Road Power


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You’ve seen the summer asphalt basking in the sun, radiating heat waves, shimmering with puddled mirages that vanish when you get there, soaking in enough rays to fry an egg. To Scott Brusaw, an electrical engineer and president of Solar Roadways, Inc., the sun-drenched blacktop is a massive energy resource just waiting to be exploited.

With the cost of solar cells now near “grid parity,” competitive with other sources of energy, perhaps the greatest major hurdle to using the sun to power homes, street lights, and everything else is the question of where to put the solar panels. Increasingly, people are pushing back on where large arrays of solar panels may be placed, be it mountainsides, unused fields, or even swaths of desert. “A lot of people don’t want to see that stuff out their window,” explains Brusaw. “The road is there anyway—it’s just baking in the sun.”

Scott Brusaw. Photo courtesy of Mark Dixon of YERT

Safer Driving and Cheaper Repair

Brusaw’s vision is to replace the black ribbons of asphalt that wind through the country with 12 x 12-ft solar panels that would power not only surrounding towns and cities but also the road itself. According to Brusaw’s calculations, a single mile of four-lane highway exposed to four hours of sunlight a day would produce enough power for over four hundred homes.

Each individual panel consists of three basic layers: Road Surface, Electronics and a Base Plate layer. Photo courtesy of Dan Walden

Reducing dependence on fossil fuels is only the most obvious benefit of a solar highway system. Brusaw envisions each panel having its own microprocessor, making driving safer and road repair cheaper. A glass top covering each photovoltaic cell would be textured to allow drivers to hug the road as safely as they do on asphalt. Embedded in it would be a heating element, such as that commonly found in the rear windshield of most vehicles, to melt snow and ice. LED lights would mark the edge of the road and lights throughout the panel could let drivers know about detours, coming exits, and other challenges of driving.

Brusaw's firm, based in Sagle, ID, landed a $100,000 grant from the U.S. Department of Transportation to build a prototype of his system. It has been developed but has not yet been driven on. To further things along, the Department of Transportation has now awarded Brusaw's company an additional $750,000.

A closeup of an Individual Electronics Module. Each module contains three yellow LEDs and three white LEDs for "painting" road lines - they look the same when not illuminated.

The modular nature of the system would mean that damaged panels could be quickly swapped out. Roads would not have to be jack hammered and broken up to get below them. The material the panels would rest on could be a mélange of recycled products—bottles, trash bags, tires, etc.—helping to ease landfill. It would also mean the end of asphalt, which is, after all, a petroleum product. You would think that asphalt companies would already be lobbying to put the kibosh on the government funded idea, but Brusaw says that the industry “sees the writing on the wall,” and are eager to be a part of whatever change is coming.

Current Challenges

Immediate hurdles to developing the panels are minor. “Everything we’re doing is old technology,” says Brusaw. The biggest challenge is finding the ideal surface, one that will give good grip without puncturing tires or blocking the path of the light to the solar cells within. A probable solution, now in the works, is a prisemed surface. “It has to be big enough to provide traction, but can’t be pointed like the album cover of Dark Side of the Moon,” he says.

Just how the glass and electronics would link together from panel to panel remains a proprietary secret.

Reducing Asphalt Usage

Brusaw sees the scheme as greatly reducing, if not eliminating asphalt as a major road building material.

Margaret Cervarich, vice president of marketing and public affairs for the National Asphalt Pavement Association, scoffs at such notions. “Believe me, in the asphalt industry, we are looking forward to a very bright future,” she says. “When you build a road you need something that is extremely durable and strong, that stands up to heavy loads. I don’t know how you would do all of that with glass.”

She also points to asphalt as one of the most recycled materials in the world;  99% of the material is recycled when an asphalt road is repaired. 

For solar roads, the longer-term challenge is the usual one: Money. Brusaw estimates the panels will cost some three or four times as much as their asphalt equivalent. One mile of a new blacktop road costs upward of $1 million. But the comparison is apples and oranges because the solar panels will begin paying back capital costs immediately, claims Brusaw. His most conservative estimate has the panels paying for themselves in 20 years, not including tax breaks, subsidies, and the savings that come with melting snow and reducing traffic jams. Others have put payback time closer to three or four years, he claims.

Brusaw hopes to solarize his own parking lot within the year. Then he’ll try to convince other private pavement owners—such as convenience store operators, who spend an average of $4,000 a month on electricity—to convert their own parking lots. If the panels prove to be as wildly sensible as Brusaw claims, the power grid and the roads we drive on could soon be linked as never before.

Michael Abrams is an independent writer.

The biggest challenge is finding the ideal surface, one that will give good grip without puncturing tires or blocking the path of the light to the solar cells within.

Scott Brusaw, president, Solar Roadways Incorporated

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July 2011

by Michael Abrams, ASME.org