Chattanooga, Tenn., has been known primarily for its Choo Choo, but lately it has been getting attention for a much faster form of transportation: electrons. The city’s municipal electric utility, the Electric Power Board (EPB) of Chattanooga, has recently built out an extensive fiber optic network that is being called the fastest in the United States. In addition to providing a new line of revenue for the local company by allowing it to offer cable television, telephone and Internet services, this effort has enabled EPB to create one of the nation’s smartest grids, which could become even more effective thanks to a new partnership with the Oak Ridge National Laboratory (ORNL).


More than simply enabling automated meter reading, the upgraded grid’s data capabilities are vastly improving overall system operations. While burying miles of fiber optic cable, the EPB also added a network of 1,200 automated switches called “IntelliRupters,” manufactured by S&C Electric Co. These switches, distributed at a rate of seven for every distribution feeder, can isolate system faults in milliseconds. As a result, customer outage time has been reduced by 40 percent, according to Jim Glass, EPB’s manager of smart grid development.


Extrapolating from a recent Lawrence Berkeley National Laboratory study on total U.S. outage costs, the EPB estimates this outage reduction translates into annual savings of $45–$50 million to businesses and residential customers across its service territory. Reduced meter-reading payroll costs and lower overtime for outage restoration also saved the utility $10.5 million last year, according to Danna Bailey, the EPB’s vice president for corporate communications.


“It’s a pretty impressive technology,” Glass said, adding that these statistics are beginning to make an impact with corporate real estate shoppers. “We can go right alongside the Chamber of Commerce and talk about how our system performs. It’s become a pretty good incentive.”


The EPB has approximately 170,000 residential and commercial metered customers with more than 60,000 now connected to the fiber network. Although it’s a relatively small city, Chattanooga’s utility managers started thinking big about fiber’s potential more than a decade ago, when the company began offering fiber-based telecommunications services to a small number of downtown businesses. At that time, the technology’s cost, along with much smaller broadband demand, made wider implementation impractical, but the group kept its eye on subsequent developments.


Rolling out the passive optical network across the utility’s service territory began in 2008, when electrical distribution managers saw advantages in fiber for supporting the advanced metering infrastructure (AMI) implementation they were planning. The implementation was further aided by a $111.5 million grant through the American Recovery and Reinvestment Act of 2009.


Today, customers who subscribe to the EPB’s cable, phone or Internet service (a business that contributes $25 million per year back to the EPB’s utility arm) have fiber extended directly to their home, at a connection point mounted next to their digital smart meter. From that point, coaxial cable is routed to cable TV boxes, Ethernet cable goes to the home’s router, and an additional Ethernet cable attaches to a port on the meter. The meters also feature 900 megahertz radio connections, which can broadcast the data from a nonfiber customer to their closest neighbor with a fiber connection for transmission back to the EPB’s data centers.


Learning how to deal with all of the information arriving at those data centers is a major goal for the EPB in the partnership deal it signed with the ORNL in October.


“A lot of it is just getting help in analyzing the huge amounts of data we’re able to collect on our system,” Glass said. 


Specifically, he sees four major areas in which the utility makes its current smart grid even smarter:


• Telemetry: Better understanding of where near-fault conditions are arising could help the EPB predict a potential problem before it occurs. “We’d love to find the tree that’s been giving us a problem,” Glass said.


• Demand response: Currently, the peak rates that the EPB pays its electricity supplier, the Tennessee Valley Authority, aren’t high enough to warrant the expense of demand-response incentives, but Glass anticipates that might not always be the case. The fiber optic network could easily interface with customer-sited energy management systems, but the utility would like more help understanding its options.


• Distributed generation: Currently, the EPB only has some 80 customers with solar panels, but the utility would like to better understand the implications of greater penetration. “We need to understand what it means to have power flowing through our lines from multiple directions,” Glass said.


• Cybersecurity: With 1,200 automated switches—and 60,000 fiber-connected meters—the EPB understands it could be a target. “The malicious element is probably getting smarter,” Glass said. “And we need to stay ahead of them.”


What might the national lab get out of the arrangement? Bailey said the ORNL hopes “to see what the electricity system of the future looks like today. We think that’s what we have here.”