A Quarry Lake provides heat sink cooling for Nashville, TN Airport


An abandoned quarry lake saves the Metropolitan Nashville Airport Authority $430,000 per year for airport terminal cooling.


The former Hoover Quarry is a 43-acre lake located east of Donelson Pike and Nashville International Airport (BNA) Runway 2R/20L. The average depth of the quarry lake is 150 feet, containing approximately 1.5 billion gallons of water. At a depth of 50 feet, the water is 50 degrees Fahrenheit year round. By the summer of 2016 it will provide water for the airport’s cooling systems with the use of Slim Jim® heat exchangers and water for landscape irrigation.

Nashville International Airport

Nashville International Airport

This is the largest project of its kind in North America and possibly the world, according to the Metropolitan Nashville Airport Authority. The $10.4 million project is expected to save the airport close to $430,000 a year in cooling costs for the next 50 years. It replaces the current centralized system that relies on Metro Nashville’s potable water as make up for cooling towers.

Feeder pipes under runway

Feeder pipes under runway connecting the quarry lake heat sink to the airport terminal.

The GeoExchange system is expected to save the city 30 million gallons of potable water a year and cut 1.3 million kilowatt hours in electricity costs, according to Robert Ramsey, the airport authority’s chief engineer.

The project was developed and engineered by Energy Systems Group, Garver, and Smith Seckman Ried. The fast-track project is being delivered by Blakley Construction Services utilizing a design-build contracting method with design and construction support services being provided by Energy Systems Group, Garver Engineers, and Smith Seckman Ried.

The Slim Jim® heat exchangers are assembled in sleds, plumbed in reverse-return parallel configuration and reside on a quarry bench at a depth of 50-60 feet to provide a consistent and permanent heat sink.

Lowering Lake Plate® assembly into the liquid heat sink.

Lowering Slim Jim® assembly into the liquid heat sink. It will reside approximately 50-60-feet deep.

The lake absorbs all the airport terminal’s summer cooling needs and remains at a relatively constant temperature due to surface evaporation, thermal conduction with the walls, bottom of the quarry, back radiation and wind action.  Thus, this geothermal heat exchanger taps a permanently renewable supply of thermal energy.

—Alan Watts (edited and posted by CaliforniaGeo)