Heat From Streets Seen As Energy Source

So far, the “heat island” effect formed by the large amounts of asphalt in cities hasn’t been much more than a nuisance to us, contributing to higher A/C usage on hot summer days. Engineering researchers at the University of Rhode Island (URI) have a better idea for the urban solar collectors known as streets–power for buildings and streetlights, and heat to melt winter ice.

The URI team has identified four potential approaches ranging from simple to complex. On one end of the spectrum, researchers are exploring the option of simply wrapping flexible photovoltaic cells around the top of the Jersey barriers that divide highways to provide electricity to power streetlights and illuminate road signs. Another practical approach is to harvest solar energy from the pavement directly by embedding water pipes beneath the asphalt and allowing the sun to warm the water as it circulates. The heated water could then be piped under bridge decks to melt ice, reducing the need for road salt, or piped to nearby buildings to satisfy heating or hot water needs.

Solar Power Cement

image via University of Rhode Island

On the complex end of the spectrum is an approach that would make use of the thermoelectric effect to generate a small but usable amount of electricity by connecting a hot spot in the pavement with a cool one, creating a circuit. With many of these distributed systems in play, enough electricity could be generated to defrost roadways (or used for other purposes).

Still more futuristic is the idea of completely replacing asphalt with roadways made of large, durable electronic blocks that contain photovoltaic cells, LED lights and sensors. The blocks could then generate solar electricity, illuminate the roadway lanes in interchangeable configurations, and provide early warning of the need for maintenance.

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Susan DeFreitas has covered all manner of green technology for EarthTechling since 2009. She is a graduate of Prescott College for the Liberal Arts and the Environment, and has a background in marketing green businesses. Her work on green living has been featured in Yes! Magazine, the Utne Reader and Natural Home.