Overpressure Protection of Battery Energy Storage Systems (BESS)

Increased awareness of sustainable development objectives is encouraging the uptake of different energy storage media. Technologies are also now rapidly developing to a point where they can be a practicable alternative to combustion engines for public and private modes of transport. Lithium-ion (Li-ion) batteries are one technology widely used to meet those targets, for use in electric vehicles and energy storage installations. There is competition to improve battery and system performance by increasing energy capacity, improving the battery lifespan, and investing in battery management systems. This competition is driving the increase in Li-ion batteries (LIBs) production volumes, with current estimates in the range of a few million tonnes per year to the equivalent of 130-225 GWh/y with the aim to de-carbonise society and meet the sustainability targets described in the UN Sustainable Development Goals.

As outlined in the US Department of Energy’s national energy blueprint, Li-ion batteries accounted for 98% of the commissioned stationary storage facilities (battery energy storage systems). This plan focuses on higher cell production in the US, enhancing and supporting supply chains, and funding additional research into new battery technology.

There are various types of energy storage systems based on application. The use of Battery Energy Storage Systems (BESS) is gaining traction in the US market because they have high energy densities and can store large quantities of energy within a small footprint 90-190 Wh/kg depending on the cell type.

BESS are also gaining wide use to support decarbonization, integrating a diverse group of energy resources to meet energy demand created by urban populations and economic growth. To meet both objectives, the energy supply needs to be balanced and reliable. With the variety of energy sources such as wind and solar, changes in weather conditions, energy supplies to local populations may not be reliable. BESS systems provide a mechanism in which energy can be stored and supplied during peak periods if the greener energy systems are unable to meet peak energy demands at different times.

BESS systems are now increasingly utilized by regional grid operators, as shown in Figure 2. With greater production and application of Li-ion BESS, the inherent hazards are more apparent with more frequent use. This white paper will explore the mechanics of deflagrations that can occur during a thermal runaway event in a BESS and methods for sizing deflagration vents to protect against such explosions in elongated geometries. Our software Process Safety Office^® SuperChems™ can adequately size blast panels to reduce the impact of deflagration on the storage system structure by incorporating venting dynamics, burning rate models, defining hot spots, and representing blockages in the geometry.