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[GreenYes] Re: Landfill methane recovery data

[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
ficiency2006-Michels.pdf> . 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

Brad Wolbert
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';
Subject: [GreenYes] Re: Landfill methane recovery data

At 03:29 PM 3/1/2007 -0700, Eric Lombardi wrote:

Hi John,

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

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 over time.

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.....


-----Original Message-----

From: GreenYes@no.address [
mailto: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 LandGEM model.)

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).

Best wishes,

John Reindl, Recycling Manager

Dane County, WI

-----Original Message-----

From: GreenYes@no.address [
mailto:GreenYes@no.address <mailto:GreenYes@no.address> ]On
Behalf Of Dennis Sauer

Sent: Thursday, March 01, 2007 2:16 PM

To: GreenYes@no.address

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 this data?



Dennis Sauer

Compost Specialist

Central Vermont Solid Waste Management

137 Barre St, Montpelier, Vermont 05602

802-229-9383 Ext. 303

800-730-9475(Vt only)

802-229-1318 fax


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