Nowadays three main ways to reduce emissions of sulphur oxides are considered: use of diesel fuel on vessels with low sulphur content, supplying ships with exhaust emissions cleaning systems (scrubbers), and installation of engines designed to use LNG as fuel.
Use of diesel oil on ships with low sulphur content is the easiest approach. The positive aspects of its application include reduced energy costs for processing oil and lack of necessity to transport bunker fuel on bunker ships with inner skins, thus reducing barging tariffs. It is also possible to pump diesel fuel by pipelines, which will definitely reduce its delivery cost and trans-shipping by 70% compared to shipping by rail.
However, there are obvious disadvantages. These include the inability to use diesel fuel for some merchant ships as the basic bunker fuel due to significant wear of the fuel equipment. There is low capacity at sea terminals built to handle diesel fuel export flows, and a consequent ability to corner the market. There will also most probably be a price increase in diesel oil in the Russian domestic oil market due to its increased consumption.
Moreover, studies of using low-sulphur fuels have displayed a number of additional problems, such as instability of combustion, incompatibility with other types of heavy fuel, obstructed ignition and combustion. Judging by experience, using low-sulphur fuel (especially for two-stroke diesel engines) means that special attention must be paid to the selection of lubricants, as in this case use of oil with a high base number may cause increased wear of the engine’s individual components.
The second way to reduce SOx emissions is the use of scrubbers. In this case high sulphur fuel oil (HSFO) can be used as a traditional fuel. The cost of HSFO is lower than the diesel oil or LNG, and there is no need to replace the ships’ supply infrastructure to bunker oil.
However, the use of scrubbers requires large investments. In addition to the high cost of a ship’s conversion, there is the problem of arranging rather awkward structures on board as well as the need to store significant reserves of caustic soda solution. Appropriate training is required, and available backup personnel are needed on board to maintain the scrubbers. There is also the possibility of increased operating expenditures associated with storage and delivery ashore of low concentration sulphuric acid as a result of exhaust gas cleaning. Salt emissions overboard should be monitored with no guarantee that the next stage of MARPOL restrictions will not prevent discharges of these chemically neutral wastes to water.
Exhaust gas cleaning systems (scrubbers) shall be surveyed according to Resolution МЕРС.184(59). However, there is a very informed judgement in the scientific community that while scrubbers reduce emissions of sulphur, they increase greenhouse gas emissions to the same extent. Their effect is therefore to decrease the energy efficiency of ships.
The most likely scenario is that scrubbers will only be widely used after 1 January 2020 in response to entry into force of the global sulphur cap of 0.5%. Until then, their application will only be economically feasible on ships that spend a long time operating in SOx Emission Control Areas.
The most innovative way to reduce the amount of SOx oxides emissions is the transition to bunkering LNG. The positive aspects of this can include the ability to implement large scale LNG operations at a very high profit as the domestic gas price in Russia is approximately three times less than the market price in Europe. Besides, ships using gas as fuel comply with all the environmental standards defined prior to 2025, and they experience reduced engine wear as well.
There are downsides. There is a high cost for the conversion of ship propulsion plants, quite complicated, a multi-stage procedure for fuel transfer on board associated with the required pipeline purging with inert gas is required and the limitation that refuelling can only be carried out at specialised berths outside the hours of loading and unloading work. This potentially increases the time of a ship’s stay in port. Also on the downside, there is an absence of skilled personnel in the labour market with experience on gas fuelled ships, and the cost of a crew failure when bunkering and during the voyage is extremely high. Further, successful implementation of this approach requires development of coastal infrastructure.
Russian Maritime Register of Shipping has over 60 skilled experts who can provide classification services during the construction or operation of state-of-the-art LNG carriers all over the world.