[Terrapreta] Hydrothermal carbonization

[Brian Hans]

Hi Gerrit,

All plant biomass is things like sugars, cellulose, hemi-cellulose, and lignin, basically carbohydrates.  The ratio of # of atoms of carbon-C, hydrogen-H, and oxygen-O; C:H:O, is very close to ~1:2:1,  as all carbohydrates are made up of multiples of CH2O molecular constructs.

Charcoal on the other hand is 93-95% pure carbon.  It does often times still contain some small amounts (5-7%) of combustible hydrocarbons and carbohydrates.  Usually this is called the volatile matter content of the charcoal.  The C:H:O ratio in charcoal then is something more like ~95:10:5.

So, where did all the H2O part of the CH2O carbohydrates go? ... from within a "sealed" and pressurized vessel?  The hydrogen and oxygen atoms cannot be transmuted into carbon atoms by this chemical process.  The answer is, that the hydrogen an oxygen is all still there.  It would not surprise me, either, if Dr. Antonietti's reactor did not vent some gases (perhaps CO2, H2, CO, N2, CH4, and O2?) upon opening.

The mass of a single carbon-C atom is 12 atomic units, 1 au for a hydrogen-H atom, and 16 au for an oxygen-O atom.  So, in carbohydrates, where ratio of # of atoms, C:H:O is approximately ~1:2:1, then then mass ratio is 12:2:16.  Then carbon-C makes up, at most ~40% (12/(12+2+16) = 0.40) of the total mass of any un-pyrolyzed, raw, biomass.  It is NEVER possible to convert 100% of the mass of any plant material (biomass) entirely into carbon.  40% is the maximum achievable yield of fixed carbon (on a weight/weight basis) from the conversion of any biomass, regardless of the method used for conversion.  Because charcoal is not entirely pure carbon (it contains volatile matter), then the actual maximum yield of charcoal is even less, perhaps 35%.

You might read some of the materials presented on this site my Dr. Michael J. Antal from the University of Hawaii.  He has great experience with conversion of biomass into charcoal and he is also Bio-chemist ro a Bio-chemical engineering professor, so he understands and has written much about this subject (charcoal yield from conversion of biomass).

Regards,

SKB
  

Sean et al.
   
  I work with HTC. We have a reactor in our lab that has been doing HTC for over 6 months now. I have met Dr. Antonietti in Germany in his lab and have had countless conversations with him about HTC and just about anything else under the stars. 
   
  Im not sure where Sean got his HTC info but its in-accurate, likely causes are translation from German into English. Obviously there is no atom shifting...what goes in comes out. If 40% weight carbon biomass goes in....  .4lbs of carbon comes out. There is no gases produced (or very little...if there is some, the recipe isnt correct and its back to the lab work). The CH2O turns into C and H2O...this is where the 'exothermic' comes from. No CH4 should be produced because of the reactants and conditions. Oils and lignins have very exotic chemical reactions dependent on the feedstock VS the easy reaction of dehydration of the carb. 
   
  If anyone cares to check out our lab in NE Wisc...they are more than welcome to sign a ND and check it out. 
   
  Brian 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: /pipermail/terrapreta_bioenergylists.org/attachments/20070829/0c9bd212/attachment.html