In some areas designated by IMO as emission control areas [ECA], much more stringent limits are expected to be applied, John Liddy, owner of Liddy Associates, told ACI conference goers. Liddy Associates, based in Middlesex, Great Britain, specializes inall technical, regulatory, andoperational aspects of the fuels and lubricants used inthe marine and powergeneration industries.

In Europe, the Baltic and North seas were designated SOx ECAs in 2005 and 2007, respectively.
The newest ECA in North America, covering SOx and NOx emissions within 200 miles of the coast, was implemented this past August. To this area will be joined Puerto Rico and U.S. Virgin Islands in the Caribbean Sea where SOx and NOx emission limits become effective from January 2014, Liddy said.

Fuel sulfur limit in ECAs has to be lowered from todays 1 percent to 0.10 percent beginning in 2015, while the global fuel sulfur cap will be reduced from the existing 3.5 percent to 0.50 percent in 2020 or 2025, according to Liddy.

Ships operating within ECAs have the option to switch from a residual to a distillate fuel. A distillate fuel contains a lower sulfur content similar to that of trucks and some small cars.

Another strategy to meet more stringent emission standards is engine technology, Liddy said. However, modifying ship engines to significantly reduce the NOx emissions will require changes to marine lubricants. Most engines delivered since 2000 meet applicable global NOx limits by in-engine modifications, Liddy noted. Ships delivered after 2016 will have to meet much tighter limits, when reduction of NOx emissions will have to be around 80 percent of the current one. It will apply only to new ships and only when they operate in emission control areas, Liddy said.

After 2016 ship owners will have to install selective catalytic reduction plants to chemically remove NOx exhausts, according to Liddy. Other expected engine modifications will be development of exhaust gas recirculation systems that can be installed in some engine types. Also there are various technologies of injecting water into the combustion process to deliver a small degree of NOx emissions reduction.

These technologies could affect lubrication requirements, Liddy contended. For example, ash in lubricants could have a detrimental effect on catalytic reduction plants. It is not a type of sensitivity as in automotive applications, but we should expect a major tailoring of marine lubricants to minimize this serious problem that could effect the NOx emissions.

Yet another alternative is employing a technique that scrubs exhaust gases with seawater or sodium hydroxide solution, which can remove more then 95 percent of SOx exhausts, Liddy said. While the economics of scrubbing can be attractive, particularly for ships operating mostly within ECAs after 2015, few ship operators have adopted the technology.

Finally, converting to liquefied natural gas (LNG) is an option, although an expensive one, Liddy said. Emissions-wise, LNG reduces SOx by 90 to 100 percent and NOx by as much as 80 percent. There is also a better long-term outlook for supplies of natural gas than for crude oil.

LNG does have several drawbacks, Liddy concluded. Among them are a large cash investment, the lack of a global supply infrastructure, high into-ship delivery costs and the lack of globally recognized standards or procedures for bunkering it.