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Green heat for Duluth’s Lincoln Park could be just a flush away

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DULUTH — The question of how to heat buildings in a cold climate without using fossil fuels keeps sustainability officer Mindy Granley awake at night.

Duluth’s answer could be just a flush away.

The city was recently awarded a $700,000 grant from the U.S. Department of Energy to study using wastewater from Western Lake Superior Sanitary District (WLSSD) to heat buildings — a clean energy solution that involves using ready-made heat instead of creating it. In the next year, it will consider the technical and economic feasibility of using this geothermal energy to cover the heating load for 2.4 million square feet of buildings — with the chance to tack on more — in the Lincoln Park neighborhood.

Duluth Mayor Emily Larson said the project is one that could decarbonize hundreds of buildings and stabilize heating fuel prices in the future.

This would be a significant move in the city’s goal of carbon neutrality. Heating buildings accounts for nearly half of the world’s energy use and about 40% of global carbon dioxide emissions, according to Granley.

“Moving heat around is way more energy efficient than burning fossil fuels to create heat,” she said. “Heat recovery is very energy efficient. This project helps us to explore the viability and cost of using heat recovery and geo-exchange in district energy systems to heat buildings.”

In introducing the plan earlier this month, Ken Smith of St. Paul-based Ever-Green Energy said it’s a concept that has been used in China, Finland and Sweden — but not yet at this scale in the United States.

How it works

It all starts with an easily accessible renewable resource: human waste. The liquid that leaves the body is about 98 degrees before it joins up with other water in the city’s thousands of miles of sewer pipes. This mix from toilet flushes, dishwashers, showers and local industry adds up to 38 million gallons a day, according to WLSSD. It’s all routed to the wastewater treatment plant between Interstate 35 and the St. Louis River.

It’s still warm when it gets there.

First the water is filtered to remove large objects and grit, then sent into a channel where it is injected with pure oxygen and stirred by large paddles. This creates an environment where aerobic bacteria can thrive and digest waste to further clean it. Then the water flows to a clarifying chamber, where sticky clumps of bacteria become sludge that is either used as fertilizer or returned to the channel. It is then sent through sand, gravel and coal to remove smaller solids, and potentially mixed with bleach.

The treated water is then put back into the St. Louis River — or potentially intercepted to use as energy. This is where the new-to-Duluth technology could begin.

Ever-Green Energy’s concept is to send the warm and cleaned-up wastewater through a heat exchanger that transfers the heat from the effluent to fresh water in an adjacent pipe. A heat pump lifts the temperature just a bit more to about 140 degrees — capable of warming a building. Air is added to it, through a furnace or other air handling unit, and transferred throughout the building.


CLEANER HEAT JUST A FLUSH AWAY

Heat lost from the processing of residential wastewater would be captured and used to heat buildings in Duluth’s Lincoln Park.

1. Wastewater is filtered to remove debris, then sent into a channel where it is injected with oxygen and stirred by large paddles. This creates an environment where aerobic bacteria can thrive and digest waste.

2. A clarifying chamber where sticky clumps of bacteria become sludge clears remaining debris. It is then filtered through sand, gravel and coal to remove smaller solids and potentially mixed with bleach.

3. The treated water is then put back into the St. Louis River — or intercepted to use as energy. This is where the new technology could begin.

4. The warm wastewater would run through a heat exchanger that transfers the heat from the effluent to fresh water in an adjacent pipe.

5. A heat pump brings the water to about 140 degrees. Air is added through a furnace or other air handling unit, transferring the heat to local buildings.

Source: City of Duluth | By Mark Boswell, Star Tribune


Duluth has a goal of carbon neutrality and net zero emissions by 2050. A big part of getting there is determining how to heat buildings with something other than natural gas.

“Waste heat from a wastewater treatment plant — which are in or near every community of every scale — is something that should be looked at,” Smith said. “It’s an idea we’ve been talking about since we’ve been involved with Duluth for the past 12 years.”

‘The potential to be a model for the nation’

AJ Axtell, WLSSD’s director of community relations, said they have long known that there was an opportunity to capture heat from effluent at the plant and turn it into energy, but there wasn’t a feasible way to fund it. WLSSD, a Lincoln Park fixture since the early 1970s, is already behind a lot of environmental work in this region, between its composting and collection of hazardous waste.

A local coalition led by Granley applied for the grant from the U.S. Department of Energy knowing that 1.6 miles of West Superior Street will undergo major reconstruction in 2026. Creating the underground infrastructure for a geothermal heating district could synch up with an already torn-up thoroughfare. Some of the 11 communities in the country that, like Duluth, were awarded the grant will be selected by the U.S. Department of Energy to receive up to 90% of the implementation costs.

This style of district heating is already in play in Finland, where steep gas prices and fees for carbon emissions have created more urgency for carbon neutrality — potentially why Europe is ahead of the United State in using wastewater to generate heat, according to Timo Piispa, vice president of heating and cooling at Fortum, an energy company in Finland. The company is among the largest of its kind in Northern Europe, and 95% of its energy is carbon neutral.

His company is also behind efforts to capture heat from city data centers in a similar way.

