Data Center Environmental Liability Insurance: Diesel, Batteries, and Cooling System Risk

Data centers carry environmental liabilities that most operators don’t fully account for in their insurance programs. Diesel fuel storage for backup generators creates underground storage tank (UST) and aboveground storage tank (AST) pollution exposure. Lithium-ion battery disposal — flagged by FM Global in its updated 2026 guidance as a new exposure category — creates hazardous material handling obligations. Cooling systems use chemicals that require proper disposal. Each of these creates a liability gap that standard property and general liability policies typically exclude.

Environmental liability insurance fills those gaps. This guide covers what data center environmental exposures actually look like, which coverage lines address them, and what’s changed in 2026 with the new FM Global guidance on lithium-ion batteries.

The Pollution Exclusion Problem

Standard commercial general liability policies contain a pollution exclusion that removes coverage for claims arising from the actual, alleged, or threatened discharge, dispersal, seepage, migration, release, or escape of pollutants. In practice, this means an environmental contamination claim — diesel fuel leaking into groundwater from a generator tank, glycol discharged into a storm drain from a cooling system failure — gets denied under a standard GL policy.

The pollution exclusion is one of the most litigated provisions in commercial insurance, with courts in different jurisdictions interpreting it more or less broadly. Some states have narrowed the exclusion significantly; others apply it broadly to exclude almost any contamination claim regardless of how routine the cause. Relying on court-by-court interpretation rather than explicit environmental coverage is a risk management position, not an insurance one. Data center operators need pollution legal liability coverage that explicitly covers their environmental exposures — not a GL policy and a hope that the exclusion won’t apply.

Diesel Fuel Storage: The Generator Tank Exposure

Backup generators are essential infrastructure for data centers — they’re the last line of defense against power failures that would otherwise cause outages. Most data center backup generator systems store thousands of gallons of diesel fuel on-site. A mid-market 50MW facility typically maintains 24–72 hours of fuel capacity, which may represent 50,000–200,000 gallons of diesel in aboveground or underground storage tanks.

The regulatory and liability framework for that fuel storage is established regardless of whether a spill or leak actually occurs:

• EPA UST regulations: Underground storage tanks above 110 gallons that hold petroleum products are subject to EPA Underground Storage Tank regulations — leak detection, spill and overfill prevention equipment, release response, and financial assurance (insurance or other financial demonstration of ability to pay for cleanup)
• State environmental regulations: Most states have UST and AST programs that impose additional requirements on top of federal minimums — Texas, for example, has TCEQ tank regulations that apply to facilities in the state
• Spill and leak liability: A diesel spill or underground leak creates cleanup liability under CERCLA (federal superfund), state environmental statutes, and potentially private nuisance claims from neighboring property owners
• Financial assurance: EPA and most state UST programs require operators to demonstrate financial ability to pay for cleanup — insurance is the most common method of satisfying this requirement

Pollution legal liability (PLL) for the generator tank system covers: cleanup costs for spills and releases; third-party bodily injury and property damage claims from contamination; and regulatory defense costs for environmental agency enforcement actions. The coverage should be structured to address both sudden and accidental releases (a spill during fueling operations) and gradual releases (slow leaks from aging tank infrastructure).

Lithium-Ion Batteries: The 2026 FM Global Update

The integration of lithium-ion battery arrays into data center UPS systems and backup power configurations has created a new environmental exposure that FM Global explicitly addressed in its 2026 loss prevention guidance. Beyond the fire risk (addressed in our AI data center insurance guide), Li-ion batteries create environmental liability in several scenarios:

Thermal runaway and chemical discharge. A Li-ion battery thermal runaway event — the cascade failure that causes rapid, uncontrolled heat and gas generation — releases chemicals including fluorine compounds, phosphorus pentafluoride, and hydrogen fluoride gas. These are hazardous materials. A thermal runaway event that triggers emergency response and facility evacuation creates environmental response liability regardless of whether a fire occurs.

Battery disposal and end-of-life management. Li-ion batteries contain cobalt, lithium, nickel, and other materials subject to hazardous waste regulations. Improper disposal — not following EPA Universal Waste regulations or state hazardous waste requirements — creates environmental liability. As AI data centers cycle through battery equipment at increasing rates (battery density improvements and AI power requirements are driving faster replacement cycles), disposal volume is increasing.

