Energy from Garbage: Another Approach

Ordinary matter contains large amounts of energy. Even garbage contains energy that can be retrieved and made to do useful work.

Researchers tested the first tactical biorefinery prototype in November and found that it produced approximately 90 percent more energy than it consumed, said Jerry Warner, founder of Defense Life Sciences LLC, a private company working with Purdue researchers on the project. He said the results were better than expected.

The U.S. Army subsequently commissioned the biorefinery upon completion of a functional prototype, and the machine is being considered for future Army development.

The tactical biorefinery first separates organic food material from residual trash, such as paper, plastic, Styrofoam and cardboard. The food waste goes to a bioreactor where industrial yeast ferments it into ethanol, a "green" fuel. Residual materials go to a gasifier where they are heated under low-oxygen conditions and eventually become low-grade propane gas and methane. The gas and ethanol are then combusted in a modified diesel engine that powers a generator to produce electricity.

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Other approaches to extracting energy from garbage involves high intensity plasmas which create very high temperatures. The higher the temperature the better, when it comes to turning garbage into useful matter and energy.