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District Energy System

History of Metro Nashville District Energy System

Shortly after taking office, Mayor Bill Purcell commissioned a study that evaluated Metro’s solid waste management system. This study included an independent evaluation of Nashville Thermal Transfer Corporation (NTTC), which found the cost of disposal at NTTC high and the plant’s operations unreliable. Based on the results of the study, the Mayor recommended, and the Council approved, the “Clean, Green, Lean” Waste Management Plan, which provides for greater waste diversion programs for the city and a new district energy system (DES).

As part of the new plan, Metro decided to phase out NTTC as a waste disposal option, enter into long-term contracts for the disposal of waste, and change the district energy plant to a natural gas-fired system. NTTC agreed to shut down the waste-burning components of the waste-to-energy facility by September 30, 2002, and to switch to natural gas-fired boilers to generate steam and chilled water. However, a fire in the waste receiving area occurred in May 2002, causing early closure of the waste-fueled system.

The Thermal plant operated as a natural gas-fired facility using four boilers to produce steam and chilled water until January 2004, when the new energy generation facility (EGF) became fully operational. The NTTC plant was then torn down to make way for urban development on the riverfront property where it currently sits.

NTTC Timeline

1970 - Nashville Mayor Beverly Briley began studying the feasibility of building a plant that would address the city's solid waste disposal needs and recapture energy to heat and cool buildings in the downtown area.

1973 - The Nashville Thermal Transfer Corporation (NTTC), a not-for-profit organization, was established to build, own, and operate the $16.5 million district energy system. Construction was financed by energy bonds.

1974 - The plant began operations in February, making Nashville the first city in the world to use solid waste as an energy source for both heating and cooling. The plant was capable of burning 1,000 tons of trash per day. The energy created by this waste-burning process was used to generate steam, which was then used to heat downtown buildings, or to produce chilled water to cool the buildings.

1976 - Electrostatic precipitators were installed to reduce air emissions at a cost of $8 million.

1984-1986 - The facility underwent a $36 million expansion, giving it the ability to generate electricity and expanding its capability to serve downtown heating and cooling customers.

1999 - The air pollution system was replaced with a combination baghouse-scrubber system to abide by new, stricter amendments to the Clean Air Act.

2001 - Despite several expansions and updates to improve operations and to increase its capacity during its 30-year life span, the NTTC struggled to meet pollution restrictions and to remain economically viable. Because of this, Metro Council voted in December to close the NTTC plant by 2004, and Mayor Bill Purcell announced plans to modify the DES from a solid waste-fired system to a fossil fuel system by 2004.

2002 - As part of the scheduled closing, the plant was to start fueling the facility with natural gas instead of trash by October 2002. This process was accelerated by a major fire on May 23, 2002, which immediately halted the burning of trash. The plant was back in operation only one business day after the fire, and continued to operate as a gas-fired facility, producing steam and chilled water as before.

Mid-December 2003 - The new DES facility came online mid-December 2003 and was fully operational serving downtown customers in January 2004. The old NTTC facility was demolished to make way for riverfront development on the property which it occupied for nearly three decades.