Advanced Conversion: Maximising the Potential for Energy from Waste
• http://www.renewableenergyfocus.com,There are many EfW processes, but most commonly waste passes through combustion chambers at high temperatures, reducing it to around 25% of its original volume.


Conversely, consider plasma. Google: "plasma garbage," or see:
http://www.wired.com/magazine/2012/01/ff_trashblaster/
http://www.plasma-wr.com/
http://science.howstuffworks.com/environmental/energy/plasma-converter.htm