There are three different types of geothermal use:
1. Direct use - Surface water is used recreationally (as hot springs) or can be pumped directly into buildings to heat them.
2. Electricity generation - Extremely hot water (at least 220o F) underground is used to create steam which turns turbines, producing electricity.
3. Geothermal heat pumps - Naturally occurring hot water is piped alongside City water or another medium, which absorbs the heat. This heated City water can then be piped into buildings to heat them in the winter and cool them in the summer.
Aspen is located in the west-central part of the rich Colorado mineral belt between the Sawatch uplift on the east and northeast and the Elk Mountains on the west and south. The precious metal-rich deposits in Aspen occur in a narrow strip of Paleozoic rocks, which are steeply upturned against a Precambrian crystalline rock basement.
In March 2008, preliminary feasibility studies were completed by Science Applications International Corporation, Water Resources Engineering, a consulting firm from Lakewood, CO. Based on the findings of these studies, there is reason to believe that warm ground water associated with hydrothermal igneous deposits of silver, lead, and zinc ore beneath Aspen may exist in sufficient quantities to supply a direct heat exchange system or for a ground-water heat pump system (SAIC 2008). Silver, lead, and zinc mining that began beneath the city during the 1800’s left a labyrinth of flooded tunnels, shafts, and stopes that could be used as a reservoir of ground water for heating and cooling purposes. Warmer ground water may also be present in mineral formations beneath these mines.
Based on the initial studies, it is estimated that between 1,000 and 5,000 gallons per minute of water may be accessible through deep, open, and stable mine shafts, or with properly constructed wells, especially if the water is returned to the bedrock aquifer to eliminate surface water discharge and recycle the heat energy (SAIC 2008). It is necessary to drill a test well and analyze this water source to demonstrate the yield and water temperature. A test well will determine definitely whether or not sufficient geothermal energy exists to fuel a district heating and cooling system. The location of the test well is on the gravel parking lot of the City-owned Prockter Open Space, adjacent to the Roaring Fork River and across Neale Avenue from Herron Park.
Questions? Contact Dave Hornbacher at (970) 920-5110 or firstname.lastname@example.org.