Hyundai Mipo Dockyard (HMD) and Bernhard Schulte Ship Management are working towards building the first ballast-free liquefied natural gas (LNG) bunkering vessel under construction to Lloyd’s Register (LR) class.
In light of increasingly stringent demands made by the International Maritime Organization’s (IMO’s) International Convention for the Control and Management of Ships’ Ballast Water and Sediments (the BWM Convention), HMD is looking to develop a ballast-free vessel. HMD has given particular consideration to a special hull form with dead-rise, forward engine room and deckhouse, and a twin propulsion system with azimuth thrusters to allow the vessel to retain its damage stability and control the trim and heel without ballasting.
The 7,600m3 vessel is under construction at HMD’s Ulsan shipyard in South Korea. According to LR, HMD’s first obstacle was speed management by deadrise. Typically, deadrise helps a ship’s stability, which is critical to a ballast-free vessel. However, it is also likely to deteriorate the vessel’s speed performance. HMD has focussed heavily on hull form optimisation to counteract this, and has developed a better performing deadrise hull form, confirmed through the wet model test.
The twin propulsion system has also been designed with two azimuth thrusters. According to LR, the smaller diameter of the propellers in the azimuth thrusters enables the vessel to achieve full immersion in all operational conditions.
The LNG on-board the vessel will be stored in two independent IMO type-C tanks, which are designed to contain the LNG with a minimum temperature of minus 165°C and maximum vapour pressure of 3.75 bar(g). The LNG will be able to be transferred to an LNG-fuelled vessel at around 1,250m3 /hour through the cryogenic flexible hoses without ballasting and/or de-ballasting. The natural vaporising gas from the bunkering vessel and the returned boil-off gas from the LNG-fuelled vessel will be compressed up to 220 bar(g), stored in two sets of 40 feet container and used for fuel and electric propulsion.
A major advantage of this ballast-free concept is that the ship will not be required to use a ballast water treatment system (BWTS). These systems are designed to prevent the movement of marine microorganisms from their native environments to non-native ones, which can lead to irreversible ecological damage. Governed by the IMO, the BWM Convention requires ships to have a BWTS in place to minimise the environmental risk of shipping. The entry into force of this regulation came on September 8, 2017, however, there is an ongoing debate as to whether it should be postponed for a further two years to give the industry time to develop and implement solutions that will significantly lower the risk of species transfer. In addition to these benefits, a ballast-free ship would also remove the need to comply with the Performance Standard for Protective Coatings for ballast tanks and related regulation, enabling maintenance costs savings.
“The ballast-free concept will be made a reality by the technology expertise of HMD. We aim to stand out in the field of eco-friendly business practice,” says Seung-Ho Jeon, SVP of HMD Initial Planning Division.
Jin-Tae Lee, Ph.D, LR’s Korea Chief Representative & Marine Manager, adds: “We are delighted to work with the shipyard helping the marine industry bring innovative designs to the market. We believe that this design is another remarkable development for HMD to realise the industry’s need for safe, efficient and clean requirements in the shipping industry worldwide.”