St. Paul Public Schools go big on geothermal energy, using the earth to heat and cool buildings

The end of the school year used to be hot at Johnson High School on St. Paul’s East Side. The 65-year-old building houses about 1,100 students and 150 staff, and until recently, had no air conditioning.

“That’s a lot of bodies in a building that doesn’t have air,” said principal Jamil Payton.

Johnson is wrapping up its first full school year with air conditioning, but despite adding a new layer of comfort, its energy use is down. That’s thanks to a new geothermal system that is using renewable energy from the ground to heat and cool the building. It’s coming in handy as the weather warms up, and paid dividends immediately during the first week of school when the metro was hit by a heatwave.

“You could tell the difference in the students and the staff,” Payton said.

Some 300 feet below the Johnson High School baseball field, wells use energy from the ground to heat and cool the building. Geothermal systems provide a highly efficient, affordable and renewable energy source by harnessing temperatures below the earth’s surface that remain constantly stable year-round.

Geothermal systems typically connect wells to heat pumps located at ground level that act as furnaces. The wells absorb hot air from the ground in the winter and pass it through the heat pumps, which then distribute it into a building. To cool a building in the summer, the heat pumps absorb hot air from the building and send it to the wells, which disperse it into the ground.

Some geothermal systems draw heat from deep within the earth and are not connected to a water supply, while others connect directly to more shallow underground aquifers and use the water to regulate temperature.

Johnson’s system does not use water. It connects 160 wells to seven heat pumps, but only runs as many pumps as needed at any given time.The heat pumps connect to a series of white pipes in a room in Johnson’s basement. The tall, rectangular pumps neatly line the wall behind the two massive furnaces that were the school’s only heat sources for decades.

“It’s really efficient in that it only runs what it needs to in order to heat or cool the building,” said Tom Parent, executive director of operations and administration for St. Paul Public Schools.

Johnson’s system can even heat and cool different parts of the building simultaneously. The school still uses its traditional furnace as a heating supplement when it’s below 30 degrees Fahrenheit, Parent said, but at a much lower frequency than in years past.

It’s the first year for geothermal at Johnson, so district officials aren’t making definitive statements yet on what the average monthly savings are or how much greenhouse gas emissions are being reduced. But it’s clear that the system is an effective and much more efficient way to provide stable comfort in the building, said Angela Vreeland, St. Paul School’s indoor air quality coordinator.

The district wants to reduce greenhouse gas emissions 45% by 2030, and sees geothermal as part of the answer to accomplishing the goal.

St. Paul Public Schools likes what geothermal brings to the table, and is currently installing it at two more buildings in the district: Bruce Vento Elementary on the East Side and Hidden River Middle School in the Macalester-Groveland neighborhood. Bruce Vento is being fully reconstructed while Hidden River is receiving a $54 million renovation.

The district is going with a different geothermal approach at the two schools. Instead of digging dozens of small wells deep underground, those systems will have a few larger wells that connect to underground aquifers. The systems will exchange heat with water instead of the ground itself, Vreeland said, adding that it’s a good option given Minnesota’s plentiful water supply.

“In this part of Minnesota, that water is everywhere,” Vreeland said.

Geothermal’s moment

Geothermal is growing in Minnesota despite representing just 1% of electricity generation in the state as of 2022, according to the U.S. Energy Information Administration .

Minnesota lawmakers approved $6 million this year for a geothermal energy system at Sabathani Community Center in south Minneapolis, and $1.2 million for planning costs. The Legislature also approved $1.5 million in funding this session for a new rebate program for homeowners who want to add geothermal heat.

The Heights, a mixed-use development that will add 1,000 new housing units and commercial space to St. Paul’s East Side, received a $4.7 million loan in March to develop a geothermal energy system. The grant was the first loan awarded by the Minnesota Climate Innovation Finance Authority, the state’s new green bank .

Geothermal projects are expected to deliver energy savings right away. St. Paul Public Schools estimates that the new Bruce Vento building will save $200,000 on energy costs annually.

The school district has 73 buildings, which are renovated on a rotating basis, Parent said. It might not always be easy to add geothermal or other renewable energy projects like rooftop solar, but it’s worth exploring, he said.

Schools across Minnesota are now eligible for a 30% tax credit on energy savings projects from the federal Inflation Reduction Act . The Johnson High School project should be retroactively eligible for the tax credit for its $18 million geothermal investment, Parent said.

“That’s game-changing,” he said.

Minnesota schools got away with not having air conditioning for years, but districts are seeing high temperatures later into the fall and earlier in the spring as temperatures rise because of climate change caused by the burning of fossil fuels.

“There’s more extreme weather events that we have to contend with,” Parent said.

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