Biochar
Biochar
is created by the carbonization of untreated wooden parts such as branches or trunks in a thermo-chemical conversion process in the absence or with very little oxygen.
Carbonization is an exothermic process. The heat released is used to dry supply wood, the process is maintained, and further energy is released, e.g. to generate electricity or to feed it into local heating networks.
During carbonation, 60% of the calorific value of wood is released.
With 1 t of wood that is 2.4 MWh. This means that a steam turbine and generator can be used to generate around 1 MWh of electricity at a sales value of around € 250, taking into account all degrees of efficiency.
Biochar is chemically neutral in the soil. It does not oxidize (i.e. rot) and remains so for many hundreds of years.
Due to the high porosity / surface structure, biochar offers a habitat for important microorganisms, bacteria and microorganisms.
It promotes and accelerates the formation of humus in the soil,
stores water and nutrients such as nitrates and keeps them available to plants. In this way, important minerals such as nitrogen, phosphorus and potassium are passed on to the plant roots with a high degree of efficiency.
Today's fertilization only goes to a significantly smaller extent at the plant roots, the rest is washed into the groundwater by rainwater.
The biochar from untreated wood can also be used as feed charcoal, medicinal charcoal, filter charcoal and much more - it is edible (E153 as a coloring agent in the food industry, detoxification of the liver, diarrhea therapy)
Carbonization with subsequent storage in the ground removes C components from the atmosphere and thus reduces the greenhouse gas CO2 and thus slows down climate change.
730kg of CO2 are sequestered from 1t of wood (this corresponds to a car journey of almost 4,000km).
Biochar can be produced for allotment gardeners on a small scale, e.g. in a Chantico terrace oven, as well as in industrial quantities of several thousand tons p.a. in appropriately designed plants.
The process temperatures of the wood carbonization are 600 to 800 deg C. Any PAHs (polycyclic aromatic hydrocarbons) that may occur in the process evaporate at temperatures between 400 degC and 500 degC so that very low PAH emissions were measured both in the Chantico furnace and in the planned industrial plants, partly below the detection limit.
The Biochar Science Network has drawn up guidelines for obtaining the biochar certificate, which describe a scientifically sound and practical control basis, the provisions of the German Compost Ordinance and the Swiss Chemicals Ordinance are taken into account, Switzerland has adopted this set of rules as a state regulation. Thanks to the control certificate, the sustainable production of biochar is ensured. With the European Biochar Certificate EBC, producers have the option of verifiably guaranteeing the quality of their biochar to farmers and other users.
Rainer Sagawe & Dr. Stephan Martini, Hameln, Germany, Feb. 2021
