1/1/2008

New energy uses for asphalt

Filed under: — Aviran Mordo

If you’ve ever blistered your bare feet on a hot road you know that asphalt absorbs the sun’s energy. A Dutch company is now siphoning heat from roads and parking lots to heat homes and offices.

Solar energy collected from a 200-yard stretch of road and a small parking lot helps heat a 70-unit four-story apartment building in the northern village of Avenhorn. An industrial park of some 160,000 square feet in the nearby city of Hoorn is kept warm in winter with the help of heat stored during the summer from 36,000 square feet of pavement. The runways of a Dutch air force base in the south supply heat for its hangar.

And all that under normally cloudy Dutch skies, with only a few days a year of truly sweltering temperatures.

Ooms’ thermal energy system is actually a spin-off from attempts to reduce road maintenance and costs.

A latticework of flexible pipes, held in place by a grid, is covered over by asphalt, which magnifies the sun’s thermal power. As water in the pipes is heated, it is pumped deep under the ground to natural aquifers where it maintains a fairly constant temperature of about 68 F. The heated water can be retrieved months later to keep the road surface ice-free in winter.

Though it doubles the cost of construction, the system is designed to provide longer life for roads and bridges, fewer ice-induced accidents and less need to repave worn surfaces.

But the same system can pump cold water from a separate subterranean reservoir to cool buildings on hot days.

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