The Overlooked Threat in BESS Failures: Toxic Gas
Most people associate battery fires with flames and explosions. But the greatest threat from a lithium-ion thermal runaway event is often not the fire; it is what you cannot see or smell.
Toxic gas emissions during battery failure pose serious risks to human health, indoor air quality, and project viability. Yet these emissions are rarely addressed in conventional battery energy storage system (BESS) designs.
This article explores what happens when lithium batteries fail, why the resulting gas is so dangerous, and how EticaAG’s HazGuard system neutralizes this hidden hazard in high-risk BESS applications.
What Is Thermal Runaway and Why Does It Matter?
Thermal runaway is a dangerous chain reaction that begins when one battery cell fails. That single failure can produce enough heat to ignite the neighboring cells, triggering a cascading effect across the entire system.
Here’s what typically happens:
- Heat builds up inside a battery due to damage, overcharging, or a short circuit.
- Internal temperatures rise rapidly, sometimes past 800°F.
- The separator and electrolyte inside the cell break down.
- Flammable, pressurized gas vents violently from the cell.
- In many cases, the venting gas ignites, producing fire and flame propagation.
The process is fast and violent. In a containerized BESS, it can unfold in seconds. Fire is the visible threat. But even if there’s no ignition, the gases alone pose a serious hazard.
The Invisible Threat: Toxic Gas Emissions
The gases released during thermal runaway are often odorless and colorless. That makes them especially dangerous in enclosed spaces. While most public concerns focus on flames and explosions, it’s the gases that frequently injure first responders and bystanders or prompt widespread evacuations.
Common emissions include:
- Hydrogen fluoride (HF): Highly corrosive. Exposure can cause deep tissue damage and pulmonary edema. HF also forms hydrofluoric acid on contact with moisture in the lungs.
- Carbon monoxide (CO): Displaces oxygen in the bloodstream. Can be fatal within minutes in high concentrations.
- Hydrogen cyanide (HCN): Extremely toxic even at low levels. Formed from burning plastic or electrolyte compounds.
- Volatile organic compounds (VOCs): Includes flammable hydrocarbons such as methane, ethylene, and butane.
Even lithium iron phosphate (LFP) batteries, often seen as safer, can emit harmful gases during failure. These emissions may not produce visible smoke, but they still cross OSHA, NIOSH, and IDLH exposure thresholds within moments.
A Real-World Example
In the 2019 explosion at the Arizona Public Service McMicken BESS site, four firefighters were seriously injured. The root cause was the accumulation of gases inside the container, which ignited when the door was opened. While fire played a role, it was the buildup of toxic and flammable gas that made the event so dangerous.
Why Most BESS Systems Fail to Address the Gas Problem
Conventional BESS safety designs focus on two things: stopping fire and preventing thermal propagation. Those are critical, but they don’t address the risk of toxic gas.
Typical features include:
- Cell spacing and insulation to slow heat transfer
- Clean-agent fire suppression systems (e.g., Novec 1230, FM-200)
- Ventilation to relieve pressure buildup
None of these neutralize gas. Suppression agents don’t treat emissions. Ventilation just relocates the hazard. And in most systems, there’s no mechanism to prevent harmful gas from entering adjacent rooms, HVAC systems, or surrounding public areas.
This oversight leads to delays during permitting. Increasingly, regulators and fire authorities are asking:
- How is toxic gas being managed?
- What happens to HF and HCN during an event?
- Is this system safe to deploy in schools, hospitals, or residential zones?
Without a good answer, projects face additional scrutiny or get denied.
Introducing HazGuard: The First and Only Neutralization System for Toxic BESS Gases
EticaAG created HazGuard to close the safety gap. It is a gas neutralization system designed for battery thermal runaway scenarios.
HazGuard doesn’t detect gas. It doesn’t just move it. It chemically transforms toxic gases like HF and CO into non-harmful compounds before they leave the container.
How HazGuard Works
- Detection: Thermal sensors recognize a runaway event is occurring.
