BESS Problems: Safety, Fire Risks & EOL Solutions | JM Batteries

BESS Thermal Runaway and Safety Risks

The rapid integration of Battery Energy Storage Systems (BESS) into modern electrical grids has established them as critical "adjustment valves" capable of balancing the structural mismatch between electricity supply and demand. By buffering the inherent intermittency of renewable energy sources, stationary storage installations stabilize grid voltage and frequency, manage localized congestion, and prevent the curtailment of clean generation. However, the physical reality of scaling electrochemical energy storage to utility and commercial levels introduces significant technical barriers, primarily centered on battery safety, precise data monitoring, and pack-level cell balancing.

The primary risk associated with lithium-ion BESS installations is thermal runaway, an unchecked, self-sustaining exothermic reaction triggered by mechanical, electrical, or thermal stress. When a cell exceeds its safe operating thermal threshold, the internal separator melts, causing an internal short circuit. This catastrophic failure decomposes the organic electrolyte and active cathode materials, vaporizing the solvent and generating highly flammable, toxic gases under pressure. If these gases are exposed to oxygen or localized hot surfaces, they can cause explosive deflagration.

LFP vs NMC Battery Chemistry Comparison

Maintaining safety over a BESS operational lifetime, which typically exceeds ten years, is exceptionally difficult due to the performance characteristics of mainstream battery chemistries. Many commercial systems utilize Lithium Iron Phosphate (LiFePO4 or LFP) chemistry due to its superior thermal stability compared to Nickel Manganese Cobalt (NMC) alternatives. However, as outlined in the Texas Instruments BESS Architecture and Design Analysis, LFP cell voltage discharge curves are extremely flat, meaning that minute cell voltage measurement errors can produce massive errors in state-of-charge (SoC) estimations. A tiny tracking error of ±3mV to ±5mV can lead to incorrect automated cell balancing, triggering localized overcharging or overdischarging. Overcharging accelerates the growth of metallic lithium dendrites that can pierce the separator, while overdischarging degrades the current collectors, both pathways leading directly to internal short circuits and subsequent thermal runaway.

Cell Imbalance and Degradation Issues

Furthermore, battery cells and packs consume current at varying rates due to localized load fluctuations and uneven cooling conditions within large-scale enclosures. These imbalances compound over a system's multi-year lifespan, gradually reducing the total usable energy of the entire storage asset. While passive cell balancing dissipates excess energy through resistors, this approach is highly inefficient for pack-level balancing as it generates excessive heat, exacerbating thermal gradients and accelerating cell aging. Replacing severely degraded packs over a ten-year operational span is technically risky, economically demanding, and labor-intensive, requiring manual charging or discharging of the replacement pack to match the exact energy levels of the surviving units in the BESS array.

BESS Fire Case Studies & Failure Trends

Lessons from BESS Fires (Moss Landing & More)

Analyzing historical failure trends reveals that BESS projects are highly vulnerable during their early operational lifecycle. The EPRI Stationary Energy Storage Failure Incident Database tracks global stationary storage failures and shows that while cumulative installed capacity has grown exponentially, the overall failure rate dropped by roughly 98% to 97% between 2018 and 2025 as early lessons were integrated into newer system designs and safety codes.

Early-Lifecycle Vulnerability in Energy Storage

However, early-lifecycle failures remain a significant challenge for the industry: approximately 51% of documented fire incidents occur within the first six months of operation, with 69% occurring during active system usage and 17% during assembly, testing, or pre-commissioning. This demonstrates that commissioning, initial thermal calibration, and mechanical assembly pose far greater immediate safety risks than long-term, calendar-based battery degradation.

The catastrophic fire at the Vistra Moss Landing facility on January 16, 2025, represents a significant turning point in the industry's understanding of utility-scale storage risks, proving that battery fires are not merely short-lived thermal events but severe long-term environmental hazards. The fire burned for several days and reignited in mid-February, releasing a toxic smoke plume that forced local authorities to close Highway 1 and evacuate thousands of residents.

