We’ve been writing a lot lately about smart grid-to-“smart city” technology migration, or the idea that networks deployed to support smart meters, distribution automation and other utility functions can also serve the general public. On Wednesday, Santa Clara, Calif. announced a milestone (of sorts) in making this concept a reality, offering free public Wi-Fi over the same network that runs its smart grid.

Specifically, Santa Clara’s municipal utility, Silicon Valley Power, and hometown partner Tropos Networks -- now owned by Swiss grid giant ABB -- have started offering free Wi-Fi access over the utility’s SVP MeterConnect network. That field area communications network was built for electric and water smart meters, but SVP plans to eventually use it for distribution automation and mobile workforce support, among other tasks to which ABB is well suited.

At the same time, Santa Clara has its own plans to use the Tropos-ABB network to connect public safety agents, building and fire inspectors, parks and recreation workers and other city employees, at a lower cost -- and with more bandwidth -- than what they’d get out of cellular.

All in all, it’s an impressive list of business cases for deploying a citywide wireless network at the utility (and city's) own expense. And, of course, Tropos/ABB are far from the first to roll them out. Indeed, we’ve seen a long list of smart grid contenders courting U.S. municipal utilities, which GTM Research has estimated will spend a cumulative $4.5 billion to $9 billion on smart grid investments between now and 2017, much of it aimed at advanced metering infrastructure (AMI), or smart meters.

That’s a big market, though spread across roughly 2,000 entities, and it’s attracted a number of would-be suitors, from the smart-grid-as-a-service offerings on hand from General Electric, SAIC, and a growing list of smart grid providers, to muni-targeted platforms from the likes of Aclara and Calico Energy, On-Ramp Wireless and ElectSolve, or Tantalus and its multi-technology municipal utility customer base, to name a few.

As for bridging the gap from smart meters to other city needs, networked streetlights are an early adoption point, with smart grid vendors like Echelon, Sensus and most recently, Silver Spring Networks laying plans for streetlight integration. Tropos, on the other hand, started out in 2000 as a municipal broadband Wi-Fi provider serving city agencies like firefighters and police, giving it experience that it shifted to the smart grid space in the latter half of the previous decade.

Tropos has landed projects with municipal utilities including Glendale and Burbank, Calif., among more than 1,000 customers that have deployed the startup’s technology across 50 countries. Since ABB bought the startup for $35 million in June, it has rolled out new customers including a Department of Energy stimulus grant-backed project with Kansas City Power & Light to link distribution grid assets.

As for how it gets its bandwidth and service strengths, Tropos describes it as “patented cognitive radio technologies to ensure reliable operation in unlicensed spectrum,” with proven ability to “provide more than 1 TB (terabyte) per day in aggregate user data transfer to an ever-increasing number of Wi-Fi-enabled consumer devices, from smart phones to personal tablets.”

SVP has a ways to go to prove its AMI vision: it’s only deployed about 150 smart meters as of this fall, or less than 1 percent of its planned 53,400 smart electrical meter deployment. Still, GTM Research senior smart grid analyst Emma Ritch noted that the utility has a “very mature plan for the smart grid, especially in data management and analytics,” which earned it a high ranking in the upcoming Utility Smart Grid Outlook in North America 2013: Technologies, Strategies & Case Studies report. (It also works with eMeter, the meter data management and analytics startup bought by Siemens in late 2011 and now integrated into the German grid giant's broader smart grid integration plans.)

As for the free Wi-Fi, it’s a pretty minor share of the Tropos network’s potential, Ritch said. SVP has about 600 radios in the service territory, which offer a tremendous amount of bandwidth, with 10 megabits of broadband service at every node, she said.

Tropos has deployed in North American markets mostly using 900-megahertz AMI mesh networking technologies from the likes of Silver Spring Networks, Itron, Landis+Gyr and Elster. Other options include point-to-multipoint wireless networks via licensed spectrum (Sensus), powerline carrier (Echelon) or a combination of 2.4-gigahertz mesh and long-range, high-bandwidth wireless (Trilliant plus acquisition SkyPilot), to name some key competitors -- and that’s not counting cellular networks, which have begun to bridge the gap from backhaul networks to direct-to-meter connectivity.

As for citywide Wi-Fi, Santa Clara had its own municipal service, but provider MetroFi went out of business in 2008, leaving Tropos its network nodes to make use of in its MeterConnect rollout. In that sense, restoring free public Wi-Fi service is just a tag-end item on a long list of integrated, citywide broadband ideas on the city’s list of future prospects.

But while free Wi-Fi may seem simple compared to DA or emergency response communications, it’s also fraught with risks. Every new endpoint that connects to a smart grid network presents a potential point for intrusion, which puts the pressure on SVP and Tropos/ABB to make sure proper cybersecurity measures are in place -- as well as to make sure downloads of the daily internet memes and crazes don’t disrupt its utility-critical operations.

In the meantime, we should note that calling SVP’s new free Wi-Fi offering a “first” for smart grid-to-general public connectivity is open to contention.  A short list of unusual, yet valuable customer broadband connectivity architectures deployed in the smart grid field include Chattanooga EPB’s fiber internet access to the home for TV, internet and telephone; SVP’s citywide Wi-Fi; Modesto Irrigation District's proposal to use excess AMI bandwidth for local water departments; Lakeland Electric's use of its city's private fiber network as a backbone for smart grid networks, as well as communications for state transportation officials, county schools and public libraries; and Tacoma Power’s Click! Network, a hybrid fiber coaxial network that serves double duty as both electrical transmission and distribution system for the city utility and cable television, broadband, and wholesale internet services for city residents.