- Extraction: A custom-built fan system pulls the vented gas through a sealed pathway.
- Neutralization: The gas passes through a multi-stage filter powered by TRAPS, a proprietary physiochemical process that scrubs and converts harmful molecules.
- Exhaust: The treated air exits the container at safe levels, meeting exposure standards for hydrogen fluoride, carbon monoxide, and VOCs.
The entire system is passive and self-contained. No water lines, no suppression agents, and no reliance on site infrastructure.
How HazGuard and LiquidShield Work Together
HazGuard is part of a broader safety architecture built into every EticaAG BESS. It complements EticaAG’s proprietary LiquidShield immersion cooling technology to create a complete thermal runaway response.
LiquidShield eliminates the risk of fire spread by submerging battery cells in a non-flammable cooling liquid. If a single cell enters thermal runaway, LiquidShield prevents ignition and stops adjacent cells from failing.
HazGuard takes the next step by treating any gases released during that failure. Together, they provide protection across the entire failure chain:
- No flame
- No fire propagation
- No toxic gas exposure
This layered approach ensures that both heat and chemical emissions are contained within the system, supporting safe deployment in even the most sensitive environments.
Built for the Projects That Can’t Afford to Compromise
HazGuard is designed for environments where air quality is critical and regulatory scrutiny is high. While it can be used in any setting, it offers the greatest value in indoor, urban, or sensitive locations where toxic gas emissions pose a greater risk to people and operations.
Ideal applications include:
- Indoor battery rooms and mechanical closets
- Dense urban sites with limited evacuation options
- Facilities adjacent to hospitals or schools
- Data centers where uptime and air quality are critical
- Projects requiring AHJ or NFPA 855 compliance
Without HazGuard, these deployments either face project redesigns or outright rejections. With HazGuard, stakeholders can show they’ve mitigated both flame propagation and gas risk.
Why HazGuard Is Different from Anything Else on the Market
The current BESS safety landscape is reactive. Some vendors offer:
- Gas detectors to trigger alarms
- Ventilation systems to dilute air
- Manual interventions for first responders
But none of these solve the problem. They only signal it.
Haz Guard is different. It eliminates the threat at the source.
Because it’s integrated into EticaAG’s immersion-cooled BESS units, HazGuard works in tandem with other protective systems. The immersion liquid stops fire spread, while HazGuard stops gas exposure.
Together, they provide the only complete thermal runaway solution on the market.
Complete Safety Solutions Will Shape the Future of Energy Storage
Energy storage adoption is growing, and so is public awareness and regulatory oversight. In many communities, one high-profile fire is all it takes to trigger a moratorium on future projects.
As a result, project developers, EPCs, and regulators are asking smarter questions:
- What if this system fails in an apartment building?
- Can I permit this system near a nursing home?
- What protections are in place for indoor installations?
EticaAG’s safety architecture provides a credible answer. LiquidShield immersion technology prevents fire and thermal propagation. HazGuard neutralizes the toxic gases that even a single cell failure can release.
Together, they enable BESS projects to move forward, even in the toughest regulatory environments, with full-spectrum protection from thermal runaway.
It’s Time to Address the Risk We Can’t See
While regulators focus on project siting and public safety, many battery storage systems still overlook a critical hazard, airborne toxins released during thermal runaway.
The solution isn’t just better alarms or ventilation. It’s chemical neutralization of harmful emissions before they harm people, compromise infrastructure, or stall project approvals.
EticaAG is addressing the full risk spectrum. LiquidShield immersion technology stops fire spread at the cell level. HazGuard goes further, neutralizing toxic gases in real time to protect indoor air and public safety.
Together, they form the industry’s most complete thermal runaway protection system.
At EticaAG, safety means more than extinguishing a fire. It means clean air. It means community trust. And it means giving project teams the confidence to move forward, no matter the permitting environment.
No flame. No propagation. No toxic gas.
Learn how HazGuard fits into your next project at eticaag.com/hazguard.
