Chilled Water Pump Upgrades Project Completed
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The Nashville District Energy Plant is currently completing a $600,000 upgrade to the six chilled water pumps that distribute chilled water through the downtown system. The modifications were necessary to increase the plant’s capacity to deliver chilled water to facilitate the new load from the Music City Center. The new convention facility will use both chilled water and steam from the District Energy Plant. Below are several stats for the pumps:
- The original pumps were rated at 7,600 gallons per minute with a differential head of 219 feet (95 pounds per square inch.) At that required head pressure, the new pumps are rated at 11,000 gallons per minute.
- The original pumps were 500 HP. The new pumps are 550 HP.
- The cost of the pump modifications is approximately $600,000.
2010-2011 Annual Report
In May of 2011, the legal entity Constellation Energy Projects & Services Group, Inc. (CEPS) was formally merged with and into Constellation NewEnergy, Inc. (CNE).
This was done due to an internal, company reorganization and did not change any existing contracts or legal documents. The services previously provided by CEPS are now being provided by the same Constellation Energy personnel under the entity Constellation NewEnergy, Inc.
With that being explained, Constellation NewEnergy, Inc., operator of the Nashville District Energy System (DES) is pleased to present their eighth “Annual Report” to the Metropolitan Government of Nashville and Davidson County, Tennessee. This report summarizes activities related to environmental, health and safety issues, sales and marketing activities, customer service, fuel procurement, finance and the overall system performance for the past twelve months. The system is made up of two basic parts, the Energy Generation Facility (EGF) and the Energy Distribution System (EDS).
Excellent operation of the EGF by an outstanding work force resulted in steam and chilled water availability and reliability both being above 99% again this year. This included scheduled outages and minor upsets so short in duration they are not required to be reported. CNE contractual efficiency guarantees also continue to be met. Efficient operations benefit everyone through utility and energy savings.
During the fiscal year July 1, 2010 through June 30, 2011, CNE continued to have a perfect environmental record with no excursions or violations. All verification data, records, reporting requirements and submittals were kept up to date and in order.
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Music City Convention Center Service Lines Installed
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The Metro Nashville District Energy System (DES) will provide the heating and cooling for the new Music City Convention Center (MCCC). Steam and chilled water will be supplied to the DES mechanical room in the MCCC via a new pipeline extension that is currently under construction. The new service pipelines from the existing DES distribution system to the MCCC are nearing completion. The new pipelines extend from the intersection of Molloy and Almond Streets and consist of: a steam supply and condensate return for heating, and a chilled water supply and return for cooling. Thermal Engineering Group, Inc. (TEG), Metro’s consultant for engineering related to DES, is providing design and technical oversight of this service installation. The Construction Management for the installation of the distribution system is being provided by Bell/Clark (BC), Construction Managers for the MCCC. The service pipeline installation project is being completed in two parts. The majority of the work is related to the pipeline extension which is now 95% complete. This work consists of the installation of the distribution system pipelines along Molloy St. to 4th Avenue, north along 4th Avenue to Demonbreun St., then west to the middle of the block between 5th and 6th Streets on Demonbreun where the new service enters the MCCC property and penetrates the building’s outer perimeter. This portion of the project was competitively bid and awarded to two contractors: Mountain States as the civil contractor responsible for opening the trench, furnishing and installing the chilled water lines, installing of all related concrete structures and providing site restoration; and John E. Green as the mechanical contractor responsible for furnishing and installing the welded steam and condensate piping systems. The remaining part of the service consists of the installation of the four pipes from the building’s outer perimeter into the MCCC mechanical room that has been designed to receive the new services. The in-building work is being performed by the contractors for the MCCC and is projected to be completed by the fall of 2011.
Extensive Tunnel Repair Projects Completed
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The Metro Nashville DES distribution system consists of approximately 4 miles of trenches and tunnels with 84,000 feet of piping. Of this total, approximately 5,800 trench feet is contained within the system’s main tunnels below Broadway (2,100 feet), 4th Avenue North (2,000 feet) and 7th Avenue North (1,700 feet). These tunnels were constructed during an expansion of the distribution system in the mid 1980's and are quite remarkable. Large boring machines drilled 8 foot diameter holes through solid rock 40 feet below the City of Nashville. Since the tunnel construction, ground water and water from naturally occurring springs in the area has always seeped through the rock and into the tunnels. This water hardly ever accounts for more than an inch or so of water in the floor of the tunnel, however its seepage through the rock walls and ceiling has slowly deteriorated the rock. This has subsequently led to portions of the rock detaching from the tunnel walls and ceiling. To fix this problem, MNDES hired a contractor to stabilize the worst tunnel sections. This stabilization involved the drilling and placement of 6 foot long rock bolts at the 10 o’clock, 12 o’clock and 2 o’clock positions in the tunnels perimeter. Drainage wicks were then installed along the tunnels length at the 12 o’clock position and also circumferentially along the tunnel with varied spacing depending upon the amount of water infiltration but a minimum of every 4 feet. Then, a 4 inch by 4 inch heavy wire mesh fabric was attached to the tunnel walls and ceiling leaving a 2" gap between the wire and the surface. A concrete mixture (shotcrete) was then blown onto the walls and ceiling to create a new interior tunnel surface a minimum of 4” thick. The goal with this design was to strengthen the tunnel walls to prevent rock detachment while also re-directing water infiltration along the sides of the tunnel so that the water could then drain to the tunnel floor. Approximately 700 feet of the Broadway tunnel was repaired, approximately 2,000 feet of the 4th Avenue tunnel and 1,700 feet of the 7th Avenue tunnel. The work took approximately 9 months to complete.
