The city of Chattanooga, Tennessee, and electric utility EPB have completed a new microgrid project.
Dubbed the “Power to Protect” microgrid, the solar plus storage installation is located at the city’s Police Services Center and Fire Department administrative headquarters.
The microgrid will serve as a backup to EPB’s smart grid technologies, which are already powering the facility.
Critical services can be supported indefinitely
The Power to Protect microgrid uses both solar and diesel generation, with the city purchasing a 155-kW solar array from Canadian Solar and a 200-kW diesel generator from Caterpillar. The solar array was erected on the roof of the administrative headquarters building. Inverters were provided by Solar Edge.
EPB purchased the microgrid’s 500-kW battery and microgrid controller from ELM Microgrid.
All told, the system can support the building’s 24/7 emergency services operations indefinitely. The headquarters houses Chattanooga’s SWAT team, homicide department, Fire Station 10, a radio control center, city surveillance cameras and other critical infrastructure.
Chattanooga Fire Chief Phil Hyman said the microgrid will provide peace of mind to first responders.
"From the Easter 2020 tornadoes to this spring's windstorms, we've seen how changing weather impacts our safety, and this microgrid will prepare us to be resilient in any event," Hyman said.
Police Chief Celeste Murphy added that electricity is critical to powering the technology they use to protect the people of Chattanooga. "It's a relief to know we won't have to worry about how we'll access power should we lose connection to the smart grid,” she said.
Resilience and savings
In addition to added resilience, the microgrid is expected to lower the building’s electricity consumption and costs.
Chattanooga Mayor Tim Kelly said the microgrid and EPB’s smart grid would protect essential services “in a sustainable manner that reduces cost and waste and ensures our first responders' ability to protect our city at all times.”
The solar panels were installed behind the meter to reduce the amount of grid electricity required by the building. This is expected to reduce the building’s energy bill by around 20%.
The battery was installed in front of the meter, allowing it to support both the microgrid and other grid services through peak shaving on extremely hot or cold days.
However, if severe weather is forecast, EPB prioritizes keeping the battery charged to capacity should there be an outage.
A smarter smart grid includes microgrids
First established by the city of Chattanooga in 1935, EPB manages a highly automated power distribution system with a 600-mile service area. Its smart grid, which began construction in 2008, includes more than 1,200 smart switches and sensors that automatically reroute power when an outage is detected, improving resilience.
The smart grid employs microgrids for additional resiliency should there be a widespread power outage in its service area.
EPB President and CEO David Wade said that microgrids like the Power to Protect microgrid further improve the resiliency of the grid, which is why the company is committed to integrating more of them into its smart grid.
"This project is a great example of how we're using microgrid technology to enhance EPB's local energy mix while providing customized energy solutions to address the specific needs of customers in different areas," Wade said.
EPB and the city of Chattanooga previously partnered on a microgrid at Chattanooga Airport.
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