LANSING, Mich. — The results of a state-commissioned audit of Michigan's two largest utility companies were made public this week, highlighting root causes of electrical grid unreliability and long service restoration times.
The Michigan Public Service Commission (MPSC) used an independent third-party to conduct the audit of Consumers Energy Co. and DTE Electric Co.
The over year-long audit process, conducted by The Liberty Consulting Group, focused on the utilities' infrastructure, programs and processes, poles and wires, substations and records from the companies.
MPSC Commissioner Katherine Peretick said the commission chose to conduct the audit because of the two utility company's electric service reliability just not being up to par.
"Michiganders really deserve better reliability than what we have right now. So in 2022 we decided to do a real deep dive into the electric distribution system of both Consumers Energy and DTE Electric, and compare them to some similar utilities in the Midwest, and see what we can learn about where the state of the distribution systems are currently. But I think even more importantly, where are those areas that we can be focusing on to improve the electric reliability and invest in cost effective ways to to improve that reliability," said Peretick.
The audit report provided dozens of recommendations to the two utility companies to improve their reliability.
"They came up with all of these ways that both of the utilities can improve their infrastructure, but also improve their processes and procedures that will hopefully translate into improved electric reliability," said Peretick. "So we're going to take those recommendations allow the utilities to respond first, hopefully they'll just start working on some of those recommendations now without us telling them to. But then if we need to tell them to, we have ways of doing that."
Consumers Energy ranked in the bottom 25% of utility companies when it came to average outage time for customers in 2022 and 2023 at about 10 hours and 30 minutes. Two comparable utility companies in Illinois saw average of outage times of seven hours and two hours and 30 minutes.
"So pretty big differences there, and we're really hoping that with some of these improvements to those processes and procedures, but I think even more importantly, just better vegetation management, or tree trimming, is really what is going to help drive that 10 and a half hours down closer to, you know, that benchmark of two and a half," explained Peretick.
That relatively low tech recommendation could make a huge difference, according to the audit. Consumers Energy aims for a five to nine year tree trimming cycle, but in practice, tree trimming more often occurs on a 10 year cycle due to backlog, the audit found.
"10 years is a long time for trees and branches and vines to grow," said Peretick. "That is a huge contributor to the the poor reliability that we're seeing. 10 years, you can have a pretty big branch that grows over over an electric wire, and then when a strong wind or storm or ice storm comes through, you know, it'll fall onto that wire, and then you'll and then you'll have a longer outage. So what the utility audit is recommending is to bring that cycle, which is currently much higher, bring that to about a five year cycle."
Another major contributor to the outage times is Consumers Energy's utility poll maintenance protocol. Right now, Consumers aims to replace utility polls after a 40-year service, whether it is in poor condition or not. An audit recommendation suggests that changing the policy could lead to better reliability.
"Instead of just replacing all of the polls every 40 years, go inspect them and figure out which ones actually need to be replaced, and replace them on condition basis, rather than on age basis. So if that poll, even if it's a smaller diameter pole and it's, you know, 45 years old, but it still looks okay, we don't need there's no point in spending money and replacing that," said Peretick.
The audit also found that over 60% of Consumers Energy's low-voltage utility polls were classified as small-diameter.
It wasn't all shortcomings in Consumers Energy's audit results, Peretick pointed out a couple positive takeaways from the utility company as well.
"I think one of the one of the positive takeaways that came out of this audit is that both companies, including including Consumers, have a pretty good inventory and pretty good handle on their distribution infrastructure. So they do understand, you know, where their polls and wires and substations are, how they're maintained. They're well recorded in their books and and they're generally in pretty good shape," said Peretick.
Peretick also noted that Consumers Energy was very cooperative with the audit, which was promising that the utility company was eager to learn from the results and take into consideration all of the findings.
"Consumers Energy was was really open with providing detailed and thorough responses to the auditor for anything that they asked for. And that's that's really encouraging, and the company is really looking at this as a way of improving," Peretick added.
Now that the audit is complete, the utility companies have until Nov. 15 to respond to the recommendations. Then, the public has a chance to comment on the recommendations and the companies' responses until Dec. 15.
The MPSC will take the responses and the public comment and then decide if any actions need to be taken to require implementation of the recommendations.
