An audit of DTE Energy and Consumers Energy, the two largest utility companies in Michigan, scrutinized both companies' response times to power outages, highlighted outdated and potentially unsafe equipment on the respective electric grids and found both companies take longer than targeted to trim tree branches hanging over power lines.
The third-party audit, commissioned by the Michigan Public Service Commission in 2022 and released this week, gives a glimpse into the oft-criticized utility companies, which both have faced barbs from customers upset with power outages and frequent rate increases. In the audit, DTE and Consumers were compared with two other private utilities, Illinois-based Commonwealth Edison and Ameren Illinois, along with the publicly owned Lansing Board of Water and Light in Michigan.
Liberty Consulting Group’s more than yearlong audit found both DTE and Consumers have worse-than-average response times to power outages, according to an index of average outage durations used by utilities. Both Detroit-based DTE and Jackson-based Consumers are in the bottom quarter of the Customer Average Interruption Duration Index (CAIDI) for the average duration of service outages customers faced in 2022 and 2023 — meaning they were among the worst-performing utilities when it comes to getting the power back on.
Both DTE and Consumers were in the bottom quarter of CAIDI for average outage duration both when accounting for and excluding outage days caused by major storms or adverse weather.
The audit found about 13% of DTE's 2.3 million customers faced at least four power outages in 2023, and 45% of DTE customers faced an outage lasting at least eight hours. For Consumers, more than 10% of the company's 1.8 million customers had the power go out at least four times last year, and more than 25% of customers had an outage of least eight hours, according to the audit.
Both utilities have outlined plans to improve the reliability of their electric service, including modernizing the grids to get the power back on faster during outages. Liberty’s audit found sizable chunks of each company’s infrastructure are decades or even more than a century old.
Aging infrastructure
Approximately a fifth of DTE’s subtransmission system, used to move electricity from power lines to substations, and more than a quarter of its distribution poles were installed more than 60 years ago, Liberty found. The age of the poles isn’t a sole factor for spotty reliability but are relatively older than infrastructure for other utilities, according to the audit.
Nearly 40% of DTE’s substation transformers were installed before 1960, with some dating as far back as 1924. Around 40% of the company’s circuit breakers were installed between 1930 and 1960, according to the audit. The audit also noted DTE doesn’t track the ages of the service transformers on its grid.
The audit also stated 45%, or just over 1 million, of DTE's electric customers are serviced by an ungrounded 4.8 kilovolt (kV) system, which take longer to repair than 8.3 kV and 13.2 kV systems which service the rest of the grid. The 4.8 kV system also poses more of a safety risk, the audit stated, since power lines on the system may not automatically be powered down in case of an overhead circuit being grounded. DTE has been using 4.8 kV circuits since the early 1900s, according to the audit.
Consumers also has aged infrastructure, per the audit — around 45% of the company’s substations were installed between 1903 and 1960, including a large portion installed in the 1950s.
Tree woes
Both major utilities have pointed to routine tree trimming as a way to reduce the frequency of power outages. By cutting down tree branches hanging over power lines, company officials have stated there’s less of a chance of downed lines during major storms.
Liberty’s audit found both DTE and Consumers take longer to trim trees over power lines than their stated goals — DTE’s current average tree trimming cycle is five to seven years, longer than the targeted five-year cycle, while Consumers aims to trim trees every seven years, on average, but its effective cycle is actually 10 years.
The audit also found both DTE and Consumers have portions of their electric grid in areas difficult to access, including "brushed filled alleys," in DTE's case. The difficulty in accessing these lots leads to longer times to get the power back on, the audit stated. More than half of DTE’s overhead primary circuits are in back lots, while about 16% to 18% of Consumers’ customers are served via back lots.
The audit’s findings are expected to be presented to the Michigan Public Service Commission, the appointed body tasked with overseeing private utility companies in Michigan, during its Thursday meeting in Lansing.
The full audit is currently available online at the MPSC’s e-docket.
“The audit underscores that now is the time for both companies to focus more on strategic investments to prevent outages rather than reacting to them,” MPSC Chair Dan Scripps said in a news release.
Utilities say they have a plan
Officials from DTE and Consumers commended the audit's findings and said service reliability will improve if the utilities can implement proposed strategies to update their grids. The MPSC has signed off on rate increases in recent years for both utilities, including portions of plans to improve service reliability.
“We appreciate the audit team confirming that DTE’s proposed investment plan will deliver the dramatic improvement in reliability that our customers demand and deserve in the next five years as well as recognizing the talent and experience of our team,” Matt Paul, DTE Electric president and CEO, said in a statement. “They also point out that our plan is both ambitious and aggressive, and we accept that challenge."
Katie Carey, Consumers Energy’s director of external relations, referenced the company’s “reliability road map,” a five-year plan unveiled last year which calls for investing billions into the company’s electric grid.
“Our investments are focused on the customers we serve by adding technology, burying power lines and clearing trees,” Carey said in an email to the Free Press. “Consumers Energy will continue to advocate to build a smarter and stronger power grid that serves Michigan reliably 24/7.”
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Contact Arpan Lobo: [email protected]
