Free Heat From An Old Window And Some Soda Cans. | EcoTech Daily
http://ecotechdaily.com/2009/07/01/free-heat-from-an-old-window-and-some-soda-cans/

In hotter places this could be used to run a (sealed) food dehydrator.

6/15/10

I like the method for determining when the pan is the right temperature.  I don't like the attempted explanations; water and protein change much more than steel between 70 and 300 degrees.

There is actually a small ideal window of heat that you should be aiming for in order to prevent sticking, optimize browning of your meat, and develop a nice fond on the pan.