Whether caused by a natural hazard or some other event, power loss at hazardous chemical facilities can lead to a variety of negative impacts. Pumps and compressors may stop running, stirrers may quit mixing, lights may go out, and instruments and controls may malfunction. These equipment outages can lead to tank overflows, runaway chemical reactions, temperature or pressure excursions, or other process upsets which could lead to a spill, explosion, or fire. Even if there is no immediate release, thermal shock or other factors could result in a delayed effect that compromises the mechanical integrity of equipment during subsequent operations. When power is restored even after a brief interruption, some equipment may automatically restart before process operations are ready, while other equipment may need to be reset and manually restarted. When a facility relies on electrical power for any aspect of its process operations, it is imperative to anticipate how power loss affects the safeguards that prevent releases of hazardous chemicals.
Power loss has resulted in serious accidents at RMP-regulated facilities. The aforementioned 2017 Arkema incident highlighted the hazard of power loss on process safety; other previous incidents have also highlighted this hazard and offered lessons on potential safeguards that could be applied to prevent accidental chemical releases. The accidents described below—all associated with power failure—are examples of these situations and their potential severity. They also highlight the in-depth evaluation needed to prevent loss of power from resulting in an accidental release.
On May 1, 2001, at General Chemical Corp., in Richmond, California, a truck struck a utility pole, causing a power interruption and total plant shutdown. Shortly after, sulfur dioxide and sulfur trioxide began to escape from a boiler exit flue. When power was restored a short time later, a steam turbine that was required to keep the boiler exit flue under negative pressure could not be immediately restarted. While the turbine could not be restarted, residents near the plant were instructed to remain indoors. Somewhere between 50 to 100 individuals sought medical attention following the release. Troubleshooting revealed that an automatically controlled governor valve had malfunctioned.
On August 23, 2010, at the Millard Refrigerated Services in Theodore, Alabama, a hydraulic shock caused a roof-mounted suction pipe to catastrophically fail, releasing more than 32,000 pounds of anhydrous ammonia. The hydraulic shock occurred during the restart of the plant’s ammonia refrigeration system following a 7-hour power outage. Downwind of the ammonia release were crew members on the ships docked at Millard and over 800 contractors working outdoors at a clean-up site for the Deepwater Horizon oil spill. Nine ship crew members and 143 of the offsite contractors downwind reported exposure. Of the victims, 32 required hospitalization and four were placed in intensive care.
National Response Center data also include information on 3,077 reported accidents from 2004–2020 that were associated with power loss.48 While most of these incidents did not involve RMP chemicals, processes, or accidental releases as defined in CAA 112(r)(2), these events demonstrate a connection between the loss of power, loss of containment, and release into the environment.
The European Union published a 2021 bulletin that presents lessons learned from incidents worldwide involving power supply failures. The findings highlight the importance of understanding the scenarios triggered by a primary failure in external power supply systems, power loss attributed to onsite electrical equipment or electrical components’ failures, and even redundant power supplies’ failures. In addition to providing statistics on the effects of power outages at chemical facilities, data provided by the European Union indicate that power failures at hazardous sites have resulted in 21 fatalities and over 9,500 injuries worldwide since 1981, as well as significant property damage and production loss from resulting fires and explosions. The most catastrophic event in the study occurred in Sakai (Osaka), Japan, in 1982. It killed six people, injured 9,080 others (of which 8,876 were offsite), and destroyed 1,788 buildings. EPA has long recognized that loss of power can threaten hazardous chemical processes and cause accidental releases if not properly managed. While EPA did not specifically require power loss to be evaluated for Program 2 and Program 3 hazard reviews and PHAs, EPA and OSHA guidance has referred to it. In addition to acknowledging power failure in the Agency’s “General Guidance on Risk Management Programs for Chemical Distributors,” in 2001, EPA issued the safety alert, “Chemical Accidents from Electric Power Outages.” These guidelines warned RMP facilities that power outages and restarts could potentially trigger serious chemical accidents. The alert outlined some of the accidents previously discussed and warned that process operations must be evaluated for the consequences of power outages to ensure that the process remains safe. It also indicates that if critical equipment needs to operate to ensure the safety of the process or work area, facilities should install backup power supplies and services.
In 2008, OSHA published an interpretation letter that addressed the concern about utility systems and their evaluation within the scope of PSM. OSHA indicated that the proper, safe functioning of all aspects of a process, whether they contain a highly hazardous chemical or not, is important for preventing and mitigating catastrophic releases of highly hazardous chemicals. OSHA’s position is that any engineering control (including utility systems) which does not contain a highly hazardous chemical (HHC) but can affect or cause a release of an HHC or interfere in the mitigation of the consequences of a release must be, at a minimum, evaluated, designed, installed, operated (with appropriate training and procedures), changed, and inspected/tested/maintained per OSHA PSM requirements. OSHA provided the example of an employer that identifies, through its PHA, that the safe operation of its covered process relies on the electrical utility system. In response, the employer could determine that an uninterruptible power supply would be an appropriate safeguard against the loss of electrical utility to the process
equipment.
