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Marking innovative use of a former rock quarry, the Metropolitan Nashville Airport Authority (MNAA) in May 2016 ceremonially “turned the valve” on the largest geothermal lake plate cooling system in North America. MNAA switched to its new geothermal lake plate system in February 2016, and officially completed the transition and project in May 2016. Prior to February 2016, Nashville International Airport (BNA) chilled water equipment’s energy consumption was 1.056 kilowatts annually on average. From February to May 12, 2016, 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.”

MNAA received the 2016 Environmental Achievement Award in the Special/Innovative Projects Award category from the Airports Council International-North America 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 on the east side of Nashville International Airport adjacent to Runway 2R/20L, the former 43-acre quarry, with an average depth of 150 feet, contains approximately 1.5 billion gallons of water. At a depth of 50 feet, the water is 50°F 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 use of the quarry water for landscape irrigation. The project is expected to reduce electricity use by 6,000 kilowatts of peak demand and result in annual savings of 1.3 million kilowatthours 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 Reid (SSR). 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 SSR.

Information provided by the Metropolitan Nashville Airport Authority (www.flynashville.com).