The operators of the decades-old energy systems that heat and cool buildings in downtown Minneapolis and St. Paul have ambitious plans underway to reduce emissions.

The mostly hidden networks of insulated pipes connected to centralized heating and cooling equipment are known as district energy systems. They’ve long been championed as an energy efficient way to heat and cool campuses or downtowns, especially in cooler climates.

Many, though, are connected to fossil fuel facilities, and the systems’ high efficiency alone won’t be enough to help schools, cities, and companies meet their goals of eliminating greenhouse gas emissions by midcentury or sooner. Climate pledges by these institutional customers are now driving efforts to repower district energy systems with clean energy.

University district energy systems began initiatives to reduce emissions years ago and “now in the last five years we’re seeing a lot of emphasis on this from cities and towns,” said Rob Thornton, president and CEO of the International District Energy Association. 

In Minneapolis, Cordia Energy, the private company that operates the largest downtown district energy system, is replacing natural gas boilers with electric models. And in downtown St. Paul, officials are seeking federal funding for a project to recover heat from a wastewater treatment plant and reduce energy use for a system currently powered by electricity and biomass.

“We’re doing decarbonization at the rate that our customer base is asking for and we can economically withstand,” said Jacob Graff, Cordia Energy’s north region president. Customers connected to its downtown Minneapolis system range from stadiums and high rises to apartments and medical facilities.

From ancient Rome to skyscrapers

The concept of district heating has been around for centuries, with its roots in the networks of hot water pipes built in ancient Rome. Some of the first modern steam-based systems were built in New York in the 1880s. Today, the United States has more than 700 district energy systems heating and cooling buildings in downtowns, universities, medical campuses, towns and communities.

Cordia Energy’s Minneapolis system opened in 1972 to serve the 57-story IDS Center, still the tallest building in Minneapolis. Today, the steam and chilled water system manages seven plants that heat and cool the IDS and more than 100 other buildings, including U.S. Bank Stadium, Target Center, and the convention center.

Hennepin County owns and operates a much smaller district energy system, connected to a downtown trash incinerator, that primarily serves county buildings and Minneapolis City Hall.

District Energy St. Paul began in the early 1980s after then-Mayor George Latimer hired Swedish engineer Hans Nyman to replace the aging steam system with a hot-water central heating system. Latimer wanted to create a national model of district energy and he largely succeeded. District Energy St. Paul has the largest hot water system in the country, with more than 200 buildings.

Together, the two systems serve some of the state’s biggest buildings, which have emerged as the largest source of greenhouse gas emissions in both cities. In Minneapolis, 65% of the emissions are from commercial, multifamily and industrial buildings. St. Paul’s data is similar.

Tapping clean electricity in Minneapolis

Cordia plans to reduce emissions from its Minneapolis system by 30% by 2030 before reaching net zero by 2050. Xcel Energy’s green tariff program will offset around half the electricity Cordia uses this year, and it wants to buy more credits if they become available.  

The company is replacing older engine-driven chillers with electric models at the former Dayton’s department store, where it has operations. Chillers modulate the temperature inside buildings and can be powered by electricity or natural gas. Geothermal is another potential solution being studied.

A potential geothermal project “hasn’t cleared the economic hurdles yet,” Graff said. “I think we’ll eventually get there.”

Minneapolis customers are not alone in seeking to reduce emissions from district energy systems, Graff said. San Francisco will be Cordia’s first system to decarbonize using hydropower from a dam the company owns in Yosemite National Park.

St. Paul looks to waste heat recovery

Downtown St. Paul’s district heating system is owned and operated by a company called District Energy, which recently worked with the city and the regional planning agency on a $152 million U.S. EPA grant application to tap heat from a regional wastewater plant for the city’s system. It would include a project with Xcel Energy to pay for an electric boiler and hot water storage. 

District Energy president and CEO Ken Smith said half the system already has been decarbonized through biomass, solar thermal and renewable energy credits. An analysis showed that recovering heat from the Metro Wastewater Treatment Plant, which manages 170 million gallons of water daily, could produce 60 megawatts of thermal energy, and heat pumps could lift the temperature up to the system average.

If District Energy receives the Climate Pollution Reduction Grant, the system would go live in 2028 and allow District Energy to provide 92% of energy from carbon-free or carbon-neutral sources, far ahead of its goal of net zero by 2050.

“This certainly would be able to accelerate that by 30 years,” Smith said. “From everything we’ve seen, there’s nothing like this, certainly not in the United States, and I don’t believe there’s anything like it at this scale in Canada, either.”