According to the Inside Climate News Review of Moss Landing Battery Fire Impacts, peer-reviewed research confirmed that a fine layer of dust containing heavy metal particulates settled over the Elkhorn Slough, a protected estuary located adjacent to the power plant. This fallout deposited an estimated 25 metric tons (55,000 pounds) of nickel, manganese, and cobalt across the marsh surface, risking long-term bioaccumulation in local fish and marine mammals.

Furthermore, community advocacy findings detailed in the Never Again Moss Landing Advocacy and Community Investigation Group report that independent testing detected elevated levels of lead, PFAS, dioxins, and polycyclic aromatic hydrocarbons (PAHs) that were not initially prioritized in standard regulatory air monitoring. While utility operators reported that multi-agency soil and water testing showed no long-term public health risk, the Central Coast Water Board raised concerns that standard water-filtering and soil-sampling protocols used by the operator’s consultants may have diluted the samples, potentially masking the true scale of the environmental contamination.

Upstream Supply Chain & Environmental Impact

Lithium & Cobalt Mining Challenges

The environmental benefits of BESS in reducing grid greenhouse gas emissions are heavily offset by the ecological and humanitarian impacts of upstream resource extraction. Lithium-ion battery chemistries rely on critical raw materials, primarily lithium, cobalt, nickel, and graphite. Global projections indicate that by 2040, demand for these materials is expected to surge by 14x for lithium, 19x for graphite, and 20x for nickel, placing extreme strain on local ecosystems and supply chains.

The localized impacts of raw material mining are severe:

• Lithium Extraction: Over half of the world's lithium reserves are located in the "Lithium Triangle," an arid salt-lake region spanning Chile, Argentina, and Bolivia. The mainstream extraction method relies on pumping deep brine reserves into massive surface ponds and evaporating millions of gallons of water. This technique depletes the scarce groundwater table in these hyper-arid regions, desiccating local ecosystems and destroying the agricultural livelihoods of indigenous communities.
• Cobalt Mining: Approximately 70% of global cobalt is mined in the Democratic Republic of Congo (DRC). Reports from international human rights organizations reveal that a significant portion of this extraction relies on informal, artisanal mining, where workers—including children as young as seven—extract ore by hand without protective equipment. Chronic inhalation of cobalt-laden toxic dust causes fatal respiratory diseases, such as "hard metal lung disease," and severe dermatitis, while acidic mine effluents heavily contaminate local rivers and agricultural soils, causing reproductive health issues in local populations.
• Nickel Refining: The pyrometallurgical and hydrometallurgical processing of nickel ores generates high levels of sulfur dioxide (SO₂) emissions, contributing to acid rain, and produces millions of tons of highly toxic, acidic slag and tailings that threaten marine and terrestrial biodiversity.

Carbon Footprint of Battery Manufacturing

At the manufacturing stage, battery production is highly energy-intensive. The electrode-drying process requires high temperatures, and when powered by fossil-fuel-heavy electrical grids, the carbon footprint of battery manufacturing can exceed the lifetime operational emissions savings of the BESS if grid-connected to high-carbon generation mixes.

BESS Integration & Operational Degradation

BMS, HVAC, and PCS Interoperability

A utility-scale BESS is not a singular asset but a highly complex integration of multiple specialized subsystems. Successful operation requires real-time coordination between the Battery Management System (BMS), Power Conversion System (PCS) inverters, Heating, Ventilation, and Air Conditioning (HVAC) thermal controls, Energy Management System (EMS) software, and automated fire suppression systems. Achieving interoperability among these components is a major challenge, as integrators must reconcile proprietary communication protocols, differing data formats, and coordinate commands with broader Power Plant Controllers (PPC) or Master Power Plant Controllers (MPPC).

Cycle-Aging vs Calendar-Aging in Batteries

Furthermore, BESS operations face a fundamental physical trade-off between economic dispatch revenues and physical asset longevity. Batteries degrade over time through both calendar-aging (passage of time under specific temperatures and states of charge) and cycle-aging (wear from active charging and discharging). The rate of degradation is a non-linear function of cycle count, Depth-of-Discharge (DoD), charge/discharge rates (C-rate), and localized cell temperatures.

