Collecting Solar Energy from Asphalt Roads
Have you walked barefoot across a parking lot on a hot summer day? You don’t have to be a space scientist to know the fact that blacktop is remarkably good at soaking up the sun’s heat because you have felt the heat underneath your feet. Researchers at Worcester Polytechnic Institute (WPI) are trying to tap that heat for alternative energy source. Asphalt roads can be used for source of electricity and hot water in future!
Blacktop stays hot for a longer duration of time and this property can help in generating the electricity even after the sun goes down. This can be an added advantage over traditional solar-electric cells. We already have stretches of prepared roads running in acres and parking lots that can be taken advantage of for energy creation. Roads and lots are typically resurfaced every 10 to 12 years and the retrofit could be built into that cycle. One more advantage is that pulling out heat from asphalt can cool the road thus reducing the city’s ‘heat island’ effect. Asphalt solar collectors will not muddle with your artistic sense because they will be invisible unlike roof-top solar panels.
Rajib Mallick, associate professor of civil and environmental engineering at Worcester Polytechnic Institute (WPI) and his research team which also includes Sankha Bhowmick of UMass studied energy generating capacity of asphalt using computer models and by conducting small- and large-scale tests. They used slabs of asphalt for their tests. They embedded thermocouples for measuring heat penetration, and used copper pipes, to determine how efficiently that heat could be transported to running water. Hot water flowing from an asphalt energy system could be used “as is” for heating buildings or in industrial processes, or could be passed through a thermoelectric generator to produce electricity. In lab they exposed small slabs to halogen lamps which can simulate the sunlight while larger slabs were placed in the real environment i.e. outside for sunlight and wind. The tests confirmed that asphalt soaks up a substantial amount of heat and the highest temperatures are experienced a few centimeters below the surface. At this spot heat exchangers can be placed for the maximum amount of energy. They also tried to increase the heat absorption by using highly conductive aggregate like quartzite. They also take into account to lessen the phenomenon of reflection by using special paint. The research team has also taken into account that they have to replace the copper pipe with some other material which will be a better heat exchanger. That heat exchanger will maximize the heat absorption already trapped in asphalt.
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August 26th, 2008
Asphalt is also “flexible”, ie, it will move when you drive over it (and it tends to ‘move’ more when it is hot)…..by placing the heat exchanger near the surface only stresses it more — perhaps too much?
September 5th, 2008
Holy cow… great idea… especially here in Arizona… unbelievable heat waves. Go from Phoenix to the outlying farm areas… what a difference. The roads retain the heat for a long time.
September 11th, 2008
Great Idea. Can’t wait to here more about it. Might as well make use of the hundreds of thousands of miles of road in the US (besides the obvious).
November 11th, 2008
This promises to be a advanced technology.But when You visualize,if used in the future could be very expensive which includes a very high instalation and maintanence cost,not forgetting the fact vehicles comes with different sizes other problems includes expansion due to overheating of asphalt which might result in constant headache to the developers.a technology with lots of hope but a flop for sure!
November 21st, 2008
Heijmans is a road construction company in the Netherlands. We have made two projects in which we collect solar heat in a asphalt pavement. The heat is collected by a heat exchanger embedded in the asphalt construction and stored in water layers at a depth of 80m below surface. This energy can be used for heating or cooling buildings in the environment or for deicing of the road in wintertime.
February 7th, 2010
Brilliant! The answer to power shortages here in India.
I hope our scientists get to hear of this..
March 13th, 2010
Though some people may think this idea a bit out thee and a potential Flop the following might help answer some questions raised above.
1. with regards to the heat softening the asphalt this is true as asphalt remains a fluid the viscosity of which obviously decreases as it heats up. This idea will actually reduce this effect by absorbing the heat generated by the sun and removing it in the fluid to be used else where.
2. the problem of the flexibility of the asphalt under heat and pressure from heavy vehicles can be over come by using heavy grades of black high pressure PVC Split I section piping which when imbeded in the asphalt I believe will support the external pressures when the fluid is pumped through in a closed circuit system under high pressure and using heat exchangers to recover the latent energy.
3. the best application of this technology would be in new housing development as the technology can be installed in the initial construction and included in the site development costs split over each unit constructed and off set by the new owners energy savings.
4. the technology would be hard pressed to make an impact on commercial or industrial use unless incorporated into the external wall and roof of the structures during construction. Which I have done in an agricultural application with fair success.