Mitsui O.S.K. Lines (MOL) Ltd organized a private view of its "Emerald Ace" carrier ship for hybrid vehicles at Mitsubishi Heavy Industries (MHI) Ltd's Kobe Shipyard prior to the completion of the construction of the ship (June 29, 2012).
The carrier ship is equipped with the "Hybrid Power Supply System," which was co-developed by MOL, MHI and Panasonic Corp. Specifically, the ship generates electricity by using 160kW of photovoltaic (PV) cells on a voyage and stores it in 2.2MWh of lithium-ion (Li-ion) rechargeable batteries. When the ship is in harbor, the diesel engine generator of the ship is stopped, and the PV cells and the stored electricity are used to supply all the electricity used inside the ship (zero emission).
The carrier ship consists of 12 layers and can carry 6,400 compact cars. On the highest layer (deck), 768 units of the "HIT Double" (output power: 210W), Panasonic's double-sided PV module, are placed.
As for the Li-ion rechargeable batteries, about 320,000 "18650" cylindrical cells are used. The 18650 is normally used for notebook computers and has a diameter of 18mm and a length of 65mm. On the lowest layer (the ship's bottom), 52 battery units are placed. Each unit consists of 20 modules, and each module contains 13 (connected in series) x 24 (connected in parallel) cells.
When discharging electricity, each unit supplies electricity to a DC-DC converter with a 250V DC bus, boosts it to DC700V in the converter, converts it into AC450V (output power: 480kW) with an inverter and supplies the electricity to the inside of the ship. For charging the batteries, AC450V electricity is supplied to the unit, and it is converted to a direct current in the charger of the unit.