BOZEMAN — Construction at a rural school in the central part of the state is giving Montana State University researchers an opportunity to help pioneer a new kind of geothermal heating and cooling system that could lower the cost of the technology.

As part of a major addition to the K-12 school in Winifred that serves about 130 students, a team of MSU engineering faculty and students have guided the development of an innovative configuration for the closed-loop piping that circulates water underground to help regulate the building’s temperature. The new system reduces the depth of the piping, resulting in shorter times required to drill the holes.

"The drilling cost is typically the most expensive part of these geothermal systems, so if we can reduce that, it could make this technology a lot more economical," said Kevin Amende, associate professor in the Department of Mechanical and Industrial Engineering in MSU’s Norm Asbjornson College of Engineering, who is leading the MSU project. "We're looking at this as a way to potentially get the most bang for the buck.”

The school expansion, which includes a new gym, classrooms and a variety of other facilities, is funded mainly with $40 million from Norm Asbjornson, who grew up in the tiny town on the edge of the Missouri Breaks. Asbjornson went on to earn his engineering degree from MSU in 1960 and found AAON, a manufacturer of heating, ventilation and air conditioning equipment. He also gave $50 million for a namesake building on the MSU campus, completed in 2018, which has a similar but much deeper geothermal system. The building consumes only about one-third the energy as comparable structures at MSU.

According to Amende, Asbjornson has a record of wanting his building projects to use the most cutting-edge technologies, and he isn’t afraid to experiment to push the industry he’s worked in for six decades. That led to discussions about how MSU could partner on the project to rethink traditional geothermal design and then study the effectiveness of the new concept.

"We're documenting every step of this process to figure out how this pencils out over the long run,” said Amende, co-director of MSU’s Integrated Design Lab, which studies energy-efficient solutions for the building industry.

Traditionally, geothermal boreholes are drilled deep into the ground — the ones at Norm Asbjornson Hall reach depths of 500 feet — and house a single loop of pipe with a U-bend at the bottom. This lets the ground optimally absorb the excess heat that HVAC devices called heat pumps extract for use later in the day or year, according to Amende. Where acreage is unlimited, sometimes the pipe loops are laid out horizontally in a much shallower layer of excavated earth. This approach is cheaper, but it is also more affected by seasonal temperature swings that reduce the system’s heat-storage capacity.

The new MSU system is something of a hybrid — 500 feet of pipe in corkscrew-like coils inserted into holes that are 50 feet deep and 3 feet wide.

"This could be ideal for certain situations,” Amende said. "It could be significantly cheaper in some soil conditions."

The holes in Winifred took about one-third to one-sixth the time to drill as a traditional, deep borehole, which meant significant savings in fuel and labor. The drilling company typically drills for oil and gas, and Amende said the expanded use of more economical geothermal technology could help provide an alternative livelihood for drillers as the world transitions away from fossil fuels.

Amende’s team will measure the energy performance of the system once it’s operational in the Winifred school. A group of three MSU engineering students, assisting the effort as part of a senior capstone project, are analyzing the costs for the new system versus a traditional configuration.

“It’s really cool that this is first time that this has been done,” said capstone team member Evan Bolen, who is majoring in mechanical engineering. “There’s been a steep learning curve, for sure, but it’s definitely something that we’re excited to be part of."

The long-term goal is to determine whether the cost savings in installation significantly overcome any reduction in energy performance from the shallower boreholes. If that proves to be the case, there could be a wide range of applications, including in residential development or in places where deep boreholes are prohibitive because of shallow aquifers or other limitations.

Collaborating on the geothermal project are Williams Plumbing and Heating, Associated Construction Engineers, Noble Casing, Major Geothermal, A&E Design, Dick Anderson Construction,  Century Companies and AAON.

"Being able to bring together trade workers, engineers and geothermal designers with a holistic approach like this isn’t something we usually get to do as researchers,” Amende said. “It's really cool to be able to do that and to include students in that as well."

- by Marshall Swearingen, MSU News Service -