Entering a new era for battery-powered ships

Battery power is an increasingly popular option for the transportation sector, with electric cars already commonly seen on the roads. Taking to the sea, the marine industry has begun incorporating batteries onboard ships in a bid to limit greenhouse gas (GHG) emissions and advance the energy transition. Over 150 ships are already operating with batteries onboard^[1], with another 100 battery-equipped vessels under construction.

Batteries present a unique raft of opportunities for marine stakeholders. This fast-evolving market can give ship owners a competitive edge, enable shipyards to gain expertise, and open new markets for equipment manufacturers. However, challenges also exist. Key concerns regarding safety, cost, installation and battery lifecycle must be addressed before batteries can be regularly integrated onboard ships.

Moreover, today’s batteries largely serve either as backup power, providing the energy needed for short voyages or for ships sailing closely to populated areas. Batteries are not yet suitable for providing the required power for long voyages, and are mostly found onboard ferries, tugs and other small or specialized vessels.

From LEAD to lithium-ion batteries

LEAD batteries have been the traditional batteries used to provide back-up power to ships, and are subject to longstanding rules for installation and maintenance. Ships may have Vented Lead Acid Batteries or Valve Regulated Lead Acid Batteries onboard; both battery types are common and require fairly low CAPEX investments. LEAD batteries are reliable and recyclable, functioning as backup power systems onboard vessels of all types.

Lithium-ion batteries are the latest evolution of battery power, offering several use cases for ship owners. Lithium-ion batteries can be used as backup power, supporting the operating profile of a ship, including maintaining Dynamic Positioning (DP) systems. They can enable ships to run in zero emissions mode, when batteries temporarily function as the only source of electricity. This limits GHG emissions, enabling ships to comply with strict port requirements and travel in environmentally controlled areas (ECA). Additionally, batteries can be used for “peak shaving”, taking over from onboard generator sets to deliver the peak load of energy.

The challenge of thermal runaway

The primary challenge for battery-powered vessels is the safety issue known as “thermal runaway.” When a battery is subject to high temperatures – either from a high current discharge rate or proximity to external heat sources – it can emit heat, flames and gas. This can cause a chain reaction, creating a large-scale conflagration that can damage vessels and threaten crew.

For this reason, specific rules and standards are used to test batteries^[2], and additional safety measures can be applied, such as Battery Management Systems (BMS). A BMS monitors the voltage, current and temperature of battery modules, packs and sub-packs, and controls the proper connection and disconnection of battery packs and sub-packs. Beyond providing critical safety information, BMS also enable ship operators to optimize energy use and availability, and increase battery lifetime.

Following mandatory battery certification^[3], ship owners and battery manufacturers can opt for voluntary battery notations that assess and limit risk, both for the battery itself and onboard integration. For manufacturers, this includes an evaluation of risk for sensor failure, internal and external short-circuiting and the possibility of gas release. For ship owners, risk analyses are crucial for onboard installation, ventilation, hazardous areas, fluid leakage and more.

Improving batteries across the lifecycle

The first question ship owners and operators face when considering batteries is cost. As of 2016, the price of battery power was $227 USD per kilowatt-hour. While costs are going down, thanks to improved technology and increased competition among manufacturers, many ship owners are holding off on ordering battery-powered vessels, anticipating lower prices.

Once an owner has chosen to install batteries, shipyards are faced with the challenges of onboard integration. Yards must perform comprehensive risk analyses, assessing ventilation systems, hazardous areas and energy storage system spaces, while following regulations for installation that ensure ships can sail safely. Ship designers and construction crews must do the utmost possible to reduce risk and prove to flag authorities that battery-powered ships are safe to dock.

During operations, ships need to recharge their batteries by connecting to the electrical grid at port. For battery-powered ships to minimize emissions, operators will need to ensure that the electricity supplied from the grid comes from renewable sources. Ship managers will need to assess full supply chain accountability in order to achieve completely greener operations. Batteries can also be charged by onboard generator sets, though this energy is not sustainably produced unless ships are using other decarbonized fuels.

Finally, there are the dual questions of extending battery lifecycle and sustainably recycling batteries. Battery capacity decreases naturally with time, and batteries must undergo endurance testing to ensure a certain capacity is maintained^[4]. Once batteries can no longer be used, ship owners must then manage recycling with shipyards, ensuring that the dangerous or polluting elements of batteries are safely handled.

What comes next for battery-powered ships?

Shipyards, designers, and equipment manufacturers all have crucial roles to play in the further development of batteries, propelling the shipping world forward. Shipyards especially have the possibility of being recognized as innovative and competitive by offering new design and concepts for lithium-ion batteries, specializing in future-facing technology.

As more shipyards begin offering battery services, the next big step will be achieving regular integration onboard large vessels. Most battery-powered or hybrid-battery powered ships today are small vessels traveling fixed routes, such as ferries and offshore supply vessels. The marine industry has already seen a handful of projects for battery integration onboard ships like Ponant’s Commandant Charcot and Louis Dreyfus’ Wind of Hope.

Batteries are part of the growing list of solutions for achieving carbon-neutral or zero-emissions shipping. While large ships may never run on batteries alone, batteries remain a strong choice for smaller vessels and can be successfully combined with alternative fuels. Batteries can also be combined with developing fuel cell technology, achieving even higher levels of efficiency and limiting emissions. In this way, batteries can provide an important boost to sustainable shipping, doing their part in developing a GHG-free ecosystem for the marine industry.

Providing support for a greener future

Bureau Veritas provides expertise for all types of batteries and battery-powered ships, with a team of dedicated in-house experts. We work regularly with ship owners, flag authorities and equipment manufacturers to ensure our clients have the best available information and technology for battery solutions. Our experts provide safety testing and risk analysis before battery integration onboard, offering a standardized approach to risk management for both classed and non-classed vessels.  

Bureau Veritas has also created a regulatory framework for battery-powered ships, and we update our rules every six months to reflect the latest technical and safety developments. We currently offer three notations for battery-powered vessels. BATTERY SYSTEM covers the safe installation and use of batteries. ELECTRIC HYBRID is for vessels using a combination of diesel engines and batteries, and our ELECTRIC HYBRID PREPARED notation is for ships designed to have batteries installed in the future.

^[1]https://safety4sea.com/352-confirmed-ships-are-using-battery-installations/
^[2] This includes standards such as IEC62619 and IEC62620, which are commonly applied by manufacturers
^[3]Based on tests determined by the IEC that assess internal short circuit, external short circuit, risk analysis, etc.
^[4]60% battery life after 500 cycles, as per IEC62620