St. Paul Resilience Officer Russ Stark said District Energy’s emissions represent a small portion of the total greenhouse gases in the city. Still, around 50,000 tons of carbon would be eliminated annually, and that’s “very impactful,” he said.

The wastewater project would allow District Energy St. Paul to expand to more buildings, decarbonizing them in the process, Stark said. Adding clients “is not a simple process but we’ve been talking a lot about that being an exciting part of the project,” he said. “I don’t know how many major city downtowns there are where there’s an opportunity to largely decarbonize most of the downtown in the way that we can.”

Systems face unique, local challenges

A one-size-fits-all solution for decarbonizing district energy systems doesn’t exist, as most are unique based on customers and geography. Not all can be inexpensively retrofitted for electricity, and the ongoing office and commercial real estate fallout from the Covid-19 pandemic adds risk to financing projects.

Thornton, of the district energy association, said electricity pricing can escalate quickly, especially in summer, creating uncertainty in the market. New technology may require more space, different controls and significant staff training. Federal policy remains unclear about what parts of a district energy system would qualify for tax incentives, he said.

Graff ticks off many challenges in decarbonizing Cordia’s Minneapolis operations. Geothermal works well on campuses and in low-slung neighborhoods where the problem of sending steam to the 50th floor of a skyscraper does not exist, Graff said.

There’s not a simple clean power source like natural gas that has the energy density to create and push steam through a network, he said. To illustrate the point during a tour of Cordia’s downtown plant, he pointed to a pipe with a modest circumference and said the natural gas flowing through it provided the heating for much of the system.

Electrification may be a goal of heating and cooling, but offsetting it with clean power is daunting. Cordia would have to install heat pumps capable of drawing more than 400 megawatts from a clean energy source, which would be no small feat, Graff said.

Hydrogen sounds promising but has no track record yet for supplying an entire downtown district energy system, Graff said. Biomass has potential, too, but sourcing enough it to service a sprawling district energy system reliably remains difficult.

Battery storage, microgrids and other technologies could all play a role, but each brings issues ranging from cost to a lack of testing in a district energy environment, at least at the size of the downtown Minneapolis system.

“We have the economy of Minneapolis in our hands, and regional economics depend on downtown Minneapolis,” Graff said “We need a reliable infrastructure that people can count on that can be delivered economically, and it’s our responsibility to do that.”

In Twin Cities and beyond, district energy systems see pressure to cut carbon emissions is an article from Energy News Network, a nonprofit news service covering the clean energy transition. If you would like to support us please make a donation.

The recent expansion of a groundbreaking transportation law in Minnesota means all major highway projects in the state will soon be scrutinized for their impact on climate emissions.

A year ago, the state legislature made headlines with a new law requiring the state transportation department and the Twin Cities’ regional planning agency to begin assessing whether highway expansion projects are consistent with state climate goals, including Minnesota’s aim for 20% reduction in driving by 2050.

A follow-up bill passed this spring expands the 2023 law to include all major highway projects statewide that exceed a $15 million budget in the Twin Cities or $5 million outside the metro, regardless of whether or not they would add new driving lanes. The updated legislation also established a technical advisory committee and a state fund to recommend and help pay for mitigation projects.

“It allows for some evolution of the law,” said Sam Rockwell, executive director of Move Minnesota, a nonprofit advocacy group that supported the legislation. “There’s more flexibility.”

The law requires transportation project planners to offset projected increases in greenhouse gas emissions and vehicle miles traveled to qualify for state or federal highway dollars. Those mitigation efforts might include incorporating funding for transit, bicycle or pedestrian programs or environmental restoration projects.

‘A waterfall effect’

Altogether, the law will now cover more than 12,000 miles of state trunk highways that account for more than 60% of all miles driven in the state. One high-profile project that may not have been covered under the initial law is the upcoming reconstruction of Interstate 94 between Minneapolis and St. Paul, which will now need to account for climate impacts.

The changes come as advocates and officials seek solutions to reverse the continued growth of transportation emissions, which surpassed electricity generation almost a decade ago as the state’s largest source of greenhouse gas emissions and are a major reason why Minnesota is not on track to meet its climate goals. 

A disconnect has long existed between even progressive states’ climate goals and the status quo of highway construction, which has long focused on maximizing efficiency for drivers. The new Minnesota law is an attempt to integrate climate action into state and local transportation planning, and to recognize that electric vehicles alone won’t be enough to achieve climate targets. 

