The preparation is a bit tricky since we have to prepare everything, loading the little car we have available at the moment and reach the spot: do the all thing then... pack up everything and get back home.
At the base four bricks are laid down to support the stove: moving the one on the front is going to regulate the primary air flow from underneath.
The stove is filled with 3 kilos of chopped up grapevine branches plus some dry hazelnut shells on top: they're very dry and hopefully they're going to ease the start. It's the biggest Elsa stove that I have ever built, patient work of the last weeks... This time we won't be cooking anything on top of it though. Anyway we are going to return to the vineyard all the biochar that we make, aiming at a carbon negative fruit production this year.
The stove is ready. The chain is going to be a handle when it's going to be emptied out... yeah it's way shorter than it could be but this is the tallest bucket that I have found for this time.
Fully open primary air and go...
After a few minutes the fire on the top of the biomass starts to lower down: this is the sign that the pyrolisys has started. Next time I would probably add an extra cone and chimney on top of this super wide mouth. We'll see.
The sign of the fire lowers down slowly, "baking" the paint and reaching the bottom of the bucket. After a few minutes the brick-door gets closed to a minimum to extend the duration of the whole process. It lasts about 45 minutes. At the end it get completely closed, as tight as possible.
When the process is done we need to do the quenching of the blazing hot biomass now turned into biochar, because we don't want to loose it into ashes... For this purpose we've collected a good bag load of river-sand to dump on top of the hot biochar, after putting it into another bucket... the combustion-chamber/bucket has the primary-air holes on the bottom so it wouldn't be air tight.
Done! The stove is empty and the biochar is cooling down under the sand.
As soon as it's cold, we can sift out the sand for further use using a metal net. Then we can weight the dry biochar.
We have produced 548 grams of biochar and we are proud and happy to return it to the soil where that very biomass was grown. Other mulch will go on top of it, supporting the development of healthier soil and sequestering carbon dioxide. The following chart shows the proportion between carbon and oxygen so we can calculate how much CO2 has been sequestered.
It's (548 / 27.27) x 100 = 548 / 0.2727 = 2009,53...
So it's about 2kg of CO2 sequestered!!!
Very happy with that. Here it goes now back to the soil.