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A Study on Safety Assessment Regarding Battery Fire and Explosion Risks for the Application of Battery Energy Storage Systems (BESS) to Ships-배터리 에너지 저장시스템(BESS)의 선박 적용을 위한 배터리 화재·폭발 안전성 평가에 관한 연구
Abstract
Due to the International Maritime Organization's (IMO) tightened environmental regulations, ship propulsion systems are shifting toward eco-friendly technologies, leading to the expanded adoption of Battery Energy Storage Systems (BESS). Shipboard BESS are implemented for purposes such as propulsion assistance, peak load shaving, and energy efficiency improvement; they operate through the integration of various components, including battery cells, Battery Management Systems (BMS), Power Conversion Systems (PCS), and Energy Management Systems (EMS). In particular, Lithium-ion batteries (LIBs) are widely adopted as the core component of BESS due to their excellent characteristics, such as high energy density, long lifespan, and high charge/discharge efficiency. However, because LIBs contain flammable electrolytes, they pose potential risks of fire or explosion in the event of abnormal conditions—such as external impact, internal short circuits, or thermal runaway. These characteristics, combined with the confined spaces, enclosed structures, and limited external firefighting support inherent to ships, make ensuring the fire and explosion safety of BESS a critical technical challenge. Currently, however, most domestic and international classification society regulations are based on land-based IEC standards, with a lack of safety testing criteria that reflect the unique operational environment of ships. Therefore, this study comprehensively evaluated the safety of shipboard BESS—considering their actual operational environment—by conducting safety tests at the cell and module levels under mechanical and thermal abuse conditions, testing for secondary explosions caused by thermal runaway and off-gassing, and assessing a targeted fire suppression system designed for initial fire response. Through this work, the study aims to propose safety measures tailored to the marine environment and provide foundational data for future regulatory improvements. In this study, domestic and international standards were analyzed to ensure the safety of marine battery energy storage systems (BESS), and empirical tests were conducted based on high-risk test items covering mechanical, thermal, and electrical abuse conditions. Evaluations of durability against high temperatures, impact, vibration, and crushing—conducted across various battery types and states of charge—revealed distinct characteristics for each cell type while confirming overall high safety levels. Furthermore, to overcome the limitations of conventional visual inspections, a new evaluation framework incorporating a 48-hour stabilization period and voltage monitoring techniques was proposed; this enables the quantitative diagnosis of subtle damage or performance degradation not visible to the naked eye. These findings underscore the necessity of establishing battery safety evaluation standards optimized for the unique operational conditions of ships and are expected to serve as practical foundational data for future improvements to relevant regulations and testing guidelines.
Secondly, the study assessed the risk of secondary explosions caused by off-gas generated during thermal runaway in marine BESS installation areas and quantitatively analyzed the structural integrity of fire-resistant bulkheads. To this end, cell-level thermal runaway tests were conducted to identify the primary flammable components of the off-gas, and explosion tests using mixed gases experimentally verified the explosive risks associated with the off-gas. Subsequently, based on these results, finite element analysis was performed on an actual vessel to evaluate the structural limit state of the battery room bulkheads. The findings highlighted the necessity of incorporating explosion considerations into effective structural design and ensuring adequate separation distances for battery rooms, providing practical foundational data for future regulatory revisions and the establishment of design standards. Thirdly, considering the difficulty of obtaining external firefighting support during a fire—due to the enclosed structure and spatial constraints of ships—a targeted-injection fire suppression system was proposed for the initial suppression of fires in battery energy storage systems (BESS). To this end, the fire suppression performance of non-aqueous (Novec 1230) and aqueous (F-500) agents was experimentally compared across single- and multi-module configurations. Both agents proved effective in addressing initial thermal runaway; the targeted-injection method, by spraying the agent directly onto the ignition point, effectively prevented fire spread by locally blocking heat release and inhibiting heat transfer. Given the shipboard environment—which necessitates enclosed cabinets and high ingress protection ratings (IP44 or higher)—an internal installation method was found to be more effective than an external supply system. This internal suppression system, integrating thermal runaway detection with targeted injection, could be incorporated into future safety guidelines for marine BESS, contributing to the prevention of reignition and the minimization of structural damage through early-stage fire suppression.
This study employed a multifaceted approach to ensure fire and explosion safety for battery energy storage systems, which are critical components of electric-propulsion ships. Mechanical and thermal abuse tests reflecting actual ship operating conditions were conducted to verify test parameters and the impact of risk factors; additionally, explosion tests were performed to experimentally demonstrate the explosion risks posed by off-gases generated during thermal runaway and to quantitatively assess the associated risk levels. Furthermore, the study experimentally validated the effectiveness of a targeted-injection fire suppression system—optimized for the spatial constraints of ships—in preventing the initial spread of fire, thereby contributing to the development of safety guidelines for shipboard energy systems. The results of this study can serve as an academic and practical foundation for strengthening regulations and technical standards related to the safety assessment of marine batteries.
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