[Digestion] Karve connecting Biochar and Biogas

[Duncan Martin]

How quickly does biochar boost biogas output? This would give some clues as
to whether biochar acts mainly as a biomass support. That is certainly a
very plausible mechanism - but it's not the only possibility.

An alternative mechanism for a biochar boost is its huge capacity to absorb
any inhibitors. This would probably give the process a rapid
boost, increasing the biogas output within a few days - or even hours. On
the other hand, microbial colonization of the extra surface would take many
days - and would probably take weeks to effect a major increase in biogas
output.

And, of course, biochar *could* improve a low C:N ratio, not by adding extra
C but by removing excess N.

Another question is whether extra biomass-support material would *always* be
of value. In a feedstock containing a lot of solids (eg manure or biomass
crops), there is already a lot of surface available for colonization by
biomass, so I suspect that one would need to add a high % of biochar to make
much difference. And too a high % of biochar would make the mixture
difficult to handle.

In contrast, biochar might have much more effect with a wholly soluble
feedstock - partly because residence times are likely to be lower.

So, *does *anyone have  rate data?

Duncan Martin
Ireland



On 6 October 2011 04:04, <rongretlarson at comcast.net> wrote:

> AD (cc four lists):
>
>     I have not previously seen the connection between Biochar and Biogas
> that you described (below) today on the gasification list.     In
> particular, you say you "..* filled the digester*
> with charcoal, my system accepted three times the normal daily input
> and produced three times as much gas."
> I think what you describe can be a very powerful push for both Biochar and
> Biogas.  Can you describe what you have learned a little more?
>
>      I know too little of digesters, so this is not clear.  I think I know
> your kitchen-sized inverted "barrel" gas chamber and think I understand the
> last part - of getting three times as much gas in the next 24 hours or less
> (and 3X is a huge change!).   Does the idea of accepting three times more
> mean essentially the same thing?  I would think you could "jam" any amount
> in;  what limits acceptance?
>
>     Do you agree that this is very important new information?  Do you agree
> this information could help speed up both technologies?  I believe there is
> wide agreement that Biochar benefits from added biological material (that
> would not be long-lived from a sequestration perspective).  Is there any
> reason to think that the traditional use of digester effluent for ag
> improvements will be in any way harmed if it is continued through the
> addition of carbon-negative Biochar?  Should this not promote sales of your
> charcoal-making stoves?
>
>    If I haven't asked quite the right question - please answer the right
> one.  And congratulations on learning and reporting this.
>
> Ron
>
>
>
>
>
> The remainder from AD Karve today on the gasification list:
>
>  There are a lot of very simple ideas that need to be tested.  I am
> currently working on increasing the efficiency of biogas digesters and
> feel that it might be possible to reduce the size and the capital
> expense of a biogas system. For instance, when I filled the digester
> with charcoal, my system accepted three times the normal daily input
> and produced three times as much gas.
>    < snip>
> Yours
> A.D.Karve
> *******************************************
>
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>
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