VESSEL REVIEW | SG Sunrise & SG Twilight – NYK's newest bulkers boast emissions-reducing technologies
Japan’s Nippon Yusen Kabushiki Kaisha (NYK) recently expanded its fleet with the acquisition of two new bulk carriers built by local shipyards.
SG Sunrise and SG Twilight were built for NYK by Namura Shipbuilding and Japan Marine United (JMU), respectively, in compliance with ClassNK rules. Although having slightly different features, both are 210,000DWT vessels measuring approximately 299 metres (981 feet) long by 50 metres (160 feet) wide and fitted with engines that can run on LNG.
SG Sunrise
SG Sunrise is the first of a series of newly developed LNG-fuelled bulk carriers built by Namura and expected to virtually eliminate SOx emissions and reduce approximately 80 per cent of NOx emissions and 30 per cent of CO2 emissions, in comparison with conventional vessels running on marine fuels with “eco-friendly” features.
Further improvements in propulsion performance and fuel saving in conformity with EEDI Phase III can be achieved with a combination of optimised energy-saving devices such as a flow control fin, a rudder-fin, additional fins behind the flow control fin, and low-friction anti-fouling paint. The fins were also developed by Namura.
The vessel is powered by one MAN B&W 6G70ME high-pressure, LNG-fuelled main engine with exhaust gas recycling capability, thus ensuring a significantly reduced risk of methane slip. The main engine and the generators generate reduced NOx emissions in compliance with MARPOL 73/78 Annex VI regulations.
The vessel itself complies with the SOLAS code covering noise levels on board ships. This then results in an improved environment within the living quarters. A ballast water treatment system is also fitted.
SG Sunrise also has the ClassNK class notation IHM, which indicates compliance with the ship recycling convention according to the Guidelines for the Inventory of Hazardous Materials.
SG Twilight
SG Twilight is meanwhile fitted with a WinGD dual-fuel engine that can run on either diesel or LNG, though the latter will be its primary fuel due to its ability to generate fewer CO2 emissions compared to conventional heavy fuel oil.
In addition, the vessel complies with IMO Tier III NOx regulations, and its EEDI has achieved a reduction rate of more than 40 per cent compared to the baseline.
The ship utilises JMU’s proprietary hull form, which offers lower resistance and greater efficiency. A number of proprietary energy-saving solutions from JMU are fitted including a custom twisted rudder and a unique bow design.
The fuel gas regulator room and the LNG fuel tanks are placed on the aft of the vessel. This arrangement will help ensure a large cargo capacity equivalent to that of vessels that operate on conventional fuel.
The WinGD main engine also features an intelligent control by exhaust recycling (ICER) system, which can help reduce methane slip in gas mode by as much as 50 per cent and greenhouse gas emissions by 28 per cent.
By cooling and recirculating the exhaust gas, the ICER system allows some of the methane in the exhaust gas to be re-combusted, thus further reducing the ship's emissions.
The generators and the auxiliary boilers are also dual-fuel capable and will run primarily on LNG. This means any boil-off gas that comes from the LNG fuel tanks can be redirected to the generators and boilers, thus reducing fuel wastage.
JMU also fitted SG Twilight with a system that monitors various parameters such as the condition of the fuel gas supply system. Through the same system, shoreside personnel can monitor the vessel’s condition along with the crew, thus reducing the latter’s workload to enable them to focus more on navigation.
