[Terrapreta] value of carbon credits

[Gerald Van Koeverden]

If the sequestering of char became accepted for carbon credits, how  
much would the carbon credit have to be to justify the cost of doing so?

Using Folke's formula, modified by Sean's factor of 90%:

Burying 1 kg of Carbon is equivalent to sequestering 3.7 kg CO2.   
Since 1.1 kg of char has 1 kg of carbon, one ton of char would be the  
equivalent to 3700/1.1= 3,400 kg. of CO2.

 From previous discussions, we've heard that a ton of char should be  
worth $200 - roughly the equivalent of that of charcoal.

Thus, if one expects carbon credits to pay the full cost of the char  
(ignoring shipping and application costs), then the credits have to  
be approx. (200/3.4=) $60/ton of CO2.

If one is going to promote putting char on farmer's fields, the  
credits will have to be close to this, especially since there are  
still trucking and application costs to be considered.

But if credits were only half, eg. $30/ton of CO2, then the net char  
cost at $100/ton, could approach being an economical substitute for  
example in replacing - at least in part - perlite, vermiculite or  
peat moss, - in growth medium used for transplants in greenhouses or  
specialty landscaping uses like roof top gardens or large indoor  
tropical potted plants.  (Note char's price would have to be half of  
what it is substituting for by since its' bulk density is about  
200kg./m3 - double that of the other three which have one around  
100kg./m3.  Of course, I'm assuming an equivalency of value by  
volume, which is like not differentiating between apples and oranges  
in the same basket...)



Does anybody have a ball park figure for how much carbon credits are  
being sold for at present?



Gerrit



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