On The (Solar) Road  

REA has an article on Idaho company Solar Roadways and their endeavours to make road building materials that generate solar power. I'm pretty dubious about the practicality of this idea - putting solar panels on rooftops seems a lot cheaper and easier than embedding them within roads - but hey, its an interesting idea anyway.

The concept of using road surfaces to generate clean solar power is moving beyond the idea stage. Roads absorb heat from the sun every day and are usually free of sightline obstructions that could otherwise block the transmission of light rays. And if the roads built for cars and driving are partly to blame for global warming, why not make them part of the solution too?

Idaho-based Solar Roadways is one of the trailblazers. Electrical engineer Scott Brusaw was inspired to start the company when he heard Caltech solar energy expert Nate Lewis suggest that covering just 1.7 percent of continental U.S. land surface with photovoltaic (PV) solar collectors could produce enough power to meet the nation's total energy demand.

Brusaw put two and two together when he realized that the interstate highway system already covers about that much of the nation's land surface, so he got to work designing a system that combines a durable and translucent glass road surface with PV solar collectors that could be wired directly into the electricity grid.

The heart of the solar roadway concept is the solar road panel. Each individual panel consists of three basic layers, the road surface layer, which is translucent and high-strength yet rough enough to provide traction. The surface layer is capable of handling today's heaviest loads under the worst of conditions and protect the electronics layer beneath it.

Next is the electronics layer, which contains a large array of cells, the bulk of which contain solar collecting cells with LEDs for "painting" the road surface. These cells also contain the "Super" or "Ultra" caps that store the sun's energy for later use. Batteries are not used in the solar roadway. Since each solar road panel manages its own electricity generation, storage, and distribution, they can heat themselves in northern climates to eliminate snow and ice accumulation.

The third layer is the base plate layer, which distributes power (collected from the electronics layer) and data signals (phone, TV, internet, etc.) "downline" to all homes and businesses connected to the solar roadway. The power and data signals are passed through each of the four sides of the base plate layer.

Overseas, Europeans are also pioneering ways to use the sun's rays to work as they beat down on roadways. The British firm Astucia has developed a road stud that contains small solar panels and emits LED light to illuminate dark roadways. On the 120 U.K. roads where the new studs have been installed, night-time accidents are down 70 percent.

And the Dutch firm Ooms Avenhorn Holding BV has developed a way to siphon solar heat from asphalt road surfaces and use it to de-ice roads and help power nearby buildings. A latticework of pipes under the road surface allows water to heat up during warm weather. The water is then pumped deep under ground where it maintains its higher temperatures and can be retrieved months later to keep road surfaces ice-free during winter months. Apartment buildings, industrial parks and an air force base have benefited from the innovation, and the firm is working on exporting its system to other countries in the coming years.