[Terrapreta] city and farm

[Duane Pendergast]

Thanks Sean,

 

I not sure there is an insurmountable problem re adding fossil fuel carbon
to the atmosphere. In fact the some could say the old carbon from fossil
fuels is better as it is less radioactive. If we have a way to use it to
build up the planet's soil, then let's bring it on. We'll need the fossil
fuel carbon it if we start building terra preta and depleting the atmosphere
of its CO2 content.

 

As to the plastics and other waste mangement let's figure out the best uses,
perhaps with respect to separating them, and proceed accordingly.

 

Duane

 

 

 

-----Original Message-----
From: Sean K. Barry [mailto:sean.barry at juno.com] 
Sent: November 14, 2007 10:16 AM
To: still.thinking at computare.org; 'lou gold'; 'Terrapreta'
Subject: Re: [Terrapreta] city and farm

 

Hi Duane, Lou,

 

The point of using biomass for carbon based fuels and for carbon based
energy production is that the resulting release of CO2 is not "new" carbon
introduced into the atmosphere, from 300 million year old carbon in fossil
fuels, but rather it is RECYCLED carbon which was taken from plants in the
biosphere.  With enough plant growth, even CO2 emitted by burning fossil
fuels may be taken up by the growing plants.

The difference between fossil fuels and biomass, is that biomass does not
ADD to the amount of carbon already in the Biosphere.

 

Municipal solid wastes are not a good choice for a feedstock for charcoal to
be used in agricultural soils.  This was discussed a couple weeks back.
Plastics make a substantial portion of the municipal solid waste stream.
Plastics do contain carbon and can be made into a form of charcoal.
However, plastics also contain many toxic chemical additives (plasticizers,
hardeners, stabilizers, dyes, etc) that give the different types of plastics
their properties for use.  These chemicals include poly-vinyl chlorides,
fluorinated carbons, some heavy metals, and they decompose slowly , leaving
toxic compounds that can pollute biological systems and water systems.
Halides and heavy metals are a big no-no for biological systems.

 

Plastics are so stable that attempting to pyrolyze them would release more
carbon in the short term than could be sequestered if they were used rather
to make recycled plastic products, or even if they were left as is and
buried in waste disposal sites.  The recycled plastic product route at least
avoids more of the potential for environmental contamination.

 

 

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