Public power utility customers experienced the lowest instances of power outages in both frequency and duration in 2016, averaging one outage and less than two hours of interrupted electric service, the Energy Information Administration said on April 5.
Investor-owned utilities' customers averaged about four hours without electric service, while co-op customers averaged about six hours without electric service, EIA said in its “Today in Energy” report.
Providing reliable electric service is a hallmark of public power utilities, noted Michael Hyland, the American Public Power Association's Senior Vice President of Engineering Services. “It is extremely gratifying to see public power’s dedication to reliability confirmed in the EIA data,” he said.
EIA collects data on the frequency and duration of outages for three broad categories of distribution utilities – IOUs, cooperatives and public power utilities.
In 2016, utilities in these three groups that reported their outage information to EIA collectively made up only 34% of all utilities but accounted for about 91% of electricity sales, the federal agency noted.
Interruptions in electricity service vary by frequency and duration across the many electric distribution systems that serve about 145 million customers in the United States, EIA said. In 2016, customers experienced an average of 1.3 interruptions and went without power for four hours during the year. “Although some distribution customers have backup generators that provide auxiliary power, most customers are without electricity when outages occur,” the report noted.
The reliability of electricity supply systems is generally measured using two metrics that show the duration and frequency of outages: System Average Interruption Duration Index and System Average Interruption Frequency Index.
Outage frequency and duration values are reported to EIA for any interruption lasting longer than five minutes. Utilities may designate if these outages occurred during major events, which can include snowstorms, hurricanes, floods, or heatwaves. Utilities can also designate periods of outages that differ greatly from its five-year history as a major event.
EIA said that in 2016, when major events are excluded, the average U.S. electricity customer was without power for 112 minutes and experienced one outage. When major events are included, the numbers increase by 138 minutes without power and 0.3 outage occurrences to a total of 250 minutes and 1.3 outages.
Association recognizes public power utilities
The Association recently recognized 128 public power utilities with a "certificate of excellence" for reliable performance, as shown by comparing their outage records against nationwide data gathered by EIA.
These utilities track their reliability data via the Association's web-based subscription service, called eReliability Tracker, which lets utilities collect, categorize and summarize their outage information.
Public power utilities are also recognized for their reliability efforts through the Reliable Public Power Provider (RP3) designation from the Association.
The RP3 designation, which lasts for three years, recognizes public power utilities that demonstrate proficiency in four key disciplines: reliability, safety, workforce development and system improvement.
Criteria include sound business practices and a utility-wide commitment to safe and reliable delivery of electricity.