David,
You wrote:
"some of the carbon in the substrate (the material being decomposed) is
released as CO2 but much of it is utilized to make more microorganisms."
Which ultimately die and break down with the release of the carbon.
During the growth of microbial populations, especially during the
exponential growth phase, carbon is, in fact, stored within organic matter
.... just as during the growth of plants, there is more carbon stored in
organic matter than is being released by the organisms due to cell
respiration.
Populations, including microbial populations, do not increase in
number/mass indefinitely or they would eventually be expanding into the
universe at the speed of light. Populations grow, peak, and either level
off, or decline based on limiting factors in their environment. Microbes die
and their carbon is released.
We've been using the same atoms over and over again for billions of
years. Ok, so some additions by way of cosmic dust and meteorites, but the
point is, matter is recycled.
"Its also important to look at the type of biodegradation that is
occurring. If its aerobic (oxygen rich degradation) then the carbon that
comes off as a gas is primarily CO2. If it is anaerobic (Oxygen deficient
environment) the gas produced is primarily Methane CH4."
Actually methane is not the primary gas released in anaerobic
conditions ..... CO2 is , (can be seen during ethanol fermentation by
yeast) other gases include H2 and H2S.
Methanogenic bacteria are chemoautotrophic, oxidizing the H2 produced by
other anaerobes in the presence of the CO2 produced by other anaerobes.
H2 + CO2 --------> H2O + CH4 + energy
"This is why secondary reactors in sewage treatment plants use
anaerobic digesters to reduce sludge volume while producing methane to be
used as fuel to be used to produce electricity that offsets some of the
outside energy demands of the plant."
True, anaerobic decomposition can produce methane gas .... whether it
be in sewage treatment plants, mud flats, or in the guts of ruminant
animals. Methane, is, in fact, a more "effective" greenhouse gas than CO2.
The ultimate fate of the C's in methane is CO2.
As you point out, methane can be burned as fuel
-----> CO2 + H2O.
In the atmosphere it tends to react w. oxygen
-----> CO2 + H20.
We could consider biomass being covered by landslides with the carbon
contained in it being locked away for a million years, or methane burps
rising from mud flats that had been part of an earlier carbon cycle. The
carbon balance is not quite as clear-cut as a business account of credits
and debits.
The original point was in response to a question re: CO2 emissions:
fossil fuels vs biofuels. My answer involved the cycling of carbon. If we
agree that we are overloading a system with carbon dioxide from ancient
times, while destroying environments that have historically served as carbon
"sinks", then biofuels, used conservatively and with consideration of how
they are produced and transported, are clearly favorable to the continued
use of fossil fuels.
Tom
----- Original Message -----
From: "chem.dd" <[EMAIL PROTECTED]>
To: <biofuel@sustainablelists.org>
Sent: Tuesday, June 13, 2006 3:37 AM
Subject: Re: [Biofuel] Hello and Question
> Tom
> Your response to Jason & Kate implied that all of the carbon in a
> biodegradation process is released as CO2 into the atmosphere. When
> organisms biodegrade organic material some of the carbon in the substrate
> (the material being decomposed) is released as CO2 but much of it is
> utilized to make more microorganisms. Its also important to look at the
> type of biodegradation that is occurring. If its aerobic (oxygen rich
> degradation) then the carbon that comes off as a gas is primarily CO2. If
> it
> is anaerobic (Oxygen deficient environment) the gas produced is primarily
> Methane CH4. This is why secondary reactors in sewage treatment plants
> use
> anaerobic digesters to reduce sludge volume while producing methane to be
> used as fuel to be used to produce electricity that offsets some of the
> outside energy demands of the plant.
> David
> ----- Original Message -----
> From: "Thomas Kelly" <[EMAIL PROTECTED]>
> To: <biofuel@sustainablelists.org>
> Sent: Saturday, June 10, 2006 11:29 AM
> Subject: Re: [Biofuel] Hello and Question
>
>
>> Jason & Katie,
>> Decomposing is the result of microbial metabolism.
>> The energy in the stalks, leaves etc. is "fuel" for the decomposers. The
>> carbon, would be released as CO2. Other nutients would be returned to the
>> soil/water/atmosphere.
>> Peat bogs, coal, and oil are the rare exceptions where decomposition
>> doesn't occur. The energy and the Carbon are "stockpiled".
>> Tom
>> ----- Original Message -----
>> From: "Jason& Katie" <[EMAIL PROTECTED]>
>> To: <biofuel@sustainablelists.org>
>> Sent: Saturday, June 10, 2006 1:42 PM
>> Subject: Re: [Biofuel] Hello and Question
>>
>>
>> > ive been thinking about this, and was wondering... if during harvesting
>> > the
>> > stalks, or supporting structure, or leaves, or whatever were left in
>> > the
>> > gardens to decompose, or were composted, wouldnt the unused material
>> > returned to the soil be a carbon reduction? it doesnt get put into the
>> > fuel
>> > and it collects and adds up over time. this could bee seen as a carbon
>> > stockpile right?
>> >
>> > ----- Original Message -----
>> > From: "Thomas Kelly" <[EMAIL PROTECTED]>
>> > To: <biofuel@sustainablelists.org>
>> > Sent: Saturday, June 10, 2006 11:45 AM
>> > Subject: Re: [Biofuel] Hello and Question
>> >
>> >
>> >> Joe,
>> >> CO2 emissions should be the same.
