MANKATO — It’s a temperature no one would set their thermostat at, not on the most frigid night in January or the steamiest afternoon in July.

But 50 degrees is a fabulous temperature for helping people heat and cool their homes if they want a minimum of bucks and pollution going up in smoke, according to Matt Soucek of the Schwickert Co. in Mankato.

Fifty degrees is the temperature of the liquid that comes out of the ground in the geothermal heating-cooling systems homeowners are increasingly asking Schwickert’s about. Soucek, in the midst of overseeing installation of a pair of the systems last week, figures the company will do a half-dozen this year.

Many more people are inquiring before being scared off by the up-front costs, Soucek said.

“I take two or three phone calls a week on it,” he said.

While the savings in heating fuel costs are substantial, sticker shock is common for a system that can cost $16,000 to more than $30,000, Soucek said.

The people who overcome that are often motivated in part by concern for the environment. Still, the systems make sense for people motivated solely by economics if they will be in their homes for a while. Natural gas bills can drop to as little as $6 to $8 a month, Soucek said. Electrical costs might increase 15 percent. But when the calculations are completed, the systems typically pay for themselves in 11 years or less.

Essentially, geothermal systems make heat pumps more efficient and make them feasible in northern climates. Heat pumps are what make refrigerators and air conditioners work, using a compressor to remove heat. The heat is then expelled (out the back or bottom of a fridge, or outside of a building in the case of an air conditioner).

Reverse the process, and heat pumps can be used to warm the building they were previously cooling. They become highly inefficient, however, when outside temperatures drop to the levels seen in Minnesota in the winter months, which is why the geothermal part of the system is needed.

A geothermal system doesn’t use ground water, it uses the constant temperature provided by the ground. The system starts with holes drilled down to 180 feet or so. Pipes are looped into the hole and covered, and a glycol solution is circulated through the pipes and to the heat pump. The result is a 50-degree starting point for the heat pump to do its cooling in the summer and its heating in the winter.

David Sullivan, a researcher for the Minnesota House of Representatives, said geothermal is different than other renewable energy systems such as solar where the technology is evolving dramatically.

“With geothermal, I think the technology has always really been there and has been pretty good,” Sullivan said.

The increased interest comes with growing concerns about global climate change and rising costs for natural gas and other fossil fuels. A number of lawmakers would like to promote geothermal heating and cooling, but the state budget crisis has put those sorts of ambitions on hold.

“This wasn’t the year to be handing out tax rebates and incentives,” he said. “... Maybe in future years. I think the future looks pretty good.”

Even without a lot of government incentives, many rural residences have already made the switch in southern Minnesota, Soucek said. Because they rely on high-priced propane heat and have enough land to use horizontal rather than vertical well drilling, the pay-back period for converting has been quicker.

While the state was unable to offer much for incentives, a federal tax credit that will cover up to 30 percent of the cost has city people taking a fresh look at geothermal, Soucek said.

“With the incentives the government has, basically you’re getting your wells for free,” he said.

That doesn’t mean geothermal is the answer for everybody. Lower-income homeowners without a large tax liability won’t be able to take full advantage of the credit. There’s the large up-front cost, meaning depleted savings or a home equity loan. And people need to be long-term thinkers, able to get excited about $6 natural gas bills in decades to come rather than depressed about a $20,000 bill due right now.

Although Soucek thinks interest in geothermal will continue to spread, Soucek said his current customers don’t yet match the typical southern Minnesotan.

“It’s middle-class and upper middle-class who are looking to do something with their money,” he said.