On the chilly Monday afternoon before Thanksgiving, Joe Waneka leads a small group to observe a massive drill rig set up behind Aspen Middle School.
A crane helps balance the drill bit as a long cable, resembling a giant spool of thread, feeds into a hole in the ground.
“We're drilling a six-inch hole to 1,000 feet to try to understand the geology,” Waneka explains. He’s the operations director for the Aspen School District.
While students were gone for a week over the holidays, crews were hard at work drilling a test borehole. They were assessing soil conditions to determine the design of a prospective geothermal system.
The geo-exchange system the district plans to install is well-established technology, but connecting that network of underground pipes to city buildings across the street is a fairly novel concept.
Adding new stakeholders and expanding the system’s capacity to generate energy brings added complications.
A warming trend
Aspen Middle School is the only building on the district’s 32-acre campus with central air conditioning.
Elementary and high school students are overheating during the warmer months, according to Waneka, making it difficult for them to concentrate.
In an interview over the summer, Waneka said he didn’t want to be resigned to the status quo of buying traditional, energy-intensive A/C units.
“Anybody could do it, and I don't like just any — I like innovation and long-term plays,” he said.
The geo-exchange technology would use stable underground temperatures to both cool and warm the schools.
Drilling hundreds of boreholes and retrofitting the campus HVAC system with ground-source heat pumps would be expensive. The current estimate is $35 million to $45 million.
But federal tax credits would cover up to 40% of that total, and the district applied for a $5 million grant from the Colorado Geothermal Energy Tax Credit Offering.
Once installed, it could shave 75% off the schools’ utility bill and reduce 92% of its heating-related greenhouse gas emissions — a big step toward the district’s goal of net-zero.
If it's successful, the city of Aspen has entertained the idea of connecting its nearby recreation center to the thermal network.
DJ Hubler is a regional director at McKinstry, the company overseeing the design and construction of the geothermal project, including the feasibility test.
He said Aspen is just one of a growing number of Colorado mountain towns exploring this subterranean energy.
“I don't know of a town in Colorado with a ski resort that we, or some of our adjacent partners, haven't talked to yet about this,” said Hubler.
Mountain towns are dependent on winter sports seasons that are getting shorter. Hubler thinks that’s driving them to seek out creative energy solutions.
“The importance of mitigating [the effects of] climate change on ski towns, to be quite frank, is something that is leading to this trend,” Hubler said.
Old technology, new ideas
Thermal energy networks can regulate indoor temperatures by circulating water-based fluid underground between buildings.
“This is not a new technology; these are tried and true technologies,” said Matt Garlick, CEO of The GreyEdge Group.
The engineering firm specializes in thermal energy networks and completed an initial geothermal evaluation for the Aspen School District in June.
In 2007, it partnered with Colorado Mesa University, which has since become one of the largest geothermal systems in North America.
“They're looking to significantly increase, if not double, the size of the current system,” Garlick said. “It's been running for almost 20 years now to incredible results, nation-leading results. That's right in your backyard there in Colorado.”
The geothermal system has saved the university $12 million in energy costs since it was installed, allowing it to offer some of the lowest tuition in the state.
“It sort of set the stage that Colorado in general is really a hot spot for thermal energy networks and geothermal technologies, among maybe two other peers — New York and Massachusetts — that are pushing the concept forward and trying new things.”
One of those new ideas is having multiple owners operate a shared network of underground energy.
If Aspen gets on board with the school district’s project, they would need to figure out who’s paying whom for what.
“When you talk about connecting several blocks of Aspen or any of these smaller communities on a common system, it changes it to a utility,” Garlick said.
One way to address that complication is to invite a third party, like a local utility company, to manage the shared resource.
That idea is being piloted in other parts of the country.
But before the Aspen School District can sort out those details, they’ll need to finish drilling their test borehole.
The team encountered challenging soil conditions in November and wasn’t able to get far enough underground before the students returned from the holiday.
They plan to return this summer. If all goes well and the Aspen School District Board of Education approves the expenditure, classrooms could be cooled with geothermal heat pumps by the end of 2027.
