A water source geothermal project at a Tennessee airport achieved a Silver-level award from the Institute for Sustainable Infrastructure (ISI), which rates a project’s environmental, social, and economic impacts.
In 2010, Nashville’s was one of 10 airports chosen for the Federal Aviation Administration’s (FAA) Sustainable Master Plan Pilot Program, in part based on its planned geothermal project to meet cooling and irrigation needs using less water and less electricity. The plan was broadly supported and approved by the Board of Commissioners, which is a diverse group with three representatives from the business and finance community, two pilots, two neighborhood representatives, one engineer, one lawyer, and the city’s mayor.
“We’re committed to making sustainability an integral part of our business model,” says Metro Nashville Airport Authority President/CEO Rob Wigington. “Not because it’s easy— it’s often a complex process—but because the benefits to our airports, region, and environment are overwhelmingly positive. This historic project reduces our electricity usage and potable water consumption, which equates to substantial annual utility savings. This is the very essence of sustainability.”
As a collaboration between ISI and the Zofnass Program for Sustainable Infrastructure at the Harvard University Graduate School of Design, the Envision system rates the impact of sustainable infrastructure projects as a whole. The ISI Envision system measures sustainability in five categories: Quality of Life, Leadership, Natural World, Resource Allocation, and Climate and Risk. These key areas contribute to the positive social, economic, and environmental impacts on a community.
Key sustainable accomplishments of this project include:
Resource Allocation: Once considered a liability, a quarry lake was reconceived as a resource. Lake plate heat exchangers target a depth in the water that remains 50 degrees Fahrenheit year-round, the airport generates chilled water for the cooling system. More than $430,000 in electricity cost savings per year are expected, a 50% improvement over the baseline established for the project.
“Harnessing the cooling effect of the quarry water created a renewable, sustainable energy source,” said Ryan Sisemore, director of Garver Aviation’s East Region. “A project like this encourages innovation in the way we create solutions.”
The project also reduces potable water consumption by more than 30 million gallons, significantly reduce the strain on the municipal water supply.
The airport’s irrigation and cooling systems used to rely on Metro Water Services, which pulls water from the Cumberland River for treatment and distribution. The closed-loop geothermal project keeps 21 million gallons of potable water from being used in the airport’s cooling towers are saved. Additionally, by harvesting rainwater, which collects in the quarry and pumping to the irrigation system, 13 million gallons of potable water used for irrigation is saved.
Leadership: As the “front door” for 12 million people traveling to and from Nashville every year, the project’s a valuable opportunity to promote sustainability and the community more broadly. It is implementing several educational programs aimed at travelers, with plans to roll out a Green Screen in the terminal building to continue educating travelers regarding the sustainability measures put in place.
In 2015, the Metro Nashville Airport Authority received the Governor’s Environmental Stewardship Award for “exceptional voluntary actions that improve or protect the environment and natural resources with projects or initiatives not required by law or regulation.”
Companies involved in the project include Garver, Blakley Construction Services, and Energy Systems Group. They and the airport authority overcame significant funding challenges.
The project team targeted energy efficiency project funds set aside in FAA’s 2012 Reauthorization Act, working with headquarters in Washington, D.C., to navigate the regulatory approval process. The successful grant acquisition, as well as the energy performance contracting for this project, has opened the door for more energy efficiency projects to be implemented at other airports across the country.
Climate and Risk: The project will significantly reduce the airport’s dependency on natural-gas fired boilers, which use on average 39,700 therms of natural gas per month. Emissions associated with the boilers is significant, but the project will reduce emissions of carbon monoxide, nitrogen oxide, particulate matter of both 10 and 2.5 micrometers or less in diameter, sulfur dioxide, and volatile organic compounds—all of which contribute to poor air quality.
“This is an innovative solution,” says ISI President and CEO John Stanton. “It will benefit not only the airport’s bottom line, but serve as an excellent example of sustainability for the thousands of people who travel through the airport each year. ISI is very pleased to present this project with the Envision Silver award for sustainable infrastructure.”
To learn more about the project, visit https://garverusa.com/iq/201683/163/bna-geothermal-cooling-system.
