Concept designs for two environmentally-friendly bulk carriers have been developed by a consortium of Japanese companies.
A 200,000 dwt class capesize LNG-fuelled and battery-powered energy-saving bulk carrier has been designed by Kawasaki Kisen Kaisha (‘K’ Line) with Namura Shipbuilding Co and Taiyo Electric Co. The other design, for a 90,000 dwt class post-Panamax bulk carrier has been jointly developed by ‘K’ Line, Shin Kurushima Sanoyas Shipbuilding Co and Taiyo Electric Co. Both concepts have received Approvals in Principle (AiP) from Japan’s ship classification society Nippon Kaiji Kyokai (ClassNK).
By selecting low-carbon LNG as the primary fuel source, an energy-saving vessel has been designed that helps reduce greenhouse gas emissions. The design was further enhanced by adopting permanent magnet (PM) shaft generator technology, along with lithium-ion batteries. By utilising batteries as part of the platform for power supply on board, the aim is to further reduce emissions going forward by later adding green energy sources with energy-saving technology.
LNG fuel will enable a reduction of greenhouse gas emissions by 25% to 30% compared to the use of conventional heavy fuel oil.
By producing electricity with shaft generator technology, fuel efficiency is improved compared to power generation with a conventional dual fuel generator, enabling, in conjunction with battery power, an expected emissions reduction of 2.5% to 3.0%, compared to an LNG-powered vessel without those two technologies.
By eliminating the need to operate generators during voyages, the maintenance workload for the ship’s crew will be significantly reduced along with the associated
maintenance costs. By adopting PM shaft generators, efficiency is improved by about 10% compared to conventional shaft generators.
Small-capacity batteries with high charge and discharge rates will be used for auxiliary power during peak hours of onboard demand. They will also store surplus electricity. In the post-Panamax carrier design, emissions will be reduced by using large capacity batteries to replace one of the dual fuel generators during cargo loading and unloading. In the capesize carrier design, the battery capacity will be greater due to amount of power required during cargo handling. Here emissions during cargo handling will be reduced by enabling vessel connection to shore power.
In addition to the equipment for greenhouse gas emissions reduction covered by the recent AIPs, the aim is to further reduce emissions in the future by installing various optional technologies, as shown in the illustration.