When an operator bids a BESS into different energy markets, the physical demands of those grid services dictate distinct degradation pathways:

• Frequency Regulation: This service requires the battery to track rapid, high-frequency fluctuations in grid frequency, demanding frequent, shallow, and high-power charge/discharge cycles (high C-rates). This operational profile creates intense localized thermal gradients and mechanical stress within the cell electrodes, accelerating micro-cracking and lithium plating.
• Peak Shaving and Load Shifting: This service typically involves one deep, slow, and complete daily charge-discharge cycle (high DoD). Deep discharging forces chemical phase transitions in the active material, causing severe volume expansion and contraction that degrades the active cathode material over time.

Consequently, choosing a service portfolio is a complex techno-economic optimization problem. An dispatch strategy that maximizes short-term market revenues can accelerate capacity fade, forcing premature, expensive cell replacement and eroding the project’s net present value (NPV).

These operational realities are further constrained by strict manufacturer warranty requirements. To maintain performance guarantees and avoid voiding multi-million dollar warranties, asset owners must collect and preserve massive volumes of high-frequency operational data. Manufacturers typically require continuous data logging at intervals as short as 1 second, capturing up to 1,000 data tags per Megawatt of installed capacity. This data-logging mandate encompasses cell-level voltages, current throughput, ambient temperatures, and HVAC efficiency. Capturing, storing, and verifying this data presents a major IT infrastructure hurdle; any data completeness errors or compounded telemetry inaccuracies can invalidate warranties, exposing operators to out-of-pocket repair costs.

BESS Recycling Challenges at End-of-Life

The High Costs of Battery Decommissioning

The rapidly accelerating global deployment of stationary storage is creating a massive end-of-life (EOL) decommissioning hurdle that requires urgent regulatory and technical standardisation. Historically, battery manufacturers designed cells and modules to maximize energy density and structural performance, paying little or no attention to post-consumer dismantlability or recyclability. Consequently, disassembling heavy BESS rack architectures is a slow, manual, and hazardous process that requires highly skilled labor to discharge stored electrical energy, remove structural enclosures, and isolate modules.

Limits of Mechanical & Pyrometallurgical Recycling

Furthermore, as outlined in the Taylor & Francis Life Cycle Assessment of BESS End-of-Life Strategies, conventional pyrometallurgical recycling methods (such as dry smelting) rely on high-temperature furnaces to melt down battery components. This approach is exceptionally energy-intensive, emits high levels of carbon, and produces toxic gaseous byproducts that must be heavily filtered. Mechanical processing steps, such as crushing and shredding to extract the "black mass" (the concentrated active materials from the electrodes), generate hazardous dust and particulate emissions that present severe safety risks to facility workers.

These technical bottlenecks directly undermine the economic feasibility of BESS recycling. In a detailed end-of-life case study conducted by researchers in the Taylor & Francis Journal Czech Republic Case Study for a 2.8 MWh/2.5 MW NMC BESS, the total cost of standard recycling was estimated at €36,000, with more than half driven by state-mandated tax obligations and over 30% consumed by high energy requirements.

Because the Czech Republic's national energy grid relies heavily on coal for 50.78% of its electricity generation, the energy-intensive mechanical processing of batteries generates significant localized emissions, directly neutralizing the overall lifecycle carbon benefits of the recycling process.

Additionally, any real-world material recovery losses (such as a 15% loss in copper extraction efficiency) proportionally reduce the environmental offset credits gained by avoiding primary resource mining. The profitability of recycling facilities is also highly vulnerable to volatile commodity markets. For NMC chemistries, nickel represents over 50% of the potential recycling revenue, meaning that any drop in global nickel prices can instantly push recycling facilities into financial insolvency.

NFPA 855 & UL 9540A BESS Safety Standards

The historical lag between rapid technology deployment and the development of safety standards has left many legacy BESS projects operational without modern safety controls. In response to this gap, regulatory bodies have shifted away from lenient, threshold-based permitting toward prescriptive, system-level safety standards. Modern BESS projects must navigate a complex, overlapping framework of design, testing, and installation standards to achieve compliance and secure financing.

