The City of Chattanooga, Tenn., and the city’s public power utility, EPB, on May 25 marked the completion of a microgrid in Chattanooga.
The new microgrid at the Chattanooga Police Services Center and Fire Department administrative headquarters can generate and provide power in an emergency and sustain operations 24/7/365 with enough energy for fire and police functions at the location to respond to the needs of the Chattanooga community indefinitely.
Functions located at the Chattanooga Police Services Center and Fire Department administrative headquarters and served by the microgrid include additional services such as SWAT team, homicide, Chattanooga Fire Station 10, radio control center, city camera surveillance, and other critical communication infrastructure.
EPB's smart grid provides two pathways for power to reach the Chattanooga Police Services Center and Fire Department administrative headquarters, so the new microgrid will serve as the third line of defense should widespread outages affect Chattanooga.
The microgrid includes two main generation and storage systems that reduce costs and allow both the City and EPB to recoup their investments more quickly:
- Generation: The City of Chattanooga purchased a 200-kilowatt diesel generator and 155 kilowatts of solar panels (installed on the building roof); these were installed "behind the meter" and reduce the amount of energy consumed at the location, lowering its monthly bill by roughly 20 percent.
- Storage: EPB invested in a 500-kilowatt battery to support the microgrid and other grid services; the battery is installed "in front of the meter" so it can be used to shave peak load during extremely hot or cold weather, reducing TVAs peak demand charge to EPB and keeping energy costs lower for local residents and businesses. (EPB does not shave peak load if severe weather is in the forecast; batteries are charged to capacity so they are prepared for an emergency.)
Because utilizing energy storage reliably reduces peak demand charges, EPB's investment will pay for itself within 6-7 years and will continue to provide value well beyond the cost of purchasing and installation.
EPB's smart grid has 1,200 smart switches, sensors and other devices on a 9,000-mile fiber optic backbone to reroute power automatically when a disruption is detected.
EPB continues to expand the EPB local energy mix with distributed energy resources across its 600-mile service region to improve power resiliency, business continuity for critical community resources and reduce costs for customers through peak demand management.
Several projects are being planned now, particularly in rural areas that take additional time to reach should the smart grid be unable to reroute power.
