Marine diesel cylinder lubricants are essential for the protection and performance of two-stroke marine engines, giving power to most cargo ships and tankers while environmental regulations constantly evolve. However, there are new things to be considered when buying marine diesel lubricants.

The Impact of IMO 2020

The IMO 2020 sulfur cap, which set a 0.5% limit on the amount of sulfur in marine fuels, was one of the biggest developments in the maritime sector. This rule aimed to reduce the damaging sulfur oxide (SOx) emissions from ships, contributing to respiratory illnesses and acid rain.

There were three primary ways that ship operators might adhere to IMO 2020:

Use alternate fuels like liquefied natural gas or methanol or switch to low-sulfur fuels like VLSFO or marine gas oil (MGO). You can also install exhaust gas cleaning systems (EGCS) or scrubbers to remove SOx from the exhaust gas.

Because different fuels have varying levels of acidity and require varying amounts of alkalinity from the lubricants to neutralize them, each of these possibilities has an impact on cylinder lubrication. The base number (BN) of the lubricant, which represents the amount of detergent in the formulations, is used to calculate alkalinity.

In the past, marine diesel cylinder lubricant oil had high BN values (70–140) to handle fuels with high sulfur content. 

On the other hand, excessive alkalinity in the cylinder due to low-sulfur fuels and high-BN lubricants might result in deposit formation and bore polishing. Thus, for low-sulfur fuels, lower-BN lubricants (between 25 and 40 BN) are advised. 

Cylinder Lubrication for Scrubber-Equipped and Alternative Fuel Engines

Because it is a polar fuel, methanol can dissolve some lubricant additives and lessen their effectiveness.  

Because it is hygroscopic, it may also contaminate the lubricant with water. As a result, methanol-fueled engines advise using specially designed lubricants with improved water separation and anti-wear qualities. 

The Future Of Marine Fuels And Engines

The IMO's goal to cut shipping-related greenhouse gas emissions by at least 50% by 2050 compared to 2008 levels began with the implementation of the 2020 sulfur cap. 

The IMO is anticipated to enact further regulations, including carbon pricing mechanisms and targets for reducing carbon intensity, in order to accomplish this goal.

By taking these steps, the marine industry will be encouraged to produce and use more low-carbon or zero-carbon fuels, such as ammonia, hydrogen, ethanol, biofuels, and synthetic fuels. Due to their distinct physical and chemical characteristics from conventional fuels, these fuels will present both new cylinder lubrication issues and opportunities. 

One possible zero-carbon fuel is ammonia, which may be made using solar or wind energy, among other renewable energy sources. On board ships, ammonia must be handled and stored with particular methods due to its extreme toxicity and corrosiveness. Because of its high nitrogen content and moderate flame speed, it can also have an impact on engine emissions and the combustion process. 

Consequently, ammonia-fueled engines will require appropriate lubricants that can stop corrosion and wear in addition to specifically constructed combustion chambers and injection systems. 

Cylinder Lubrication for Zero-Carbon Fuels: Hydrogen and Ethanol

Another potential zero-carbon fuel is hydrogen, which can be created via carbon capture and storage (CCS) from fossil fuels or renewable energy sources. However, because hydrogen is highly flammable and has a very low energy density, ships must have cryogenic systems or high-pressure storage tanks to handle hydrogen. 

Because of its small molecular size and strong diffusivity, it can also lead to embrittlement and cracking in metal components. As a result, specific materials and coatings, as well as lubricants resistant to hydrogen permeability and degradation, will be required for hydrogen-fueled engines.

Ethanol biofuel can be made from various biomass sources, including wood, corn, and sugarcane. Compared to traditional fuels, it has less carbon intensity and less sulfur but a higher octane number and a lower energy density. Because of its hygroscopic and polar properties can also result in water contamination and phase separation in the fuel system. Consequently, marine cylinder oil, marine lubricant filters, and injection systems for ethanol-fueled engines will need to be changed, and lubricants that can stop corrosion and water intrusion will also be required.

Cylinder Lubrication for Biofuel-Blended and Synthetic Fuel Engines

Fuels made from organic materials, such as algae, animal fats, or vegetable oils, are known as biofuels. 

Depending on the production process and feedstock, they can have a carbon intensity that is lower or similar to that of conventional fuels. 

Depending on the type and blend of biofuel, they can also have characteristics comparable to or different from those of conventional fuels. For instance, depending on the engine specifications, biodiesel, a type of biofuel, can be blended with diesel fuel up to a particular amount. 

Compared to diesel fuel, it has a greater cetane number and a lower sulfur level, but it also has a higher viscosity and less stability.

Additionally, its reduced lubricity and higher oxygen concentration may result in increased wear and deposits in the engine.

Consequently, improved fuel filtration and monitoring systems and lubricants that can offer sufficient wear protection and deposit management are required for engines that blend biodiesel.

Cylinder lubrication for GTL- Blended Engines 

Fuels made from non-biological sources, such as coal, natural gas, or biomass with CCS, are known as synthetic fuels. Depending on the production process and feedstock, they can have a carbon intensity that is lower or similar to that of conventional fuels. 

Moreover, depending on the kind and blend of synthetic fuel, they may have attributes that are identical to or dissimilar from those of conventional fuels. For instance, depending on the engine specification, gas-to-liquid (GTL), a synthetic fuel, can be blended with diesel fuel up to a particular amount. 

In comparison to diesel fuel, it has less sulfur and aromatics, but it also has less density and lubricity. Because of its higher cetane number and greater purity, it can also result in less wear and deposits in the engine. As a result, GTL-blended engines will require modified fuel injection and monitoring systems in addition to lubricants with sufficient viscosity and lubricity.