The Future Engine Forum

Themed ‘engine performance and condition in a new environmental age’, the roundtable discussion explored how ship owners and engine manufacturers are reacting to current emissions regulations, and what changes they anticipate future regulation will bring. Among the attendees were representatives from MAN Diesel & Turbo, Winterthur Gas & Diesel (WinGD) and five ship owners/operators: Columbus Ship Management, Hammonia Reederei, John T Essberger, Rickmers Ship Management and Wagenborg Shipping.

The discussion was chaired by Jakob Buus Petersen, director, Vessel Performance Solutions, who put the topic into clear context. “What is it that drives development and innovation, and leads companies’ decisions to invest?” he asked. “It is what people believe can happen in the next 20 years or so, and that has to be governed to a large extent by regulation.”

Regulation comes in many forms – particularly when it comes to shipping emissions. Over the past two years the industry has faced the introduction of Emission Control Areas (ECAs) for SOx, from January 2015, and NOx at the beginning of this year. Both have required affected operators to change engine configurations, fuels or operational procedures (and possibly all three). Two future regulatory changes are also looming large: the introduction of a global sulphur cap in 2020 or 2025; and the increasingly stringent energy efficiency requirements of the IMO’s Energy Efficient Design Index (EEDI), intended to curtail CO2 emissions.

ECA experience

The most immediate challenge for many shipping companies is sulphur ECA operations – a challenge that will be extended globally when the worldwide cap is introduced. All the companies at the roundtable had ships operating in the ECAs, and for most the preferred solution was to switch from high-sulphur heavy fuel oil (HFO) to marine diesel oil (MDO) or marine gas oil (MGO) with the required maximum fuel sulphur content of 0.10%.

Fuel switching has caused challenges for engine running, Steve Walker, global marine equipment builder manager, ExxonMobil, reported. “Even when bunkering similar fuel at both ends of a voyage, we would have cases when engines complained for a couple of days – it was just that there was some fuel mixing and fuels didn’t necessarily fit well together. Our worry with ECAs was that there would be more fuel switching and more of these issues.”

Despite the concerns, for many operators fuel switching when entering and leaving ECAs has been a relatively painless adaptation. But there are still pitfalls to be avoided. Vladimir Shnurkov, fleet manager, Rickmers Ship Management, shared one typical instance. “There was a case in the US when we changed over fuels in a short time, and we nearly lost power because the MGO was blocked by paraffin wax. So we came to the solution of heating the fuel line to 30-35°C.”

The difference in viscosity between HFO and MGO is an important consideration when switching. Jan Vinder, promotion manager & customer support, MAN Diesel & Turbo, reported that the engine designer had seen fuel pump seizures in tests where the viscosity of MGO was too low. “The main thing is to keep MGO above two centistokes,” he said. “We also recommend testing before you go into the ECA if your fuel equipment is worn. You should install a cooler for operating in hot areas, because if you are on a lower viscosity the temperature outside is 40-50°C, viscosity can fall below two centistokes. And there could be some instances where you need a chiller, if you are running on really thin oil.”

The challenge of maintaining the correct fuel viscosity for low-sulphur fuels highlights one shortcoming of the ISO 8217 fuel quality standard, noted Iain White, global marketing manager, ExxonMobil “The specification is written for 1.5cSt to 6.0cSt, but you never really see the high end. And when it comes to the winter and the refineries add pour point depressant, if anything the viscosity goes down. So viscosity can also vary throughout the year.”

Operators also shared experiences of working with ECA fuels – a range of fuels with low sulphur content and high viscosity, designed to be easier to switch from and to HFO. Kay Thürnagel, technical director, Hammonia Reederei, explained that the company’s vessels had been using ExxonMobil Premium HDME 50 – an ECA category fuel supplied by ExxonMobil – with no problems. “Our chief engineers also have an on-board kit so that they can test for compatibility before mixing fuels.”

The lower price of oil was noted as a potential obstacle to the uptake of such ECA category fuels. Thomas Geberbauer, fleet manager, Columbus Ship Management noted: “We did a trial in 2014. It was worth doing to look at an alternative to MGO, but then the fuel price collapsed and the spread between [ECA category fuels] and MGO was not as attractive.”

