Natural gas-fired turbines and coal plants provided 66% of North America’s electricity in 2015, with renewables being only 13%. In 2025, wind and solar energy play a bigger role in utility-scale power (renewables, or “green energy,” accounted for over 21% in 2023), and how that energy is stored has become increasingly important (see Figure 1). By 2030, these renewable energy sources could account for nearly 50% of all electricity produced. A high-priority focus in the near future will be how to store excess energy (e.g., batteries) and return it to the grid. This enables energy storage during periods of low demand and reintroduction of stored energy back into the grid during high demand. This helps stabilize electrical grids and reduces the likelihood of rolling brownouts.

Storing Wind and Solar Energy Production in Batteries

Lithium-ion (Li-ion) batteries play a significant role in how energy is stored for future use. Popular Li-ion battery chemistries include lithium iron phosphate (LFP) and lithium nickel manganese cobalt oxide (NMC). These batteries are of particular importance to responders and planners.

According to the U.S. Energy Information Administration, Texas accounted for 28% of the nation’s total wind production in 2024, and that number is growing. A U.S.-based organization, Underwriters Laboratories (UL), has a certification process for Li-ion batteries to ensure their safety and performance. The certification process involves rigorous testing and verification to meet specific safety, performance, and environmental standards. This includes testing for electrical safety, mechanical durability, thermal management, and vibration resistance. The certification process also includes testing for discharge safety, ensuring that batteries operate safely during discharge and do not release excess energy that could cause failure.

Often, non-UL-certified batteries do not contain critical safety systems such as a battery management system or a current interrupter device (see Figure 2). Because current or voltage equals temperature in a battery, if it cannot regulate its temperature, thermal runaway (i.e., an uncontrollable increase in heat) is a risk. Users of batteries lacking these safety systems place themselves and others in a potentially hazardous situation when batteries are allowed to remain on a charger after the battery reaches 100% state of charge.

During thermal runaway, the separator (i.e., a polymer membrane that separates a battery’s positive and negative electrodes) becomes compromised and creates a risk of an electrical short, adding even more heat to the system, triggering additional breakdown. This compromises other battery components and contributes to a combustion reaction if a battery cell catches fire (see Figure 3).

Battery Energy Storage Systems

The stored-energy field has grown significantly, and battery energy storage systems (BESS) projects are expected to continue growing. The Department of Energy expects a nearly 80% year-on-year increase in utility-scale BESS installations. Adding electricity capacity through BESS would support the nation’s energy grid.

BESS configurations can be tied to wind, solar, or merely “float on the grid,” buying power and recharging batteries when rates are low and selling it back to the grid during peak demand. This is a straightforward cycle of charging and discharging batteries (see Figure 4).

However, there are some unintended consequences from harnessing power from green energy sources. Two recent fires at BESS facilities, both in California, have raised concerns for residents and first responders. Both facilities were “common roof” BESS, containing thousands of battery racks in one facility. During the first BESS fire, a significant amount of firefighting water was used, hundreds of thousands of gallons, and the fire burned for days. This creates the potential for significant downwind exposure and contamination from fire-impacted BESS facilities.

The real hazard does not reside in battery mechanics but in chemical composition and state of charge. There has been a movement to adopt LFP batteries in BESS operations, due to several advantages. LFP batteries have longer life cycles than NMC batteries. Additionally, they are less prone to overheating, are cheaper to produce, and have potentially less environmental impact than their NMC counterpart. Further, LFP batteries do not contain nickel or cobalt, which are more toxic, but share some chemical properties with NMC batteries.

A battery’s state of charge is a major consideration during an emergency. A fully charged battery has more energy potential than a discharged or partially charged battery and could cause a protracted event if the energy potential is not decreased. During response operations, consider ways to discharge the impacted or potentially impacted battery.

Response Challenges and Safety Concerns

While the likelihood of Li-ion batteries catching on fire is low, the consequences are high. The Texas A&M Engineering Extension Service (TEEX) at the Southwest Research Institute laboratories conducted research on Li-ion batteries and their impact on first responders and their protective equipment. During testing, researchers forced 36-volt, 12-amp-hour NMC batteries into thermal runaway and measured contamination levels on firefighter personal protective equipment (PPE), including all three layers of bunker gear, self-contained breathing apparatus (SCBA) straps, and other apparatus materials.

TEEX determined the following about battery fires of this type:

• They are an extreme emissions event of highly toxic gases and particles that are respirable and dominated by metallic compounds that well exceed the Occupational Safety and Health Administration (OSHA) permissible exposure limits.
• Particulate matter and metallic particulate exposure ranged from 12,000 to 17,000 times the Environmental Protection Agency limit for exposure.
• Semi-volatile organic compounds (SVOCs) and polycyclic aromatic hydrocarbon exposure, especially lithium, ranged from a few times to hundreds of times the OSHA eight-hour limit, making them highly toxic.
• Response to Li-ion battery fires must be done in the appropriate PPE, and the use of a positive-pressure SCBA is critical to protect respiratory systems.
• Cleaning efficiencies of bunker gear varied during the NFPA 1851 water-based cleaning and liquid carbon dioxide (CO₂) cleaning analysis. These are some findings:
  • Water-based extraction efficiency ranges from 21% to 92% in removing SVOCs. The current standard is a minimum of 50% removal.
  • CO₂ cleaning is effective, showing many SVOCs at undetectable levels.
  • The outer shell of protective gear is effective at stopping the penetration of metallic particles to the vapor barrier.
  • Cleaning efficiency is over 99% for most metals. One cycle of water-based and CO₂-based cleaning of exposed swatches is effective for removing metallic compounds deposited on the outer layer of gear samples. CO₂-based cleaning is slightly more effective than water-based cleaning.
  • Even after cleaning, metals such as cobalt, copper, manganese, and nickel remain on bunker gear swatches at levels above unexposed gear.
  • Introducing contaminated PPE into an apparatus cab can lead to serious contamination issues. The U.S. Environmental Protection Agency’s ambient standard for particulate matter is 9 ug/cm2. During TEEX lithium-ion battery destructive testing, analysis showed that clean cab materials averaged 226 ug/cm2 of metallic particle contamination, while traditional cab materials averaged 418 ug/cm2 after battery thermal runaway events. Of all materials exposed and analyzed, SCBA straps had the highest potential for retaining contamination, averaging 780 ug/cm2 of metallic particle contamination.

Research concluded that Li-ion battery fires are difficult, if not impossible, to extinguish using currently available methods and substances. Traditional suppression methods such as water-based, dry chemical, and firefighting foams are not effective. Responders should have a plan and be flexible as conditions change. The remaining state of charge in batteries poses a post-emergency problem, since batteries can go back into a thermal runaway even after initial fire suppression. Because protection from exposure is critical, responders should determine whether batteries can be moved away from fire exposure and whether water spray can lessen the thermal impact of exposure. Finally, it is important that agencies and municipalities develop a battery charging strategy, indoor vs. outdoor charging. Batteries present a fire risk even if a fire is out. They continue to off-gas after a fire and may pose a hazard for days, weeks, and possibly months after the incident.

Harnessing and storing green energy comes with inherent risks. With time and progress, battery chemistry will become less volatile, but even then, “legacy” battery chemistry issues will remain. In a dynamic, ever-changing environment, first responders should train for an unlikely but dangerous circumstance. As the use of green energy and Li-ion batteries expands, communities must be aware of the potential hazards and dangers they pose to first responders and to others throughout the community who increasingly use and store this energy.