Discussions of communications networks for smart grid initiatives tend to focus on private, radio-frequency (RF) mesh solutions in the United States, or narrowband-power line communications (N-PLC) in Europe and Asia. As utilities look ahead to a truly integrated and robust smart grid, though, more and more demands will be placed upon the underlying communications network. The need for high bandwidth, low latency, signal prioritization, and high security will only become greater over the course of the next decade.
At the same time, the integration of distribution automation (DA) applications with advanced metering infrastructure (AMI) is highlighting the limits of many AMI communications networks to support critical DA applications today. (For more on AMI/DA integration, see Navigant Research’s forthcoming report on Integrating Distribution Automation Applications with Advanced Metering Infrastructure.) Limits, that is, unless the network is built upon fiber optics.
“Fiber-to-the-meter” isn’t a concept that many utilities talk about, primarily because of the very high cost of deploying fiber. Passing a home with fiber can range from $700-$800 per home in densely populated areas to $4,000-$5,000 per home in lower density areas. Despite the expense, a number of utilities in the U.S. have decided to deploy fiber to the meter—and their smart grids are among the smartest in the nation.
Generally speaking, municipal utilities have led the way in installing fiber optics, justifying the investment by offering a triple-play service (voice/video/data). With consumers willing to spend upwards of $100 each month or more for triple-play services, the utility can justify the investment apart from the improved efficiency of its grid.
Electric Power Board (EPB) in Chattanooga, Tennessee, is the largest such fiber-to-the-meter deployment in the U.S. to date, and the reported results have been impressive. EPB’s 6,500-mile fiber network provides 5 millisecond (ms) speeds, enabling a full suite of DA applications, including automated self-healing and fault location, isolation, and service restoration (FLISR).
EPB reports that when remnants of Tropical Storm Lee hit Chattanooga in September 2011, even though its system was only about half deployed and less than 20% was automated, nearly one-third of homes and businesses in its service area avoided outage altogether or experienced less than a 2-second interruption, thanks to the automation built into the network. In 2012, EPB’s average interruption duration index (SAIDI) fell 24% from 109 minutes to 82.5 minutes. EPB also says its AMI applications are helping it avoid truck rolls and more easily verify restoration. The robustness of fiber means that the number of applications the utility may now integrate is virtually unlimited—no other smart grid communications network today offers that kind of capacity (although 4G wireless may get there).
Unfortunately, fiber isn’t an option for all utilities today, and not only because of the costs. Sixteen states have enacted legislation to prevent electric utilities from competing against franchised video service providers (cable and DBS); in other locales, the cable industry has filed lawsuits to stop the competition. Without the monthly triple-play service revenue that fiber enables, many utilities will be unable to justify the expense. Longer-term, cooperation among the cable, telecom, and utility industries might result in the ultimate in smart grid and robust communications and entertainment infrastructure—but that will no doubt require regulatory intervention.