Harvesting Solar Energy Using Roads

Solar energy, in the form of light and heat, could be harvested from highways and put to a variety of uses including powering streetlights, illuminating signs and advertisements, even powering buildings.

We’ve reported previously on solar panels as a road surface, but the millions of square kilometres of ashphalt around the world can also be used to harvest solar energy in other ways.

According to a engineering research team from the University of Rhode Island (URI), heat emanating from streets and roadways is why city temperatures are often considerably warmer than nearby suburban or rural areas.

“If we can harvest that heat, we can use it for our daily use, save on fossil fuels, and reduce global warming.” said K. Wayne Lee, URI professor of civil and environmental engineering and the leader of the team.

The team has identified several potential ways to turn city streets into solar energy collectors, ranging from the simple to the complex.

The first is to wrap flexible photovoltaic cells around highway dividing barriers and median strips, and embed toughened solar panels on dead ground between barriers.

“This is a project that could be implemented today because the technology already exists,” said Lee. “Since the new generation of solar cells are so flexible, they can be installed so that regardless of the angle of the sun, it will be shining on the cells and generating electricity.”

Another more solar thermal approach is to install water-filled pipes under roadways which would heat up to the point of being used to drive a small turbine, providing electricity. Graduate student Andrew Correia has built a prototype of such a system in a URI laboratory to evaluate its effectiveness.

“One property of asphalt is that it retains heat really well,” he said. “My tests showed that during some circumstances, the water even gets hotter than the asphalt.”

Finally, the team says it would like to see asphalt city streets replaced and made entirely out of large, durable electronic blocks that contain photovoltaic cells, LED lights and sensors. These solar roadways would generate electricity, direct traffic, and flash warning lights in emergency situations. According to Lee, these futuristic streets are inevitable.

“This kind of advanced technology will take time to be accepted by the transportation industries. But we’ve been using asphalt for our highways for more than 100 years, and pretty soon it will be time for a change.”

(Image credit: University of Rhode Island)