From an engineering perspective, the most critical aspect in creating biochar is to maximize surface area (pore space) with an objective of trying to create surface areas approaching activated charcoal to maximize the capture/sequester of Greenhouse gases in soils (CO2, methane, nitrous oxide).
In order to achieve high surface areas the key engineering parameter of oxygen starved biomass gasification is temperature formation, where the optimal range is approximately 500 to 700 degrees C (~900 to 1,300 F).
While quite a bit of research is on-going to create biochar with small scale gasifiers (e.g., laboratory, stove, etc.), our research and demonstration effort is focused on large-scale, commercial up-draft gasifiers where the biochar is a waste product in creating biogas (for end-use applications such as product drying/heating, electricity, steam).
In our approach, we extract biochar (just above the incandescent zone) on a semi-continuous basis using nitrogen to �quench and cool� the biochar removed/recovered from the bed cooled to room-temperature for storage and eventual soils application. The recovery of biochar from the gasifier will not significantly impact the gasifier continuous operation of biogas generation for power/heat/steam. It is also important to note that our approach to "quench and cool" in a nitrogen environment is also attempting to address the extremely high carbon/nitrogen ratio of biochar.
On a final blog note, recent published studies suggest that biochar has the potential of sequestering ~12 percent of global CO2 emissions.
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