Consumers Energy told 13 ON YOUR SIDE that since the audit is part of an open MPSC case, they won't respond to specific findings until the case concludes. However, the utility company provided the following statement in response to the audit results:
“The MPSC audit on our company’s storm response has been constructive, and we appreciate the deep experience and expertise Liberty brought to the process. Consumers Energy proactively provided data, information and access to our facilities to Liberty. Michiganders are facing more severe and frequent storms, which is why we announced our Reliability Roadmap in 2023, a blueprint for fewer and shorter outages including no customer going more than 24 hours without power. Our investments are focused on the customers we serve by adding technology, burying power lines and clearing trees. Consumers Energy will continue to advocate to build a smarter and stronger power grid that serves Michigan reliably 24/7.”
Some of the key findings from the audit of Consumers Energy were published on the MPSC website, and are also listed here:
- Consumers’ 2022 and 2023 CAIDI metrics both including and excluding MEDs were in the 4th Quartile, worse than average among utilities. Consumers’ 2022 and 2023 SAIDI metrics placed them in the 4th Quartile including MEDs and in the 3rd Quartile excluding MEDs.
- Consumers operates an unusually high number of different low distribution voltages, owing to mergers over the years with legacy utilities. This requires Consumers to use isolating transformers to connect circuits with different voltages. The diverse and non-standard substation and circuit assets require the utility to maintain mobile substations and additional inventory beyond what’s needed for standard voltage substations and circuits.
- About 62% of Consumers’ low voltage distribution poles are classified as small-diameter class 5, 6 and 7, which are more susceptible to breaking in storms.
- As many as 18% of Consumers customers have electric distribution infrastructure in difficult-to-service back lots.
- Consumers aims for a tree trimming cycle of 5 to 9 years, depending on circuit voltages, for an average or “effective cycle” of 7 years. But in practice, the current average effective cycle is nearly 10 years because of a trimming backlog. Shortening the cycle is a significant, cost-effective way to reduce outages.
- More than 10% of Consumers’ customers experienced four or more interruptions (CEMI4) and more than 25% of its customers experienced interruptions of eight hours or more (CELID8hours) in 2023.
- The utility’s use of catchall “weather” and “unknown” cause codes for outages is imprecise and masks what actually causes outages.
- Consumers’ low voltage distribution lines have consistently caused the most SAIDI minutes, approximately 87%.
The audit also looked at DTE Energy, which is the major provider of energy in and around the Metro Detroit region. Some of the key findings from the audit of DTE include:
- DTE Electric’s 2022 and 2023 Customer Average Interruption Duration Index (CAIDI) metrics, which measure the average time required to restore service, were in the 4th Quartile when both including and excluding major event days (MEDs), worse than average among utilities.Major event days occur when the distribution system experiences major impacts, such as from extreme weather.
- DTE Electric’s 2022 and 2023 System Average Interruption Duration Index (SAIDI) metrics were in the 4th Quartile including MEDs and in the 3rd Quartile excluding MEDs. SAIDI measures the total number of minutes of interruption the average customer experiences.
- About 45%, or about a million of DTE Electric’s customers, are served by an ungrounded 4.8 kilovolt (kV) system that requires more time to locate and fix faults than more modern 8.3 kV and 13.2kV systems, and also exposes workers and the public to direct higher risk of electric shock hazards.
- Nearly 40% of DTE Electric’s 4.8kV substation transformers were installed between 1924 and 1960, and some of its 13.2 kV transformers date to the 1960s, older than comparable utilities’ transformers. The condition of transformers, and not solely their ages, should drive transformer replacement, and periodic excessive loadings leave DTE Electric with a high substation transformer failure rate.
- The company doesn’t track the age of its service transformers and in many cases doesn’t track the number of customers served by the transformers.
- About 40% of the utility’s circuit breakers and reclosers were installed between 1930 and 1960. Its legacy oil circuit breakers need more intense maintenance and lack in performance compared to modern gas circuit breakers.
- More than half of DTE Electric’s overhead primary lateral lines are located in back lots, including brush-filled alleys in Detroit and some older suburbs. It’s more costly to maintain these circuits and trim trees near them because of the difficulty of getting equipment to these locations.
- DTE Electric aims to have its lines trimmed of trees every five years, but the effective cycle is currently 5-7 years. Utilities with shorter vegetation management cycles have seen significant reductions in outages.
- The number of DTE Electric customers experiencing four or more interruptions (CEMI4) each year and the numbers experiencing more than eight hours of interruption (CELID8hours) are greater than usually acceptable for utilities. More than 13% of DTE Electric customers experienced four or more interruptions in 2023, and nearly 45% experienced interruptions of eight hours or more.
- Approximately 88% of all DTE Electric customer outages are caused by the distribution circuits.
You can find the complete audit and accompanying filings here.
The MPSC heard a presentation of the audit findings from The Liberty Consulting Group Thursday, you can watch that commission meeting here: