[Terrapreta] Char made made under pressurized conditions?

[Sean K. Barry]

Hi Jim,

Would you explain more about "sheet composting"?  Where (what plant or biomass source) do you think is enough and the kind of biomass needed to make enough charcoal to sequester massive amounts of carbon?

Any annual growth that decomposes anyway is probably the best source, I would think.  Fallen leaves and other yard wastes, grass clippings, annual crop residues, etc? Maybe not all woody, but at least carbon rich.  Consider municipal yard wastes, crop residues, coppiced Salix (willow) and Miscanthus grass, or industrial hemp?  Many hectares of something with large #'s of tons of biomass per hectare could produce a large CO2 reduction, if it were mostly carbonized, I would think.

You are right that reducing atmospheric CO2 concentrations would require massive amounts of biomass.  It is easily 25-40 Gt per year of dt biomass to make ~6-10 Gt of charcoal.  This is as large as and perhaps larger than the amount of biomass handled worldwide every year by humans now.  I think harvesting annual growth for charcoal and biomass energy, along with reducing the burning of fossil fuels, has a good chance at reducing the growth rate in CO2 concentrations.  If both are practiced widely enough, the combination can actually reduce atmospheric CO2 concentrations.

We can do this and eventually will need to be doing much of this work anyway (the looming energy crisis when fossil carbon fuels are too expensive to mine and too expensive for atmospheric considerations.  Hey Richard, here is a plank ... Tax fossil fuels heavily to subsidize renewable energy development and Terra Preta development.

Regards,

SKB
  ----- Original Message ----- 
  From: Jim Joyner<mailto:jimstoy at dtccom.net> 
  To: Terra Preta List<mailto:terrapreta at bioenergylists.org> 
  Sent: Sunday, March 30, 2008 2:34 PM
  Subject: Re: [Terrapreta] Char made made under pressurized conditions?


  Why cling to this romantic idea of composting? On practically any scale it is not worth it.

  First, with the exception of the most ideal situations, it is uneconomical. I used to make 200 tons of compost each year. The materials (bedding and cattle manure) were free, eight miles away. They loaded my truck too. But after calculating the cost of hauling, turning, spreading, the profitability on crops was only marginally better than just a good rotation scheme. There was no difference in quality. And putting any sort of cost on opportunity for the time wasted, it was a wash or a loss.

  Second, using compost, it is almost impossible to know what nutrient mix is going to result. Compost is not magical. What one puts in is what one gets out.

  Compostable materials are getting harder to find whether you are a gardener or a farmer. That is because the efficiency of land/crop use has been forced to increase. There is little waste in crop production. In fact, what appears as waste is often the sign of bad soil management. Taking crop residues is self defeating because, such a practice just moves the cost somewhere else. (I'm excluding the use of sheet composting here, for that is basically a practice of best utilizing field wastes right on the field. But this would have little relationship to the use of charcoal).

  The best and most effective way increase OM in the soil, at least in the temperate climes, is to grow it there -- good cover cropping and rotations. The most economical and best way to control and replenish nutrients in the soil is with the use of rock powders. Ultimately, that is where all the nutrient comes from anyway. Using composted materials from nutrient mined soils may increase OM temporarily but does a poor and uncontrollable job of replenishing. 

  So, back to charcoal in the soil. Grow the OM in the soil. In a balanced soil (just like good compost), there will be no ammonia given off. What little there is will be quickly converted to nitrites and then to plant-usable nitrates.

  Unless compost is subsidized with tax money (e.g., like municipalities composting leaves and tree waste), there is no sense in using compost at all. Even then, once the cost of using  it is calculated in, it may not be worth it. The only place it can make sense is if there are materials available for free and labor is very cheap.

  For those thinking about saving the world by reducing CO2, composting maybe a nice academic subject but it has no place in the practices for sequestering massive amounts of carbon.

  Jim
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