Energy giant Chevron Corporation and the U.S. Department of Energy's National Renewable Energy Laboratory have announced that they have renewed research to produce liquid transportation fuels using algae.
This is not a joke. Previous scum-to-energy research halted in the 1990s, when crude oil prices were low. Now, with economic and political factors, as well as environmental concerns putting a lot of pressure on energy companies to find an alternative to petroleum, slime slides to the head of the list of bio-fuel sources. Algae is easy to grow in a lot of places that would not be suitable for other crops that might be used for needed food supplies. You don't need a green thumb, just a neglected fish tank.
The thing is, if we are really going to look to the scum of the Earth to save us from ourselves, we will find out in short order what nation harbors the most of it. Scum is power! Because we're talking about literal rather than figurative scum, we're talking about a genuine resource.
Algae probably seems plentiful now, but wait until we're avidly scraping it as fast as it can form, to feed our voracious appetite for energy.
Personally I like the idea of humanity being saved by scum. It scoops up so many great metaphors into one neat, slimy bucket.