Half a croissant, on a plate, with a sign in front of it saying '50c'
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Turn garbage into charcoal

since charcoal is flavour of the month
  [vote for,

There are currently two main types of waste disposal: incineration and landfill. There are problems with each.

Incineration releases environmentally damaging gases (carbon dioxide, dioxins, etc). Landfill releases methane (a "greenhouse gas") as the garbage slowly decomposes.

I suggest garbage should be pyrolysed (ie baked) in a low oxygen (ie airtight) kiln. This will result in the following end products: charcoal, ash, syngas (hydrogen and carbon monoxide) and other gases.

-the charcoal and ash can be buried in a more inert and compact form than regular landfill
-the carbon in the charcoal is "sequestered" when buried
-the gases produced are less environmentally damaging than from an incinerator (eg less carbon dioxide). I'll also take a wild guess that less nasties such as dioxins would be produced
-the syngas can be used to power the kiln

xaviergisz, Jul 31 2009

Garbage converted to Charcoal http://www.greenpla...rash-into-charcoal/
there are other examples of industrial garbage cookers [xenzag, Aug 01 2009]

CHP http://www.chp.ca.gov/
[normzone, Aug 03 2009]


       Hold on, just going to root through a bin.
Right, the contents consisted of: tin plate (shouldn't be in there), soya milk cartons (shouldn't be buying soya milk), coffee packets (should be buying it in paper), bubble wrap, clingfilm, polythene, in other words all the things i don't bother to reuse or recycle. The last three are from a supplier, so i'm not as responsible for them as the others. If it were heated anaerobically, i can see that maybe the polythene would produce something useful, but i'd expect the clingfilm to produce something chlorinated, whereof i like not the sound.
Given that that stuff is in my bin, the tin plate is pretty useful, the cartons can be shredded and melted together into boards, the coffee packets are composites and therefore probably pretty unreusable, so my problem is, how to separate the PVC from the polythene? If you heat that lot up, how much chloriny stuff would stay in it and what would you do with it? Do you fractionate it?
Not a criticism, just a thought.
nineteenthly, Jul 31 2009

       / Landfill releases methane (a "greenhouse gas") as the garbage slowly decomposes./   

       Biogas from landfills is now widely captured and burned - usually for small scale energy used at the landfill. I have never read or heard of anything done to optimize biogas production from a landfill - water addition, starter culture etc. I suspect that the anaerobic processes that generate biogas also convert much waste to charcoal-like substances - old style charcoal kilns are similar in many ways to landfills. It gets hot under there and bakes itself.
bungston, Jul 31 2009

       Hmm... I was wondering what that flavour was.
pertinax, Aug 01 2009

       I don't know enough chemistry to tell what would happen to plastic baked in a low oxygen kiln. My guess would be it would be similar to baking hydrocarbons with the non-carbon elements evaporating off. It's possible that the chlorine evaporating off the plastic would combine with the hydrogen evaporating off the plastic and organic waste to form hydrochloric acid. The gases would be scrubbed to remove as much nasty chemicals as possible.   

       The collection of biogas from landfills has always struck me as being inefficient way of utilising the 'power of garbage'. I agree with bungston that there is a lot of room for improvement in this area, and probably a lot of money to be made.
xaviergisz, Aug 01 2009

       There are already high pressure, high temperature, vessels that seem to cook all waste into hydrocarbons and water. Baked, not widely known to exist.   

       [Vernon] and [Unabub...] had a shot at it with various ideas....
4whom, Aug 02 2009

       It seems that clingfilm is no longer made from chlorinated plastics, but other things are.   

       I'm saving my coffee packets to use as insulation in the roof. Probably silly, but I can't bear to throw away that lovely laminated stuff.   

       Garbage contains a lot of heavy metals; perhaps the charcoal could be used to smelt mined or recycled heavy metals, thus turning a vice into a virtue.
spidermother, Aug 03 2009

       Does a Combined Heat and Power (CHP) plant throw all the crap combustion products into the air?.
I might have to Google this.
gnomethang, Aug 03 2009


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