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BATTERY SAFETY AND COMPLIANCE IN BUILDING AND FIRE REGULATIONS
Batteries have greatly influenced the utility industry, but the evolution of battery chemistries has revolutionized their applications. With the emergence of new technologies and advancements in existing ones, standards committees and code writers are working to develop best practices and establish minimum safety guidelines. These groups, comprised of volunteers from diverse industry segments, are actively involved in shaping the standards and model codes that govern battery usage and safety. Their efforts are aimed at keeping pace with the rapidly evolving landscape of battery technology and ensuring its safe and efficient implementation.
Battery Applications
Batteries are used in a variety of applications in Battery Energy Storage (BESS). Below is a list of common applications used in the utility market and how batteries are used to support operations:
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Grid Stabilization: A stronger grid is required with the increased power requirements and demand being placed on the grid. More devices, including automobiles, are demanding more energy. Energy storage may help stabilize the grid by providing energy back to the grid when the demand rises and store energy when excess power is available.
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Renewable Energy: Renewable sources of energy are typically intermittent, and their outputs fluctuate with weather conditions such as with solar and wind. Batteries will store excess energy during periods of high renewable generation and discharge the batteries when generation is low. As a system, this provides a more consistent and reliable source of energy.
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Microgrids and Off-Grid Systems: Batteries help create micro grids that can operate independently from the main power grid. In remote areas together with renewable energies, batteries can provide electricity to communities without access to the central power grid.
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Grid Resilience and Backup Power: Batteries provide backup power during outages and emergencies. This includes substations that have powered switches, SCADA control systems and end users such as data centers, telecommunications companies, and other mission critical infrastructure for organizations.
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Demand Response: Conducted by a utility, batteries can be used where electricity consumers reduce their demand during peak hours in exchange for incentives. This helps reduce peak loads while managing demand fluctuations and alleviate strain on the grid.
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Peak Shaving: Consumers can reduce a consumer’s maximum hourly power requirement. Knowing the load signature of the building and peak intervals, consumers can use batteries to reduce electric charges from peak usage where price per kW is higher to off-peak usage where the price per kW is lower.
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Electric Vehicle Integration: As electric vehicles become more prevalent, EV batteries can be used to store excess renewable energy and discharge it back to the grid during periods of high demand.
Battery Types & Chemistries
Over the years, lead-acid batteries have been the primary choice for utility batteries, enhanced with additives like calcium, antimony, and selenium. These additives were employed to optimize their performance in terms of service life, cycle life, and load profile, specifically tailored for various applications. In environments with demanding conditions, where operating temperatures surpassed the capacity of lead-acid batteries, nickel-cadmium batteries emerged as a crucial solution due to their wider temperature range. However, as the 1990s approached, alternative technologies gained popularity and entered the mainstream. These included lithium-ion batteries, lithium metal polymer batteries, sodium-based (salt) batteries, flow batteries, and other innovative energy storage technologies.
Each battery type contains different chemistries that has proven beneficial for specific applications:
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Lithium Ion and Lithium Metal Polymer Batteries: They include battery chemistries such as Lithium Iron Phosphate (LFP) and Lithium Cobalt Oxide (LCO) which are commonly used in Battery Energy Storage Systems (BESS). They have high energy density, long cycle life and fast response times. Depending on the chemistry, some have higher deflagration potential than others causing fire code to regulate where they can be installed or impose additional site requirements. These batteries are typically used in energy storage applications including grid stabilization, renewable energy, microgrids, demand response, peak shaving, and backup power.
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Flow Batteries: They include chemistries such as Vanadium Redox Flow Batteries (VRFB) and Zinc-Bromine Flow Batteries (ZBFB). Flow batteries have advantages with scalability and long duration energy storage (several hours). They store energy in liquid electrolytes contained in separate tanks allowing decoupling of power and energy capacity. Flow batteries are great in applications for load shifting, frequency regulation, and grid backup power.
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Sodium-Sulfer (NaS) Batteries: They have high energy density and long-life cycle making them a good choice for large-scale energy storage. They operate at high temperatures (~300-340 degrees C) and use molten sodium and sulfur as active materials. They provide high output power and are used in grid-level applications to stabilize frequency, smooth renewable energy output, and provide backup power.
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Lead-Acid Batteries: Lead Acid batteries: Lead Acid Batteries have been used for decades due to low cost, high reliability, availability of materials and they are recyclable. Vented-Lead Acid (VLA) batteries have free flowing electrolyte, long life, and reliable performance. They are used in most substation and emergency power applications. Absorbed Glass Matt (AGM) and gel batteries are considered non-spillable batteries and have long cycle life with a tolerance to deep cycling. These batteries are used in smaller-scale energy storage, load shifting and emergency backup power.
