[Gasification] [biochar] ICM gasifier project comes to a close

[Peter & Kerry Davies]

Thanks Tom,

Yes I agree that more gasifier chars are being used than most people 
realise, the growing use of TLUD stoves can only accelerate this, and 
may yet be one of the important legacy's of the good people (many on 
this list) who have developed and promoted them.

Unfortunately amongst the research community in Australia a peculiar and 
unwritten bias developed where only pyrolysis chars seem to be accepted 
in testing trials, I suspect in part because it is easy to make and 
study such chars in a lab.

The alkalinity statement came from our experience working with Bluescope 
Steel on metallurgical chars, their testing showed our gasifier chars 
from both softwood & hardwood chips (pine and eucalyptus) to have a 
lower alkalinity compared to pyrolysis chars from oil mallee residues 
which were quite alkaline (fixed carbon <60%), so much so that the 
latter could not be used alone as a reductant but had to be blended with 
other carbon sources.

We have since put oil malley leaf and stems through our system and came 
up with fixed carbon numbers >80% similar to our original trial results 
with wood chips above, though the ash analysis would be different.

Perhaps interestingly we have noted our livestock greatly prefer 
gasifier chars to chew on when given two sources to choose from, and 
much preferred hardwood char to softwood, results mirrored in the 
Bluescope testing on steel making suitability, they all make steel 
better than coke, but hardwood gasifier chars were exceptional.

However the Bluescope work example is the only one I have PH data for, 
more generally you may be right and my assumptions may not hold true 
either for other types of gasifiers or feed stocks. This is one the 
reasons we have been trying to get gasifier chars accepted over here in 
the biochar research, to get proper independently documented comparative 
information.

I was told by one research source that gasifer chars would be inferior 
for agronomic use compared to pyrolysis chars because of the different 
crystalline structure between them, however they were unable to point me 
to any work on this, published or unpublished, that supported this 
conclusion. Whereas work by Greening Australia over here using our chars 
showed them to have equal or superior outcomes to baseline control and 
pyrolysis char plots.

Cheers,
Peter



On 28/12/2012 7:00 AM, gasification-request at lists.bioenergylists.org wrote:
> Peter,
>
> There are probably more gasifier chars used as biochar than most people
> realize. I agree that gasification chars seem to be very useful for use as
> biochar. I haven't really seen enough thorough analysis of gasifier chars to
> be able to generalize on their characteristics as distinct from pyrolysis
> chars.  I do question your statement about gasifier chars being less
> alkaline than pyrolysis chars. Given the same feedstock a gasifier char will
> have higher ash, higher pH, and likely higher alkalinity than a pyrolysis
> char.
>
> Tom