PFAS Observer
Data centers use various chemicals that have recently been the focus of regulatory efforts at the federal and state level. The historic or future use of these chemicals may create liabilities, obligations, or new costs for both existing and planned data centers.
PFAS Use in Data Centers
Per- and polyfluoroalkyl substances (PFAS) are a class of approximately 15,000 synthetic fluorinated organic compounds (by EPA’s most recent reckoning) that have been widely used for decades in a wide range of products and industries. The carbon-fluorine bond is among the strongest in organic chemistry and gives PFAS their physical properties: fire, water and grease resistance. These properties—chemical stability, resistance to degradation, and oil and water resistance—make PFAS both useful and concerning from an environmental and health perspective, as they tend to persist in the environment and bioaccumulate in living organisms.
As a result, PFAS have become a major focus of regulatory action and litigation in recent years, with governments and plaintiffs increasingly targeting their use, disposal and presence in consumer products and water supplies. Regulatory definitions of PFAS vary depending on the regulatory body. The most expansive definitions of PFAS are those adopted by certain states that classify as PFAS any chemical featuring a carbon atom that is saturated with fluorine.
PFAS that meet this definition serve several necessary functions with respect to data centers. For example, certain server components and cables, including switchgears, either integrate or are coated with PFAS, particularly fluoropolymers. The presence of fluoropolymers in such equipment is hardly unique to the data center industry. Because of their relative stability and molecular size, fluoropolymers are not as bioaccumulative or toxic as long-chain alkyl PFAS (i.e., straight-chain PFAS with molecular backbones that are at least seven carbons long).
On the other hand, more focused applications of PFAS occur with respect to one of the main concerns at data centers—namely, the propensity for servers and other equipment to malfunction as a result of overheating. Because of their low boiling point and fire-resistant qualities, PFAS (as defined per the state definitions) are used as refrigerants and cooling agents within chillers and air conditioning centers, which are an important aspect of most data center designs. In addition to impairing server operability, overheating can give rise to a risk of fire, which is exacerbated by the concentration of electrical equipment and combustible materials like cabling and plastics. As such, data centers are equipped with fire suppression systems, which may contain PFAS.
PFAS in Fire Suppression Systems
Because data centers are packed with server racks, they require fire suppression systems that will not destroy the equipment. The best suited are dry pipe fire sprinkler systems and a clean agent fire suppression system.
- Historically, dry pipe fire suppression systems have used Class B aqueous film-forming foams (AFFF) and automatic reactivation AFFF. These AFFF formulations may contain PFAS, and the activation of fire suppression systems may result in the sudden discharge of large quantities of PFAS-containing AFFF. Furthermore, the long-chain alkyl PFAS present in AFFF—perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS)—are dispersible in the environment and (a) subject to stringent de facto cleanup standards in the form of maximum contaminant levels of 4 parts per trillion (ppt) in groundwater, orders of magnitude lower than those for other industrial chemicals, and (b) formally designated as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), meaning that sites contaminated with these chemicals are subject to strict, joint and several liability. Accordingly, some of the largest PFAS settlements to date have occurred in multidistrict litigation involving the discharge of AFFF to the environment. To date, 15 states (AK, CA, CO, CT, HI, IL, ME, MD, MN, NH, NJ, NY, RI, VT and WA) have banned the sale of firefighting foam containing PFAS. There is an expanding market of synthetic fluorine-free foams (SFFFs). However, SFFFs do not have the same efficacy as AFFF technologies.
Clean fire suppression systems use gaseous agents to quickly extinguish fires, leaving no residue behind, which makes them ideal for protecting sensitive equipment and areas where water damage would be undesirable. The most commonly used clean agents like FK-5-1-12 (Novec 1230), HFC-227ea (FM-200), HFC-125, HFC-236fa, and 2-bromo-3,3,3-trifluoropropene are PFAS under various definitions, though they have different properties from PFOA and PFOS and are not subject to CERCLA regulation. Even so, data centers may be regarded as a target for litigation in areas where contamination with fluorinated organic compounds has been identified.
HFC-Refrigerants
Hydrofluorocarbons (HFCs) are synthetic chemicals commonly used in commercial refrigeration and cooling systems. Data centers produce large amounts of heat and often need complex cooling systems to ensure their systems do not overheat.
Starting in the 1990s, HFCs came to replace traditional refrigerants, classified as ozone-depleting substances, in the aftermath of the 1987 Montreal Protocol. However, HFCs themselves present environmental risks as greenhouse gases. Indeed, studies exist to suggest that the global warming potential of HFCs may be many times greater than that of carbon dioxide, and the data center industry is coping with an increasingly stringent regulatory framework focused on HFCs. Hydrofluoroolefins (HFOs), which are increasingly being seen as alternatives to HFCs, have a lower global warming potential but may carry their own risks such as flammability.
Congress passed the American Innovation and Manufacturing (“AIM”) Act of 2020, mandating an 85% phasedown of HFC production and consumption by 2036. Under the Biden administration, the U.S. Environmental Protection Agency (EPA) moved aggressively to implement the AIM Act through a suite of interconnected regulations:
- A cap-and-trade system, which became effective on November 4, 2021, and which is intended to phase down over time the total volume of HFCs in the U.S. market.
- The Technology Transition Rule, 88 Fed. Reg. 73098 (October 24, 2023), restricting the use of most HFC-based refrigerants in new equipment.
- The Emissions Reduction and Reclamation (ER&R) Rule, 89 Fed. Reg. 82682 (October 11, 2024), which mandates leak prevention, repair, and in some cases the replacement of HFC-based cooling systems.
This regulatory approach means that both new and existing data centers may be impacted. Existing data centers that rely on HFCs may be impacted by the ER&R rule, as it imposes extensive and likely costly compliance obligations on such systems. For example, operators of existing systems may be required to install automatic leak detection equipment, meet detailed recordkeeping requirements, promptly repair leaks that exceed specified thresholds, and even retrofit or retire systems that cannot be repaired within certain timeframes. New data centers may be impacted by the limitations on new cooling technology available, as the Technology Transitions rule removes HFC-based systems from the market. For example, new data centers systems will be legally prohibited from using systems that rely on R-410a, a popular refrigerant in data center cooling systems.
Despite the increasing availability of alternative refrigerants coming onto the market, it may be difficult to retrofit existing refrigeration systems to use these products. Additionally, the new refrigerants—including some that are HFOs and hydrochlorofluoroolefins—may present other risks not customarily associated with HFCs. For example, A2L refrigerants may raise new concerns due to their flammability, CO2-based systems may require higher energy consumption particular in warmer climates, and adiabatic cooling (heat reduction via pressure drop) may be water-intensive and therefore unsuitable for drier regions.
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