Danish ship design company Knud E. Hansen (KEH) has unveiled the X-gas Project – a series of medium-capacity small-scale LNGCs, which are designed to bunker cruise ships among others.
The project’s flagship design is a 126.5 m vessel with a cargo capacity of 9,000 cu m and fitted with two Type C tanks.
However, the company said that the designs could be tailored to accommodate a range of tank capacities, as well as various containment systems, including membrane tanks.
KEH said that the most unique feature of the X-gas platform is a low-profile, forward deck house. This will enable the vessel to safely approach and moor alongside cruise ships fitted with low-hanging lifeboats.
The design also minimises the need for ballast during cargo transfer, thereby lowering operational costs. In addition, the forward deck house allows for larger cargo tanks without impeding bridge visibility.
For improved maneuvering and safety, the design features two propulsion thrusters aft and two bow thrusters, as well as an autodocking system for alongside mooring.
What is claimed to be an extremely fuel-efficient diesel electric power and propulsion plant will be installed consisting of a dual-fuel 4-stroke engine.
Integrated with the propulsion plant is an energy storage system (ESS) with a lithium-ion battery bank to allow for engine load optimisation with reduced methane slip. The batteries also provide all of the power required during cargo transfer, resulting in no emissions or exhaust affecting the ship being bunkered, an especially important feature for passenger vessels.
Cargo tanks’ Boil-off gas (BOG) is captured and consumed in the dual-fuel engines and the energy surplus generated can be stored in the batteries. Waste heat from the engine cooling water is converted to electric and thermal power through a number of ORC (organic rankine cycle) waste heat units.
In a new approach, wasted energy captured during the operation can be stored in accumulators and released as required to drive absorption chiller and reduce the electrical load onboard. This approach boosts energy efficiency to a very high level, KEH said.
Another unique feature of the design is an aft ‘energy bay’ that allows the vessel to provide containers loaded with fuel or stored electrical power to a receiving vessel. It also allows the vessel to provide fully charged battery banks to remote locations ashore, where current infrastructure does not allow sufficient power to be provided.