Half a croissant, on a plate, with a sign in front of it saying '50c'
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Use that waste!
  [vote for,

Many cultures burn dung as a primary fuel source. First world cities have tremendous supplies of dung, funneled to a central location, yet there has been no systematic effort to exploit the fuel value of this. Enter the Dungboiler system.

In this system, waste solids in the water stream are screened and conentrated, then shunted to the Dungboiler. There they are bubbled with oxygen and ozone. This oxidizes the wastes, giving off heat - essentially burning them. The water becomes very hot, accelerating the reaction and the heat produced can be controlled by the oxygen / ozone delivered. The heated water turns a turbine, and the energy produced runs the rest of the water treatment plant, with extra energy going back to the grid.

After maximum energy is extracted, boiled dung is returned to the waste stream.

Advantages: 1. The Dungboiler system operates wet. Wastes do not need to be dried.

2. Oxidation in a water environment means most of the CO2 emissions remain safely dissolved in the water, not spewed into the sky. Likewise with particulates, etc.

3. The high temperatures generated sterilize the wastes.

4. Current microbial methods of sewage treatment can be damaged by pesticide, motor oil, and other non-waste items which get in the wastewater stream. This stuff is all just fuel for the Dungboiler.

5. Effluent from the Dungboiler can go on to be treated just as wastes are currently. The Dungboiler can be added in line with current systems, to extract energy before treating. It is compatable with existing wastewater treatment.

bungston, Apr 14 2005

Sewage waste to energy http://www.hindu.co...002053000090200.htm
[daseva, Apr 14 2005]

more shit fuel http://feeds.bignew...id=0911c350996925b6
[daseva, Apr 14 2005]

Fuel cell powered by... poop! http://www.msnbc.msn.com/id/5335635
[daseva, Apr 14 2005]

San Diego biogas project http://www.signonsa...e-gas-clean-energy/
I worry that this is only feasible because of the large subsidies [bungston, Apr 13 2011]

Things that make you go... http://www.dnr.stat.../biophos/3fract.htm
What ? Could you repeat that ? [FlyingToaster, Apr 13 2011]

Compost research http://www.uow.edu....ch.dir/compost.html
Some details on the two processes [bungston, Apr 14 2011]


       So this is a kind of chemical digester? I don't know, but would imagine that the biological methods would be more efficient, wouldn't they?
zen_tom, Apr 14 2005

       [bungston], is it ok if we build this upwind of your place ?
normzone, Apr 14 2005

       You can put it in my bedroom! The Dungboiler is better at energy extraction because it runs hotter than biological digesters can tolerate.   

       As I think about it, some of the CO2 might bubble out of solution. Maybe it better not be in my bedroom.
bungston, Apr 14 2005

       I think this idea name would make a great off-Broadway musical.
waugsqueke, Apr 15 2005

       Wouldn't it use more energy to boil the water than to recieve energy from it? Why not use something less dense, or that heats up more. Oil? Maybe? Or let's pressure cook it! Use some sort of gas, pack it into the burning chamber, pressureize it into a liquid, and then burn it! I don't know of any gases that might do this, and I know it's dangerous and difficult to press something down that hard, but hey, I'll chance it!   

       *sparks another idea* Why not compact all the waste into a tight block? Might burn more efficiently. Aww, I don't know what I'm saying...
EvilPickels, Apr 15 2005

       Producing the oxygen/ozone to bubble through the dung would surely cost more energy than you would be able to extract. Why not just burn dung in a regular boiler, ignited with a gas/oil flame? The fact that it won't be dry isn't a problem, as most industrial woodwaste and recovery boilers seem to handle wet fuel all right. "Modern" low opacity boilers are probably just as environmentally friendly as this idea.
Texticle, Apr 16 2005

       This might still work with plain bubbled air.
bungston, Apr 17 2005

       1) Uncountable anaerobic reactors are working in entire world to produce biogas from slurry & use left out material as fertilizer.   

       2) What would be the cost of oxygen/ ozone to run the system ?   

       3) Please throw some light on the reaction that would cause tremendous rise in water temperature ?   

       4) Are you aiming at putting turbine operating with flash steam generated from pressurized hot water ?
vedarshi, Apr 17 2005

       1. Biogas. Good! But I want my energy _now_.   

       2. Cost of oxygen / ozone: This would need to be cheap enough to be generated by a small fraction of the energy released from the waste. A high voltage low current source could be set up and air used for the bubbler passed over it. Essentially one of those ionic air cleaners, which generate loads of ozone. However, the ozone is probably superfluous and this would run OK on plain air once it was hot.   