Electrolyte spills during maintenance. Battery maintenance and replacement operations create potential for electrolyte spills — lithium salt solutions that are corrosive and subject to environmental handling requirements. Maintenance contractors performing battery work need contractors pollution liability coverage for this exposure, and the facility’s environmental policy should address the premises-side liability.

Cooling System Environmental Exposures

Data center cooling systems use several categories of chemicals and fluids with environmental liability implications:

Glycol-based cooling fluids. Propylene glycol and ethylene glycol are commonly used in cooling tower systems and liquid cooling circuits. Neither is acutely toxic, but both create environmental liability if discharged to storm drains, waterways, or soil — they’re oxygen-depleting in aquatic environments. A cooling system failure that discharges glycol to a storm drain can trigger an EPA or state environmental agency response and cleanup obligation.

Refrigerants. Chiller systems use refrigerants that are subject to EPA Section 608 regulations under the Clean Air Act. Refrigerant recovery, recycling, and disposal requirements apply to all commercial HVAC and refrigeration equipment. Improper handling or unauthorized discharge of refrigerants creates Section 608 enforcement liability and environmental cleanup obligations.

Immersion cooling fluids. Facilities adopting immersion cooling for AI workloads — where servers are submerged in dielectric fluids — use specialty cooling fluids (fluorinated or hydrocarbon-based) that require proper management and disposal. This is an emerging exposure category as immersion cooling adoption accelerates; the regulatory framework is still developing, but environmental liability exists for improper discharge or disposal.

Cooling tower water treatment. Cooling towers require water treatment chemicals — biocides, scale inhibitors, and corrosion inhibitors — that are regulated under water treatment chemical handling requirements. Discharge of treated cooling tower water requires compliance with NPDES permit terms for facilities above certain discharge thresholds.

Contractors Pollution Liability: The Vendor Gap

Environmental liability for data centers isn’t just about the facility’s own operations. Maintenance contractors who service fuel systems, cooling equipment, and battery installations bring their own environmental liability into the facility. If a contractor accidentally spills diesel fuel during a generator maintenance operation, or discharges glycol during a cooling system repair, the liability question runs to both the contractor and potentially the facility operator as the premises owner.

The solution is requiring contractors to carry contractors pollution liability (CPL) insurance. CPL is a specialty line that covers contractors for environmental liability arising from their work — not covered under their general GL because of the pollution exclusion. Any contractor performing fuel handling, cooling system maintenance, battery work, or environmental compliance work at the facility should have CPL as a vendor insurance requirement.

The facility’s own environmental policy should include premises pollution liability that covers the facility for third-party claims arising from contractor operations on-site — a backstop for situations where the contractor’s coverage is inadequate or where the pollution liability is attributed to the premises owner. This coordination between contractor CPL and facility premises pollution liability is the environmental equivalent of requiring additional insured status on contractor GL policies.

What Environmental Liability Insurance Covers for Data Centers

A comprehensive environmental liability program for data centers typically includes:

• Pollution legal liability (PLL): Third-party bodily injury, property damage, and cleanup costs from pollution conditions on, at, or migrating from the facility — including diesel releases, battery chemical discharges, and cooling fluid releases
• Remediation cost coverage: Costs to investigate, assess, and clean up pollution conditions — first-party cleanup of the operator’s own property as well as third-party cleanup claims
• Regulatory defense: Legal defense costs for environmental agency enforcement actions, including EPA, state environmental agencies, and local fire/hazmat departments
• Business interruption from environmental incidents: Revenue loss during operational shutdowns caused by environmental incidents or regulatory enforcement actions that require facility closure
• Transportation coverage: Environmental liability for hazardous material transportation — relevant for battery disposal and waste chemical transport

Policies are written on either a claims-made or occurrence basis — environmental policies are typically claims-made, meaning the claim must be made during the policy period. Tail coverage (extended reporting period) is important at policy expiration to ensure coverage for future claims arising from conditions that existed during the policy period.