photo by Chad Johnson
The idea, if not the practice, of using the heat absorption capabilities of asphalt roadways to heat water is not new. About nine months ago we reported on a Dutch civil engineering company which places water pipes underneath and then pump it to nearby buildings for heating. Additionally, the system is constructed so that it can actually pump cold water in the summer for use in cooling.
In a similar vein, researchers at Worcester Polytechnic Institute are investigating whether roadways might also be able to generate electricity. Science Daily provides the details:Tests Done to Determine Maximum Heat Absorption of Asphalt
The entire project is being directed by Rajib Mallick, associate professor of civil and environmental engineering at WPI, and is studying the heat absorption capabilities of asphalt using computer models, as wells as small and large scale practical tests. The goal of these tests is to measure heat penetration into the asphalt to determine the best location for heat exchangers, as well as testing how well heat can be transferred to water contained in copper pipes embedded in the asphalt.
The tests show that maximum heat occurs only a few centimeters into the asphalt. It was also determined that by adding highly conductive aggregates, such as quartzite, heat absorption can be increased significantly. Reflection-reducing paint can also increase heat absorption.
Water heated in such a system could be used as is for heating buildings (like the Dutch have done) or by feeding it to a thermoelectric generator to produce electricity.
Roadway Energy Systems Could Be Retrofit as Roads Resurfaced
Mallick says that because roads and parking lots are resurfaced every 10-12 years, a roadway energy system could be retrofitted at the same time. Furthermore, extracting heat from asphalt could reduce the ‘heat island’ effect in urban environments.
While we certainly have an abundance of roads and parking lots in the United States, I wonder if the cost and maintenance of such systems would be prohibitive.
Some other things that stick out to me: If maximum heat absorption occurs just a few centimeters and that’s where you want to put your heat exchanger, would you have to move the whole system every time the road got resurfaced after installation? Or to resurface the road? What would be the wear and tear on such a system in highly trafficked areas?
Any civil engineers out there want to weigh in on this one?
via :: Science Daily
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