This study is researching whether adding ash to the pyrolysis stage increases the overall amount of Biochar produced in a production run.
What did they find?
Yes! It does. Adding ash to the process of producing biochar increases the final quantity of biochar.
Exactly what this does for carbon stored is currently unclear but very interesting.
Note that this technique doesn't work with ash rich feedstocks (maize or biogas residues).
They found that ash from wood bark is the best for increasing biochar production.
Also that the optimum quantity of ash added is ~9%. Higher ash content that 9% doesn't increase the production of biochar.
Significant sidenote:
The potassium in the fertiliser mineral k-fertiliser is reduced by the amount in the ash amended biochar.
So this is such an captivating finding, and it's going to be very interesting to see how kiln groups go about separating ash for runs.