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Fire Suppression for Energy Storage Systems – An Overview

Updated: Jul 13

What is an ESS/BESS?


Energy Storage Systems (ESS) are defined by the ability of a system to store energy using thermal, electro-mechanical or electro-chemical solutions.

Battery Energy Storage Systems (BESS), simply put, are batteries that are big enough to power your business. Examples include power from renewables, like solar and wind, which are stored in a BESS for later use.

Purpose of ESS/BESS

There has been an incredible rise in the number of Energy Storage Systems (ESS) utilizing lithium-ion (Li-ion) batteries in recent years. They are the primary system for wind turbine farms, solar farms and peak shaving facilities where the electrical grid is overburdened and energy supplementation is needed to support peak demands. Because these systems are able to provide reliable, consistent power to facilities like hospitals, data centers and homes, they are becoming more and more widely used. But with newer technologies come newer risks. It is important to understand the uses, benefits, hazards and solutions for fire protection in ESS and BESS so that your people and property are protected.

What Makes Up an ESS Container?

· Container

· Batteries

· BMS (Battery Management System)

· PMS (Power Management System)

· PCS (Power Conditioning System)

· Cooling

· Fire Suppression

ESS Applications

ESS have many useful applications which contribute to the popularity of their use, including:

Supplementing Renewables Solar panels and wind turbines are limited by the fact that they only produce electricity when the sun is out or the wind is blowing. Supplementing these renewable energies with ESS allows users to take advantage of the production of electricity that is generated by ESS when renewable energy sources are not producing electricity.

Peak Shaving ESS allows for cost savings during peak hours of the day when energy is more expensive (thus the name “peak shaving”). Users can draw power from the batteries during these peak times and then allow the batteries to recharge during the lower-cost nighttime hours.

Load Leveling Throughout the cycle of the day, power generation facilities ramp up and down to keep up with the changing demand for electricity. This taxes the system. ESS can help flatten out the demand curve by charging when electrical demand is low and discharging when it is high.

Uninterruptible Power Supply Downtime and interruptions of a power supply can be some of the most disruptive and impactful issues facilities face. ESS can provide an immediate response to power interruptions and are able to keep hospitals, data centers and homes online.

Risks Associated with ESS

The use of Li-ion Batteries can create the potential for a variety of fire protection hazards. While battery safety risks do exist, it is important to remember that energy storage technologies are robust and reliable. Mitigating hazard risk is critical in the safe operation of these systems, and to do that properly understanding each risk is key. For example, thermal runaway, a common hazard in BESS, is a Class B fire. This is not the same as an electrical or Class C Fire. If your fire protection design is for a Class C fire, you may not be prepared for this catastrophic threat. Concentration levels for a Class B fire are different from that of a Class C fire and suppression alone will not stop thermal runaway. So, let’s break down the hazards one at a time.

Thermal Runaway

Thermal runaway describes the rapid, uncontrolled release of heat energy from a battery cell; the battery generates more heat than it can effectively dissipate. The runaway action comes when a single battery cell causes a chain reaction that heats up neighboring cells. Continuous heating up for subsequent cells often results in a battery fire or explosion, which can, in turn, become the ignition source for larger battery fires.

Stranded Energy

Even after being involved in a fire, ESS can still present danger. As with most electrical equipment, there is a shock hazard present. But unique to ESS, there is still energy within the system that can cause risk. Once the terminals are damaged, they are difficult to discharge which can cause risk to those involved in the overhaul. Stranded energy can also cause the reignition of the fire hours or even days later.

Toxic and Flammable Gases

When batteries experience thermal runaway, most often, they create toxic and flammable gases. If the gases do not ignite before the lower explosive limit is reached, it can lead to the creation of an explosive atmosphere inside the ESS room or container.

Deep Seated Fires

Most ESS are usually comprised of batteries that are housed in a protective metal or plastic casing within larger cabinets. While these layers of protection help prevent damage to the system, they can also block water from accessing the seat of the fire. So, large amounts of water are needed to effectively combat the heat generated from ESS fires, and cooling the hottest part of the fire is often difficult.

Accidental Discharge

One of the top risks to ESS include accidental fire suppression system discharges. Depending on the firefighting agent that is used in the system, major operational interruption of the unit will occur. This includes a costly cleanup and potential damage to the equipment.