The Metro Nashville District Energy System congratulates its customer The Hermitage Hotel for being named one of the 10 Best Hotels in the USA by U.S. News and World Report.
http://travel.usnews.com/features/10_Best_Hotels_in_the_USA/
Music City Center, Nashville, Tennessee
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Metro Nashville District Energy System Will Provide Steam and Chilled Water for the Music City Center During Construction and for Ongoing Operations
The pipeline design is completed and construction will begin shortly to install the new District Energy System pipelines needed to serve the Music City Center. Steam and Chilled Water services are scheduled to go online next Spring so that DES can serve the facility during project construction, then continue providing ongoing services once the center is fully operational. The new underground distribution system includes a 12” steam line, a 6” condensate return line, and two 24” chilled water lines that extend from the existing distribution system serving the Schermerhorn Symphony Center to the point of entry at the Music City Center on Demonbreun Street.
DES will provide heating and cooling during construction of the Music City Center that otherwise would require temporary services. DES chilled water will provide cooling during the warmer months of the year primarily to remove humidity from the building during construction. During winter months, steam will be used to heat the enclosed areas of the building. DES offers a very good fit with the new environmentally friendly Music City Center both during construction and on an ongoing basis for many reasons including: a reduced carbon footprint when compared to alternative stand alone heating and cooling options, lower capital costs and overall savings on heating and cooling costs for the center, and the aesthetic advantage of not having cooling towers and other stand alone components competing with the overall design of the center.
First Avenue, Nashville, Tennessee
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How did the flood affect the Metro Nashville District Energy System?
On Saturday, May 1, 2010, most everyone in the middle Tennessee area was watching local television coverage of the severe thunderstorm warnings, tornado watches and flood watches. The storms continued throughout the night and all the next day without letting up. Record rainfall was recorded in the Nashville area on both Saturday and Sunday, with more than 6 inches both days. Creeks and rivers flooded neighborhoods, roads and the interstates surrounding Nashville. This made it nearly impossible to navigate to and around the city.
On Sunday afternoon, as the flood waters started spilling over the banks of the Cumberland River in downtown Nashville, DES' steam system was shut down to avoid potential safety issues, such as water hammers.
Sunday night, water spilled onto First Avenue, filling the energy distribution tunnels on
Broadway.
By Monday night, the river finally crested. Water reached as far as the Country Music Hall of Fame on Fourth Avenue.
During this time, the Energy Generation Facility was never in jeopardy of being flooded, as the chilled water system continued to supply cooling to the DES customers.
When the water receded and the operators of the DES were allowed access to the area, approximately 800,000 gallons of water were pumped out of the tunnels over the next two and a half days. After all structures, piping, insulation and electrical components were inspected, boilers were lit at the Energy Generation Facility to restore steam service to the DES customers. Condensate in the steam lines had to be evacuated slowly, and the wet insulation had to be dried as the system came up to operating pressure. At approximately 7 p.m. on Saturday, May 8, the steam system was back to normal.
The following statement was issued by the Metro DES liaison: "We greatly appreciate the outstanding work of CEPS (Constellation Energy Projects & Services Group) in working to restore service to district energy system customers in very difficult conditions. A job 'very well done' is extended to the staff and crew for their dedicated efforts."
Did You Know District Energy Offers More Favorable Carbon Footprint?
In cases where buildings are considering electric resistance heat or heat pumps, utilizing District Energy for heating results in a more favorable “Carbon Footprint.” Read More
View the Comparison of the Production of Carbon Dioxide.
Schermerhorn Symphony Center
The Symphony started with a design
to accept DES because of the
lower capital costs.
Photo by Marie Lancaster
Incorporating District Energy at the Design Stage of a Project Yields Greatest Savings.
Incorporating district heating and cooling services (DHC) from Metropolitan Nashville District Energy System (MNDES) into a new development at the design/conception stage can achieve reduced capital costs and reduced operating costs over the life of the development.
Perhaps the most significant economic benefit is in the form of avoided capital costs. Capital cost avoidance can have a material affect on the customer’s project viability. This is particularly true if the proposed facility is large enough to warrant chilled water generators. When DHC is designed into the project, the total building area, as well as the costs, can be reduced as a result of removing the chillers, cooling towers and a portion of the pumps and related piping and electrical. There are also structural savings, as well as aesthetic benefits, by not having to locate cooling towers atop or adjacent to buildings and by avoiding cooling tower plumes. Read More