[Terrapreta] energy balance and emissions

[mariska evelein]

Thanks Ron
Going back to working it out from calorific values is useful.
I guess I was thinking about some external energy source that might be needed
initially, but of course the biomass can be used for this, which will just result in lower energy that can be harvested in the end.

This confusion was probably fueled by a remark I found in Ullrichs' Industrial Chemistry Encyclopedia:

"For the production of 100 kg of charcoal, including the drying of the wood, 250 MJ of heat
and 27 MJ of electrical power are needed, as well as 5m3 of water"

Which suggests that this energy comes from an external source.

Mariska

From: rongretlarson at comcast.net
To: mariska_evelein at hotmail.com; terrapreta at bioenergylists.org
Subject: Re: [Terrapreta] energy balance and emissions
Date: Tue, 13 Nov 2007 09:52:26 -0700










Mariska:
 
    1.  Good question below.  
There is no doubt that there is plenty of exothermic energy release 
during pyrolysis (we ususally hear of a starting biomass energy content 
about 18 MJ per kg and with about 25% by weight charcoal left over at 30 MJ per 
kg (or 7.5 MJ in 250 gm) - there was about 10 MJ per kg available for 
productive use.  However, if none is captured for productive use (cooking 
etc) and one places about half of the initial carbon (and energy) into the 
ground - one is justified in asking about net energy balance.
 
   2.  However, even then, I believe one 
can show (eventually - haven't seen it yet -  in the published 
literature) that the later increased productivity of the soil and the need 
for less fertilizer will again show an even bigger positive net energy 
benefit.
 
   3.  Great that you are working on this 
problem.
 
Ron

  ----- Original Message ----- 
  From: 
  mariska evelein 
  To: terrapreta at bioenergylists.org 
  
  Sent: Tuesday, November 13, 2007 7:35 
  AM
  Subject: [Terrapreta] energy balance and 
  emissions
  

  
  Hello

Sorry if this has come up before, I'm quite new on this list and 
  haven't seen this discussed before.

I'm doing some research into the 
  benefits and draw backs of biochar production on a large scale,
which has 
  led me into looking at the energy use and emissions of the production 
  process.

Has anyone found any publications or other information 
  covering this, I have pretty much exhausted the www and available literature 
  on pyrolysis - but they are all evading this issue.

I'm assuming that 
  the energy balance of the production is positive - ie some energy will be 
  produced in the exothermic stage which will make up for the energy used to set 
  the process off - but I want to find some hard numbers.


Any info is 
  helpful
Thanks
Mariska


  
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