One factor on which all operators agreed was that increasing sulphur regulation was leading to a more complicated fuel scenario. According to Geberbauer, it is a complexity that has yet to be factored in to vessel design. “Ships should be designed to accommodate more fuel treatment,” he said. “Today we see ships designed for one or two fuels – they need more if you want the flexibility to change. We normally have to use the same bunker line for HFO, MDO and MGO.”

There is a corresponding complexity in cylinder lubricants, Geberbauer added: “For worldwide trading you can have sulphur levels of all different kinds. But we don’t want to have to use two or three different types of cylinder oil, because it makes it complicated for the people on board. So we would like to see just two kinds of cylinder oil that can cover the full range of fuels on the market today.”

Konrad Räss, general manager, combustion systems R&D, WinGD, was able to provide some reassurance on that front. “Our recommendation today says that you can run with just two lubricants: a high base number (BN) oil for higher-sulphur HFO, and a low BN oil for lower sulphur fuels and MGO or ECA category fuel.” Recent tests confirmed the use of BN100 in ECA areas to be harmless provided feed rates are adjusted correctly and engine condition to be closely monitored.

Looking forward to the global sulphur cap, participants were asked whether they would be considering scrubber installations. The lukewarm response suggested that most will prefer to try other options.

A particularly robust rebuttal came from Thomas David, head of newbuildings, John T. Essberger. “If you want to talk about a truly green scrubber system, you don’t throw the washwater into the sea,” he said. “So you need a closed loop scrubber, and then a treatment plant, and whatever else. Then to comply with Tier III NOx you need selective catalytic reduction (SCR) or exhaust gas recirculation (EGR). To fit all that equipment you need space, but you cannot build a ship bigger because then you can’t go to certain ports. It’s much easier to say that we will use 0.5% sulphur fuel worldwide.”

Tackling Tier III

While ship owners appear to be dealing with SOx restrictions with only minor modifications to engines and fuel systems, the same cannot be said for new limits on NOx emissions. Both compliance options for Tier III NOx regulations require the installation of new equipment – either SCR or EGR. And they are both pricey; Vinder reports for medium size engines, installation will cost upward of US$1.5 million.

“At the smaller sizes, we think SCR will be cheaper at first cost,” Vinder told delegates. “But then there are the other factors, which is why we are offering both solutions.”

One ship operator who knows all about the downside to SCR is Onno Steenweg, superintendent fleet management department, Wagenborg Shipping. Having operated the units for several years, he reports that his crew are always happy to turn them off. “The SCR works perfectly, but when it is connected to the main engine you can get temperature fluctuations, calcium deposits in the engines, condensation and soot collecting,” he said. “You have you buy urea, clean the system regularly, and you need cost rebates from port authorities to make it profitable.”

Urea injection and engine temperature can be controlled more accurately in modern systems, Vinder explained. But there is still the potential for cold corrosion to occur while the SCR system heats up, Räss noted – a high operating temperature is needed if the exhaust gas is to be treated properly, and while the system is warming up engine heat is used, potentially reducing in-cylinder temperature.

Although the Tier III market is in its infancy, EGR is the most popular choice for two-stroke engines based on current orders, Vinder notes. But here too there can be engine condition challenges. Räss said: “You have to treat the exhaust gas first, otherwise sulphur-containing exhaust gas blown back into the piston underside can react to sulphuric acid. In the worst case you could corrode piston rod and other components, as well as having sulphuric acid in the crankcase, depending on the condition of the stuffing box.”

With little to separate the alternatives in terms of cost or performance, the choice is very much up to the individual owner, says Vinder. “It’s a discussion we need to have for each project, whether to use EGR or SCR – and then whether low-pressure [after turbocharger] or high-pressure SCR. It depends for instance on the initial cost, or whether you have waste heat recovery – in latter case we think low-pressure SCR is the solution.High pressure SCR is being used for smaller engines, but for big engines [over 40,000kW] you would need very thick materials for high pressure SCR, so it would be a huge reactor.”