[Terrapreta] Biochar Packing Strategies

[Robert Klein]

Hi Sean

I will add one quick comment at the moment.  The
earthen kiln that is constructed would be a closed
shell including a topping of dirt.  This will tend to
naturally grab the heavies coming off the hot zone. 
And the operator would stand by to throw dirt on any
breakthroughs.

As you also pointed out, the shell is naturally leaky
to gases, including oxygen.  Thus it is reasonable to
suppose that there is a steady but slow supply of
oxygen which sustains the burn.

I suggested that the burn is initiated through the
expedient of emptying a bowl of red hot wood coals on
the top of the stack,  tipping the bowl on top of the
burn and covering same with mud.  This prevents the
burning charge from been stifled as the charge
migrates to the bottom of the stack.

This hot spot will draw in oxygen through the stack
and  force production gas into the walls of the
glowing chimney been created.

Now I want to talk about the stoichiometry of the
production gases.  The gases will burn preferentially
with the hydrogen and methane burning first,
especially since they are been produced at a high
temperature as you pointed out.

This means that the methane and hydrogen end will be
substantially reduced throughout the burn.  The dirt
shell helps a second time by slowing the exit of the
gases.

And yes there will still be leakage.

Field trials can resolve the actual numbers relating
to a well managed biochar burn.  At this point,
though, I suggest that light flammable gases will be
much less than anyone imagined.

By the way,has anyone determined the methane
production of a smoldering forest floor that is the
result of a forest fire or a slash and burn operation?
 It will clearly be at least equivalent to the
carefully controlled earthen kiln as described.  Such
a global calculation will actually give us an upper
limit to the  amount of gases we want to permit
globally since this method can replace and eventually
displace slash and burn.

regards

Bob


--- "Sean K. Barry" <sean.barry at juno.com> wrote:

