I fancied a sausage. There is fire in the fire-place, I can grill there. Place it in a metal folie container, then I can do other things. But the heat and fire was more intense than expected, and when I looked the whole sausage was on fire. Black as coal. But I could extinguish. And – underneath the coal layer it was quite fine. But smaller.
It made me think about biochar. That is a kind of burning (ok – pyrolysis), preferably of biomass, some gases are collected and there is a rest, biochar. Applied on soil it is stable for a long time. The carbon dioxide captured by the biomass will then be permanently withdrawn and stored as carbon in the soil. It is a way to store carbon and reduce climate gases.
But I have a sceptical thought: You have let us say one kilo biochar. You could burn it in an energy production unit and in that way save one kilo fossil carbon otherwise needed. Or you could store it in the soil. Is the difference important? Some say so, also scientists and professors, but I am not totally convinced.
Biochar should make the soil more fertile. It has a large active surface (but not as large as clays, it absorbs water and improves soil structure (but what amounts are needed to make practical impact?). There is a nutrient content, but that factor is not much mentioned. The P and K present in the biomass should end up in biochar.
Wonder products make me sceptical, maybe too much.
Maybe sewage sludge could be used for biochar? That should give a product combining carbon, P and K for agriculture. The metals will also be there, I am afraid.
An important environmental problem is organic substances (hormones, medicins, the chemical palette used in our society) which pass the sewage work and end up in waters. Promising attempts have been made to absorb at least some of them by means of active carbon. That sounds expensive. Is biochar active?
Then you could imagine a nice combination: Biochar is added in the sewage treatment, it absorbs harmful organic substances and ends up in the sludge. The sludge is incinerated, the biochar gives extra energy, all organic substances are eliminated, the ash is extracted and a pure P fertilizer results. Especially advantageous would be if the biochar is produced by another sewage work where burning and extraction is not feasible. Biochar production could be more smallscale. You get a more transportable product and the P from both works are taken care of.
If someone will use this idea, kindly refer to this blog.