The story

Pond scum. The thought typically evokes images that leave most people cringing, but it may one day occupy an important role in the nation's energy supply.

The current fuel crunch, driven fundamentally by a rising global demand for oil, has spurred debate among consumers, political leaders, academics and entrepreneurs about plausible alternatives.

A good bit of the discussion has focused on biofuels, commonly defined as energy derived largely from plants and crops like corn, soybeans, switch grass among other sources. Read full article »

CNN's Miles O' Brien, Marsha Walton, Rachel Oliver and Manav Tanneeru contributed to this report.

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