Hey, let's turn our streets into giant solar panels

One of the big drawbacks to solar energy is that it takes up a lot of square footage.  Enthusiasts are constantly looking for new places to stash solar panels, such as the expansive roofs of big-box retail stores – an initiative which President Obama recently congratulated Wal-Mart for supporting, to the consternation of Wal-Mart’s union critics.

The Solar Roadways project, as described at The Week, figures there’s already 18,000 square miles of real estate covered by concrete and asphalt, so people won’t mind replacing those roads with glass:

The Solar Road Panels can be installed on roads, parking lots, driveways, sidewalks, bike paths, playgrounds — literally any surface under the sun. Yes, they are covered in a kind of glass, but the glass is strong and grippy enough to drive on — apparently they can withstand trucks weighing up to 250,000 lbs — while generating power to light the road, charge electric vehicles, and melt ice and snow. 

“You first mention glass, people think of your kitchen window,” Solar Roadways’ Scott Brusaw told Fast Company. “But think of bulletproof glass or bomb resistant glass. You can make it any way you want. Basically bulletproof glass is several sheets of tempered glass laminated together. That’s what we have, only our glass is a half inch thick, and tempered, and laminated.”

This is all supposed to generate triple the amount of electricity America currently consumes.  Unsurprisingly, federal grants have been secured for further research.  Solar energy is catnip for government funding.

It’s a grandiose idea, and while solar energy always seems to under-perform the promises made by its advocates, it’s clever to think of using road space to install solar panels, rather than chopping down forests to set them up.  (Unless the technology undergoes a quantum leap, there’s never going to be enough space on rooftops to make solar energy more than a minor supplemental resource.)  

But there are many reasons to think this idea is as loopy as it is clever, beginning with the obvious problem of driving on that allegedly “strong and grippy” glass.  That sounds like one of those claims I’d have to see to believe, especially given the variety of inclement weather conditions that affect roadways in different parts of the country, and the driving hazards inherent in transitioning from a solar road to the old-fashioned kind – that seems like a pretty significant change in the driving environment, and I doubt people will want to dramatically reduce speed or stop every time they enter or leave a solar road.  And aren’t solar panels typically reflective?  We’re going to drive on roads that throw blinding flashes of light into our faces?

Let’s table the driving-quality issue for a moment, since that will be an early empirical hurdle solar roads would have to cross – either they’re safe to drive on, or they’re not, and it won’t take much R&D to answer the question definitively.  Another obvious problem is the staggering cost of replacing most of the country’s roads with this solar material.  Advocates of the project cheerfully assure us it would pay for itself over time… but that’s not much consolation if the initial cost is astronomical.  President Obama has repeatedly assured us that the trillion dollars he spent on infrastructure in 2009 vanished without a trace – it wasn’t even a drop in the bucket for our road-and-bridge needs, because he wants hundreds of billions more.  One shudders to think what the initial cost of replacing every major road, all at once, would be, not to mention the cosmic levels of inconvenience to drivers.  There are ideas so impractical that no amount of long-term gain can make them work.

There are also maintenance costs to consider.  These solar roads would be many times more expensive to repair or modify than conventional road material, with the added cost of the systems needed to transmit power from the panels to their ultimate destination.  

The article at The Week mentions the rather significant problem of using all this solar energy, since it’s both difficult to store and unreliable.  Despite all those promises of replacing fossil fuels, solar-energy advocates never have a good answer for the problem of weather conditions interfering with power generation – you can’t hook the entire country up to a power grid that doesn’t always run anywhere near nominal capacity in various areas.  What good are the solar roads of Minnesota going to be, when they’re covered with snow?

Barring some astounding improvements in the efficiency of solar panels and storage systems, large-scale terrestrial solar power is always going to be a very expensive sideshow that sucks down public money because it sounds so wonderful to environmentalists, and politicians who love to spend other people’s money on high-minded crusades.  The only way it’s ever going to work on a national scale is to put the solar panels in space, and find a way to bring the harvested energy back down to Earth.  That would be a daunting feat of engineering, but it’s not impossible, and given more time to work on the technology, I tend to think it would become practical long before replacing our highways with glass.