Protecting marine engines in a lower carbon world

The portfolio of MAN Energy Solutions (MAN ES) includes two- and four-stroke engines designed for marine applications as well as turbochargers and propellers. And, with approximately 50% of global trade transported by MAN ES engines, the organisation is committed to the provision of a range of technologies to help reduce fuel consumption and meet emission regulations. Part of this vision, as Dr Julia Svensson from MAN ES explains, is supported by their strategy to raise the performance level of marine cylinder oils. “In 2020 we introduced two performance levels for cylinder oils Category I and Category II (Cat. I and Cat. II), with Cat. II being overall the higher performing category. We worked hard on this together with industry because we wanted them to move to developing and using cylinder oils that are fit for our new engines and for the future.”

Engine cleanliness is key

These Cat. II oils have specific requirements that match the needs of the latest designs of highly fuel efficient MAN B&W engines, which have higher temperatures and pressures than their predecessors. Cat. II has introduced higher performance for piston cleanliness and the need to maintain wear protection and provide sufficient corrosion protection to ensure an acceptable time between overhaul of the cylinder unit is achieved. "MAN Cat. II cylinder oils have excellent performance overall, but have a special focus on cleaning ability. The way we define Cat. II is that a lube oil should have the same or better cleaning ability as a 100 BN oil. So we started with 100 and 140 BN as the first oils to go through the Cat. II process, with the aim that other grades, such as 40 BN, would follow. This proved to be a challenge, but the industry was up for it, and now Cat. II 40 BN oils have the same cleaning ability as that offered by 100 BN oils.”

However, as Julia continues, the oils are applicable to different MAN engine types. “Cat. II cylinder oils are for all engines, but we recommend them especially for MAN B&W two-stroke Mark 9 and higher and for our dual fuel engines. The 100 and 140 BN Cat. II oils are of course best suited to high sulphur fuels applications, those vessels with a scrubber, whereas the 40 BN oils are for low sulphur fuels such as very low and ultra-low sulphur fuel oils (VLSFO and ULSFO), liquified natural and petroleum gases (LNG and LPG) and methanol. Cylinder oils with a current No Objection Letter (NOL) are considered to be in Cat. I and are applicable for Mark 8 and lower engines.”

MAN ES sees engine cleanliness as a really important factor in the quest to protect the engine and to obtain reliable and efficient engine operation. “You need the piston, the top land, the ring lands, the back of the rings and the ring grooves all to be free from deposits. This means we can have the right flow of gases and ensures we can get the right efficiency for our engines. We have now withdrawn the NOLs from the older low BN oils because we saw that they did not have the performance needed for the engines of today.”

Efficiency gains for existing ships are increasingly important as International Maritime Organization (IMO) measures to reduce the greenhouse gas (GHG) emissions include a Carbon Intensity Indicator (CII), which enters into force on 1 November 2022. By 2024, ships will receive an A to E energy efficiency rating and those rated for three consecutive years as D or one year as E will have an obligation to adopt a plan of corrective actions to improve their energy efficiency performance and bring them back to a C rating.

Route to net-zero

However, it is not just existing ships that need to focus on GHG emissions. As the pressure to reach net-zero by 2050 intensifies, the IMO is working to strengthen its level of ambition on the reduction of emissions from shipping. With a theme of ‘New technologies for greener shipping’ the organisation is looking for ways to introduce a new generation of ships that are energy efficient, have a low environmental impact, have a very good safety record and use the most recent digital innovations.

As Julia goes on to explain, MAN ES is already very active in ship decarbonisation. “We have new fuels coming in and we need to make sure everything fits together and that the fuel system is designed based on the fuel being used. A lot of work goes into fuel systems and into increasing the efficiency and reliability of our engines. In addition, the use of digital innovations in the marine industry is coming in, which means we can increase the efficiency, safety and availability of MAN products while also providing a more interactive cooperation with our customers.”

Illustration of MAN ES ammonia engine

The new fuels being introduced as part of the decarbonisation efforts are likely to have a big impact on future hardware technology. “With these new fuels, for example ammonia, we must check that the materials in our hardware are compatible and we will need to design new types of fuel systems so we can get the fuel into the combustion chamber. In addition, we already have two different technologies for NOx reduction - exhaust gas recirculation (EGR) and selective catalytic reduction (SCR), and I would say we have to make sure everything fits together if we are going to have an efficient system.”

“First of all, we are working on lowering fuel consumption, then increasing efficiency of the normal engines and ensuring the engines can run on biofuel. And now the use of green methanol is really picking up, plus we already have LNG, ethane, and LPG engines. However, the next step is green ammonia.”

As Julia explains, the introduction of biofuels and even more complex fuel mixes have presented new challenges. “What we have seen with engines running on LNG, methanol, ethane, LPG and VLSFO is that it didn't really matter which engine it was or what fuel the engines were running on - they all had the same problem: cleanliness. But the Cat. II 40 BN oil aims to get the cleanliness in place for the low sulphur fuels and we haven't really seen any challenges for these other fuels. Of course ammonia is another, completely different beast that we are taking on. We are working with the industry to see what is needed. Hopefully there will be a solution, but we have to take it one step at a time, starting with what we have and then building on that. I think it's important to go back to what the cylinder oil should be designed to do. In my view it needs to lubricate the liner and the piston, provide wear protection, keep the piston rings, ring lands and ring grooves nice and clean it should protect from seizures and provide neutralisation ability because there is still sulphur out there and we need to have the right amount of neutralisation ability in the lubricating oils.”

With the huge drive to net zero it is uncertain how fast alternative fuels such as ammonia and methanol will penetrate the market and be used more widely by the marine industry. Julia suggests there will be different timelines for different fuels. “Methanol will have a faster penetration because we already have the engine technology in place and orders are coming in. For ammonia, we are already working on the engine technology because this is of course a completely different kind of fuel and we need to have all the safety systems in place. In my view it may not be the engine technology that is the main barrier – it is the availability of renewable methanol and ammonia fuels.”

In Julia’s opinion the advantage of methanol and ammonia is that they are not completely new. “There is a huge industry that knows a lot about these different fuels, different systems and different ways of bunkering. The complexity will be a challenge, and the marine industry has to work to overcome it. We live in a complex world, and it will not become less complex.”

Julia’s view of success is clear “I think the key is to have a clear goal and then for the whole marine industry to work together so that we get there. We know that it's extremely difficult, but we are working hard on developing energy solutions for two-stroke engines and we want to succeed. So we hope you want to be part of the journey.”

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