Star Tribune
The massive, centralized systems that keep the Twin Cities comfy
Below the downtown streets of Minneapolis and St. Paul is the key to keeping the Twin Cities comfortable on the year’s hottest and coldest days.
Most people aren’t aware of them, but the centralized district energy systems that span both downtowns heat and cool hundreds of buildings and homes year round — including major structures ranging from the State Capitol, to U.S. Bank Stadium to the IDS Tower.
“The honest truth is, 95% of people or more don’t have any idea what we do or that we even exist,” said Jacob Graff, regional general manager for Cordia Energy, which heats and cools about 100 buildings across downtown Minneapolis.
Ken Smith, president and CEO of District Energy St. Paul, said his facility also operates in relative obscurity, although many residents are familiar with the plume the site gives off along Kellogg Avenue on cold days.
“It’s water vapor,” Smith said, noting the system gets about half its energy from burning tree waste. “The colder it is, the more you see it.”
How it works
Central facilities create steam or hot water and chilled water that’s sent to customers through insulated underground pipes in a closed loop. Satellite locations help with demand.
Buildings and homes use that energy for their heating and cooling needs. When the water is no longer at a useful temperature, it returns to the plants through the piping loop.
Both systems use a process called combined heat and power generation that burns fuel, such as wood chips or natural gas, to power turbines, boilers and water chillers.
How the systems differ
In St. Paul, District Energy and its subsidiary Ever-Green Energy operate the largest hot water heating system in North America, spanning more than 200 buildings. Tree waste is the primary fuel, but natural gas also creates steam that powers a turbine and makes electricity.
About two-thirds of that electricity is sold to Xcel Energy. The remainder helps power the system. Residual, lower-pressure steam makes hot water for heating.
In Minneapolis, Cordia Energy operates a steam centralized heating system. Its biggest plant is in the heart of downtown, encircled by a parking ramp.
Cordia also uses a combined heat and power system with natural gas as the primary fuel. Boilers create heat to produce steam and hot water and run compressors that chill water.
Why are these systems there?
Advocates for district energy systems say they are more efficient than individual heating and cooling systems. They almost never go offline because there is so much redundancy built into the plants.
“The thing about district energy is you need to be there, all the time,” Graff said, noting that even brief outages are noticed. “It can be 20 minutes, once every 20 years, but they are going to remember those 20 minutes.”
District energy plants have been around more than a century and are growing in popularity. Colleges like the University of Minnesota, hospitals like Hennepin County Medical Center and big cities from New York to San Francisco use them.
When they were built
Minneapolis’ system dates to the early 1970s and was built to heat and cool the IDS Center, the city’s tallest building. Over the past 50 years the system has grown with the city and now stretches from Target Field to U.S. Bank Stadium.
St. Paul’s system rose out of an old steam heating site that was slated for closure in the late 1970s. Instead, then Mayor George Latimer and city officials looked to Swedish engineer Hans Nyman to create a hot-water central heating system they hoped would be a national model.
Biomass and the HERC
The Minnesota Legislature made some policy and spending decisions this year that will affect district energy systems in both cities.
St. Paul District Energy received $16 million in grants to burn ash trees removed because of the emerald ash borer. Policy changes will help the site keep selling excess power to Xcel.
“If we were not taking this wood waste, it would have to be open burned,” Smith said.
Changes in state law mean the Hennepin County Energy Recovery Center (HERC), which burns trash to create electricity and steam, will no longer be considered a green energy provider after 2040. Cordia buys steam from the HERC, and Hennepin County officials are looking at plans to close the facility before 2040.
Environmental challenges
District energy systems are efficient, but that doesn’t mean they don’t have emissions. The St. Paul facility burns about 240,000 tons of tree waste a year. The Minneapolis plant is one of Hennepin County’s largest users of natural gas.
But system leaders say their emissions are significantly lower than if each customer was heating and cooling their own building. Both systems aim to be carbon free by 2050.
To get there, Smith said district energy will need to tap into a mix of clean energy sources, something that’s not feasible for individual customers. “I can deploy a lot more technologies and techniques than an individual building,” he said.
It’s already happening. St. Paul provides carbon-neutral cooling to all of its customers through renewable energy credits and uses solar to heat some of its water.
