Do you recognize the image of yourself jumping on your toes on the beach, in a hurry to reach the shore and get to the cool water. Well, the same happens to the asphalt our cars roll on. Why not use that heat to power things on highways and thus save tons of carbon dioxide a year?
A University of Rhode Island team of engineering researchers studied four methods that we could implement to generate energy for our highways for different purposes.
“We have mile after mile of asphalt pavement around the country, and in the summer it absorbs a great deal of heat, warming the roads up to 140 degrees or more,” said K. Wayne Lee, URI professor of civil and environmental engineering and the leader of the joint project. “If we can harvest that heat, we can use it for our daily use, save on fossil fuels, and reduce global warming.”
The first and the most obvious would be to put solar panels on the barriers that divide the highway, to create electricity for lighting and road signs.
The second would be to embed water pipes into the asphalt, and collect the energy in the form of heat, which can further drive steam turbines and produce usable power. “One property of asphalt is that it retains heat really well,” he said, “so even after the sun goes down the asphalt and the water in the pipes stays warm. My tests showed that during some circumstances, the water even gets hotter than the asphalt,” says graduate student Andrew Correia, who also built a prototype of such a system.
The third idea proposes inserting thermoelectric materials into the asphalt. Thermoelectrics harvest the heat difference between their two ends, so embedding them into the ground with the ends at different depths would generate electricity. Highways could be defrosted with the obtained energy and would ease the work of those special utility trucks that clean the asphalt in winter.
The fourth involves an idea first proposed by Solar Roadways, and consists of embedding solar panels into the asphalt. We’ve written about Solar Roadways on previous occasions, and if you can remember, they have recently won a $50,000 Ecomagination prize.
I find the first two as the most realistic, and the second two reserved for the next 20 to 30 years, for when solar cells and road materials will evolve in some way or the other. For the moment, these technologies are pretty expensive to implement.