There are about 16,000 water treatment plants in the U.S., Smith said. And they will probably still exist 100 years from now.

“This is a really unique opportunity for reliable, sustainable, carbon-free energy — stable and affordable for this community — by using wasted energy that’s already in the community,” Smith said. “The innovative geothermal district energy project for Lincoln Park is a bold, big idea that is capable of delivering on those expectations — and it has the potential to be a model for the nation.”



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Star Tribune

After defeat, supporters of St. Paul’s childcare payment plan not giving up

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In compiling a workable plan that shows a way to help families fill the gaps in state and federal aid for childcare, years of planning and advocacy paid off in greater visibility of low-income families’ struggles — and a possible way forward., Loewen said.

“The problem’s not going away, and neither are we,” he said. “We just have to determine what‘s next.”



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Star Tribune

Minneapolis Park Board recommends closure of four outdoor rinks partially because of last year’s warm winter

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After only one week when people could skate on outdoor ice rinks during a record warm winter last year, Minneapolis wants to scale back its number of rinks.

In late October, the Minneapolis Park and Recreation Board recommended closing five outdoor rinks in its proposed 2025 budget due to climate change, increased supplies and materials needed due to inflation as well as fluctuating lake ice and warming house costs. The number of suggested rink closures has since been reduced to four, according to Park Board staff.

The rinks that are recommended to close this winter are in Webber, Windom and Powderhorn Parks. The Lyndale Farmstead Park rink will close in 2025-26.

“Powderhorn and Webber are both built on water bodies, and that makes it more challenging to open and maintain than rinks built on land due to changing ice thickness and quality,” said board spokeswoman Robin Smothers.

The decision to close the Windom and Lyndale Farmstead rinks are “based on proximity to other rinks and the challenges of constructing the various sites,” Smothers said.

The Matthews Park rink was originally recommended to be closed, but Smothers said the rink will stay open since the board would not want two rink closures in one district.

All of this is subject to change until the budget gets approved by the board on December 10. If all the proposed rinks close, it would bring the number of Minneapolis outdoor rinks from 22 to 18.

Joe Dziedzic, a former Minnesota Golden Gophers hockey player who went on to play professionally for the Pittsburgh Penguins and the Phoenix Coyotes, grew up near the Windom Park rink in northeast Minneapolis. He said it saddened him to see the city potentially discontinue the rink.



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Minneapolis Labor Standards Board plan gets mixed reception

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After years of speculation, Minneapolis City Council members have finally laid out their long-awaited Labor Standards Board proposal, which would bring workers and employers together to deliberate new regulations for industries with well-known problems, such as labor trafficking in construction.

Labor unions are pushing for it, and two years ago Mayor Jacob Frey and a majority of council members said they supported creating a Labor Standards Board. But the notion of creating a new layer of government, with workers having a role in regulations that impact business owners, has led to a wave of opposition from local and national industry groups.

Council members promised to pass the Labor Standards Board by the end of the year. At Wednesday’s public health committee, City Clerk Casey Carl, Council Vice President Aisha Chughtai and Council Members Aurin Chowdhury and Katie Cashman presented the structure of the panel for the first time.

Facing a phalanx of competing signs for and against the Labor Standards Board, they described the proposed board as being composed of an equal number of business owners, workers and other community stakeholders (such as consumer advocacy representatives), who would create sector-specific work groups as needed to discuss issues in specific industries and recommend policy solutions to the City Council, which would then go through its regular process of vetting new policies.

“The goal of this structure is to foster collaboration among stakeholders and creative solutions instead of one-size-fits-all policymaking,” said Chughtai. “It’s supposed to increase participation and engagement of those affected day to day by our workplace policies, and ultimately to allow for data informed policy recommendations to be considered by the City Council.”

Chowdhury said: “What this is about is trusting our local businesses, trusting our workers and trusting consumers and experts and saying, ‘Hey, we trust you, we believe that you’re the experts, you should have a table to come together on and have a robust discussion to inform us as policy makers. Most [businesses}, they aren’t acting in an egregious way that’s impacting their workers in a negative fashion, but we want to go and examine the sectors where workers are struggling, where labor standards that are needed are missing, to improve the workplace and in turn improve our economy.”

Earlier this year, national organizations that opposed raising wages for fast food workers in California conducted an ad blitz opposing the Minneapolis Labor Standards board. Since then, a growing number of business groups — the Minneapolis Restaurant Coalition, Hospitality Minnesota, the Minneapolis Regional Chamber, the Downtown Council and Minnesota Retailers — have also urged the council to abandon the board. Small business restaurateurs of color have been the most outspoken, saying they cannot withstand any new regulations after previous years’ passage of minimum wage and sick time ordinances, and do not want workers telling entrepreneurs how to run their businesses.

Speaking for business owners on Wednesday, Council Member Michael Rainville predicted the Labor Standards Board would pit small business owners against their employees. “This makes the city government become a union organizer,” he said. “This will do nothing to decrease the amount of empty storefronts in Uptown or downtown. The business community has made it clear that when their leases are up, they’re going to leave Minneapolis and or just simply close the business.”



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