[Terrapreta] a braoder theory of torrefaction and TP

Sean K. Barry sean.barry at juno.com
Tue Dec 11 13:55:17 CST 2007

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Hi Greg,

This is a minor point to make from you. You should note, that the time weighted global warming potential (GWP) of Methane-CH4 (this is measured in what are called the "CO2-equivalent" units) is 23-26 times that of CO2 over a 100 year time span and 62-72 times as potent as CO2 over a 20 year time span. The half-life of Methane-CH4 in the atmosphere is ~7 years. This does not mean its all gone in 14 years! Methane-CH4 does degrade and concentrations do naturally decrease, but it is still a slow process and the GWP of the CH4 molecules far outweighs CO2.

>From http://en.wikipedia.org/wiki/Green_house_gas<http://en.wikipedia.org/wiki/Green_house_gas>

Examples of the atmospheric lifetime and GWP for several greenhouse gases include:
a.. CO2<http://en.wikipedia.org/wiki/Carbon_Dioxide> has a variable atmospheric lifetime, and cannot be specified precisely[22]<http://en.wikipedia.org/wiki/Green_house_gas#_note-18>. Recent work indicates that recovery from a large input of atmospheric CO2 from burning fossil fuels will result in an effective lifetime of tens of thousands of years.[23]<http://en.wikipedia.org/wiki/Green_house_gas#_note-carbon_lifetime1>[24]<http://en.wikipedia.org/wiki/Green_house_gas#_note-carbon_lifetime2> Carbon dioxide is defined to have a GWP of 1 over all time periods.
b.. Methane<http://en.wikipedia.org/wiki/Methane> has an atmospheric lifetime of 12 ± 3 years and a GWP of 62 over 20 years, 23 over 100 years and 7 over 500 years. The decrease in GWP associated with longer times is associated with the fact that the methane is degraded to water and CO2 by chemical reactions in the atmosphere.
c.. Nitrous oxide<http://en.wikipedia.org/wiki/Nitrous_oxide> has an atmospheric lifetime of 120 years and a GWP of 296 over 100 years.
d.. CFC-12<http://en.wikipedia.org/wiki/CFC-12> has an atmospheric lifetime of 100 years and a GWP(100) of 10600.
e.. HCFC-22<http://en.wikipedia.org/wiki/HCFC-22> has an atmospheric lifetime of 12.1 years and a GWP(100) of 1700.
f.. Tetrafluoromethane<http://en.wikipedia.org/wiki/Tetrafluoromethane> has an atmospheric lifetime of 50,000 years and a GWP(100) of 5700.
g.. Sulfur hexafluoride<http://en.wikipedia.org/wiki/Sulfur_hexafluoride> has an atmospheric lifetime of 3,200 years and a GWP(100) of 22000.
Regards,

SKB
----- Original Message -----
From: Greg and April<mailto:gregandapril at earthlink.net>
To: 'Terrapreta preta'<mailto:terrapreta at bioenergylists.org>
Sent: Tuesday, December 11, 2007 12:39 PM
Subject: Re: [Terrapreta] a braoder theory of torrefaction and TP

Let's also keep in mind, that while methane is a stronger greenhouse gas, it's life expectancy in the atmosphere is about 12 yrs, before it breaks down into CO2 and H2O. OTOH, CO2 is believed to have a life expectancy exceeding 120 yrs.

Greg H.

----- Original Message -----
From: Sean K. Barry<mailto:sean.barry at juno.com>
To: still.thinking at computare.org<mailto:still.thinking at computare.org> ; 'Jim Joyner'<mailto:jimstoy at dtccom.net>
Cc: 'Terrapreta preta'<mailto:terrapreta at bioenergylists.org>
Sent: Monday, December 10, 2007 20:55
Subject: Re: [Terrapreta] a braoder theory of torrefaction and TP

Hi Duane, Jim,

You've made a super good point here! Methane-CH4 from buried wood would be an absolutely important issue. A volume Methane gas-CH4 has the same global warming potential as 25 times that volume of CO2 over a 100 year period and the same global warming potential as 72 time that volume of CO2 or 20 years. As the buried wood decomposes it will release Methane.

Here is maybe an interesting idea, though. Suppose wood is buried and kept wet and warm under the subsoil. Then, like a landfill, it is sealed from below and it is integrated with pipes from above. This "wood-fill" could be then treated like a source of natural gas. What would you think of that? Of course, as you harvest the Methane, you would reduce the carbon storage and the ground would eventually subside.

Regards,

SKB
----- Original Message -----
From: Duane Pendergast<mailto:still.thinking at computare.org>
To: 'Jim Joyner'<mailto:jimstoy at dtccom.net>
Cc: 'Terrapreta preta'<mailto:terrapreta at bioenergylists.org>
Sent: Monday, December 10, 2007 9:29 PM
Subject: Re: [Terrapreta] a braoder theory of torrefaction and TP

Good thoughts there Jim, but it would likely perform similarly to a landfill. Those tend to generate methane which we are told is a much more effective greenhouse gas than carbon dioxide. Charcoal might be a good substitute for some of the goals you mention and seemingly would avoid the methane production.

Duane

-----Original Message-----
From: terrapreta-bounces at bioenergylists.org<mailto:terrapreta-bounces at bioenergylists.org> [mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Jim Joyner
Sent: December 10, 2007 7:47 PM
Cc: Terrapreta preta
Subject: Re: [Terrapreta] a braoder theory of torrefaction and TP

You know, We've all been looking at the sexier uses of various forms of burned wood in the top soil, but if you want a cheap way to sequester carbon, burying sawdust or chips in the subsoil accomplishes the same thing (burying charcoal below the topsoil makes no economic sense, serves little or no purpose). It works because there is little or no biological activity in the subsoil.

I don't know how long it lasts but it gotta be at least decades. But it might be forever. I was always involved with the farming side, not the research, but I know of experiments that were started 25 to 30 years ago in Missouri. They took sawdust, mixed it with subsoil and buried it as much as six feet deep in long trenches. The purpose was to give certain deep rooted perennials (grapes, in this case) more root room and create a moisture reservoir.

The moisture reservoir is a good idea for not only plants but for good water shed. And, it buries a lot carbon waste product that doesn't need to be processed.

There are even less invasive ways to bury woody material in the subsoil too. For example, I subsoil my beds for annuals to about 3 feet. I balance the subsoil by adding limestone (I built a device that subsoils and adds lime at the same time. Not all soils need the lime) so that it will be lose not only physically but electrically. Then, every year a crop sends a new set of roots down and leaves them behind. The blackness of the soil gets deeper and darker every year. The water holding capacity of the subsoil increases every year.

Jim

Gerald Van Koeverden wrote:

I like your idea....we 'soils peoples' have to broaden our scope of interest from 'biochar' to the whole range of "torrefied wood". Let me try to build a new 'theory."

Torrefaction does something to the wood so that it lasts much longer in the soil than non-torrefied wood. What happens in torrefaction? "This process removes all naturally occurring resins, sugars and oxygens while collapsing the cells. This accomplishes two things: First, it gives the lumber a deep, rich brown color...Second, and more importantly, it alters the wood to make it extremely stable, moisture resistant and decay resistant."

This extended life effect is not just because it drives out enough moisture to inhibit decomposing organisms, but it also provides a suitable habitat for non-decomposing soil-dwelling organisms - not dependant on as high moisture contents - which in turn protect their habitat from rapid decomposition. If these MO don't completely inhibit decomposition, they at least have a significant effect in slowing that process down. It is the biological activity of these micro-organisms inhabiting the torrefied wood, which increases the fertility of those soils and make TP's what they are.

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