The faithful at Mount Olive Lutheran Church just wanted to make their 80-year-old building energy-efficient, a tangible step to care for God’s creation. They didn’t know they’d be blazing a trail for geothermal heating.

Just a handful of churches have tried this hot approach in Minnesota. The construction crew that drilled 48 wells in the parking lot had never worked on a church before.

“We soon realized we were doing something pioneering,” said Art Halbardier, manager of the church building committee, as he watched the forklift on the Minneapolis construction site this week. “Geothermal is rarely used by churches, and especially by an inner-city church without much land for drilling.”

While religious institutions across Minnesota are exploring green energy options, installing systems ranging from solar panels to rain barrels, a geothermal energy system is generating excitement.

Mount Olive is not a wealthy church, and it is located in the heart of the city — not exactly a logical candidate for a relatively expensive and innovative investment.

“It’s a very impressive demonstration by the church,” said longtime environmentalist John Dunlop, a board member of Minnesota Interfaith Power & Light, which facilitates energy conservation programs for religious institutions. “It shows a strong commitment to climate change.”

The project is part of a $1.8 million plan to upgrade heating and add air conditioning to the church building, which includes a social hall and offices. Installing a geothermal system added $300,000 to the cost.

Mount Olive church leaders acknowledge it all requires a significant chunk of cash for a community of 600 members.

The congregation had mixed feelings about the investment.

“Every time the idea came up, the counterargument was we should be serving our neighbors,” said Mount Olive’s pastor, the Rev. Joseph Crippen. “But this building is the base from which we do that. It’s an asset to our neighborhood ministries.”

The church, for example, runs a variety of neighborhood efforts, including community meals, a youth job program and donations of backpacks and school supplies.

Walk into the church offices and you quickly discover Mount Olive’s environmental zeal. A lifesized poster of Martin Luther, wearing 16th-century robes, looks down from the wall with the words “Paris Accord!” coming from his mouth. It refers to the 2015 Paris agreement signed by nearly 200 nations to cut planet-warming greenhouse gases in half.

The church adopted that goal for itself. It calculated it was producing 140 tons of carbon dioxide a year and hopes to lower it dramatically.

In the church basement, a dozen construction workers are installing pipes, wiring and ductwork next to chalkboards asking the question, “What do you love and hope to never lose to climate chaos?”

Across the whizzing traffic on 31st Street, a crew is finishing the pipe installations in the dirt-covered parking lot. The dirt is dotted with the tops of 48 tubes that capture the heat far below the parking lot and transfer it to a series of pumps inside the church building.

“Instead of a furnace burning gas, we have pipes that capture the Earth’s energy to heat and cool the building,” explained Halbardier.

But digging holes for the geothermal wells in an inner-city parking lot had its surprises, he said.

“There were three house foundations still buried under the parking lot from when they were torn down in the 1940s,” said Halbardier, surveying the scene. “They had to be removed. That required us to do some asbestos abatement. It ended up being a much bigger thing than what we thought it would be.”

Only a handful of other churches in Minnesota have installed geothermal systems. They include Our Lady of Grace Catholic Church in Edina, Sts. Peter and Paul Catholic Church in Elrosa and St. John the Divine Episcopal Church in Moorhead. Likewise nationally, geothermal systems lag far behind the installation of solar panels, which have taken off in recent years.

The prospect of bringing geothermal energy to another church, especially an inner-city church, was exciting to LuAnn Ferguson, regional manager the Mission Investment Fund, a loan fund of the national Evangelical Lutheran Church in America (ELCA) that supported the Minneapolis project.

“The last geothermal project we financed was in 2009 in Colorado,” said Ferguson. “I know of several others that have looked into it, but it was cost prohibitive. It’s a real treat to be part of this.”

While too costly for many churches, Mount Olive members were remarkably generous. The midsize congregation has pledged $1.25 million toward the $1.8 million project, said Halbardier. The rest will be financed by the ELCA loan and a $60,000 state grant for the solar panels being installed on the church rooftop to help supply green electricity.

Church leaders still don’t know how much money they’ll save on energy bills. The church didn’t have air conditioning before, so there’s no clear comparison of before and after expenses, they said.

“But we hope that our bills will be at least half, and probably two-thirds of what they were,” said Halbardier, who predicted the project would begin producing energy within the month.

In the weeks ahead, work crews will build a new parking lot surface over the geothermal installation, adding trees, shrubs, some permeable pavers and a rain garden to control water runoff.

The thousands of cars that drive by this busy area each day will have no idea they’re passing a divine experiment.

“They’ll never see it,” Halbardier said, laughing. “I think it’s exciting that underneath is a treasure of heating and cooling for a church.”