> Hi Robert,
> 
> The pyrolysis reaction (otherwise known as
> destructive distillation and/or partial combustion)
> of biomass in air as the oxidant, generates
> "producer gas".  "Producer gas" is a mixture of
> exhaust gases from complete combustion; Carbon
> dioxide gas-CO2 and Water as a gas-H2O, un-reacted
> inert gases; Nitrogen gas-N2, and some energy
> containing fuel gases; Hydrogen gas-H2, Carbon
> monoxide gas-CO, and Methane gas-CH4.  There are
> also some longer string hydrocarbons (e.g. Ethane
> gas-C2H4, etc.) and some vaporized tars (these are
> even longer string hydrocarbons and/or aromatic
> hydrocarbons, consisting partly of 6-carbon benzene
> rings and parts of benzene rings) in very small
> amounts (15-2000 ppm).  There can be un-reacted
> Oxygen-O2, too, if the reaction has been quenched
> (dropped below the ignition temperature of the
> biomass feedstock and the other gases).
> 
> The "producer gas" is not generated in any large
> volume until most of the water is driven out of the
> feedstock and the temperature of the biomass exceeds
> about 250 degrees C, when the pyrolysis reaction
> begins in earnest.  The reaction requires an input
> of external heat (or enough input of oxygen to keep
> combustion occurring in the feedstock) until the
> temperature exceeds about 400 degrees C, when the
> reaction becomes exothermic and generates enough
> heat on its own, to continue without external energy
> being supplied.  Reducing the supply of oxygen to
> the reaction STOPS the combustion of fuel gases and
> thus increases the output volume of the fuel content
> of the "producer gas".
> 
> In an "open-air" kiln, a dirt mound with biomass
> inside of it, there must be a supply of oxidant (the
> air) until the reaction becomes exothermic. 
> Otherwise the "burn" will smolder out.  During this
> part of the process, Water as gas-H2O, Carbon
> dioxide gas-CO2, and soot (exploded off particles of
> carbon) will be the bulk of the output volume of the
> exhaust.  The feedstock will be is in a state "full
> combustion".
> 
> The atomic weight of Hydrogen gas-H2 molecules   is
> 1+1 = 2, ~10-20% by volume of producer gas
> The atomic weight of Carbon monoxide gas-CO
> molecules is  12+16 = 28, ~10-20% by volume of
> producer gas
> The atomic weight of Carbon dioxide gas-CO2
> molecules is 12+16+16 = 44, ~10-25% by volume of
> producer gas
> The atomic weight of Nitrogen gas-N2 molecules is
> 14+14 = 28, ~40-50% by volume of producer gas
> The atomic weight of Methane gas-CH4 molecules is
> 12+1+1+1+1 = 16, ~2-4% by volume of producer gas
> 
> Hydrogen-H2 is the lightest and Methane-CH4 is the
> second lightest of these gaseous components.  Only
> if the oxygen is limited and there is not complete
> combustion will there be any fuel gases left from
> the reaction.  There has to be flame to burn the
> fuel gases.  If there is no flame, then the fuel gas
> components will rise out of the pyrolyzing biomass
> and emit right into the open atmosphere.
> This is a measurable fact, not a hypothesis.
> 
> >At the time I made any such comment, this was a
> very
> >sleepy group and you had not weighed in.  And you
> are
> >still the only person who has chosen to not agree
> so
> >far.
> 
> This is not true, Robert.  Adriana Downy at BEST,
> Tom Miles, and Michael Bailes, have all voiced the
> same opinion as me about Methane-CH4 from a
> pyrolysis reaction.  They said it in response to you
> too.  Do you need for me to produce those postings? 
> I know Stephen Joseph at BEST and Danny Day at
> Eprida would agree with me on this too.  Tom Reed
> and Aqua Das at the Biomass Energy Foundation, Dr.
> Michael ANtal, Jr. at the University of Hawaii have
> all discussed this in their very close work with
> biomass gasification and biomass-to-charcoal
> reactions.  I have read from ALL of these peoples
> work.  They and the others on this list who really
> understand what a pyrolysis reaction in biomass is
> know that what I am saying is true.  Methane-CH4
> emissions from a pyrolysis reaction at only 2-4%
> levels are still potent GHG contributers.
> 
> Just because some do not respond to you does not
> constitute agreement with you.  Just because you
> miss or ignore the contradictory responses does not
> constitute agreement with you.  I am not a member of
> the "sleepy" part of this group.  I am not
> disagreeing with you based on just being contrary. 
> I am arguing a valid point with you.  I disagree
> firmly and I can back up what I say about it.  You
> can't believe I think it is fair for you to go to
> your blog and say I and everyone else here on the
> 'terrapreta' list agrees with you.
> 
> Robert, the troposphere is the lowest part of the
> atmosphere.  Methane-CH4 concentrations in the
> atmosphere from the troposphere all the way up
> through the stratosphere and ionosphere are rising
> and have been rising for some time.  Methane-CH4 is
> decomposed in the atmosphere by reactions with
> oxygen, just like combustion.  The half-life of
> Methane-CH4 in the atmosphere is ~ 7 years.  That
> means it takes ~7 years for only half of the
> Methane-CH4 to decompose.  It does not all decompose
> within 7 years.  Methane-CH4 has a much greater
> ability to absorb and reflect infrared radiation
> shooting up from the Earth's surface, than
> Carbon-dioxide does.
> 
> Natural gas is predominantly Methane gas-CH4, some
> Carbon monoxide gas-CO, and some Hydrogen gas-H2. 
> When we burn it, those fuels are "fully combusted"
> in flames (that is evidence of the exothermic nature
> of combustion) and the fuel gases are gone,
> converted into exhaust gases, CO2 and H2O.  That is
> also accepted chemistry and a measurable fact.  I
> have told you that Methane-CH4 emissions from a
> pyrolysis reaction can be "flared".  That means
> burning them.  No flames means emission of the
> un-burned gases, including Methane-CH4.  It is that
> simple.
> 
> I suggested to you that you could read
>
http://en.wikipedia.org/wiki/Methane<http://en.wikipedia.org/wiki/Methane>
> and
>
http://en.wikipedia.org/wiki/Green_house_gas<http://en.wikipedia.org/wiki/Green_house_gas>
> to get a better understanding of what I am reporting
> to you.  I do not believe that I am contradicting
> anything that is said there.  Those pages are
> correct information, that is widely accepted and is
> documented in several other reputable sources.
> 
> Look here->
>
http://en.wikipedia.org/wiki/Global_warming_controversy<http://en.wikipedia.org/wiki/Global_warming_controversy>
> ...
> Look here->
>
http://en.wikipedia.org/wiki/Climate_change_denial<http://en.wikipedia.org/wiki/Climate_change_denial>
> for even more information.
> 
> This is an important issue to me, Robert.  You can
> dismiss it, if you want to.  You sure seem to want
> to.  But, please DO NOT associate your views with
> agreement from me anymore.
> 
> Please note that I am not brow beating you in front
> of the rest of this group.  I want to, but I am not
> doing it, because some of them get their panties in
> a bunch over reading ti, thinking that I need to not
> argue so vigorously with you anymore.  You keep
> coming back to me with claims that my views are
> remarkable assertions and imply that they are just
> opinions or unwarranted.  I do present valid support
> for what I say.  Go ahead and read some of it.  You
> do not discuss this in scientific terms with me and
> you do not rebut effectively anything I say.
> 
> I appreciate any interest or traffic that you can
> bring to the 'terrpreta' list.  But, would you
> please give me some level of respect by not saying
> agreements with you were made with ALL of the
> members on this list and then go post that to your
> blog anymore?
> 
> 
> Regards,
> 


       
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