FUELS & LUBES: Meeting the Low-Emissions Challenge

There is no shortage of solutions as manufacturers struggle with the trade-off between reduced sulfur content and higher contaminant levels.

By Wendy Laursen

When Man Diesel & Turbo celebrated the centenary of the first ocean-going, diesel-engine vessel in February, it was hailed as an environmental triumph over the coal-fired steam power plants of the day. The company used the occasion to proclaim a new era of even cleaner LNG-burning vessels. But for today’s fleet, still burning heavy fuel oil, 2012 is just another transition year in the move to dramatically reduce SOx emissions from diesel engines.

Catfines and Other Contaminants
The Petroleum Services arm of DNV (DNVPS) was established in 1981, and the first fuel it sampled showed a high catfines content. Catfines are highly abrasive particles of spent aluminum and silicon catalysts used in the refining process. An excess in bunker fuel, even after the fuel has gone through the onboard treatment plant, can lead to cylinder damage within several hundred operating hours.

High catfine levels continue to be a problem today to the point where DNVPS recently added a new service aimed at resolving disputes between ship operators and centrifuge manufacturers. Onboard centrifuges should act as a safeguard against catfines, but they are most efficient removing particles above five to ten microns as cleaning efficiency increases with particle size. DNVPS’ new service will analyze the size of the catfines to confirm whether or not the centrifuges have successfully removed particles of different sizes because smaller catfines can also cause cylinder damage.

“What we see now is that fuel sulfur content is going down but catfines are going up,” says Charlotte Rojgaard, Global Technical Manager for DNVPS. The problem is not all with fuel suppliers or equipment manufacturers, though, says Rojgaard. A thorough inspection and maintenance plan for the fuel treatment system should be followed, and alarm settings should reflect the properties of the fuel being bunkered. “You would think that after 31 years the industry had learned, but this is still a very common and costly problem,” she says. DNVPS offers an online service, Fuel Insight, where ship operators can trend and benchmark the quality of fuel deliveries from individual suppliers and individual ports based on the extensive statistics gathered by the company.

Testing house Intertek Lintec began offering a chemical analysis for fuels in 2004 after a number of vessels that took on bunker at Fujairah suffered engine blackouts due to filter clogging. The contaminant in this case was dry cleaning fluid. But that is just one of many possibilities and, like catfines, the problem is getting worse, not better, as fuel blending focuses on sulfur content rather than viscosity, density and ignition properties. “The real issue is that heavy fuel oil is a waste fuel and what these emissions regulations have done is actually make the fuel quality worse in real terms,” says Geoff Jones, Global Leader for Bunker Fuels at Intertek. “We are seeing more and more exotic contaminants.” Highlights from the long list of incidents he cites include polyethylene that caused a blackout on a vessel that bunkered in London and styrene that caused a blackout on a vessel that bunkered in Singapore.

Jones believes that the introduction of increasingly lower sulfur fuels, which engine manufacturers have little experience with, will require extra vigilance: “Once you start reducing lubricity and the thermal properties of a fuel, you are potentially causing engine and operational problems on board.”

Countermeasures
Shipowner NYK takes measures to protect engines from damage including analyzing bunker samples and using fuel additives or adjusting the pre-treatment system if abnormalities are present. The company only buys from reliable suppliers. “We believe chasing prices too much will lead to unnecessary troubles,” says a spokesman. The company believes there should be a penalty system for suppliers who sell off-spec fuel oils.

2015 is expected to result in a surge in demand for distillate fuel oils as SOx limits within Emission Control Areas drop from 1.00 to 0.10 percent. Most ships won’t have the alternative – exhaust gas scrubbers – in place in time. The transition is expected to aggravate fuel-quality problems, and Wilhelmsen Ships Service is launching a new, rapid bacteria test kit for microbial contamination of distillate fuels. More and more problems are seen with distillate fuels being infected by microorganisms such as bacteria, fungi and algae, says the company, mainly because sulfur protects against microbial growth.

Low-sulfur fuel options are being expanded with technologies that also aim to tackle CO2, NOx and particulate matter emissions. Nonox’s emulsion fuel is currently being tested on a third Wallenius Wilhelmsen Logistics vessel. Nonox claims a payback period of three to six months on the installed equipment and fuel savings of around three tons a day. Neftech’s emulsion is being tested on an APL container ship, and another company – NAI – says its Next-Fuel emulsion technology can generate fuel savings of approximately 20 percent.

