Prospects for battery power are positive

Not just the realm of Norwegian ferries, many shipowners are looking to benefit from the increased energy efficiency they provide as part of a hybrid propulsion system.

“Wherever you can use batteries, it’s better than, for instance, electro-fuels, because the energy efficiency is much higher,” he says. “You get almost the same energy out of a battery that you put in. In contrast, if we are talking about hydrogen, ammonia or methanol, you put in one euro and you get back 20 cents.”

Mjøs also highlights the excellent safety record of the systems. There hasn’t been serious accidents, he says, because system providers and class are taking safety very seriously. Thermal runaway, for example, is prevented by design: it must be able to be stopped at the battery module level.

Back in 2020, DNV released a report on battery safety prepared in collaboration with the Norwegian, Danish and US maritime authorities, battery manufacturers, system integrators, suppliers of fire extinguishing systems, shipyards and shipowners. The report’s recommendations included research-based ventilation system design requirements that stipulate the appropriate size and type of system based on a vessel’s battery installation.

Julien Boulland, Global market leader for sustainable shipping, Bureau Veritas Marine & Offshore, notes that as per BV rules, batteries must be subjected to a series of tests to measure their tolerance and the point where they would enter thermal runaway. “Those tests are rigorous and comprehensive for the series, including external short circuit, impact, crush, drop test, thermal abuse, overcharge, forced discharge.”

With fast-paced technology development, some battery chemistries that were previously considered less safe are now recognised as safe, due to better temperature control, for example. As a result, more and more chemistries are considered.

“Battery chemistry is an area under constant development, and these new types of batteries (such as solid state, lithium sulfur, etc.) will definitely provide benefits to the shipping industry, provided they pass the rigorous tests.”

Mejdi Kammoun, ABS, Principal Engineer, Corporate Technology, says more designers and operators and taking an interest in fully-electric vessels using high-efficiency energy storage as the main power source onboard. He says new technologies including metal-air batteries, REDOX flow batteries, sodium metal chloride batteries and solid state batteries have the potential to replace the liquid electrolyte used in lithium-ion batteries, and in the process offer increased energy density and reduced risk.

Solid state batteries, for example, have solid electrolytes that are not prone to thermal runaway, and they are being tested with several different electrode and electrolyte materials, with lithium metal being a popular anode due to its high energy density.

These various new chemistries are in different stages of research, he says, but they hold the potential for battery systems to become more practical and widespread in maritime applications in the future as the maritime industry further electrifies.

“These new battery designs are currently undergoing fine-tuning at the prototype stage for various components such as battery cells, modules, packs, and battery management systems before entering mass production. We estimate that with the necessary testing, production and regulatory process, these new technologies could be widely available for marine applications by 2030.”

It is possible that new battery technologies may initially be more expensive than current Lithium-ion batteries due to the development of new materials and the need to scale up production. However, as the technology matures and production scales up, costs are expected to decrease over time. Additionally, some new battery technologies such as, sodium-metal, REDOX flow batteries and metal air batteries have the potential to significantly reduce the production cost by using abundant material in their designs. ABS recently agreed a sponsorship program with Texas A&M Engineering Experiment Station to research topics including vessel electrification using battery technology to underscore and broaden its own research efforts.

“Together, these new technologies are a potential game changer in the application of batteries at sea,” says Kammoun. “By combining the advantages of longer lifespan, greatly improved energy capacity and an improved safety profile, they have the potential to accelerate the energy transition in the maritime industry, supporting shipping’s global decarbonization goals.”