[co-author: Kate Thoreson, WilmerHale]

Battery technology has become ubiquitous in daily life with the growing use of lithium batteries powering consumer products ranging from handheld electronic devices to electric vehicles. Besides their use in consumer products, increasing demand for lithium batteries is driven by the advancement of renewable energy sources where batteries store energy for release into the power grid during peak electricity needs. In this application, large lithium battery storage facilities require responsible planning and proactive stewardship to reduce potential risks to people or the environment and prevent or contain failure events that could otherwise result in fires or chemical releases. As the unprecedented growth in volume and diversity of battery applications continues, companies operating these facilities can proactively ensure the successful and safe implementation of renewable energy storage solutions, which requires multidisciplinary coordination.

Rising demand for renewable energy storage solutions

In the renewables industry, wind and solar utilities require high-capacity energy storage sites (ESS) to store generated potential energy for later distribution to the electrical grid. Batteries, notably lithium batteries, have become popular for use in ESS[1] because of their high energy density and capacity to store large amounts of energy until needed. For example, during the 2023 Texas heat wave, 2.2 megawatts (MW) of battery-stored energy was fed back into the grid during peak usage times, ultimately preventing imminent large-scale blackouts caused by periodic spikes in energy demand.^[2] Texas increased its battery power capacity 12-fold from 2020 to 2023 and plans to triple this capacity again within the next year. Likewise, New York plans to deploy 1,500 MW of energy storage by 2025.[3] Battery storage capacity is expected to double this year across the U.S., growing from approximately 15 gigawatts (GW) in 2023 to 30 GW available by the end of 2024.[4]

Large-scale battery ESS (or BESS) consist of batteries arranged within enclosures (40 or 53 ft long) and contain components such as battery management systems, fire suppression, HVAC, and power-conversion equipment.[5] Some of the largest BESS installations in the United States may spread over 30 football fields and can consist of well over 100 battery storage containers capable of storing 400 MW.[6] Around 300 utility-scale battery storage projects are expected to be active in the U.S. by 2025.[7]

Understanding potential hazards is critical

As the adoption of these battery storage technologies increases, so does the need for awareness of the potential hazards in the event of a system failure. Equipment failures, poor climate control, complex cell chemistry, and battery damage can lead to thermal runaway within lithium batteries, which can result in fires or explosions and the release of flammable gases and combustion products.⁶ According to the Electric Power Research Institute, worldwide there were an estimated 13 BESS failure events reported in 2023,[8] though data tracking such events are limited. Only recently have studies investigated the chemical hazards associated with lithium battery failures. The chemicals released during a battery failure depend on the specific battery chemistry, encasement materials, scale of the thermal runaway event, and how the fire is suppressed (e.g., using water or other suppressant materials).[9] Recent laboratory-based studies have reported chemical and particulate emissions during lithium battery combustion or thermal runaway events. Compounds like hydrogen fluoride, sulfur oxides, fluorinated substances, volatile organic compounds, and metals such as cobalt, nickel, manganese, and lithium chemistries have all been reported in emissions.[10]^,[11]^,[12]^,[13] However, most chemical data have been collected in laboratory studies assessing combustion of electric vehicle batteries,¹¹ with fewer “real-world” monitoring data available during or after large BESS failure events.

Understanding how people and the environment could be impacted is critical to preventing potential risks. During and after a BESS fire, first responders and nearby residents may be exposed to emissions from combusting battery components that volatilize into the air.[14] In large-scale events, environmental releases may occur due to firefighting liquids leaching into groundwater or runoff spilling into surface waters used as drinking water sources[15]. Laboratory studies have reported potential environmental risks to aquatic organisms from runoff containing these compounds.¹⁴ Combustion products formed at or near the burn site can also be a source of contamination in soils. These exposure pathways and potential hazards are likely driven by location-specific characteristics (e.g., nearby communities or waterways, wind direction, soil type) and ultimately will require scientific site-specific investigation to determine risks or necessary remediation after a BESS fire.

Not only are there environmental risks from BESS fires, but there are also legal risks. When there is a release of hazardous chemicals, companies need to comply with the Emergency Planning and Community Right-to-Know Act (EPCRA), the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), the Clean Air Act (CAA), and the Clean Water Act (CWA). Under EPCRA, CERCLA, and the CAA, there are hazardous chemicals that are subject to reporting upon release into the environment and/or the air.[16] Hydrogen fluoride,[17] sulfur dioxide,[18] sulfur trioxide,[19] cobalt,[20] nickel,[21] manganese,[22] various PFAS chemicals,[23] benzene,[24] and hundreds of other chemicals have individual reporting requirements. If there are releases into Waters of the United States (WOTUS), that would also implicate the CWA. Finally, the EPA may require an emergency response under CERCLA, followed by continued remedial action, to restore the environment after the release. In these cases, the EPA would require the company to pay for the clean-up.

Proactive planning and coordination can mitigate risks

For companies operating BESS facilities, responsible product stewardship requires managing risks to reduce liabilities and protect people and the environment. Doing so first requires awareness and coordination with multiple stakeholders, including battery manufacturers, site operators, first responders, public agencies, risk assessors, and most importantly communities in proximity to BESS sites. For operators of BESS facilities, developing emergency response procedures is necessary not only to mitigate risk for first responders and nearby communities but to address potential environmental hazards created by battery fires or explosions. For example, California adopted a law in 2023 requiring owners/operators of BESS to develop emergency response plans for their facilities, which should include consideration of offsite impacts such as poor air quality and threats to waterways.[25] EPCRA also requires emergency response plans, which are meant to be coordinated with the State or Tribal Emergency Response Commission.[26] Such plans can also consider proactive risk communication strategies to inform and protect nearby communities and procedures to engage with government agencies.

Other stakeholders can also provide essential support in preventing and managing risks. Battery manufacturers and developers can identify cell chemistries and investigate risks of malfunctions. Environmental risk assessors can develop environmental monitoring plans, conduct onsite sample collection, and assess risks by analyzing chemical releases during and after BESS failure events.

Proactive, multidisciplinary coordination can ensure that risks are properly managed and minimized and support the widespread safe implementation of BESS to meet the growing needs of the renewable energy sector.