Minneapolis also is exploring cleaner energy sources and constantly looking for ways to be more efficient. “Every project we do has a piece of it that’s improving our efficiency,” Graff said.
Two people from Minnetonka were killed late Friday afternoon when their GMC Suburban ran a stop sign and was struck by a GMC Yukon headed north on Hwy. 169 west of Palisade, Minn.
According to the State Patrol, Marlo Dean Baldwin, 92, and Elizabeth Jane Baldwin, 61, were dead at the scene. The driver of the Suburban, a 61-year-old Minnetonka man, was taken to a hospital with life-threatening injuries.
The Suburban, pulling a trailer, was headed east on Grove Street/County Rd. 3 at about 5:15 p.m. when it failed to stop at Hwy. 169 and was struck by the northbound Yukon. The Yukon then struck two westbound vehicles stopped at the intersection.
Four people from Zimmerman, Minn., in the Yukon, including the driver, were taken to HCMC with life-threatening injuries, while two passengers were treated for non-life-threatening injuries. Three girls in the Yukon ranged in age from 11 to 15.
The drivers of the two vehicles struck by the Yukon were not injured, the State Patrol said. Road conditions were dry at the time of the accident, and alcohol was not believed to have been a factor. All involved in the accident were wearing a seat belt except for Elizabeth Baldwin.
Hill City police and the Aitkin County Sheriff’s Office assisted at the scene.
Amid the cacophony and chaos of the pregame preparation before a recent Minnetonka High School football game, an exceptional group of six girls is gathered together among the school’s deep and talented cheerleading and dance teams.
The cheerleaders, a national championship-winning program of 40 girls, dot the track around the football field. As the clock ticks down to kickoff and their night of choreographed routines begins, the six girls, proudly wearing Minnetonka blue T-shirts emblazoned with “Skippers Nation” and shaking shiny pom-poms, swirl around the track, bristling with excited energy.
Their circumstances are no different from any of the other cheerleaders with one notable exception: The girls on this team have special needs.
They’re members of the Minnetonka Sparklers, a squad of cheerleaders made up solely of girls with special needs.
A football game at Minnetonka High School is an elaborate production. The Skippers’ recent homecoming victory over Shakopee brought an announced crowd of 8,145. And that is just paying attendees; it doesn’t include school staffers, coaches, dance team, marching band, concession workers, media members and others going about their business attached to the game.
The Sparklers program, now in its 12th season, was the brainchild of Marcy Adams, a former Minnetonka cheerleader who initiated the program in her senior year of high school. Adams has been coach of the team since its inception, staying on through her tenure as a cheerleader at the University of Minnesota.
She started the program after experiencing the Unified Sports program at Minnetonka. The unified sports movement at high schools brings together student-athletes with cognitive or physical disabilities and athletes with no disabilities to foster relationships, understanding and compassion through athletics. Many Minnesota schools offer unified sports.
“I grew up in a household that valued students with special needs and valued inclusion,” Adams said. “I saw a need to give to those students. At Minnetonka, we have a strong Unified program, and this was a great opportunity to build relationships and offer mentorship opportunities.”
Elite runners are in a league of their own.
To get a sense of how far ahead elite runners are compared to the rest of us, the Minnesota Star Tribune took a look at how their times compare to the average marathon participant.
The 2022 Twin Cities Marathon men’s winner was Japanese competitor Yuya Yoshida, who ran the marathon in a time of 2 hours, 11 minutes and 28 seconds, for an average speed of 11.96 mph. He averaged 5 minutes and 2 seconds per mile.
That’s more than twice the speed of the average competitor across both the men’s and women’s categories, of 5.89 mph, according to race results site Mtec. The average participant finished in 4 hours, 26 minutes and 56 seconds. That comes out to an average time of 10 minutes and 11 seconds per mile.
And taking it to the most extreme, the fastest-ever marathon runner, Kelvin Kiptum of Kenya, finished the 2023 Chicago Marathon in 2 hours and 35 seconds, for an average pace of about 13 mph. Kiptum averaged 4 minutes and 36 seconds per mile.
Here is a graphic showing these differences in average marathon speed.
