Science Buddies: "Ask an Expert"

Hi, I was wondering where I might research for information about an element, metal or alloy perhaps
that when heated will work hard to come back to its cool state. I want to know if there is any energy that
can be captured from this effort. If this element were somehow implanted in asphalt could it be a
source of passive energy collection. Anyway, just trying to figure out where to start. Thanks. P.

Hi Payton,
Asphalt itself will cool as long as the ambient temperature is lower than the asphalt temperature. There are other substances that will cool faster or slower, depending on their thermal properties, such as thermal conductivity and specific heat capacity. Things with high thermal conductivity (like metals) tends to gain or lose heat more rapidly than things with low thermal conductivity (like insulation). Things with high specific heat capacity (like water) require more heat energy to raise their temperature by a given amount as compared to things like air, which has a low specific heat capacity.
You might be interested in this article, which describes a company using asphalt to capture solar energy:
http://www.abqtrib.com/news/2008/jan/01 ... ar-energy/
This is an example of what is known as a "heat pump".
Chris