Park City residents and visitors may have noticed a mobile drill rig near the corner of Kearns Boulevard and Bonanza Drive, its mast rising above the tree line.
City Lands and Sustainability Director Luke Cartin said the truck is drilling a 500-foot borehole to see if a thermal energy network — a more energy-efficient way to heat and cool buildings — is possible in the area.
“You can view it as almost like we're sticking a temperature probe down 500 feet just to see what's going on down there,” Cartin said. “We're also seeing what does all that subsurface geology actually look like.”
Jennifer Eden is a senior climate and clean energy associate from Utah Clean Energy. She said buildings are typically heated and cooled using air and electricity. But that isn’t very efficient because air temperatures can be extremely hot or cold
A geothermal system, on the other hand, uses water and Earth’s temperature. Eden said it works by circulating water through pipes 10 to 20 feet underground.
The water starts in the building, absorbing the summer or winter air. It’s then pumped underground where the temperature is around 50 degrees Fahrenheit year-round.
Eden said it takes just a few minutes for the water to release or absorb heat before it’s pumped back up and the process repeats.
The result is a more efficient system and a lower energy bill.
“You're using 50-degree temperatures to help cool your very hot house, and so those are two to three times more efficient than using the air,” Eden said.
Cartin said Park City’s police station, post office, city hall and the 3Kings Water Treatment Plant are heated and cooled with geothermal. Now, the city is looking into creating a thermal energy network, which heats and cools multiple buildings.
“The larger one of these could scale, the more efficient they could become,” Cartin said.
That’s something Colorado Mesa University has done. Its geothermal system is the largest in the Intermountain West.
Capital Planning and Sustainability Vice President Kent Marsh said the system has reduced the university’s carbon footprint by almost 18,000 metric tons annually. It’s also saved nearly $12 million since 2008.
The school completed a system expansion about two months ago, adding miles of pipe going up to 600 feet underground. The network now heats and cools 79% of campus buildings, or over 1.8 million square feet.
Marsh said while the upfront costs can be expensive, the energy and dollar savings are worth it.
“The stuff that we installed back in '07 has absolutely paid for itself,” he said. “The new drill field that we just installed beneath our flagpole and our rugby pitch — it's going to take 10, 12 years for the university to pay that upfront investment back.”
Eden agreed the systems are a great investment, lasting more than four times as long as an air conditioning unit. She said the cost to build them could also go down with new innovation. The University of Utah is developing a smaller system called a geospiral that only requires eight-foot holes.
Still, as networks require drilling, Eden said they’re best for new build developments or big remodels — and more colleges, cities and developments are looking into it.
The Point development in Draper, Utah conducted a feasibility study to see if a thermal grid would be possible on the 600-acre development.
Eden said Weber State University also recently implemented a thermal system into its Lindquist Hall.
“Post construction, their energy use intensity, so the amount of energy per square foot, was reduced by more than 80%,” she said. “Their electricity use without solar was reduced by 55%. Then once you add the solar, the electricity consumption was reduced by more than 90%.”
Cartin said other Colorado mountain towns are considering geothermal. According to The Aspen Times, Aspen School District completed a 1,000-foot geothermal bore test in July.
As for Park City, the borehole test on the Bonanza Park 5-acre site will take around five days to complete. Cartin said he and his team hope to bring their findings to the Park City Council by the fall.
