Providing air conditioning through traditional means for the million-square-foot Nashville International Airport proved to be expensive, costing more than $430,000 a year. The airport looked to the abandoned Hoover Rock Quarry, which sits next to one of its busiest runways, as a source of cooling power for the air conditioning system. Once considered to be hazard, the quarry contains approximately 1.5 billion gallons of water with a temperature around 50 degrees Fahrenheit and a depth of 400 feet at some points. The result: The largest geothermal lake plate cooling system in North America, and perhaps the most technologically advanced. The project uses a series of closed, looping pipe systems to run water from the quarry through the airport’s air conditioning apparatus to cool the entire complex. Several geothermal heat exchangers allow water that has already been through the terminal to be cooled again in the quarry, rendering the project entirely sustainable. Simultaneously, the same looping system enables some of the water to be used for irrigation purposes on the property, solving two major challenges with one coordinated solution.
Gamechanger added in 2016.