Hot asphalt: A sustainable power source

The alternative energy blogs are buzzing with news of a compelling new idea, an idea so utterly obvious that it will make you bang your head and say, "Hey, why didn't I think of that?" The revelation comes from Worcester Polytechnic Institute, where someone must have walked in bare feet down a country road in summertime only to discover that asphalt gets, you know, hot.

WPI scientists have been toying with ways to capture the heat in asphalt to heat water or to generate electricity. Blacktop as a solar collector. Why not?

"Asphalt has a lot of advantages as a solar collector," says Rajib Mallick, the study's director. "For one, blacktop stays hot and could continue to generate energy after the sun goes down, unlike traditional solar-electric cells. In addition, there is already a massive acreage of installed roads and parking lots that could be retrofitted for energy generation, so there is no need to find additional land for solar farms. Roads and lots are typically resurfaced every 10 to 12 years and the retrofit could be built into that cycle. Extracting heat from asphalt could cool it, reducing the urban 'heat island' effect. Finally, unlike roof-top solar arrays, which some find unattractive, the solar collectors in roads and parking lots would be invisible."

Testing seems to have gone very well. The biggest stumbling block may be finding a cost-effective way to pass the water through the asphalt. During research, copper tubing was used, but that's obviously not a real-world solution.

Don Willmott's blog posts are provided by LifeWire, a part of The New York Times Company.