Navigating NFPA 855 Hazard Mitigation

The 2026 Edition of NFPA 855 introduces significant updates that redefine BESS project design and permitting:

• Mandatory Hazard Mitigation Analysis (HMA): Prior editions of NFPA 855 only required an HMA if an installation exceeded specific stored-energy thresholds. The 2026 edition removes this threshold-based approach. An HMA is now the default regulatory requirement for almost all BESS installations. This analysis must formally evaluate the likelihood of thermal runaway initiation, toxic gas dispersion, deflagration and overpressure risks, and the reliability of containment and ventilation systems.
• Active Explosion Control Systems: Legacy installations often relied on NFPA 68 deflagration venting (e.g., blow-out panels) as their primary safety strategy. The 2026 edition of NFPA 855 restricts the use of passive deflagration venting. Systems must now incorporate active explosion control designed in accordance with NFPA 69, or performance-based alternatives validated by large-scale testing.
• Combustible Concentration Reduction (CCR) Systems: Enclosed BESS installations must install robust CCR systems designed to remain operational during thermal runaway events. These systems utilize real-time gas sensors to detect off-gassing early, automatically activating high-capacity exhaust ventilation to dilute flammable gas concentrations below 25% of their Lower Flammable Limit (LFL).

Meeting UL 9540A Fire Test Requirements

Concurrently, the publication of the 6th Edition of UL 9540A on March 13, 2026, marks a major shift toward real-world fire scenario validation. The updated test protocol requires developers to conduct large-scale, installation-level fire testing under worst-case, real-world failure conditions rather than relying solely on component-level certifications. It introduces rigorous test criteria for characterizing gas generation rates, evaluating overpressure risks, and assessing fire spread between adjacent unit enclosures. Local Authorities Having Jurisdiction (AHJs) increasingly use this testing data to enforce separation distances, establish zoning setbacks, and approve municipal permits.

Conclusion: Strategic Pathways for Risk Mitigation and Circularity

While BESS remains a critical tool for grid decarbonization, addressing its multidimensional challenges requires coordinated technical, environmental, and regulatory interventions. Transitioning from legacy cobalt-heavy chemistries to more sustainable alternatives represents a key pathway for risk mitigation.

Sodium-ion batteries, which utilize globally abundant sodium derived from salt, offer a lower environmental mining footprint, eliminate human rights concerns associated with cobalt extraction, and reduce geopolitical supply chain risks. Similarly, Redox Flow Batteries utilize liquid electrolytes that can be cycled semi-permanently, offering a highly stable long-term energy storage solution with minimal fire risks.

To minimize the environmental impacts of decommissioning, the battery industry is advancing several key technologies and practices:

• Direct Cathode Recycling: Unlike conventional high-temperature pyrometallurgical smelting, direct recycling regenerates degraded cathode material directly from spent batteries without melting the metals. This approach reduces energy-related carbon emissions by up to 47% while substantially improving metal recovery rates.
• Second-Life Repurposing: Repurposing electric vehicle (EV) battery packs that have degraded below automotive standards (typically 70–80% capacity remaining) for stationary BESS applications extends their useful lifespan. This practice defers immediate recycling costs, reduces global mining demands, and improves circular economy metrics.
• Liquid Immersion Cooling: Submerging battery cells in a non-conductive, dielectric fluid provides highly efficient thermal management. If a cell undergoes localized failure, the surrounding liquid absorbs and dissipates the heat faster than the reaction can propagate to adjacent cells, preventing rack-level thermal runaway and reducing toxic off-gas generation.

Ultimately, the long-term success of utility-scale energy storage depends on moving beyond simple short-term installation cost metrics. Project developers, financial institutions, and regulators must integrate full lifecycle costs—including safety systems, high-frequency performance tracking, supply chain transparency, and standardized recycling pathways—directly into the planning, permitting, and operational dispatch of modern grid energy storage.