September 14, 2021

Effective BESS Fire Safety Design Update

Parker Lohrenz, Lead Electrical Engineer, Black & Veatch

This is a guest blog post from Black & Veatch. Connect with Black & Veatch at #ESACon21 in Phoenix, AZ, December 1-3. Registration is open!

What are Safety Concerns?

Safety is a core concern in the power industry. The protection of workers and the public is paramount. Equipment and the surrounding facility must be safeguarded. As battery energy storage systems (BESS) transition from a miniscule presence on the grid five years ago to the most common new storage solution today, safety must always be at the forefront.

Handle BESS fire safety issues by understanding the following:

  • Codes: BESS is evolving rapidly. Complying with the most recent codes is necessary yet insufficient. Code bodies react to events not otherwise envisioned by the published code, and those bodies plan updates on a multiyear cycle. Meanwhile, supplier and contractor innovations are rapid. Projects can end up with outdated solutions if guidance is based only on published codes.

Often, alternative approaches can address risks associated with new technology. Code coverage may provide solutions that do not match new risks. BESS owners must ask themselves “Which is the most appropriate way to mitigate each risk, given the site and technology?”

  • Design: Ineffective mitigations can result in either excessive property damage and/or safety and hazard issues. The resulting impacts can be costly with project owners left to determine what may be a better design compared with what may get approved.

Steps to Attain Safe Operations

To attain safe operations, understand the context of relevant codes as well as the industry’s equipment offerings. Safety at a BESS site goes beyond mere compliance. It requires making considered decisions, thoughtfully incorporating industry lessons-learned.

Some of the questions to resolve for effective and efficient fire protection are in the planning phase:

  • How will this design decision affect the long-term safety of the project?
  • What is the most efficient way to reduce risk to attain safety?

A thorough review of specifications and design can help answer these questions to ensure safe operation.

Design and Specification Review Checklist

The Underwriter Laboratories (UL) 9540A Test Method for Fire Propagation in BESS produces data for understanding the safety requirements of the battery chemistry and its enclosure. Additional consideration of site and equipment specifications will help ensure an appropriate fire protection design.

Consideration of the following can improve design, attain cost savings, and avoid unnecessary requirements.

  • Battery chemistry: Lithium Ferrous Phosphate (LFP) batteries have a reduced risk and avoid fire propagation due to the battery chemistry, as demonstrated by the UL9540A test method at the cell, module, and unit level.
  • Liquid-cooled battery modules: Liquid cooling of battery modules is more effective than air-cooling. The cooling is directed to the batteries themselves more effectively and more efficiently than what air-cooling can achieve.
  • Fire Prevention measures: Preventative measures increase safety by providing early warning and giving time to shut the system down before an event ensues. Other sensors, such as heat and smoke sensors, detect only after an event happens, too late to safely shut down.
  • Fire Suppression: Design selection can eliminate oxygen (clean agent) or remove flammable gasses (ventilation) and/or provide water deluge of the subject container.
  • Enclosure designs: Enclosure design evolution now favors containers with exterior access that need not be occupied even by workers, which results in containers with far less interior free space. Recently smaller, modular cabinet designs are available from BESS suppliers. These factory-built cabinets balance increased equipment cost and better quality against lower site construction costs.

The reinforced cabinet design lowers the probability of a catastrophic event that would impact nearby personnel or equipment. This approach also modularizes the BESS such that the individual failure of a single rack or cabinet affects a small portion of the overall system.

  • Redundancy: It is important to understand the benefits and risks of redundancies and mitigation measures to determine what adds value and what is unnecessary. For instance, BESS must have auxiliary power source redundancies to maintain operations to support the following:
  • Controls for energy management system (EMS) and battery management system (BMS).
  • Electrical Protection Equipment controls.
  • Cooling equipment to maintain the battery supplier’s temperature specification.

Selecting an Owner’s Engineer (OE) or EPC Contractor

Should you be lacking energy storage expertise in your organization, be sure to select an OE or EPC who knows the strengths and weaknesses of industry practices. In just a few months – from bid stage to project start – knowledge can become outdated. Selecting a company with relevant project experience and demonstrated current knowledge would assist you in making appropriate decisions.

The earlier you think about safety, the better and more effective you can be with fire protection design. Work with someone who provides safety collaboration throughout the process.

In summary, know the risks, understand the risks, and plan for risks with effective mitigation strategies.

About the author, Parker Lohrenz: Parker is a Lead Electrical Engineer within Black & Veatch’s global Power business. He has managed and executed all aspects of electrical design, specification development, equipment procurement, and contract administration on energy storage, wind, and solar projects. He specializes in the electrical models required for collection system design, field quality assurance, and SCADA commissioning and testing. Parker has been involved in the design and construction of over 30 battery energy storage, wind, or solar projects, totaling nearly 4,000 megawatts across North America. 

ESA Note: Refer to the ESA Member Whitepaper “Operational Risk Management in the U.S. Energy Storage Industry: Lithium-Ion Fire and Thermal Event Safety,” a product of ESA’s Corporate Responsibility Initiative for more information.

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