The annual PUC report tracks reliability and reliability-related spending by the state’s investor-owned electric utilities with distribution service.
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This online glossary includes definitions of important ERCOT-related terms.
Oncor Electric and CenterPoint Energy — the state’s two largest electric transmission and distribution utilities — have more than doubled their gross capital expenditures for additions to their distribution systems, according to a new report filed with the Texas Public Utility Commission.
Entitled “Electric Utility Distribution System Spending and Reliability,” the annual PUC report tracks reliability and reliability-related spending by the state’s investor-owned electric utilities with distribution service. Included in the report are data for Oncor and CenterPoint, plus six other utilities: El Paso Electric, Entergy Texas, Sharyland, Southwestern Public Service Company, Southwestern Electric Power Company and Texas-New Mexico Power. PUC staff released the report earlier this month.
Oncor and CenterPoint hold positions roughly in the middle of the pack as compared to other distribution utilities with regard to the frequency and duration of outages, the report shows. However, the Sharyland distribution system — a system acquired by Oncor in December 2016 — rates comparatively high among all utilities on both counts, according to the report.
The report benchmarks the frequency of outages through a “System Average Interruption Frequency Index,” or “SAIFI”. SAIFI measures the average number of service interruptions per customer — a figure calculated by summing the number of customers interrupted for each event and dividing that figure by total customers. (All else held equal, lower SAIFI figures indicate better reliability.) The report shows CenterPoint with an average annual SAIFI of 1.95 and Oncor with an average annual SAIFI value of 1.67 for the years 2011 through 2020. However, the distribution utility with the highest average annual SAIFI during the 2011-2020 period was Sharyland, with a score of 3.16. The utility with the lowest annual annual average SAIFI among those surveyed was Texas-New Mexico Power, with a .89.
Separately, the report employs the “System Average Interruption Duration Index” or “SAIDI,” to rank Texas distribution utilities. SAIDI, expressed in minutes, measures the average interruption time on a per-customer basis. All else equal, a lower SAIDI represents better reliability.
CenterPoint’s average annual SAIDI was 216.03 minutes for the years 2011-2020, while Oncor’s had an average annual SAIDI for that period of 239.96 minutes. Sharyland’s average annual SAIDI was 518.79 minutes, the second highest among those surveyed. The utility with the highest annual average SAIDI was Entergy Texas, with annual average per customer outage time of 704.24 minutes during the survey period. However, much of Entergy’s high SAIDI was attributable to damage-related outages following Hurricane Harvey. El Paso Electric had the lowest annual average SAIDI, at 85.65 minutes.
The report also includes a number of charts showing distribution system spending and reliability calculations by utility. The charts do not include specific numerical values, but do include graphical representations of spending and reliability trends.
Report highlights pertaining to Oncor include:
- A chart on page 51 appears to show that ONCOR had SAIDI attributable to “forced” interruptions at a bit less than 100 minutes per customer in 2011. (“Forced” outages are the result of mechanical failures or human error.) The chart also shows Oncor’s SAIDI number dropping somewhat by 2019, to roughly around 75 minutes. Oncor also reported “forced” SAIFI of approximately .9 in 2011, according to an examination of a separate chart on page 50. By contrast, in 2019 SAIFI attributable to “forced SAIFI” was about .8 per customer. Forced interruptions are those related to equipment failures or human error.
- The report shows Oncor’s expenditures on gross capital additions on its distribution system more than doubling in recent years. From an examination of a chart on page 45, it appears that spending in this category went from between $300 million and $400 million in 2011 to more than $1 billion in 2019. Similarly, gross capital addition spending per distribution customer more than doubled, from a bit more than $100 per customer in 2011 to about $270 in 2020, according to an examination of a separate chart on page 45. These figures exclude spending on meters.
- Oncor distribution operation and maintenance spending (again excluding spending for meters) generally increased between 2011 through 2020 — although the company registered year-to-year declines periodically. Distribution O&M spending in 2011 was slightly above $150 million, according to an examination or a chart on page 48. In 2020, it was slightly above $250 million. On a per customer basis, that spending went from about $50 in 2011, to around $70 in 2020.
- In 2013, Oncor spent approximately $70 million on vegetation management on its distributions system, and in 2019, it spent a bit less than $90 million, according to a chart on page 49. On a per customer annual basis, Oncor spent approximately $22 for vegetation management on its distribution system in 2013, compared to about $23 million in 2020. Those figures include both routine and storm-related vegetation management spending.
Report highlights pertaining to CenterPoint include:
- A chart on page 19 of the report shows that the Houston-based utility more than doubled its gross capital additions on its distribution system — from approximately $180 million in 2010 to approximately $425 million in 2019. Similarly, distribution gross capital spending per customer increased from about $80 in 2010 to about $160 in 2019. These figures exclude spending on meters.
- CenterPoint’s distribution operations and maintenance spending (excluding meters) increased from around $160 million in 2010 to around $220 million in 2019, according to a chart on page 22. CenterPoint’s distribution O&M spending per customer (excluding meters) increased from about $75 in 2010 to $85 in 2019. However, the utility also recorded year-to-year fluctuations with regard to its per customer O&M distribution expenditures, and reached the high mark in 2018 of about $95.
- In 2012, CenterPoint spent approximately $27 million on vegetation management on its distributions system, and in 2019, it spent approximately $32 million. On a per customer basis, CenterPoint spent approximately $13 for vegetation management on its distribution system in 2013, and a similar per-customer amount in 2019. Those figures include both routine and storm-related vegetation management spending.
- CenterPoint reported SAIFI attributable to major events (such as from major storm damage) in 2010 at about 1.5 per customer, and “forced” SAIFI (from equipment failures) of about 1.1. By contrast, in 2019 SAIFI attributable to major events was about .1, and “forced SAIFI” was about 1.3.
- CenterPoint reported SAIDI attributable to forced interruptions at around 80 per customer in 2010, and about 150 in 2019. CenterPoint reported SAIDI attributable to major events at less than 25 per customer in 2010 and between 25 and 50 in 2019.
Electric Utility Distribution System Spending and Reliability report can be found on the PUC website, on the project interchange page, at Docket #46735. For a glossary of useful utility and ERCOT terms, go to this link.
Is a policy analyst consultant for TCAP, a coalition of political subdivisions in Texas that purchase electricity in the deregulated market for their own governmental use. Because energy costs are typically a significant budget item to our members, TCAP is consistently looking for ways to save our members money, through cost-saving contracts, energy efficiency or demand response programs.