Q FUEL TECHNOLOGY Fuel for the journey New alternative fuels are giving 18 W
ith the introduction of a range of various environmental regulations over recent years, restricting the levels of NOx, SOx, and
CO2 from vessels, the shipping industry has
found itself at a crossroads. Staying in compliance with the new rules ultimately boils down to this choice – use technology to cut emissions or use alternative fuels. For some, the adoption of exhaust gas
cleaning systems (EGCS) provides the perfect solution for reducing SOx emissions; however, other options are also available. Technical challenges posed by new regulations have become the impetus in the shift towards green energy. Fuels such as LNG, methanol, and LPG, widely recognized as environmentally-friendly alternatives to fossil fuels, are rapidly becoming a viable source of energy for ships. The IMO outlined many possible emission
scenarios that could arise during the 2012-2050 period in its third Greenhouse Gas Study (2014), specifi cally a general prediction of increased effi ciency in conventional fuels, as well as an increase in the use of LNG. The fi rst LNG fuelled vessel was introduced in 2000,
and by 2016 there were more than 90 vessels using LNG as fuel. A total of 140 vessels are expected to use LNG at some point during 2018. LNG can reduce NOx emissions by more than 90% compared to conventional fuels – making it a suitable candidate when consider- ing Tier III regulations. Currently, there are three types of LNG
powered propulsion system in general use: mid-speed electric propulsion systems, mid-speed propeller systems, and low-speed propeller systems. Mid-speed electric propulsion systems are
generally employed by inland ferries and workboats, and can be either gas-only or dual-fuel. By employing a number of electrical generators, this system offers reliability. Mid-speed propeller systems can also be
either gas-only or dual-fuel, and have been installed on chemical tankers and tugboats. As there is no conversion loss to electricity compared to the electric propulsion system, this option is most suitable for vessels that require high load-following capabilities. Low-speed propeller systems are available
for dual fuel use. Their high output makes them ideal candidates for larger ships, and they are currently used in container vessels in North America and PCCs in Europe.
Gas-fi ring engines are yet another option.
However, some variations of this type can be prone to the knocking and methane slips. Furthermore, high pressure engines do not meet Tier III regulation standards. Japan’s fi rst LNG-fuelled tugboat, Sakigake,
was delivered to NYK Line by Keihin Dock Co. Ltd. in 2015 after exhaustive research carried out with the assistance of Tokyo Gas Co. Ltd., Niigata Power Systems Co. Ltd., Air Water Plant & Engineering Inc., Wing Maritime Service Corporation, Japan’s Ministry of Economy, Trade and Industry and the Ministry of Land, Infrastructure and Transport. ClassNK carried out the feasibility study and
provided technical advice for the project. The vessel is equipped with the 28AHX-DF dual fuel engine developed by Niigata Power Systems, and runs on both diesel and gas fuel. LPG has been expected by the industry to
be a suitable alternative. Today, there are more than 1,000 LPG carriers in operation across the world. As well as meeting IMO SOx require- ments, the recent development in shale gas and shale oil has led to an increase in the transportation of LPG. And, because LPG can be stored safely in liquid form at ambient temperatures at roughly just above 10 bars (approximately ten times normal atmospheric
ship owners more options to stay in compliance, explains Tokyo-based classifi cation society ClassNK
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