Safe explosion venting of Battery Energy Storage Systems (BESS)
Lithium-ion batteries contain electrolytes that can create off gases in the surroundings, if the battery undergoes thermal or mechanical abuse. These off gases typically contain high amounts of combustible gases such as hydrogen and various hydrocarbons. If the battery racks are located in an enclosed space (such as a container), ignition and combustion of these combustible gases can lead to an explosion that can be detrimental if insufficient explosion protection devices are installed.
The battery off-gases can contain high amounts of Hydrogen, resulting in a high burning velocities which can lead to very steep pressure rises if vent panel size, location and design are not optimized. A second challenge that comes with the BESS protection is the geometry of the internals. Conventional explosion protection often involves empty vessels and containers. In the case of BESS the battery racks often cover a large portion of the volume and the simple theory of spherical flame propagation is no longer applicable.
This session covers design best practices for explosion protection with vent panels for battery energy storage systems, based on the results of combustion modeling. The impact of vent panel size on the opening behavior of the panel is discussed. Different vent panel masses (e.g. with and without insulation) are compared and the impact on the opening delay evaluated. The difference between venting burnt and unburnt gas is addressed and resulting recommendations on vent panel location is discussed. Obstructions near the vent panel reduce the efficiency of the vent panel which leads to an increased pressure build up. Different obstructions are evaluated and their impact on the maximum pressure (pred) is given.