ESS Fires

Due to the unique pattern of ESS fires, it is critical to understand the process from failure to fire. This helps us to identify opportunities to intervene before disaster strikes. There are four stages or phases of battery failure:

Stage One: Battery Compromise

Stage Two: Off-Gassing

Stage Three: Smoke Production

Stage Four: Fire

Fire can erupt rapidly after the evolution of smoke. On the other hand, the thermal runaway event can continue for hours without any flame production. During the period between smoke and fire, large quantities of flammable vapors and gases are produced and contained in the enclosure creating an explosive atmosphere. Often, ignition occurs, and a fire develops inside the BESS enclosure. Fire inside the enclosure can cause or escalate the speed of a thermal runaway, leading to a devastating and difficult-to-extinguish event.

Real-World ESS Fires

Arizona Public Service in Surprise, Arizona operates a large-scale BESS at their solar array site. After smoke was reported coming from a lithium-ion BESS container, the fire department was called. Three hours later, when fire crews opened the doors to the still-smoking container, an explosion occurred when fresh air mixed with the flammable vapors inside the container. Four firefighters were injured.

Tesla’s 300 MW ”big battery” project on Moorabool, Victoria, Australia on July 230, 2021 suffered a catastrophic fire that burned for four days. This is reported to be the largest such BESS fire in the world to date. There were significant difficulties in extinguishing the fire and the local fire service struggled to manage it. Eventually, they were able to cool surrounding structures and the fire to burned out.

In Seoul, South Korea on April 6, 2021, a BESS installed on a private solar farm caught fire and burned for hours. The damage included the destruction of 140 batteries, structural damage to the plant and seven burned power generation modules. While no injuries were reported, the fire caused over $300,000 in damage.

Direct losses are the most impactful losses to life and property, but indirect losses can include downtime and bad press (which can erode public trust) that can ultimately exceed the loss of damaged property or equipment.

Using the NFPA 855 Code to Evaluate Risk

The NFPA Code 855 should be used to help you know if you can support a catastrophic fire event such as thermal runaway. If you are not prepared, a complete loss of assets can happen. According to the NFPA, you should evaluate the following:

· If the facility is in a remote location or if it is a dedicated use building or a container?

· Should your design include gas detection?

· How does the Local AHJ fit into the discussion?

· Is life safety a factor?

· What is the fire risk with a lithium-ion BESS?

The UL9540a Test Method

Another code that addresses ESS/BESS is the UL9540a that went into effect on July 15, 2022. It includes updates for large-scale fire testing. Results from the UL 9540A Test Method address the following key issues identified by building codes and the fire service:

· BESS installation instructions

· Installation ventilation requirements

· Effectiveness of fire protection (integral or external)

· Fire service strategy and tactics

IFP’s approach for ESS

Thermal Management - Battery Protection

One of the most important aspects of fire safety in ESS is mitigating risk of thermal runaway. So, the earlier in the failure of ESS you can intervene, the more likely you are to limit or remove thermal runaway. IFP has a unique and proprietary solution for ESS. Direct injection is a highly effective thermal management system to combat thermal runaway in lithium batteries. This method works by spraying clean agent or water directly into the offending cell in the battery case, thereby preventing the fire from spreading to other cells. Clean agent or water is stored in the red discharge cylinder. When the system is activated, the fluid moves through the brass pipe network and discharges through specialized nozzles.

Our system is designed to detect a thermal event at it's earliest stage, creating the advantage of getting ahead of fire before it starts. Direct injection works directly at the source of the thermal event.

Modular - Protection

IFP provides an optional secondary framed system that is intended to safeguard the container against fire incidents. This system is an all-in-one fire suppression solution that comes equipped with a cylinder, frame, nozzle, pull station, and control panel. Its factory-wired feature (not including detection wiring), along with its frame design, ensures hassle-free and prompt installation, thereby reducing installation expenses and enhancing peace of mind.

Micro System - PCM Protection / Other

It is crucial to bear in mind that the ESS (Energy Storage System) unit comprises various electronic components, aside from the batteries themselves. To effectively utilize their stored energy, the batteries require conditioning through the use of an inverter. Our micro fire suppression system presents a viable solution to safeguard these cabinets. One of its notable advantages is its ability to function without reliance on electricity. Instead, it operates by utilizing pressurized detection tubing. When a fire occurs, the tubing detects the heat and melts, leading to the release of pressure and activation of the cylinder discharge.

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