Initial readings on water found in the city of Aspen’s geothermal test well indicate temperatures of around 90 degrees at the bottom of the 1,500-foot-deep hole, which is at the low end of the range needed for an energy utility.
Drilling and other site work is complete in the area off of Neale Avenue where a large drill rig had been since late April. The city began drilling the hole during about six weeks in the fall of 2011, with a break in the work until this spring.
Earlier this month drillers reached their goal of 1,500 feet beneath the surface in a parking lot adjacent to city-owned open space. The project carried a total price tag of around $300,000.
“We are so thankful to the neighbors for their patience and support during this project,” Jeff Rice, utilities energy efficiency manager for the city of Aspen, said in a press release. Rice noted that the project encountered difficulties along the way leading to delays; at one point, drillers had to start a new hole after the original kept caving in on itself.
The test well had water flowing to the surface, indicating water pressure of around 30 pounds per square inch, according to the city statement. That means that should a geothermal utility, which converts heat underground into energy above the surface, be developed, there is the potential that pumping systems could be minimized, Rice said.
Initial temperature readings were only taken on water that bubbled up to the surface of the well, which is now capped, showing water around 70 degrees. According to geothermal specialists who are consulting on the project, it’s reasonable to assume, based on that, that water temperatures at the bottom of the well are 90 degrees or higher.
Ninety degrees would be about the lowest temperature where a geothermal heating utility might be worth while, Rice said. To generate electricity, temperatures would have to be closer to 180 degrees, he said.
A consultant will do more thorough testing on the well in the coming months, after the well is allowed to “settle.” The work will include temperature readings; studying the chemical content of the water; and geophysical logging, which is a probe to determine what geologic layers the well has penetrated.
“If the scientific tests prove positive, the city will investigate the viability of a geothermal utility district in the future; however, there are no plans to develop this test site any further,” the city’s press release says.
Anecdotal evidence from the mining days, which sent workers underground, as well as a 2008 feasibly study, indicated that there might be hot enough temperatures beneath the surface for a geothermal utility. The city is pursuing the project because of a desire to increase the amount of local renewable energy.