PROJECT SUMMARY
The Metro Nashville District Energy System (DES) provides heating and cooling for approximately 40 buildings in downtown Nashville, including the State Capitol and other government buildings, the NFL's Tennessee Titans, The Gaylord Entertainment Center, home of the NHL's Nashville Predators, and a number of privately owned office buildings and hotels.

This new DES replaced an existing system that was in service for 30 years, relying on an aging trash-burning plant with limited reliability and capacity. Despite numerous efforts to improve operations and safety and increase capacity, the facility struggled to remain economically and environmentally viable. Constellation Energy Projects & Services Group (CEPS) was retained by Nashville Metro Council to design, develop and operate a new state of the art $46 million DES. CEPS worked to increase the interim efficiency of the old plant while constructing the new DES, resulting in a seamless transition for all downtown customers.

The DES plant consists of nine (9) 2,600 ton dual compressor chillers and four (4) 65,000 lbs/hour duel-fuel water tube packaged boilers, giving it the capacity to provide 23,400 tons of cooling and 260,000 lbs/hour of steam heat. The chilled water system also contains eighteen (18) 1,300 ton cooling towers, and utilizes variable speed chilled water pumping and constant speed condenser water pumping to maximize plant efficiency. The steam system produces 150 psig steam, and includes a fully redundant feed water system.

The new DES was completed seven months ahead of schedule and began operation in December 2003. The DES is part of a waste management initiative that is projected to save Nashville approximately $66.9 million by 2014, in addition to significantly lowering heating and cooling costs for downtown customers.

The project was funded entirely with municipal bonds. The City of Nashville retains ownership of the facility and CEPS will operate and maintain the facility under a 15-year agreement. CEPS operates the facility 24-7 with a full-time staff of 25 employees.

Originality
CEPS presented several alternative approaches in their response to the Nashville RFP that would result in a better project for Nashville; and, Nashville and its private consultant, Gershman, Brickman and Bratton, were very receptive to these ideas. The two biggest alternative approaches were related to project finance and site location. In regards to project finance, CEPS proposed to finance the project directly, using its own equity; or, to use the more traditional method of selling tax-exempt municipal bonds. Nashville chose to sell bonds; however, under the different economic circumstances, a CEPS investment could have been a reasonable option for the city. In its RFP, Nashville provided several possible site locations for the new DES. While evaluating these locations, CEPS, took the initiative to consider additional locations not proposed by Nashville. As a result of these other options, CEPS found what it thought was a better alternative. Nashville agreed, and the end result was that the property in which the old plant was built on could be cleaned up and used for future economic development. This property is in a prime location relative to Downtown revitalization efforts and is now expected to generate millions of dollars in economic benefit to the city that would not have materialized had CEPS not looked at the DES project form a customer focused perspective.

Quality
This new DES replaced an existing system that was in service for 30 years, relying on an aging trash-burning plant with limited reliability and capacity. Despite numerous efforts to improve operations and safety and increase capacity, the facility struggled to remain economically and environmentally viable. CEPS was retained by Nashville Metro Council to design, develop and operate a new state of the art $46 million DES. The new DES was designed to be both more efficient and more environmentally friendly. During the project development stage of the DES project, there was a major fire at the existing plant. The recovery of the old plant was questionable and the new DES was still up to 12 months away from start-up. The city asked CEPS to take over operations of the old plant and help get them through this very tenuous time. CEPS responded immediately, bringing in temporary equipment and resources, and had the old plant providing services within 72 hours. CEPS continued support of the old plant right up to the start up of the new DES. The result was a seamless transition for all downtown customers and the city of Nashville.

Implementation
CEPS designed the plant to maximize efficiency and reliability. As part of a 15 year operating agreement, CEPS has very specific performance and efficient guarantees that it is required to maintain. The chiller plant consists of high-efficiency dual compressor chillers, each with two cooling towers. The chilled water system utilizes variable speed chilled water pumping and constant speed condenser water pumping to maximize plant efficiency. The 150 psig steam system utilizes high efficient duel-fuel water tube packaged boilers and includes a fully redundant feed water system.

Economics
The DES plant is part of a waste management initiative that is projected to save Nashville approximately $66.9 million by 2014, in addition to significantly lowering heating and cooling costs for downtown customers. For FY 2003, the City of Nashville was required to supplement DES operations to the tune of $14 million. For FY 2006, this number has been reduced to $1.6 million.

Longevity of Successful Operation
The DES began operation in December 2003. Since this time there has been no appreciable downtime due to system failure. The new plant has only experienced one forced outage (due to electric supply utility) since coming on-line in December 2003. The previous trash burning plant typically experienced more than 40 forced outages per year. As part of its 15 year operating agreement, CEPS has very specific performance and efficiency guarantees that it is required to maintain. In addition, CEPS is fully responsible for plant related repairs for the term of its contract.

Public-Private Partnership
Right from the RFP phase of the project, the City of Nashville and CEPS have worked collaboratively to create a business partnership that has been truly beneficial to all parties. In addition to the collaborative development, design and construction efforts related to the new DES, both Nashville and CEPS have worked together to sign up new customers and to market the new plant's capacity. CEPS is also responsible for metering and invoicing of customers, and has maintenance and repair responsibilities that extend to each customer's building. CEPS went into this project with a customer focused approach while Nashville has continuously maintained a partnership approach.