EPA believes making this already-existing accident prevention program requirement more explicit about evaluating hazards of the process will ensure the threats of power loss are properly evaluated and managed to prevent or mitigate releases of RMP-regulated substances at covered facilities. EPA believes many facilities with RMP processes are managing the hazard of power loss. However, some recent RMP accidents are linked to power loss. EPA’s review of RMP accident history data from 2004–2020 shows that at least 20 accident history reports have specifically indicated that power failure was a contributing factor to an accident. However, only 63 percent (310) and 44 percent (1,971) of facilities with Program 2 and Program 3 processes, respectively, have implemented backup power at their facilities, despite identifying that the loss of cooling, heating, electricity, and instrument air is a major potential hazard to their process operations.
The frequency and severity of extreme weather events may exacerbate power failure events if the impacts of potential power failures are not identified and control strategies are not implemented. Climate change poses long-term challenges because it affects the frequency, intensity, and duration of weather events that represent the largest source of disruptions to the U.S. electricity grid. New studies have shown that the threat of power loss is increasing for utility customers. The Department of Energy reported that an increase in extreme weather events has led to an increase in power outages in recent years. Specifically, the Department of Energy’s U.S. Energy Information Agency’s data showed that electric power for U.S. customers was interrupted for an average of 7.8 hours (470 minutes) in 2017, nearly double the average total duration of interruptions experienced in 2016. Data indicate that more major weather events, such as hurricanes and winter storms, occurred in 2017 than in previous years, and the total duration of power interruptions caused by major events was longer.57 58 Recent major power outages also provide examples of this threat. In February 2021 in Texas, Winter Storm Uri left 4.5 million customers without power for several days.59 In January 2022, one of the five worst winter storms in Virginia’s history resulted in approximately 400,000 Dominion Energy customers experiencing a power outage when heavy snow and high winds impacted utility services. Events like these also have the potential to impact hazardous chemical process operations.
Therefore, EPA is proposing to further emphasize the loss of power in the hazards evaluated in hazard reviews and PHAs for Program 2 and Program 3 RMP-regulated processes. EPA believes the further emphasis on these accident prevention program provisions will ensure that the risk of power failure is properly evaluated and managed to prevent or mitigate releases of RMP-regulated substances at covered facilities. EPA is proposing to include emphasizing that hazard evaluations under 40 CFR 68.50(a)(3) and 68.67(c)(3) address standby or emergency power systems.
EPA expects facilities to continue to use available resources to properly evaluate whether power loss is a hazard to their process and, if so, implement appropriate controls to prevent or reduce that hazard. In addition to the hazard evaluation guidance offered by CCPS and other industry-specific resources, below are resources that broadly discuss options for evaluation of power loss and standby power:
- National Fire Protection Association (NFPA) 70: National Electrical Code.
- NFPA 110: Standard for Emergency and Standby Power Systems.
- NFPA 1600: Standard on Continuity, Emergency, and Crisis Management.
3005.4-2020: Institute of Electrical and Electronics Engineers (IEEE) Recommended Practice for Improving the Reliability of Emergency and Stand By
Power Systems. - 3006.7-2013: IEEE Recommended Practice for Determining the Reliability of 7×24 Continuous Power Systems in Industrial and Commercial Facilities.
- National Renewable Energy Laboratory (NREL), “Backup power cost of ownership analysis and incumbent technology,” NREL, NREL/TP-5400-60732,
Golden, CO (2014). - NREL, “A comparison of fuel choice for backup generators,” NREL, NREL/TP- 6A50-72509, Golden, CO (2019).
The Agency is concerned that the threat of extreme weather events has and will be used by some owners or operators to justify disabling equipment designed to monitor and detect chemical releases of RMP-regulated substances at their facility. EPA is concerned that air monitoring and control equipment is often removed from service before natural disasters to potentially prevent damage to equipment or, conceivably in some cases, evade monitoring requirements and therefore may not become operational again until much later, after the event or threat has passed. To prevent accidents, RMP owners or operators are required to develop a program that includes monitoring for accidental releases. EPA does not believe natural disasters should be treated as an exception to this requirement. A large–scale natural disaster may threaten multiple RMP facilities in a community simultaneously, leaving communities to endure the direct effects of a natural disaster without receiving warning of associated chemical releases.
EPA wants to ensure RMP–regulated substances at covered processes are continually being monitored so that potential exposure to chemical substances can be measured during and following a natural disaster. Some industry standards already require continuous monitoring of process chemicals. For example, the International Institute of Ammonia Refrigeration’s (IIAR’s) “Minimum Safety Requirements for Existing Closed-Circuit Ammonia Refrigeration Systems” requires facilities with ammonia refrigeration systems to provide a means for monitoring the concentration of an ammonia release in the event of a power failure. While EPA is not requiring implementation of standby or emergency power for the entirety of an RMP process, EPA is proposing to require air pollution control or monitoring equipment associated with the prevention and detection of accidental releases from RMP–regulated processes to have standby or backup power to ensure compliance with the intent of the rule. EPA seeks comment and data on this proposed provision, particularly on any potential safety issues associated with it.