The story of the new Carbon County Senior Center is much deeper than reported so far. About 300 feet deeper, to be exact.
That is how far down beneath the parking lot the building's geothermal energy system extends. Hidden by asphalt now, 31 wells carry loops of plastic pipe 300 feet down into the earth. At that depth, the temperature is always 69 degrees - give a take a degree - according to County Quality Control Inspector Tom McCrary.
That temperature is cool compared to a July afternoon, but warm in contrast to winter. It doesn't take much energy to get to 72 degrees when you start at 69, and that's the key to the efficiency of the system. In simple terms, all it does is borrow the earth's natural heat to warm air and water in winter, and in summer it absorbs heat from the building and sends it back into the ground to cool things down.
Spence Bowman of Geo-Energy Systems of Cedar City explained that the system circulates a mixture of water and methanol (wood alcohol) to carry the heat to and from the building and ground. This antifreeze moves in closed loops of high-density polyethylene piping.
A maze of pipes, valves and pumps regulate all the circulation involved. Some of the fluid flows under the sidewalks around the building to melt snow and ice. The system does cost more to install than conventional heating and cooling, but the payback over time is in greatly reduced energy expense, McCrary explained. Based on current costs of natural gas and electricity, the system will pay for itself in about nine years. That leaves 91 years of cheap energy for the rest of the building's planned life.
The county expects to get at least a century of use out of the new building. "That means we're building this to serve senior citizens who haven't even been born yet," McCrary said.
This is not new or untested technology. Bowman said his firm has been in business for 12 years and has installed the system in about 25 schools and 15 commercial buildings. The Senior Center is in fact the second building in the county to adopt geothermal power. The county's Utah Department of Natural Resources building on Carbonville Road was the first.
McCrary said the DNR building's system is performing as promised.