by John Snyder
With battery-hybrid and electric propulsion growing in the OSV market, a DNV GL workshop provides a valuable forum for examining lithium-ion battery technology
Advances in storage technology combined with a focus on energy efficiency and emissions reduction continue to drive the application of battery-hybrid and electric propulsion in offshore support vessels and shipping as a whole. A small fire and secondary explosion on board a Norwegian battery-hybrid ferry in October, however, raised concerns about the safety of lithium-ion batteries.
Whether used on their own or paired with an alternative fuel, batteries are likely to play a prominent role in shipping’s future. Close to 250 battery-hybrid and electric vessels are now in operation and another 202 are under construction or on order. There are 43 offshore vessels with battery-hybrid or electric propulsion and another 28 under construction or on order, according to class society DNV GL.
With some of the first installations in Norway, DNV GL has been a leader in developing guidelines and rules for maritime battery-hybrid and electric applications. That is why it is no surprise that the fire on board the non-classed car ferry Ytterøyningen was central to the agenda at the third annual Maritime Battery Workshop at DNV GL’s Houston headquarters in February. The event drew about 140 participants from across the industry.
During the workshop, energy storage system (ESS) manufacturer Corvus Energy joined the Norwegian Maritime Authority and DNV GL in discussing the car ferry fire.
“The use of batteries on board offers a lot of opportunity for reduced emissions, reduced costs, and increased operational integrity,” says DNV GL global OSV segment director Arnstein Eknes. “However, like so much in our industry, there may be serious consequences when things go wrong,” Mr Eknes cautions. “We need to share more and educate each other. With more knowledge, more well-informed decisions are made, and individuals are better prepared to face the challenges that exist, and in turn, do their job more efficiently and effectively.”
DNV GL maritime technology and LNG business development director Anthony Teo, organiser of the event, adds, “With so many vessels operating now, we can really dig into the critical learnings, which is important with even more vessels utilising electricity in the future.”
Initial results from a preliminary investigation released by Corvus in conjunction with authorities indicate the probable cause of the fire was a small leak of coolant in the liquid-cooled energy storage system. The leakage of the ethylene glycol-water mixture created arcing between electrical components, igniting a fire and caused external heating of the battery modules.
“Safety is a joint industry effort,” says Corvus Energy executive vice president, sales and marketing Halvard Hauso, “and you need all of the stakeholders involved. Everyone from the battery manufacturer, shipowner, designer, regulator and class to the shipbuilder, flag state, government and fire department.”
As a result of the incident, Mr Hauso says Corvus was going to take greater responsibility in the form of recommendations for battery management systems, battery room design and fire suppression equipment.
Built as a diesel-electric ferry in 2006, Ytterøyningen was undergoing conversion to an all-electric vessel. When the fire occurred, the vessel was sailing on its diesel engines only. Once the fire was detected, the ferry was taken back to the dock where passengers were safely disembarked.
Due to ongoing service work, no part of the battery system was connected to the shipside systems at the time of the incident on Ytterøyningen. Consequently, no alarms from the battery system were sent through the ship’s alarm system.
“In this incident, the battery management system (BMS) was switched off,” says Mr Hauso. “If it is switched off, it cannot provide the information on what is happening in the system and modules.”
Mr Hauso says Corvus recommends the BMS should always be on, even if the battery is not being charged or discharged.
Both the ferry’s inert gas system and saltwater fire sprinkler system were deployed during the incident.
He points out that fire suppression equipment must match the type of battery. In the case of its Orca model, which was used on Ytterøyningen, Mr Hauso says a water-mist system would have had the best cooling effect, with an inert gas system as a secondary system. For its Dolphin ESS model, he says it would be just the opposite.
After the ferry was monitored overnight by firefighters, a secondary explosion occurred which is still under investigation by authorities.
Report on battery risks
In January, DNV GL released a report on battery safety in ships, assessing the explosion and fire risks in maritime battery installations and the effectiveness of fire extinguishing systems in the event of a battery fire.
Launched two years ago, the report, Technical Reference for Li-ion Battery Explosion Risk and Fire Suppression, was developed through the Maritime Battery Joint Development Project, a collaboration between Norwegian, Danish and US maritime authorities, battery manufacturers, system integrators, fire extinguishing system suppliers, shipyards and shipowners.
Battery fires can burn extremely hot, producing toxic and explosive gases. The report details the results of research on battery compartment fires and the usefulness of various extinguishing systems in combating the fire and preventing explosions.
One of the key findings was the role of ventilation systems in removing an accumulation of explosive gases in battery fires.
Early fire and gas detection are also essential, says the report.
Groundbreaking refits in US
In the US, Harvey Gulf International Marine (HGIM) is breaking new ground by refitting battery systems on two dual-fuel platform supply vessels (PSVs).
Discussing the ‘tri-fuel vessels’ with Offshore Support Journal, ABS director offshore, offshore support vessel lead Dr Wei Huang explains the benefits of the refit. “Harvey Energy will become the first ABS-classed dual-fuel and battery vessel and the first US-flagged OSV equipped with a battery-converter system,” says Dr Huang.
Harvey Energy and its four sister vessels were the first PSVs built in the US to be powered by LNG. A sixth vessel is under construction at HGIM’s Gulf Coast Shipyard Group in Gulfport, Mississippi. Power for each of the PSVs is supplied by three Wärtsilä 6L34DF dual-fuel gensets providing 7,530 kW, with fuelling provided by Wärtsilä’s LNGPac system.
Harvey Energy and one of its sister vessels, either Harvey Supporter or Harvey Champion, will be refitted with an ESS, energy management system, transformer and drive, all mounted in a single container.
Wärtsilä has been selected by HGIM to supply the equipment for the refit of Harvey Energy, while GE will furnish its ESS for either Harvey Supporter or Harvey Champion.
All of HGIM’s LNG-fuelled PSVs are expected to be fitted with battery-hybrid technology, according to Dr Huang.
“The battery installation, which is expected to achieve the ABS class notation ESS-LiBATTERY, will significantly enhance the efficiency and environmental performance of the vessels,” she says.
HGIM anticipates the installation of a Wärtsilä 1,450-kW battery-hybrid solution will significantly reduce Harvey Energy’s exhaust emissions, fuel consumption, and noise level. Overall fuel cost savings are projected in the range of 10 to 20%, according to HGIM. Using battery power to sail in and out of harbour will reduce engine usage, while also supplementing hotel load electricity when docked. As a result, noise and pollution levels are expected to be reduced during harbour operations. Furthermore, the ability to operate on battery power will assist redundancy during DP operations at the offshore platform.