A research team at Worcester Polytechnic Institute is developing a solar collector that could turn roads and parking lots into sources of electricity and hot water. Roads and parking lots are typically resurfaced every 10 to 12 years, so the massive acreage of already installed roads and lots could be retrofitted at that time for energy generation. The solar collectors in asphalt would also be invisible.
The WPI researchers conducted tests on slabs of asphalt containing imbedded thermocouples, to measure heat penetration, and copper pipes, to gauge how well that heat could be transferred to flowing water. Hot water flowing from an asphalt energy system could be used "as is" for heating buildings, or could be passed through a thermoelectric generator to produce electricity. The tests showed that the highest temperatures are found a few centimeters below asphalt's surface, which is where a heat exchanger would be located.