[Terrapreta] energy balance and emissions

[Kevin Chisholm]

Dear Mariska

Attached for your information is a simplistic spread sheet showing the 
approximate energy distribution in char and pyrolysis gases, depending 
on calorific value of the starting wood, and other variables. Enter your 
input data in the yellow cells, and the answers appear in the green squares.

I put the spread sheet together using Imperial Units, and didn't have 
time to convert over to metric.

Hope it is helpful.

Best wishes,

Kevin
mariska evelein wrote:
> 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 <mailto:mariska_evelein at hotmail.com>
>         *To:* terrapreta at bioenergylists.org
>         <mailto: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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