All around the machines, a thick gray water flowed over the dirt. Matt Desmarais, the founder of Troy-based Energy Catalyst, which was the primary contractor on site, said this was groundwater colored by liquidated rock.

“It’s like you’re grinding the stone into a rock flour,” he said.

After the holes are dug — each slightly more than the length of one-and-a-half football fields — they send heat exchangers down into the Earth. These are long tubes that circulate water. The tubes contact rock and groundwater.

In the winter, the tubes pull warmth from deep in the ground — where it is consistently 50 degrees. In the summer, heat from the school building is pumped back into the ground.

Pulverized rock from deep in the Earth, strained from the discolored groundwater, seen behind, was brought to the surface as crews installed a geothermal heat pump system at Northern Lights School on Wednesday. (Enterprise photo — Aaron Marbone)

To raise the temperature high enough to heat the building and provide hot water in the bitter cold winters, the water circulating through the ground passes through a refrigeration system. This system uses a refrigerant, which gets compressed by a heat pump, raising its temperature. In turn, the circulated water then transfers that heat to air or water, which gets circulated through the building.

In the summer, Desmarais said it works the same as a refrigerator — which is cold inside, but emits heat outside. If the school is the inside of the refrigerator, the system absorbs the heat in the box and rejects it into the ground.

The school runs on fuel oil right now. Desmarais said it costs around one-third to run a geothermal system as it does to run a traditional oil heating system to get an equivalent amount of energy.

In addition to the financial benefits of geothermal heating and cooling, the energy is renewable.

The initial work is a bit of an investment, but Desmarais said it will save money over time. He added that the system should last for 100 years.

Hawk Drilling employees drill a hole 500 feet into the Earth as they installs a geothermal heat pump system at Northern Lights School on Wednesday. Flowing on the ground beneath the truck is groundwater colored gray by liquefied rock. (Enterprise photo — Aaron Marbone)

Last July, NLS was awarded a $320,000 grant from the Dormitory Authority of the State of New York to do the work. The grant requires matching funds from the school, which will also be used to install an insulated roof on the building.

Will Deininger from Hawk Drilling drills a hole 500 feet into the Earth as he installs a geothermal heat pump system at Northern Lights School on Wednesday. Flowing on the ground beneath him is groundwater colored gray by liquefied rock. (Enterprise photo — Aaron Marbone)