Forget roofs, are solar roads the next big thing?

May 20

The inventors imagine a roadway system that not only harvests energy, but also uses heat to remove surface ice, and lights up dark pathways with embedded LEDs. (Solar Roadways)

In most communities, solar cells typically do the brunt of its energy-harvesting atop roofs. It’s here that the implementation of the technology has been most practical, where the conversion of sunlight into electricity can be carried out unabated.

And while the U.S. Census Bureau estimates that installing solar panels on every home in America would produce 3.75 trillion kilowatt hours of electricity a year, nearly on par with all the energy the United States generated in 2011, such a sweeping sea change realistically isn’t going to happen anytime soon — if ever. That’s because the onus rests largely on consumers and businesses to adopt solar, with regulators playing a limited role in crafting policies to incentivize and nudge folks to buy in. And yet despite these efforts, photovoltaics still account for no more than 1.13 percent of America’s power production.

But what else can municipalities do? It’s not like they can pave the streets with solar panels.

Scott and Julie Brusaw have been developing special solar cells encased in rugged, hexagonal-shaped glass.
Scott and Julie Brusaw have been developing special solar cells encased in rugged, hexagonal-shaped glass. (Solar Roadways)

That’s where the husband and wife team of Scott and Julie Brusaw would beg to differ. Since the mid-2000′s, Scott, an electrical engineer, and Julie, a psychotherapist, have been developing special solar cells encased in rugged, hexagonal-shaped glass. Lay enough of these mechanical cobblestones together and you’ve built yourself a kind of hybrid driveway-slash-solar array. There’s even a section of a parking lot — located outside their engineering lab in Sagle, Idaho — that’s claimed to produce an output equivalent to a 3600-watt solar array.

For the Brusaws, the prototype, while impressive, makes up but a tiny chunk of a much more ambitious vision. According to their calculations, covering the nation’s nearly 28,000 square miles worth of roads, highways and parking spaces with these special panels would produce three times the nation’s total energy consumption. Under this scenario, the panels would serve as the foundation for a do-it-all “smart” roadway system that’s capable of not only harvesting energy, but also making roads safer by using heat to remove surface ice and lighting up dark pathways with embedded LEDs.

“One of the biggest benefits is that the new system can serve as a hub for all green energy technologies because it’s not vulnerable to disruption the way the centralized grids are,” Julie Brusaw explains. “It’s a perfect way to create an energy-producing ‘Smart Grid’ while also modernizing our antiquated highway system at the same time.”

The “Solar Roadway” project, which the Brusaws proposed, was promising enough that, in 2009, the U.S. Federal Highway Administration awarded them a series of contracts to further their concept. With the initial investments, they assembled a team to help create a clear, impact-resistant casing, similar to bulletproof glass, and strong enough to support up to 250,000 pounds. To test the glass’s strength, a tractor was even driven over the panels. Housed inside the road traction-molded shell are self-powered heaters to prevent icing during freezing winter months and tiny LED bulbs that can be networked to relay signals that warn drivers of hazardous conditions ahead. They’re also exploring ways to integrate other useful technologies, such as wireless induction recharging for vehicles.

“Even with all these useful features built-in, what’s great is that the surface material is still stronger and more durable than asphalt,” Julie Brusaw points out. “Potholes will be a thing of the past and even if any of the panels need to be repaired, at 110 pounds, they can be easily removed and have another installed in its place without causing any traffic delays.”

A less obvious benefit, as pointed out by Jan Kleissl, an environmental engineering professor at University of California-San Diego, is how carbon footprints can be reduced simply swapping out asphalt altogether. “The problem with asphalt is that it’s a dark surface that absorbs energy in potentially harmful way,” he explains. “Energy is turned into heat and thus increases the temperature of the air, which causes the urban heat island effect where people end up using more air conditioning.”

At this point you may be thinking that it all sounds pretty good, so what’s what’s the holdup? Well, in this case, we’re talking about an undertaking with astronomical costs, as is often the case with anything that involves having to overhaul infrastructure that’s spread across almost an entire continent. Over at Vox, Brad Plumer hashes out some hypothetical figures that make it clear why the project is gaining little traction:

Back in 2010, the company assumed that a 12′ by 12′ glass panel would cost around $10,000. At this rate, covering all of our roads would cost $56 trillion — nearly 20 times the annual federal budget. Even on a smaller scale, these panels are at least 50 percent more expensive than regular roads, and possibly more.

That’s not to mention the additional expense of developing technologies to store and transport the energy over long distances, Plumer argues.

For the time being, there still aren’t many practical ways to store solar-generated electricity for hours when the sun isn’t shining. What’s more, electricity generated on remote roads would have to be transported to where it was needed. That would all require a lot of infrastructure.

There’s also the issue of maintenance costs, though the couple contends the systems would pay for themselves over the course of 22 years.  Moreover, the degree in which flat, ground-level photovoltaics can be beneficial also varies widely depending on the region. “It is a good option for the southern parts of the United States like Arizona,” Kleissl says. “In the North, the sun angle is low, so it’s not as efficient since you’ll want panels to be tilted at 30 or 40 degrees.”

But for the Brusaws, they’ll continue to plow forth in hopes of carrying out as much of their grandiose plan as they can. They’ve recently launched a crowd-funding campaign on Indiegogo to raise $1 million, which, if successful, will go toward putting the finishing touches on a final product as well as figuring out a cost-effective method of producing the panels. Initially, residential versions of the system will be available locally to homeowners in Sandpoint, Idaho, where there are currently four customers waiting to have their driveways repaved, they said.

“Imagine driving from Seattle to Florida in an EV that is being charged with clean sunshine while driving on the highway,” Julie Brusaw adds. “Imagine the jobs that will have been created, how many families will have been supported while getting to that point.”

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