Biofuels are generating interest, notably with the U.S. Navy, and companies from Dynamic Fuels in the U.S. to MBD Energy and Licella in Australia and Aquaflow Bionomics in New Zealand are developing biomass and algae-based technologies. The Port of Rotterdam is currently running the first marine trial of Neste Oil’s NExBTL renewable diesel on a patrol boat, and biofuel tests are also being conducted by a group consisting of Maersk, MAN and two Danish universities.

One Lubricant or Many?
MAN’s engines can run heavy fuel oil with sulfur levels between 1.5 and 3.5 percent using BN70 engine lubricants that automatically adjust the lubricant dosage to suit the inherent detergency of the fuel, a characteristic dependent on sulfur content. BN is a measure of a lubricant’s ability to neutralize potentially harmful acids in the fuel. A lower BN number means reduced neutralizing capacity, suitable for lower sulfur fuels.

When sulfur levels below 1.5 per cent are required, Winkel believes that heavy fuel oil and scrubbers will predominate, but MAN is still researching suitable lubricants. “The reason we put so much emphasis on getting a proper cylinder lubricant for low-sulfur fuels is for operation with LNG,” he says. “There is no sulfur in the gas, or very little. As we see it, it is the same lube oil that we would need for low-sulfur diesel fuel, distillates and LNG.”

The debate over whether a single lubricant will meet all sulfur requirements continues. Total’s Lubmarine claims a new lubricant chemistry that is independent of sulfur content for its BN57 Talusia Universal lubricant, which is suitable for sulfur levels between 0.5 and 4.5 percent.

Competitor Castrol claims practices such as slow steaming mean there is no single solution. Paul Harrold, Technology Manager for Marine Lubricants, believes that if a mismatch occurred between 1.0 percent sulfur fuels and the BN of the lubricant, problems could occur after several weeks. But in the case of 0.1 percent sulfur, operational problems could occur much faster. “We believe the current challenge of slow steaming, combined with impending fuels legislation, means optimal cylinder lubrication for vessels can only be achieved under all load conditions by a range of lubricants,” he says. “Operators that adopt a single lubricant strategy should be mindful of the compromises they are making.” 

Tim Roadnight, Global Leader for Lubricants at Intertek, says fuels at or below 0.5 percent sulfur will have dramatic effects on how lubricants work as these levels mean a dramatic loss of lubricity from the fuel. “It is very easy to make the sweeping statement that a lubricant is going to fit the bill, but the problem is we are dealing with million-dollar engines and for a vessel not to be out at sea costs companies hundreds of thousands of dollars a day. There will definitely be a requirement to undertake more regular lubricant testing as well as reduced maintenance intervals in the beginning.”

The recent industry move towards more environmentally friendly, biodegradable lubricants adds another dimension to pending fuel-compatibility issues. “We don’t know whether the green lubes are going to be bio-friendly and low sulfur-friendly. We are focusing so much on the green aspect, we could be losing out on these other aspects,” says Roadnight.

Black Carbon
As if all that weren’t enough for harried shipowners, “black carbon” is up next on IMO’s air emissions agenda. In February, while MAN was celebrating the Selandia centenary, the Institute of Marine Engineering, Science and Technology (IMarEST) released a working definition of this component of particulate matter. IMarEST stated that black carbon is a “strongly light-absorbing carbonaceous material emitted as solid particulate matter created through incomplete combustion of carbon-based fuels.” Black carbon is closely associated with global warming, and the snow-covered Arctic is particularly vulnerable to its atmospheric effects. By defining black carbon, IMarEST hopes to raise awareness and assist IMO in developing regulations.

A report from the International Council on Combustion Engines released in January states that switching to low-sulfur, lighter fuels instead of heavy fuel oil in large engines is unlikely to reduce black carbon and could have the opposite effect. Scrubbers will probably reduce black carbon emissions, but the magnitude of the reduction is not yet clear. The report does not mention LNG. Further regulatory developments on black carbon are expected from IMO in 2014. – MarEx

Wendy Laursen writes from Australia.