Battery-power has become a critical component for a fleet of Black Sea icebreakers, ensuring safe, reliable and continuous operation
Every year, the Azov Sea, a northern extension of the Black Sea, becomes wholly or partially frozen for up to five months. These severe conditions call for a fleet of icebreakers to act as the lead vessels in cargo convoys that export goods from industrial regions across Ukraine and Russia through the Black Sea, the Mediterranean and beyond.
Apart from making the narrow, 4 km-long Strait of Kerch passable, the icebreakers also are essential to Russian sea transport infrastructure. The Azov sea port of Rostov-on-Don is the southern gateway to Russia’s inland waterways that stretch from the Caspian Sea to Moscow and as far as the Baltic Sea. The icebreakers ensure the effective use, maintenance and development of the Azov seaports.
The icebreakers, operated by Russian Federal State Unitary Enterprise Rosmorport, must be available throughout the winter. This is in spite of wind chill that causes very low temperatures and ice thickness that can reach 80 cm, due to the shallowness and low salinity of the Azov Sea.
Rosmorport’s 35-strong icebreaker fleet is the largest in the world and performs 10,000 ice escorts each year. The icebreakers cut various routes through the ice and escort convoys of vessels over distances of up to 210 nautical miles between November and April. To make year-round navigation possible for the Azov, Rostov-on-Don and Taganrog ports, Saft batteries are providing critical engine starting and backup power.
Having supplied nickel technology batteries to shipbuilder Wärtsilä more than 30 years ago, Rosmorport turned to Saft once again to replace batteries for eight of its icebreaking vessels. The longevity of the original batteries is due to their tough industrial construction, coupled with the professionalism and good care of the icebreaker crews.
As the lead vessels in the cargo convoys, the performance of safety equipment such as backup batteries are of vital importance. Apart from supplying critical startup and backup power, the batteries must be able to perform reliably in extremely low temperatures, as well as withstanding the shock and vibration of icebreaking and storm conditions.
Temperature is an important factor when designing batteries because chemical reactions are driven by voltage and temperature – the colder a battery, the slower the chemical reaction and vice versa. In extremely low temperatures such as those experienced in the Azov Sea,
batteries must often be uprated to ensure that they are capable of delivering the energy to start a large diesel engine or to power safety-critical equipment. The technique of uprating is calculated by the battery’s de-rating factor, which depends on the electrochemistry of the battery.
Lead-acid batteries have a relatively large de-rating factor, which means they would need significant oversizing to tolerate cold environments. In addition, there is the danger of the electrolyte freezing as the electrolyte’s chemical composition has a similar freezing point to water when the batteries are fully charged. In turn, this can crack the enclosure.
Nickel batteries have a smaller de-rating requirement compared to lead-acid batteries at low temperatures. This attribute means they require less oversizing and, as a result, less capacity needs to be installed.
Because of their construction and materials, these batteries are exceptionally robust, and exempt from risk of sudden failure. And they can be made with very thin electrodes to enable high discharge currents needed for engine starting.
One challenge that presented itself during installation of these components was the limited space onboard the icebreakers. In the 30 years since the original batteries were installed, Saft’s approach to battery design has evolved. As such, the size and shape of the new batteries are somewhat different to the originals and could not be installed in the same footprint as the existing batteries. Experts from Saft’s Moscow office worked closely with the technical crews on the icebreakers at an early stage to identify alternative locations for the batteries.
To deliver cranking power for starting the diesel engines, Saft supplied its new generation nickel technology SBH batteries. Each ship has several diesel generators for different purposes, these include an auxiliary power generator, a harbour generator (which is used to supply power when the icebreakers are in port) and emergency power generators.
SBH batteries function in a wide range of temperatures, and resist electrical abuse, shock and vibrations so are ideal for starting applications offshore. Maintenance costs are low and there’s no need for water for up to 10 years. The batteries have a long lifetime of over 20 years.
Backup power for radio communication, navigation and emergency lighting systems (including navigation lights and lighting for crew members) came in the shape of Saft’s SBM batteries. These block batteries are constructed from robust Nickel pocket plate technology, which resist electrical abuse, as well as mechanical shock and vibration in extreme weather conditions (from - 20°C to + 50°C). They are designed to sustain electrical loads for between 15 minutes to two hours, including ‘mixed’ loads with fluctuating discharge rates. The batteries require only basic maintenance and have a long-service life of 20 years or more.
In support of its approach to sustainability, Saft makes a significant proportion of its nickel batteries from recycled batteries in its own facility in Sweden. By working with the Federal State Unitary Enterprise Rosmorport to find a solution to the critical running of their icebreakers, Saft was able to make a meaningful contribution to strategically important operations.
Battery technology will be discussed at the Maritime Hybrid & Electric Conference, Singapore, 27-28 May. Book your place now.