Joint Industry Development of Maritime Battery Safety

The Battery Safety Joint Development Project was established to enable persons assessing energy storage installations, whether from a design, engineering or regulatory perspective, to better evaluate risks, capabilities and solutions with regard to safety. The focus and context are on installations in the maritime environment although most findings will apply to other applications and industries. The project partners consist of stakeholders across the in the maritime industry, from battery suppliers, system integrators, yards, ship owners and authorities. Understanding the behavior of a battery fire and off-gassing has been prioritized, since it is challenging to handle both the risks related to fire and explosion at the same time with the existing mitigating safeguards. Systems and tools are available which are fully capable of handling these risks, but it is necessary to better understand both these risks as well as the tools available so that they may be appropriately selected and implemented. The first objective was quantifying off-gas content related to toxicity and explosion risks. Different test setups can give different results and it was needed both to normalize these inputs and provide characterization of gas contents and quantity that can be used for consistent evaluation of explosion and toxicity risks. Testing was performed at both the cell and module level, for different chemistries and form factors, and under different failure modes. Cell and module testing results were used as input to calibrate Computational Fluid Dynamics (CFD) models of the battery space, which were then used to evaluate a wider range of configurations. These results provide reference and guidance on the amount of ventilation and the effectiveness. In general, the magnitude of potential consequence depends heavily on the number and size of the battery cells expected to be involved in an incident. Ventilation recommendations related to the size of the battery system involved in a fire has been developed. Generally, it is seen that the risks related to heat propagation goes down, while the risks related to increased gas production goes up if oxygen is limited in the battery space or the battery module itself. The battery gas toxicity level, specifications for the explosion proof equipment to be installed in a battery space and gas detection strategies have also been evaluated based on the test results. The second objective was to evaluate the capabilities of various fire suppression and extinguishing media with respect to lithium-ion battery fires. A methodology for comparative tests between different battery fire suppression systems available in the maritime market is proposed. Both heat and gas mitigation performance are evaluated. Each of the systems available has different strengths and weaknesses, and thus different systems may be more effective or necessary depending on the key risks posed by a particular battery arrangement or installation. In general, fire suppression is more effective when deployed early in the fire development and if it can be released into the module. Key factors to evaluate as far as requirements are short term cooling, long term cooling, and gas absorption. The third objective was to develop a Quantitative Risk Assessment (QRA) framework which quantifies the risks involved to an acceptance criterion. Frequencies of failures has been calculated with and without common safeguards to highlight the importance of the protection systems.

Results deliverd in this project will enable persons assessing energy storage installations, whether from a design, engineering or regulatory perspective, to better evaluate risks, capabilities and solutions with regard to safety. The focus and context are on installations in the maritime environment although most findings will apply to other applications and industries. Risks and soulutions related to mitigating safeguards of fire and off-gas will be improved. Soulutions, rules and guidelines related to fire supperssion, ventilation, gas detection and explosion proof equiptment is expected to be affected.

This project will lead to improved safety of the products and services provided by the project participants; including battery cell and system vendors, power system providers, yards, ship owners and charterers, fire detection and extinguishing system providers, and finally classification societies and maritime authorities. This will be accomplished by developing novel approaches for assessing risks and ensuring battery system safety. These aspects will be evaluated by execution of the following tasks: Initial Model Development and Assessment: Existing knowledge and modeling tools will be combined to develop a baseline of competency with regard to the underlying physics and to identify knowledge gaps to provide guidance and efficacy to the project. Lithium Ion Battery Risk Assessment: This activity will consist of assessments of battery failure modes, prevention mechanisms and other barriers to catastrophic top events at the battery level as well as relative to the battery room. Battery Safety Testing Program: Tests will be conducted to answer questions of risk, as well as calibrate models. The testing program will be conducted at the cell level, the module level, and on systems representative of real scenario environment. Battery Safety Simulation and Analysis Tool Development: Based on the results, final tools for efficient lithium ion battery risk assessment in the maritime environment will be developed. Input to Requirements and Rules: Lessons learned and risk assessment methodologies developed will be shaped into input that will be given to future DNV GL class rules and NMA requirements pertaining to battery systems. In addition to these inputs, results will be disseminated through training materials and public presentations. These activities will facilitate the harmonization of approval requirements of maritime battery systems globally and create a green safety competitive advantage for the project participants, the Norwegian maritime industry and NMA.