Welcome to Renewable Energy Info

Renewable energy sources have diverse origins, a feature that demands equally diverse technologies to capture them. My interest in these (new) technologies resulted in this blog. If will focus on well developed technologies that are already put into practice, and on promising technologies that are still under development.

If you like (one of) the posts and you want to recommend it to others, you can digg it by clicking the yellowy button displayed top left of every post. This would seriously increase the traffic to my blog and I would be very thankful!

Enjoy it!

Interesting books on Amazon..

Saturday, October 4, 2008

Using hot asphalt to collect solar energy

Source: Science Daily, Ecogeek, Ooms Avenhorn Groep BV

I just surfed into a really cool idea! Why not use asphalt's heat-soaking property for an alternative energy source?! Indeed, why not turn the world's roads into cheap collectors of solar power. Everybody knows that asphalt gets extremely hot when the sun shines on it, so why not harvest this solar energy?!

Actually, the Dutch company Ooms Avenhorn, has been exploring this patch for almost a decade now, and has already proved that it is working! They have developed a so-called Road Energy System® (RES), where the collection of solar energy from the asphalt is combined with underground storage, to create a year-round system which can cover heating requirements in the winter and cooling in the summer.

A latticework of flexible plastic pipes, held in place by a plastic grid, is covered over by asphalt, which magnifies the sun's thermal power. As cool 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.

Recently, researchers at Worcester Polytechnic Institute have done a batch of research on this and their experiments figured out that the part of the asphalt gets hottest, 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 photo-voltaic 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.
Modifying the chemistry of the asphalt specifically to make it a good solar collector is a new move, which could further improve this technology.

No comments: