has paid dividends, where the lubricant is seen as an integral part of the design of new equipment. This, these companies say, could be the next step forward in the marine area.