Reuters reports that Genachowski is arguing that the plan could work given that “the highly valuable spectrum currently allocated for broadcast television is not being used efficiently—indeed, much is not being used at all.” (Full speech here.)

The goal would be to free up 500 megahertz, which is in line with the amount the Department of Commerce proposed in President Barack Obama’s 2011 budget proposal. Clearly, broadcasters are not using all of the spectrum allotted to them. Of the 300 megahertz of spectrum set aside for broadcasters, only 36 megahertz are typically used in markets with less than 1 million people, and only about 100 megahertz are used in cities with more than 1 million people. He said: “Even in our very largest cities, at most only about 150 megahertz out of 300 megahertz are used.”

While Sprint (NYSE: S) and Verizon Wireless likely have enough spectrum for their 4G roll-outs, carriers like T-Mobile USA, are less fortunate. In Sept., T-Mobile USA asked lawmakers to allow the FCC to sell airwaves to them that were initially designated for police officers and firefighters. That chunk of spectrum failed to be successfully sold in the last auction. It’s still unclear what that fate is of that block.