Solar Roadway's crazy plan to replace America's roads with solar panels has always been met with a mixture of public glee and pragmatic criticism. Now, though, the company is getting a new, tiny public test, with a stretch of solar sidewalk to be installed on Route 66. According to Missouri's News Tribune, Solar Roadway's hexagonal, LED-embedded solar panels will be used to generate electricity for the Route 66 Welcome Center at Conway, as well as possibly fund future pilots.

"Solar roadways can hopefully create new revenue streams," Tom Blair, an engineer for Missouri's Department of Transportation (MoDOT), told the Tribune. "If their version of the future is realistic, roadways can begin paying for themselves." The solar panels will be tested first on a pavement leading to the rest stop's entrance, with plans to then expand onto the parking lot.

But there have always been practical obstacles, with cost being the biggest. It's been estimated that paving the nation's roads with solar panels would cost in the region of $56 trillion (although this figure has been disputed, and since its publication the price of solar panels has dropped). And once initial costs have been met, there's the issue of maintenance.