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District Energy System

Metro Nashville DES Facts

  • Construction began on the $48.3 million Metro Nashville District Energy System (DES) facility in November 2002; work was completed and the new DES facility began operating in December 2003, seven months ahead of schedule.
  • The DES facility provides steam and chilled water to heat and cool 40 downtown buildings.
  • DES employs 26 people, including 19 former Nashville Thermal Transfer Corporation employees. Tim Hestle is general manager of the DES.
  • There is approximately 84,000 feet of piping in the DES system. Of the 84,000 ft, approximately one-fourth is chilled water supply, one-fourth is chilled water return, one-fourth is steam (supply) and one-fourth is condensate (return.) These four pipes are run parallel through most of the system in approximately one and a half miles of tunnels and two and one half miles of direct buried trenches. Some chilled water piping also hangs from the Woodland Street bridge.
  • DES is one of Nashville Electric Service’s largest customers.
  • The largest DES customer is the state of Tennessee, which has 14 buildings on the system, including the state Capitol.
  • The facility operates nine chillers and four boilers, and has the capacity to provide 23,400 tons of chilled water for cooling and 260,000 pounds of steam for heating.
  • DES circulates chilled water at a rate of up to 42,000 gallons per minute.
  • Steam travels through the pipes to downtown buildings at an average rate of 70 miles per hour.
  • Nearly 100 percent of the chilled water supplied to customers for cooling is returned and recycled, while 70 percent of the water used for steam is returned and recycled.