Japanese startup PowerX has unveiled the detailed design of what it believes to be the first ever ‘Battery Tanker’, i.e. a tanker-type vessel transporting electric power rather than fossil fuels.
The first vessel aims for completion by 2025, with domestic and international field testing planned to commence in 2026.
Furthermore, a new company called ‘Ocean Power Grid’ is to be established in the third quarter of 2023 to advance the maritime power transmission business utilising battery tankers. This company will own, sell, and operate the battery tankers in Japan and abroad. PowerX is seeking business partners worldwide for this new technology and business endeavour.
PowerX has signed a memorandum of understanding and a partnership agreement with Kyushu Electric Power Co and the city of Yokohama to pursue its battery maritime power transmission concept and achieve carbon-neutral ports. The first battery tanker will be of 140m overall length and will be equipped with 96 containerised marine batteries, providing a total capacity of 241MWh.
The onboard battery system is based on Power X’s proprietary module design, featuring lithium iron phosphate (LFP) battery cells that ensure a lifespan of over 6,000 cycles. Additionally, the battery system is scalable, allowing for the installation of additional batteries to create larger electric transport vessels to meet specific mission requirements. The system includes dedicated gas emission control and fire suppression mechanisms to ensure safety. Real-time monitoring of the battery system, charging controllers, and power conversion systems further enhance safety measures. All batteries will be manufactured in-house in Okayama Prefecture and are scheduled to obtain international ship classification certifications and applicable standards such as DNV and Class NK, undergoing testing to meet strict conditions. Delivery of the batteries is scheduled to commence by mid-2024.
The onboard battery systems will allow the vessels to store and transport surplus electricity generated from renewable sources. Decommissioned or idle thermal power plants located near ports can be retrofitted into charge/discharge points for the battery tankers, where the power is transmitted to users via grid connections on land, enabling effective use of renewable energy. As areas with high potential for renewable energy generation are often distant from urban areas and regions with high power demand, strengthening of transmission infrastructure will become increasingly important. Given the current energy density of lithium-ion battery cells, the battery tanker is considered an optimal solution for short-distance maritime power transmission from land to land, complementing existing inter-regional grid transmission lines. For instance, in Japan, a battery tanker can carry power from regions with high renewable energy supply potential, such as Kyushu and Hokkaido, to high-demand areas of Honshu or for inter-island power transmission.
Battery tankers could establish new power transmission networks across the sea, promoting renewable energy storage, supply, and utilisation. As the energy density of batteries improves and their cost decreases, it is expected that longer-distance maritime transmission from offshore wind power plants to the land will become feasible. Battery tankers offer a practical solution, especially in Japan, which is prone to earthquakes and has deep-sea surroundings. The ship-based solution resolves issues such as extended downtime from undersea cable malfunctions and repairs and the high costs associated with ultra-high voltage connections and substations. As a result, the battery tankers will enable installation of offshore wind farms in areas where undersea cable deployment has proved challenging. PowerX believes that using maritime power transmission via battery tankers can address various challenges associated with offshore wind power, not only in Japan but also contributing to the widespread adoption of renewable energy worldwide.
