Thousands of miles of highways stretch across the U.S., and every day they soak up heat from the sun, sometimes to the tune of 140 degrees and more. Harnessing the solar energy in highways would go a long way toward helping to replace oil and other fossil fuels with a far safer and more secure source of power, and now researchers at the University of Rhode Island have come up with four potential avenues of approach.
Solar Power from Jersey Barriers
Jersey Barriers are those unattractive but effective modular walls that are often used to separate opposite lanes on narrow roads. According to the Rhode Island researchers, existing technology could be used to fix flexible photovoltaic cells along the tops of the barriers, and also on the narrow stretch of road alongside them. The energy could be used to power street lights and road signs.
Solar Powered Roads and Melting Ice
Existing technology could also be used to install water pipes under the roadway. The heated water could be used to melt ice on bridges, which are often frozen even when the surrounding roads are not. This would reduce the need for salt but would also reduce carbon emissions related to hauling and spreading salt by truck. Nearby buildings or small power plants could also use the water-sourced heat.
High-Tech Approaches to Harvesting Solar Energy from Highways
One alternative being explored is the use of the thermoelectric effect, which occurs when hot and cold spots are linked by semiconductors. The effect could be induced in highways by planting semiconductors at different depths. Another would be to replace asphalt with self-contained, durable modules that include photovoltaic cells and other equipment to generate electricity and provide illumination. Both of these alternatives are far in the future, partly because the technology is not developed, or the cost is currently prohibitive.
A Better Road to…Better Roads
In addition to harvesting energy from roads, the conventional asphalt road is also in need of a sustainable makeover to reduce the use of crude oil and other petroleum products. One emerging alternative could be a sand-and-bacteria mixture that produces a hard surface. In another experiment, pig manure is being used to make bio-crude, which can be used as a low grade binder for road materials.
Image: Highway by Wolfgang Staudt on flickr.com.