It's the holy grail of green - a clean, sustainable way to turn waste plant material into a biofuel replacement for petrol.
Everybody knows that if you gently heat used frying oil to about 60 degrees in the presence of the right catalyst you get biodiesel - plus lanolin that can be used for soap and cosmetics.
But until now the only substitute for petrol was ethanol, which requires modifications to engines and has to be grown on arable land that would be more profitably used growing food for people.
Now scientists at Tulane University in New Orleans say they've bred a new strain of the bacteria Clostridium that attacks cellulose and turns it into butanol.
What's butanol? It's an aromatic compound, similar to ethanol but with longer hydrocarbon chains, that can be substituted for petrol - or at the very least mixed with petrol - in existing engines without any modifications.
Why haven't we heard about it? Butanol is no secret; it's just been prohibitively expensive to make - until now.
Associate professor David Mullin, postdoctoral fellow Harshad Velankar and undergraduate student Hailee Rask spent two years working on more than 100 strains of Clostridium before they came up with TU-103, which they are currently testing on bagasse - the worthless fibrous waste that's left over after all the goodness has been squeezed out of sugarcane.
But they reckon it'll work on any source of cellulose: paper, grass, leaves, corn cobs, corn stalks and other agricultural waste products that are available on a vast scale because they're usually just thrown away.
Mullins explained: "In addition to possible savings on the cost of fuel, bio-butanol produced from cellulose would dramatically reduce carbon dioxide and smog emissions in comparison to petrol, and have a positive impact on landfill waste."
Butanol, he says, is much more sustainable as a fuel than ethanol; it uses valueless by-products from existing crops, rather than growing crops specifically for fuel, and it has almost the same energy content as petrol but with less CO2 and other harmful emissions.
Mullins said: "I really would like to see this process developed into something people could use, if there was an industrial partner that had the capability to produce butanol on a large scale. It would give me great pleasure to know that our research in some way contributed to reducing our energy dependency on fossil fuels."
Does it sound too good to be true? We hope not.