Yesterday, startup Spectrum Bridge announced that it will work with Google to conduct tests using the white space in the digital TV spectrum in California's Plumas-Sierra County.

White-space spectrum shares many of the potential advantages that smart-grid-over-cellular and smart-grid-over-broadband have. The network already exists, and most people own the equipment (TVs, DSL boxes) that can be used to access the system. Thus, the rollout could potentially be cheaper, easier, and involve less equipment.

Some utilities balk at cellular, broadband and white space for two reasons. One, it is hard to guarantee universal coverage, which goes against their charter to provide comprehensive service. Two, the funds used to pay for service on an existing network comes out of operating budgets, whereas creating your own network can be justified as a capital expense. Capital expenses can be paid for with rate increases; operating expenses often can't and thus, somewhat counterintuitively, can wind up being more difficult to fund.

But we had a question about white space that Spectrum Bridge answered today. Can you do two-way transmission of data? Radio stations and few startups have begun to look at the Radio Data System -- the communications system that lets stations send small amounts of data over FM broadcast signals -- as a foundation for demand response and energy efficiency programs. Have you ever rented a car in Europe and heard the national traffic report come over the airwaves, or seen the name of the currently playing song pop up on the small LCD screen of your stereo? Both of those instances are examples of RDS in action.

The big drawback with RDS, however, is that it can only send signals one way: a utility can shut off your power or curb consumption through a demand response program, but it can't do remote meter reading or perform other tasks.

The system being tested in the Plumas-Sierra County trial would offer two-way communication.

"The white spaces network provides a bidirectional data link and a Google power meter can be setup by the homeowner so the meter uploads its data to Google for accumulation and display on the user's home page," a company representative wrote. We're now trying to find out how exactly the two-way communication works. Does the TV signal go to a DSL box, which then uploads it to PowerMeter or are all communications handled within the white space? More details to come.