Under the law, the Twin Cities’ regional planning agency, the Metropolitan Council, must include strategies for reducing greenhouse gas emissions and vehicle miles driven in its next 25-year regional plan in 2026. All metro area communities will then use that plan as the basis for their local comprehensive plans, which are due to the regional council in 2028. 

“It’s a waterfall effect here,” Rockwell said.

The Met Council’s last planning document, Thrive 2040, already outlined a focus on multimodal travel options, encouraging walking and biking options while setting a goal of decreasing vehicle miles traveled per capita by 20% by 2050, in line with the state’s official goal.

Conversations already underway

Many metro area communities are already having conversations about how to reduce dependency on driving. Abby Finis, a consultant who has helped several communities draft climate action plans, said reducing driving can bring broader benefits than simply focusing on electric vehicles.

“It offers more active lifestyles, more opportunities to incorporate nature, and has less impact on natural resources needed for electric vehicles,” she said.

Most communities focus on increasing the ability of residents to walk and bicycle for short trips by adding bike lanes, pedestrian islands and safer crosswalks, she said. Some cities see telecommuting and co-working spaces as options for reducing commutes.

But transforming the suburbs will be challenging, Finis said. Sustaining transit service often requires denser development, which continues to be politically controversial in many communities. 

“I have yet to see any community push hard on those strategies in a way that meets what is necessary to reduce [vehicle miles traveled] and adapt to climate change,” Finis said.

For example, Minnetonka, a western suburb of Minneapolis with more than 52,000 residents, boasts a considerable bicycling community. But transit ridership is low except for a modest ridership at the regional mall, one commercial development area, and park-and-ride lots, said Minnetonka’s Community Development Director Julie Wischnack.

Developed in the 1950s and 1960s, Minnetonka’s current land use is a barrier to fixed route transit. But the city is among a collection of suburbs along Interstate 494 that has been pushing for transit and other commuting options, including telework.

Another member of that commission, Bloomington, faces many of the same challenges. The city has a few dense neighborhoods near transit stops and the Mall of America, but much of the community remains single-family homes and small apartments. A recent report Bloomington commissioned on transportation found that 75% of trips by residents were more than 10 miles. 

Transit, biking, and other modes could replace trips that are less than 10 miles, said Bloomington Sustainability Coordinator Emma Struss. A recent city transportation study suggested several strategies to decrease driving, including transit-oriented development, free bus and rail passes, bike parking, subsidized e-bikes and more transit. Removing barriers to walking and biking were highlighted.

“We’re hearing more and more from residents that they want safe ways to get around the community without needing to take a car,” Struss said.

Similar challenges in larger cities

St. Paul has made changes to create denser neighborhoods, including removing parking minimums for new development and letting up-to-four-unit complexes be built in single-family neighborhoods. The biggest challenge continues to be the spread-out nature of the region, which forces people to drive to suburban jobs and big-box merchants. 

“The fundamental nature of those trips is hard to serve with anything but driving in the car,” said Russ Stark, St. Paul’s chief resilience officer.

Minneapolis has focused less on vehicle miles and more on “mode shift,” or decreasing trips, said the city’s Public Works Director Tim Sexton. The goal is to replace three of five trips by car with walking, biking, or other modes. A city transportation action plan features more than 100 strategies, including creating around 60 mobility hubs where residents can rent e-bikes, scooters or electric vehicles, or take transit.

Patrick Hanlon, the city’s deputy commissioner of sustainability, healthy homes and the environment, pointed out that Minneapolis has one of the country’s best-developed bike networks, which continues to grow. The city’s comprehensive plan drew national attention for removing barriers preventing denser development, which typically leads to fewer transportation emissions. Several transportation corridors now feature bus rapid transit lines.

What Finis described as a “patchwork” of conversations around developments like these are expected to become more comprehensive as the state law’s planning requirements take effect in the coming years.

The legislation has also made Minnesota a national inspiration for other states looking to make progressive changes to highway planning, Rockwell said.

“We know of a number of other states that are looking at trying to replicate parts of this (law), which is great,” he said. “We’ve been on the phone with folks from New York, Michigan, Illinois and Maryland who are trying to bring some pieces of this into their legislative sessions and their legal framework. That’s exciting.”

Minnesota highway projects will need to consider climate impacts in planning is an article from Energy News Network, a nonprofit news service covering the clean energy transition. If you would like to support us please make a donation.