Home | Contact ST  
Follow ST

Feature Article

The Marine Hybrid Battery is Here
Corvus Energy Develops a Greener Power Solution for Vessels


Grant Brown

The Østensjø Edda Ferd, a 926-meter platform supply vessel, currently in service with Shell UK.
In 2009, Corvus Energy (Richmond, Canada) began working on a next-generation battery to provide energy storage for commercial marine propulsion. In the five years since, the company has defined a new industry and built itself into a market leader.

Mention the word 'hybrid' and people immediately think of the Toyota Prius; the not-so-attractive economy car preferred by coffee-house enthusiasts around the world. Most people don't think of offshore supply vessels in winter storms in the North Sea, tugboats safely escorting chemical tankers through busy ports, or 700-foot-long passenger ferries running on a near 24-hours-a-day schedule, day in and day out.

But Corvus Energy does, and these vessels are the reason they designed the award-winning industrial lithium battery used in most commercial hybrid vessels on the water today.

In 2009, the founders of Corvus Energy saw a significant need for high-power energy storage. The world was in the midst of a global economic crisis, and companies were reeling from increasing fuel costs. In the years leading up to the crisis, marine environmental laws had been strengthened and the shipping industry was facing increasing pressure to cut emissions. It was, in fact, the perfect storm to create the hybrid vessel. The Foss-owned Carolyn Dorothy, a newly refit hybrid tugboat, had just launched and became a successful demonstration of a hybrid system at work. Using a lead-acid battery weighing about 18,000 pounds, it was able to achieve a 25 percent fuel reduction, a 25 percent carbon dioxide reduction and a 75 percent reduction in particulate emissions. The only weak point was the batteries; it went through so many that it was spending more time running on diesel than as a hybrid.

The Carolyn Dorothy was proof that a hybrid tugboat could work to reduce emissions and save money—a better 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 refined 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 resulting battery is a tough, smart and powerful product for the hybrid marine marketplace.

Technology Design
The Corvus Energy solution is based on the AT6500 lithium-polymer energy storage module. At 6.5 kilowatt-hours per unit and only 70 kilograms, its modular format allows great flexibility 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 ability 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 right from the beginning. The Corvus systems have four levels 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 W'rtsil' (Helsinki, Finland) 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 first 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 profitability, human life and potential 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 application, such as a commercial vessel, are extreme and will destroy any equipment that is not designed and built to a commercial marine rating. The Corvus AT6500 has been designed and validated to withstand a 4G five-axis continuous vibration and a 50G impact. It is waterproof, meeting or exceeding IP67 submersion ratings. Further, unlike other brands of batteries, the unit is thermally efficient, meaning that, in most cases, it requires no cooling system and is able to operate with full performance in temperature extremes that would destroy 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 system 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 first, 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 distinctive abilities is their involvement with Norwegian workboat fleet owner Østensjø Rederi (Haugesund, Norway). Specifically, Corvus has supplied a lithium energy storage system for the fleet'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 flexibility,' said Johannes Østensjø, owner of Østensjø Rederi. 'Corvus's engineering support has been outstanding, and we look forward to growing this supplier relationship.' To continue this article please click here.

Grant Brown is the vice president for global marketing at Corvus Energy. He has been connecting people and products for more than 20 years. One of the original six members of the Corvus Energy management team, Brown's passion is to make the world a better place. This passion, combined with innovative ability to harness the power of modern technology, has helped drive Corvus Energy to the forefront in the new world of sustainable capitalism and increase the bottom line for customers.

-back to top-

-back to to Features Index-

Sea Technology is read worldwide in more than 110 countries by management, engineers, scientists and technical personnel working in industry, government and educational research institutions. Readers are involved with oceanographic research, fisheries management, offshore oil and gas exploration and production, undersea defense including antisubmarine warfare, ocean mining and commercial diving.