Solar Streets: using the heat from asphalt for energy

There was a loud crash, and I got up out of my chair in time to see my vintage British motorcycle laying on its side in the parking lot of the apartment complex I was living in.  I could see a group of kids running away and I yelled after them; gaining the unwanted attention of my neighbors afterwards. 

I explained to one of the parents that the kids must of knocked over the bike; these things don’t just fall over by themselves.  To my embarrassment I watched out the window later as it did just that.  The asphalt had softened in the Texas heat and the side stand simply sank into the pavement and the bike fell over.  I move it to the sidewalk and tried not to look anyone in the eye after that. 

Motorcycle riders and well… anyone who has had to walk across a black asphalt street in July in Texas can tell you that the streets hold in a substantial amount of heat.  Heat is energy, and if it’s there we can and probably should use it.  According to The Wall Street Journal a Dutch company has found a way to do exactly that.

Solar energy collected from a 200-yard (180-metre) 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 (14,864 square metres) 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 (3,344 square metres) of pavement. The runways of a Dutch air force base in the south supply heat for its hangar.

Plastic pipes are put in place under the roadway and the asphalt is laid over them.  Then water is pumped through the grid. After it is heated by the sun, it goes back into the natural aquifer, where it maintains a constant temp of around 68 degrees.  Months later it can be pumped back through to de-ice the road.  In addition cool water is pumped from a separate reservoir for cooling buildings.  

There is more to solar power than just photovoltaic panels;  combine systems like this with solar powered water heaters, geothermal heat pump systems, and responsible building designs and we can really make a difference without having to wait 50 years for it to pay for itself. 

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