Researchers at Purdue University have created a portable refinery that converts food, paper and plastic trash into electricity. The prototype biorefinery generates approximately 90 percent more energy than it consumes.
Its efficiency owes to a series of steps:
1. Separate organic food material from residual trash, such as paper, plastic, Styrofoam and cardboard.
2. Ferment food waste into ethanol with industrial yeast.
3. Transfer non-food waste to a gasifier, where it is heated under low-oxygen conditions until it breaks down into low-grade propane gas and methane.
4. Combust gas (from non-food waste) and ethanol (from food waste) in a modified diesel engine that powers a generator to produce electricity.
Much of the process is carbon-neutral, according to Nathan Mosier, a Purdue professor of agricultural and biological engineering involved in the project. The ash output amounts to a 30 to 1 waste volume reduction.
And finally, most importantly (to the U.S. Army that is now supporting this research)–the whole apparatus could fit in a minivan.