Monday, August 18, 2008

WPI turning roads into solar collectors


Researchers at Worcester Polytechnic Institute have just done a batch of research that they hope will help turn the world's roads into cheap collectors of solar power.

They started with the assumption that asphalt gets frakking hot when the sun shines on it, and then started making some serious leaps.

First, they decided to figure out what part of the asphalt gets hottest, which turns out to be about two centimeters below the surface. Then they tried to figure out how to make it even hotter. The painted an anti-reflective coating to their test blocks, and then added highly thermally conductive quartzite to the mix.

The result is blacktop that gets even hotter and stays hotter for longer than regular asphalt. Of course, this left them with the problem of how to get the energy out of the road. By laying down a series of flexible and highly conductive copper pipes before pouring the asphalt they were able to pump water through the asphalt, picking up the heat, for use in power generation.

However, project leaders hoped to replace the copper pipes with a "highly efficient heat exchanger." Whether or not that would be water based, or exchange heat some other way, we don't know.

The system has several large advantages over traditional photovoltaic power.

  1. It's really cheap
  2. They don't need to find extra land
  3. It's invisible to the average person
  4. Blacktop stays hot, and could produce power for hours after the sun goes down
  5. There are roads and parking lots everywhere power is needed.

There are already a examples of similar technology in use around the world, but modifying the chemistry of the asphalt specifically to make it a good solar collector is a new move.


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