Burning Trash to Zapping Trash

If any of you are from a rural area you may have once burned your trash instead of paying for the garbage man to come to your house to dispose of the trash in the local landfill.  This has been a common way for many to dispose of their trash for quite some time now.  In recent history however, companies and towns have taken this same idea and upgraded that old rusty barrel to huge electricity production facilities.  There are several ways that everyday trash can be used to produce electricity.

First, you can incinerate it.  This is just a fancy way of saying "burn the heck out of it".  After sorting through the trash and making sure non-combustibles are sorted out, the trash is sent into a furnace that reaches nearly 1000 degrees C.  This ensures that all material is combusted.  The trash is then continually fed into the furnace and burned in the presence of oxygen.  The large amount of heat that is released from the furnace is then harvested and used in a boiler to produce steam.  This steam can then be distributed to area schools and hospitals for heating purposes, or used to produce electricity.

Another way of harvesting energy from everyday wastes is to gasify it.  This follows the same principle as above but the trash enters a reactor instead of a furnace.  The only difference being, that there is no oxygen in the reactor.  Again at very high temperatures, this causes the trash to be gasified.  Gasification is achieved when the chemical bonds of the trash are broken and the trash is converted into syngas.  Syngas is primarily made up of hydrogen gas and carbon monoxide.  This syngas can then be burned just as natural gas is burned to power a generator to produce electricity.  It may be hard to see how everyday trash can be turned into a natural gas like substance, but lets take a closer look.  When thinking about trash, paper and paper products account for the majority of the trash.  Paper is made from trees, that is made up of cellulose and lignin, that are made up carbon and hydrogen.  So when you break paper down to its base components you will be left with carbon and hydrogen.  When gasification occurs all the chemical bonds that hold these carbons and hydrogens together are broken.  When there is a bunch of hydrogen atoms around two hydrogen atoms will tend to bond to each other to make hydrogen gas.  The carbon atoms will also likely bond to any oxygen atoms released from gasification and form carbon monoxide or carbon dioxide.  This is what makes up syngas.  The picture below is a gasification reactor.

A third way of extracting energy from trash is to zap it.  This follows the same idea as traditional gasification except that an electrical arc is used to break the chemical bonds of the trash.  An inert gas (non reacting gas) is also used in the reactor.  When the electrical arc comes into contact with the inert gas, very high temperatures can be reached, on the order of 3000 to 4000 degrees C.  This very high temperature is then responsible for breaking the many chemical bonds of the trash down into its elemental components.  Syngas that is produced can then be burned to produce electricity for the local community.  The picture below shows a plasma gasification reactor and some of the supporting equipment.