MNAA Completes Geothermal Lake Plate Cooling System
Marking an innovative use of a former rock quarry, the Metropolitan Nashville Airport Authority (MNAA) on May 17, ceremonially “turned the valve,” on the geothermal lake plate cooling system in North America during a project completion ceremony.
MNAA switched to its new geothermal lake plate system in February and officially completed the transition and project in May. Prior to February, Nashville International Airport (BNA) chilled water equipment’s energy consumption was 1.056 kilowatts annually on average. From February – May 12, energy consumption has reduced to 0.525 kilowatts annually on average, a 50 percent reduction.
“This is a remarkable project for its scope, ingenuity and efficiency,” said Rob Wigington, president and CEO of MNAA. “The Airport Authority is committed to making sustainability an integral part of our business model. Not because sustainability is easy—rather, it is often a complex process—but because the benefits to our airports, the region and our environment are overwhelmingly positive. This historic project will significantly reduce our electricity usage and potable water consumption, which will result in substantial annual utility savings. This is the very essence of sustainability.”
The project recently accorded industry-wide recognition by a leading airport trade association. MNAA received the 2016 Environmental Achievement Award in the Special/Innovative Projects Award category from the Airports Council International-North America (ACI-NA) for the geothermal lake plate project. The Environmental Achievement Awards are presented to airports that strive to protect and preserve the environment through their programs, initiatives, and projects. MNAA was also awarded the 2015 Governor’s Environmental Stewardship Award in the Sustainable Performance category by the Tennessee Department of Environment and Conservation.
Located east of Donelson Pike and Nashville International Airport Runway 2R/20L is the former 43-acre Hoover rock quarry, with an average depth of 150 feet, containing approximately 1.5 billion gallons of water. At a depth of 50 feet, the water is 50 degrees Fahrenheit year round.
The project takes advantage of that cool temperature by circulating water through closed looping and geothermal heat exchangers submerged in the quarry to the airport terminal’s central plant, providing cooling for the entire terminal. In addition to the geothermal system, the project also allows for the use of the quarry water for landscape irrigation.
The project is expected to reduce electricity usage by 6,000 kilowatts of peak demand and result in annual savings of 1.3 million kilowatt-hours and 30 million gallons of potable water. The utility savings to MNAA are expected to exceed $430,000 per year.
The project was developed and engineered by Energy Systems Group, Garver, and Smith Seckman Ried. The fast-track project was delivered by Blakley Construction Services utilizing a design-build contracting method with design and construction support services provided by Energy Systems Group, Garver Engineers, and Smith Seckman Ried.