>> >> You wrote:
>> >> "If the CO2 reduction number of 78% attributed to biodiesel is a
>> >> result
>> >> of
>> >> the crops it comes from, does the 78% number assume that no crops
>> >> would
>> >> have
>> >> been grown on the land if it were not being used for fuel crops, or is
>> >> the
>> >> 78% in addition to whatever crops were previously growing there."
>> >>
>> >> No. The % "reduction" in CO2 refers to a reduction in Carbon that is
> not
>> >> part of our short-term Carbon Cycle.
>> >>
>> >> Let me try to explain:
>> >> All crops are fuel crops. Even wilderness meadows and forests are
>> >> fuel
>> >> "crops". The energy captured during photosynthesis and stored in
> organic
>> >> molecules will be released either as a result of metabolic activity of
>> >> living things or as a result of combustion.
>> >> The amount of Carbon released as CO2 will be the same as the
>> >> amount
>> >> taken in to construct the organic molecules (fuel). Whether or not the
>> >> land
>> >> is used for food crops, fuel crops, or left wild, there is a balance
>> >> between
>> >> the amount of carbon taken from the atmosphere and incorporated into
>> >> organic
>> >> matter and the amount released when that organic matter is burned.
>> >> This
>> >> balance is unaffected by whether the organic matter becomes fuel for
>> >> cells,
>> >> or for automobiles.
>> >> Fuels that do not disrupt this balance are said to be Carbon
> Neutral.
>> >> The carbon in fossil fuels has been sequestered away for tens of
>> >> millions of years. Upon burning, the release of CO2 from fossil fuels
> has
>> >> the potential to overwhelm mechanisms that maintain relatively stable
>> >> atmospheric CO2 levels, and hence disrupt the balance between CO2
> "fixed"
>> >> into organic matter and CO2 released during burning. CO2 from fossil
>> >> fuels
>> >> is NOT carbon neutral. It is not part of the short-term Carbon Cycle.
>> >>
>> >> I think that there is no actual reduction in CO2 produced when
>> >> biodiesel is burned vs. petro diesel. The significance is that with
>> >> biofuels, we are not unleashing Carbon that has long been trapped
> beneath
>> >> the earth as we do when we burn fossil fuels.
>> >>
>> >> Any %, whether 50%, 78%, or 90% emissions reduction depends on
>> >> the
>> >> amount of fossil fuel used to produce the biofuel. Inorganic
> fertilizers,
>> >> large fossil fuel tractors/equipment, fossil fuel powered
> transportation
>> >> of
>> >> raw materials and finished product over great distances, all have an
>> >> impact
>> >> on the carbon neutrality of the biofuel produced. Ex: Using coal or
> oil
>> >> or
>> >> natural gas to distill ethanol compromises the benefits, and hence the
>> >> overall "% reduction" in emissions.
>> >> The wealth of information on small farms, small-scale local
>> >> production,
>> >> the use of appropriate technology, sustainability.... some of the
> things
>> >> that make JTF and the biofuel mailing list so valuable. Be a thief.
> Take
>> >> it
>> >> all.
>> >> Best Wishes Joe
>> >> It's really quite an adventure
>> >> Tom
>> >>
>> >> ----- Original Message -----
>> >> From: "Joe Jackson" <[EMAIL PROTECTED]>
>> >> To: <biofuel@sustainablelists.org>
>> >> Sent: Friday, June 09, 2006 8:08 AM
>> >> Subject: [Biofuel] Hello and Question
>> >>
>> >>
>> >>> Hi, I'm new to the list. My name is Joe; I've been interested in
> clean
>> >>> fuels for years and have become very focused on biodiesel - I drive a
>> >>> Prius
>> >>> and recently my wife purchased a Jetta TDI and we are interested in
>> >>> finding
>> >>> a cooperative in our area. Any Anne Arundel/PG County Maryulanders
> out
>> >>> there?
>> >>>
>> >>> I have a question. There is an oft-repeated statistic that the use
>> >>> of
>> >>> B100
>> >>> reduces CO2 emissions approximately 78%, and from what I have read
>> >>> the
>> >>> vast
>> >>> majority of that reduction comes from the fact that the plants that
>> >>> biodiesel is derived from absorb CO2 as opposed to fossil fuels which
> do
>> >>> not
>> >>> do so, and that the actual tailpipe emissions are virtually the same
> as
>> >>> if
>> >>> the car was running regular diesel. Am I correct here?
>> >>>
>> >>> If so, I have been called to task on another online community to
> answer
>> >>> this
>> >>> question: If the CO2 reduction number of 78% attributed to biodiesel
> is
>> >>> a
>> >>> result of the crops it comes from, does the 78% number assume that no
>> >>> crops
>> >>> would have been grown on the land if it were not being used for fuel
>> >>> crops,
>> >>> or is the 78% in addition to whatever crops were previously growing
>> >>> there.
>> >>>
>> >>> I hope my question is clear, thanks!!
>> >>>
>> >>> Joe
>> >>>
>> >>>
>> >>> _______________________________________________
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>> >>> Biofuel@sustainablelists.org
>> >>>
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>> >>>
>> >>> Biofuel at Journey to Forever:
>> >>> http://journeytoforever.org/biofuel.html
>> >>>
>> >>> Search the combined Biofuel and Biofuels-biz list archives (50,000
>> >>> messages):
>> >>> http://www.mail-archive.com/biofuel@sustainablelists.org/
>> >>>
>> >>>
>> >>>
>> >>
>> >>
>> >>
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>> >>
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>> >>
>> >>
>> >
>> >
>> >
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>>
>>
>>
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>
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