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20 st / July 2014 www.sea-technology.com right from the beginning. The Corvus systems have four lev- els of safety starting at the DC bus and ending at 24 failsafe fuses, one on each cell in the core of the battery. Quality and safety go hand in hand; when Wärtsilä (Helsinki, Fin- land) conducted an audit of the Corvus production systems, they awarded Corvus a score only two points off the best ever score, and more than 20 points higher than their best ever frst audit on a new supplier. Not only is the battery extremely safe and adaptable, it is also designed and built to be very rugged. When a work boat's proftability, human life and po- tential damage to the environment are at stake, the Corvus system must do its job day in and day out without any interruption in service. The rigors of working in a heavy industrial applica- tion, such as a commercial vessel, are extreme and will destroy any equipment that is not de- signed and built to a commercial marine rating. The Corvus AT6500 has been designed and vali- dated to withstand a 4G fve-axis continuous vi- bration and a 50G impact. It is waterproof, meeting or exceeding IP67 sub- mersion ratings. Further, unlike other brands of bat- teries, the unit is thermally effcient, meaning that, in most cases, it requires no cooling system and is able to operate with full per- formance in temperature extremes that would de- stroy a lesser technology. The battery has also been built as a smart unit; each module contains its own computer. This computer is part of the battery management system (BMS). The BMS monitors the energy going in and out of the sys- tem and a variety of other data points, with two end goals: increasing system lifespan and providing controlled shut down should the need ever occur. The complete Corvus Energy system has been tested and validated and, as an industry frst, is the only energy storage system to have obtained type approval from the American Bureau of Shipping (Houston, Texas), DNV (Høvik, Norway) and Lloyd's Register (London, England). Østensjø's Edda Ferd—Hybrid Offshore Supply Vessel One notable example that demonstrates Corvus's distinc- tive abilities is their involvement with Norwegian workboat feet owner Østensjø Rederi (Haugesund, Norway). Specif- cally, Corvus has supplied a lithium energy storage system for the feet's newest vessel, Edda Ferd. The new platform supply vessel (PSV) will be used to support oil rig operations in the North Sea and features the latest in technology and environmental standards. "Our internal tests have been impressive, with quick charge rates and superior fexibility," said Johannes Østen- sjø, owner of Østensjø Rederi. "Corvus's engineering sup- port has been outstanding, and we look forward to growing this supplier relationship." Corvus's AT6500 modules are ideally suited as the build- ing block for a vessel's marine hybrid propulsion needs. Based on the standard 8D format that is recognized and battery was all that was needed. Corvus Energy founders saw the opportunity and jumped to action. During the next three years, a battery was developed and refned to provide all the attributes required for a heavy industrial application like a tugboat: waterproof, impact and vibration resistant, capable of high power charge and discharge rates, and able to communicate with the system it is powering. The result- ing battery is a tough, smart and powerful product for the hybrid marine marketplace. Technology Design The Corvus Energy solution is based on the AT6500 lith- ium-polymer energy storage module. At 6.5 kilowatt-hours per unit and only 70 kilograms, its modular format allows great fexibility when designing an energy storage solution. Corvus Energy is able to use the 48-volt module to design systems up to 1,050 volts with unlimited capacity. This abil- ity to provide a diverse range of solutions for their customers with one proven modular format gives Corvus the advantage of simplifying engineering while reducing production costs, as compared to companies who often build a new battery type for each project. The Corvus solution was designed to provide energy storage to vessels, such as tugboats and passenger ferries. Therefore, the safety of the vessel and crew was the number one criteria and the single most important element of design (Top) The Kotug RT Adriaan, a 28.7-meter har- bor RotorTug, currently in service in the Port of Rotterdam. (Middle) The Scandlines MF Prinsesse Benedikte, a 142-meter passenger ferry, currently in service between Rødby, Denmark, and Putgar- ten, Germany. (Bottom) Fini Hansen, technical superintendent of feet management for Scandlines, discusses battery technol- ogy with Odd Moen, director of sales for Siemens, aboard MF Prinsesse Benedikte.