Regional wastewater officials threw cold water Tuesday on a proposal to draw heat from raw sewage at a new mini-neighborhood being developed in Minneapolis.
Staff members with the Metropolitan Council, which collects and treats Twin Cities wastewater, said they will stop analyzing an experimental plan to tap into a sewer near TCF Bank Stadium — after three years of talks. The heat extracted from the sewage would feed a collective energy system planned for Towerside, a sustainable “innovation district” taking shape near the University of Minnesota.
Met Council leaders emphasized they are still interested in pulling heat from the warm wastewater. But they said it may make more sense to do so after the sewage has left the treatment plant.
“We’re going to be looking very closely at the technology around sewage thermal,” Leisa Thompson, general manager of the Met Council’s wastewater division, told the council’s environment committee Tuesday. She said it would be more feasible, however, to implement it within the council’s system.
The planners behind Towerside want to draw wastewater out of the council’s large pipe and run it through a heat exchanger to help heat nearby buildings, likely starting with a mixed-use development that would replace the Days Hotel off University Avenue. They say such systems could ultimately help the Twin Cities combat climate change.
But the proposal poses a number of challenges, staff members said, notably that the council lacks the legal authority to sell or give away energy. They added that the project would cost more than projected, has little precedent elsewhere, and would be difficult to construct, among other concerns. The council would also need to own the facility, staff said, due to stringent permit requirements.
“We would in effect be competing with private businesses that provide energy to private customers,” Jeannine Clancy, assistant general manager in the council’s wastewater division.
The council already creates heat from wastewater in other ways. It draws heat and power at its massive Metropolitan Plant in St. Paul from the incinerators that torch wastewater sludge. Several other systems recover energy from the water at other plants around the metro area.
Three members of the Minneapolis City Council — Cam Gordon, Andrew Johnson and Phillipe Cunningham — submitted a letter asking the Met Council to reconsider, saying the project will help the city meet its goals to reduce carbon emissions.
The firm developing the plan, Ever-Green Energy, took exception with several elements of the council’s analysis in another letter.
“I recognize that there are a lot of challenges with this,” Met Council Member Cara Letofsky, who is also a Towerside board member, said during the meeting. “I feel like the conversation between the council and the project team is not over yet.”
Letofsky later added she was “extremely disappointed with some of the attitudes up here.”
Towerside leaders were not giving up hope. Stephen Klimek, Towerside project manager, said he expects there will be additional opportunities to meet with Met Council leadership to “see what we can make happen.”
“They’ve kind of pointed out some legal and technical issues as roadblocks without getting into the weeds of how we’ve proposed to deal with them,” Klimek said.
Council Member Wendy Wulff said the council should seek the biggest bang for its buck for the region’s ratepayers — across 109 cities.
“That heat has a value to us in energy recovery,” Wulff said. “And if the most efficient way to use that is after the effluent is coming out of our plants, then we kind of owe it to our customers to go for the most effective place to get that energy out.”