       3: Reaction: CxH2x + O2 = CO2 + H20 + heat.   

       4. Flash steam turbine - ok. I had not thought about this detail.
bungston, Apr 18 2005

       You could call it the "Bungston Burner" or even the "Dungston Burner" (laughing at own joke...pitiful)
Asta, Apr 18 2005

       Hey bungston (+ to Asta for the name) contact me at gmail (my user). In a month our electric co is going to publish the price at which they will buy electricity from biogas. There's going to be a rush for investments and technology development. The idea is to do this with extra heat from concentrated solar energy.   

       By the way. 10 months ago, I boiled dung at a large farm, to see what the smell would be. I had to wash myself for over an hour, and did not eat till the next morning.
pashute, Apr 13 2011

       See linked story. I was surprised that the waste plant here in San Diego burned off their biogas. One problem is even though natural gas is now prized, biogas is dirtier and expensive to clean up. So generally it is used on site - the landfill for example uses landfill gas to generate some electricity for itself. I am not sure why electricity was not generated on site and put into the grid - you will see in the article that it was seriously proposed that the gas be loaded onto trucks and trucked across town.
bungston, Apr 13 2011

       I still don't get why bubbling air (or even oxygen, which would be uneconomic anyway) would extract energy from dung. You can boil sugar or sawdust as long as you want, but not much will happen. But maybe I missed something.
MaxwellBuchanan, Apr 13 2011

       Max: consider the simple haystack, a form of protodung if you will. It rains. And later the haystack catches on fire of its own accord! Why?
bungston, Apr 13 2011

       Because bacterial action generates heat (actually, I'm not convinced the haystack will ever catch fire, but it will certainly get hot).   

       Why did you think it got hot?
MaxwellBuchanan, Apr 13 2011

       Sewage (well actually most free flowing water) has both BOD & COD (biological and chemical oxygen demands). It's certainly measurable in the output of treatment plants (I did that at some point for the min.environment), so the input would be moreso.   

       That being said, I'm not sure how warm or even hot water is going to run a turbine.
FlyingToaster, Apr 13 2011

       //Fermenting sewage could generate the pressure to run the turbine directly//   

       Any particular reaction, that produces a gas, that only bonds to 1 Oxygen atom ? If you bond to 2 or more then you have no net increase in the number of gaseous molecules, ie: no increase in pressure.   

       eg: Fe3O4 isn't gaseous and even if it was there'd be half as much gas produced as consumed.   

       CO2 is neutral.   

       CO would be a net gain in pressure, but CO tends to bond to another O to make CO2.
FlyingToaster, Apr 13 2011

       Fermentation evolves gas and does not require oxygen. If you let oxygen in you will make vinegar instead of champagne.   

       Re the haystack: it is microbial metabolism to a point, but then things get so hot that they die. Abiotic processes then take over. I here assert these processes, given encouragment, could get hot enough to boil the water.
bungston, Apr 14 2011

       From the table <link> it looks like total Oxygen Demand for sewage is typically in the range of 0.75g/litre. (Don't ask me about specifics: I'm not sure what most of those terms are, mostly I wasn't even chief cook, but IIRC "activated sludge" is about as evil as it sounds)
FlyingToaster, Apr 14 2011

       // I here assert these processes, given encouragment, could get hot enough to boil the water.//   

       Well, then, I assert that sewage can generate a voltage when exposed to sunlight, and therefore be used as a cheap photopholtaic.   

       Hey! This asserting business is really effective!
MaxwellBuchanan, Apr 14 2011

       You're making my assert.
bungston, Apr 14 2011

       Well, it's your *.
MaxwellBuchanan, Apr 14 2011

       Given that it is mine to risk, I risk it a little further here: if it is true that bubbling oxygen thru a hot liquid rich in oxidizable carbon will cause the mixture to heat further and boil, this should also be true of a very thick potato chowder. A pilot project involving soup would have the added benefit of yummy soup, and less cooties.
bungston, Apr 14 2011

       Methanogenesis also produces more gas than it consumes.   

       On the other hand, oxidation of fats and alcohols produces less gas than it consumes, assuming that the water remains liquid.
spidermother, Apr 15 2011


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