Once thought to be waste, rice husks now can be used as clean, cheap fuel for developing countries.
250 million years ago, rising greenhouse-gas levels set off catastrophic changes.
The G-20 nations, representing most of the world's economy and population, are convening with the knowledge that they will sink or swim together.
Gyms hook up exercise bikes to TVs, laptops, and batteries to let their patrons power the place.
The Carbon E7 has 'buzz,' but will departments buy it?
Some economists see some rays of light amid the economic gloom.