Last week Marine Safety Center engineers Cdr. Sean Brady and Lt. Kate Woods gave presentations on plan review for battery power installations at the Passenger Vessel Association annual MARITRENDS convention and the Pacific Maritime’s forum on Liquefied Natural Gas and alternative fuels. The following is an excerpt from the presentation comments.
As designers and operators are looking to alternative power sources in order to reduce vessel fuel costs or air emissions, battery power is becoming an increasingly attractive option. The Marine Safety Center (MSC) currently has more than a dozen different battery powered vessel designs under review. There is quite a bit of variation among the different proposals, however each faces the same challenge. Any battery powered design submission must demonstrate that the new technology is equivalent to the level of safety afforded by the current regulations.
With the newly affordable, high performing, light weight lithium ion batteries on the market today, many designers and operators are looking toward new hybrid vessel designs, and in some cases even modifying their traditional propulsion systems. Prior to the development of lithium ion batteries for widespread applications in the maritime domain, alternative chemistries did not see much use aboard commercial vessels. Therefore, the current regulations address installations based on traditional lead acid battery design. While these regulations are well developed and appropriate for lead acid battery installations, there are key differences between the technologies described in the regulations and the battery technology that is commercially available today. These differences stem from the chemical make-up of the battery cells, the physical design of the casing or components, and methods for managing the charging/discharging cycle.
The MSC has the authority to evaluate equivalencies to the existing regulations in the absence of specific regulations. To best respond to the rapid innovation in the absence of a comprehensive industry standard for battery installations, MSC has taken a performance based approach to their equivalency reviews. A primary concern with non-traditional battery installation is the risk of thermal runaway and subsequent fires which threaten crew, passengers, cargo and the structural integrity of the vessel. To reduce overall risk, the MSC has identified the need to review designs for preventative controls and mitigation strategies should thermal runaway occur.
Designs should address the following factors:
- Maintenance of the system and emergency procedures in case of failure.
- Battery module design and functionality of the monitoring system.
- Capability of the battery management system to regulate charging and discharging.
- Climate control of the battery compartment and ventilation arrangement.
- Fire detection and suppression capability within the battery space.
- Structural fire protection surrounding the batteries, and emergency electrical isolation.
- Automation testing for the propulsion system where required.
With rapid advances in new battery technology for other transportation sectors, we are likely to see more interest and use in the maritime sector. While there are technical and operational challenges that must be addressed, those who desire to pursue this option have a path forward. We recognize that there is a wide variety of configurations that could address these concerns. We encourage designers, operators or manufacturers who are considering this technology to reach out to the Marine Safety Center and discuss their proposals.
For more information or questions about battery installations on U.S. flag commercial vessels, please contact Lt. Steven Lewis of the Marine Safety Center (Steven.A.Lewis@uscg.mil or 202-795-6775).
This blog is not a replacement or substitute for the formal posting of regulations and updates or existing processes for receiving formal feedback of the same. Links provided on this blog will direct the reader to official source documents, such as the Federal Register, Homeport and the Code of Federal Regulations. These documents remain the official source for regulatory information published by the Coast Guard.