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Hi folks ~
This has been a very useful exchange, and yet skirts around a practical
question: doesn't it make sense that if the objective is to generate and
harvest methane a controlled system, both controlled in its feedstock and
controlled in its scale and design, would make more sense than a landfill?
Alan Muller mentioned a study of a digester ("... there are data from
in-vessel anaerobic digestion processes that can be used to validate
generation calculations. I found it somewhat convincing and also
disturbing in the low percentage recovered. I don't recall the source or
the authors but can probably find it..."). It would be useful for Alan to
find and forward this study. It sounds from the findings ("low percentage
recovered") that the digester in the study was not designed to control
methane? Not sure however why a study of a digester could be used to
"validate" landfill capture...
I have felt for some time that we need some information to smoke out the
claims of landfill operators that they are preventing climate change by
harvesting methane. This is real greenwashing.
At 03:04 PM 3/1/2007, Wolbert, Brad - DNR wrote:
>[Here's a reply I attempted to post earlier, only to find out I couldn't
>post to the entire group. I think that's been fixed; we'll see.]
>Dennis -- on the technical question, I can only point to one specific
>study, and it was a conference presentation, not a refereed published
>article. For what it's worth, it's at
>Unfortunately, no one knows what the correct values are for the model
>inputs that were used, so I would take the conclusions with a very large
>grain of salt. Still, it may be useful in understanding the issue.
>My own discussions with researchers in this field lead me to conclude that
>there is no firm consensus on system collection efficiencies of methane
>from landfills, and it is highly variable in any case. There are periods
>in the life of landfills when there is no gas collection system installed
>or operating. Even when the gas system is running, in the best of
>circumstances, there is an open working face where landfill gas can
>escape. I tend to believe that lifetime capture efficiencies are closer
>to the higher percent range you cite below in cases where the landfill is
>recovering gas for flaring or utilization. Probably during the operation
>of the gas systems, the capture efficiency is even higher. Otherwise
>these facilities would stink like crazy, all the time. Well-run landfills
>are generally able to control their odor problems most of the time.
>Two other points are important. The food scraps very likely have more
>value outside the landfill, as compost, than buried in the landfill, but
>you'd need a life-cycle analysis to prove it. Maybe there's one out
>there, I don't know. Also, given the realities of landfilling (lots of
>plastic, lots of places where moisture doesn't reach) some of those
>landfilled food scraps won't break down for many years, long after the gas
>utilization system is gone; that fraction has no value as fuel at all.
>Hydrogeologist - Wisconsin DNR
>From: GreenYes@no.address [mailto:GreenYes@no.address] On
>Behalf Of Alan Muller
>Sent: Thursday, March 01, 2007 4:44 PM
>To: Eric Lombardi; Reindl, John; 'Dennis Sauer'; GreenYes@no.address
>Subject: [GreenYes] Re: Landfill methane recovery data
>At 03:29 PM 3/1/2007 -0700, Eric Lombardi wrote:
>>I am on the Colorado Climate Project, and we are discussing the fact that
>>we can't find any studies on "life-cycle methane emissions" from
>>landfills. It seems that everyone keeps citing that 75% gas recovery
>>rate for best-available-technology, but my understanding is that this
>>number reflects only a point-in-time recovery rate when all systems are
>>up and running at peak performance. My understanding is also that that
>>special "point in time" begins and ends over a short amount of the time
>>that buried organics are actually off-gassing.
>>The lack of real data is probably attributable to the fact that no one
>>has ever covered a landfill from day one and measured the gas generation
>>Have y'all in Wisconsin ever done a life-cycle estimate on the percent of
>>gas that is actually captured?
>There is a report based on a look at a bunch of California landfills that
>estimated a number on the order of 30 percent recovery. As I recall it
>was based on calculations of how much gas should be generated by the
>garbage, over what period of time (with respect to the dumping) vs what
>was actually recovered.
>As you say, nobody has apparently ever bagged a landfill and measured
>accurately. But there are data from in-vessel anerobic digestion
>processes that can be used to validate generation calculations. I found
>it somewhat convincing and also disturbing in the low percentage
>recovered. I don't recall the source or the authors but can probably find it.
>As far as I am concerned it confirmed my sense that landfill gas burning
>should NOT be regarded as desirable from a carbon point of view. Mostly
>because if you do that it may lead to support for continued dumping, which
>will cause more gas to be leaked than recovered.....
>>From: GreenYes@no.address [ mailto:GreenYes@no.address] On
>>Behalf Of Reindl, John
>>Sent: Thursday, March 01, 2007 1:40 PM
>>To: Dennis Sauer; GreenYes@no.address
>>Subject: [GreenYes] Re: Landfill methane recovery data
>>Hi Dennis ~
>>I work for a county that owns a landfill and has very up-to-date
>>technology for gas extraction and energy production, with revenues of
>>over a million dollars a year.
>>When we did our food scraps recovery study, this very question came up
>>and our study's conclusion was that the removal of food would have
>>negligible impact on gas recovery at the landfill. (We used the EPA
>>On the other hand, removal of food from landfills will cut down on odors
>>and the attraction of birds, flies and other vectors. And, for waste
>>generators, it means that materials don't need to be set out frequently
>>for collection (I set out material only 2-3 times a year).
>>John Reindl, Recycling Manager
>>Dane County, WI
>>From: GreenYes@no.address [ mailto:GreenYes@no.address]On
>>Behalf Of Dennis Sauer
>>Sent: Thursday, March 01, 2007 2:16 PM
>>Subject: [GreenYes] Landfill methane recovery data
>>Does anyone have recent data or studies relating to the capture rate of
>>methane from landfills? As we expand our food scrap diversion programs
>>we have received criticism that we are stealing fuel from a co-generation
>>facility at our regional landfill. I realize that in dry tomb landfills,
>>any reduction of methane from removing food scraps is negligible due to
>>the rapid decomposition of food scraps. This has been answered by
>>critics who state that the latest landfill and methane recovery
>>technology does capture methane from food scraps and all of the methane
>>generated by a landfill. I have read one study that states: despite
>>claims of 70-75% recovery rates, the actual amount being recovered is
>>more like 20%. Can anyone direct me to additional information to back up
>>Compost Specialist firstname.lastname@example.org
>>Central Vermont Solid Waste Management District
>>137 Barre St, Montpelier, Vermont 05602
>>802-229-9383 Ext. 303
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