Safety Standards
Every battery type has specific guidelines for installation, operation, and maintenance, which can be found in the manufacturer's installation and operations manual. To ensure consistency and best practices across the industry, the IEEE PES Energy Storage and Stationary Battery Committee (ESSB) develops standards documents that cover the characterization, selection, operation, and recommended practices for batteries. In addition, the NFPA (National Fire Protection Association) produces standards documents that focus on electrical safety in relation to batteries. These standards serve as valuable resources for industry professionals and help promote safe and efficient battery usage.
Building and Fire Codes mandate that batteries undergo testing according to UL standards or other internationally recognized standards. UL 1973 is a safety standard specifically designed for batteries used in electric vehicles (EVs) and hybrid electric vehicles (HEVs). This comprehensive standard covers a range of critical aspects, including electrical, mechanical, thermal, and environmental considerations. Its primary objective is to minimize the potential risks associated with fire, explosions, and other hazards.
In the context of Energy Storage Systems (ESS), including Battery Energy Storage Systems (BESS), UL 9540 and 9540A standards have been developed. UL 9540 is the original standard, while 9540A represents the updated version. These standards outline the requirements and guidelines for safe and efficient ESS operation. Fig 1 provides a visual representation of the specific requirements outlined in these standards. Adhering to these UL standards ensures that battery systems meet the necessary safety criteria and helps mitigate potential risks in various applications.
To ensure consistency and best practices across the industry, the IEEE PES Energy Storage and Stationary Battery Committee (ESSB) develops standards documents that cover the characterization, selection, operation, and recommended practices for batteries. In addition, the NFPA (National Fire Protection Association) produces standards documents that focus on electrical safety in relation to batteries.
Figure 1
While UL standards are recognized across North America, other regions have similar standards such as IEC 62619 and 62485. Other industry specific standards may cover abusive environments such as Telcordia (Bellcore) Testing Standards.
Model Codes
In addition to the UL standards and other international standards, model building codes play a crucial role in ensuring the safety of battery systems. Notably, the International Building Code (IBC) includes provisions for the seismic design of battery racks and cabinets. This ensures that these structures can withstand seismic events and maintain the integrity of the battery systems.
Similarly, model fire codes such as Chapter 12 of the International Fire Code (IFC) and the National Fire Protection Association (NFPA) 855 focus on establishing safety requirements specifically for Battery Energy Storage Systems (BESS). These codes serve as comprehensive guidelines that address various aspects of BESS safety.
These model codes are widely adopted by states and are sometimes supplemented by local municipalities. Local authorities have the flexibility to make state-adopted codes more stringent, although they cannot relax the requirements, resulting in what is known as a local modified code. A notable example is New York City's FDNY B-28 Fire Code, which incorporates additional provisions from the National Fire Protection Association (NFPA) 855 while complying with the city's adopted International Fire Code (IFC).
To further ensure compliance with the codes, most states and local governments establish minimum system sizes to comply with code and set maximum limits for BESS installations. These size requirements and limitations are crucial for meeting code compliance and are often depicted in guidelines such as Figure 2.
Figure 2
Hazardous Mitigation Plan (HMP)
The model fire codes outline essential safety requirements for both safeguarding Battery Energy Storage Systems (BESS) and ensuring the protection of individuals. It is strongly advised to include the items listed in the Battery Safety Requirements table (Fig 3) in your Hazardous Mitigation Plan (HMP) for the battery system. These items encompass the following:
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Identify the hazards: Fire, explosion, chemical risks, electrical hazards, environmental impacts.
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Assess the risk to your site: Identify the consequences to the above risks.
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Safety Measures: Implement safety measures to prevent or mitigate hazards.
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Designing engineering controls to prevent and mitigate hazards.
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Creating the operating procedures
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Develop a training program.
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Assess the fire system for the battery technology.
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Assess the ventilation, gas detection and environmental controls.
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Document the Emergency Response Plan (ERP)
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Document all maintenance activity and inspections.
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Document and communication: Maintain detailed safety inspection records, training sessions, hazards, safety procedures, and emergency response protocols.
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Perform an ongoing improvement plan: Update the site based on codes & standards updates and safety inspection findings.
By adhering to these guidelines and incorporating them into your Hazardous Mitigation Plan, you can enhance the safety and security of your battery system and effectively manage potential risks.
Figure 3
Conclusion
Battery technology has undergone significant advancements since the 1990s, introducing a range of new and exciting chemistries to cater to the increasing demands of the power grid. As these technologies start to materialize in practical applications, ensuring safety becomes crucial for their successful operation. This involves the establishment of safety testing standards and the implementation of site and personal safety protocols. It should be noted that not all battery chemistries are suitable for every application. Therefore, engineers must carefully consider the distinct characteristics, maintenance requirements, and operational prerequisites of each technology before implementation. Additionally, regulatory bodies responsible for enforcing safety measures will adapt model codes to incorporate specific attributes relevant to their respective states or municipalities.
