I know, I know, it's a mistake to hype every unproven energy idea that comes along, since surely most of them won't ever pan out. But it's too hard to resist quoting from this story about a possible new "smart roof" made from waste cooking oil:
Top a building with a light-colored "cool roof," and it reflects sunlight, cutting air conditioning bills in summer, but increasing winter heating costs. Choose black shingles, and the roof soaks up sunlight to cut winter heating costs but makes the roof bake in the summer sun. One or the other. You can't have it both ways. Until now.
Scientists reported the development of a "smart" roof coating, made from waste cooking oil from fast food restaurants, that can "read" a thermometer. The coating automatically switches roles, reflecting or transmitting solar heat, when the outdoor temperature crosses a preset point that can be tuned to the local climate. ...
Roofs coated with the material would reflect scorching summer sunlight and reduce sticker-shock air-conditioning bills. When chilly weather sets in, the coating would change roles and transmit heat to help warm the interior.
Sadly, you can't achieve the same effect by pouring ordinary cooking oil on your roof—it first has to be processed into a liquid polymer coating that will change from reflecting light to absorbing it below a certain temperature. And yeah, more tests, commercial development years away, etc. etc.
(Flickr photo credit: myooz)