Beth LeBlancThe Detroit News
Lansing — Michigan's two largest utilities had "worse than average" interruptions and restoration delays than other utilities, and tree-trimming cycles for both DTE Electric and Consumers Energy were more delayed than their colleagues', according to a third-party audit that state regulators released Monday.
The audits of the two utility companies — which serve about 4.1 million customers or about 80% of Michigan's electric customers — were ordered by the Michigan Public Service Commission in 2022 "amid a string of widespread outages and public frustration with unreliable service." The analyses were performed by Pennsylvania-based The Liberty Consulting Group and are considered a first of their kind for the state's two largest utilities.
The reports paint a picture of attempts to slowly replace or repair aging infrastructure and prune damaging branches and trees amid major weather events that have consistently disrupted services for hundreds of thousands of Michigan residents in recent years.
The audit, public service commission Chairman Dan Scripps said, provides "a roadmap to achieving a grid that meets customer expectations.
"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," Scripps said.
Commissioner Katherine Peretick said the reports provided "unprecedented transparency" into the utilities' infrastructure, while Commissioner Alessandra Carreon said state utility regulators have never had "this deep of a look" at the utilities' equipment, maintenance and tree trimming schedules.
Liberty Consulting Group is expected to present its findings to the commission at its Thursday meeting in Delta Township.
“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," Consumers Energy spokeswoman Katie Carey said in a statement.
DTE Electric President Matt Paul said the Detroit-based utility company is still reviewing the audit but remains "laser-focused" on a goal of reducing power outages by 30% by 2029.
“We are always looking for ways to improve our processes and programs and thank the audit team for recognizing our progress, as well as providing recommendations on improvements we can make to better serve our customers," Paul said.
The audits found that both Consumer and DTE's customer average interruption duration index in 2022 and 2023 — the average time it takes to restore service — was worse than average among other utilities, ranking in the fourth quartile for reliability. The report also noted in those same years that the number of Consumers and DTE customers who experienced four or more outages as well as the customers that experienced outages of 8 hours or more was "greater than usually acceptable for utilities," again ranking the fourth quartile compared to other utilities.
In 2023, 25% of Consumers customers had outages lasting more than eight hours and 10% of its electricity customers had four or more interruptions that lasted more than five minutes.
DTE customers that same year fared worse, according to the audit. In 2023, more than 13% of DTE customers had four or more interruptions and 45% had outages greater than 8 hours.
The report noted "two similarly situated investor-owned utilities," Ameren Illinois Co. in southern Illinois and Commonwealth Edison Co. in northern Illinois, had four-year tree trimming cycles and rated better than DTE or Consumers for consumer outages and restoration.
Consumers, by comparison, is targeting a five-year, seven-year or nine-year trimming cycle depending on circuit voltage, but its current average is almost 10 years, "and it still has backlogged circuits awaiting trimming," the report said.
DTE, for its part, is targeting a five-year tree trimming cycle and currently averages five to seven years, the report said.
The Lansing Board of Water and Light, which serves about 100,000 customers in the Lansing area, greatly increased its ranking "after spending significantly" to manage vegetation rather than invest in automation, according to the report.
The report did not find that Consumers' electricity distribution assets were of advanced age compared with other systems, but underscored the age of some of DTE's assets.
For DTE, its underground mainline or "system" cable dates to the early 1900s, and underground residential distribution cable dates back to the late 1960s. The report noted, in 2023, the company had 255 system cable failures and 864 underground cable failures.
Additionally, about 20% of DTE's subtransmission and 28% of its distribution poles were installed more than 60 years ago. About 40% of DTE's 4.8 kV substation transformers date before 1960, including some going back a century to 1924, and some of its 13kV transformers dating back to the 1960s, according to the report.
"These circumstances make a portion of the company’s (DTE's) substation transformer plant more aged than that of similarly situated utilities," the report said. "While condition rather than age should drive transformer replacement, periodic excessive loadings contribute to high DTE’s substation transformer failure rates."
The report also noted about 16-18% of Consumers' 480-volt or less service transformers and 52% of DTE's overhead primary circuits were located in backlots, making it difficult to access them for maintenance and tree trimming.
Consumers is focusing its spending in the electric grid on new technology, burying power lines and clearing tree limbs that can fall during storms and disrupt service, Carey said.
"Consumers Energy will continue to advocate to build a smarter and stronger power grid that serves Michigan reliably 24/7," she said.
eleblanc@detroitnews.com
