With the sequestration of carbon being our main goal here at ASCO2, let's talk about how biochar uniquely accomplishes that end. As trees grow, they breathe in carbon dioxide and increase in mass. It's a pretty incredible process, really: trees' huge structures of trunks, branches, and leaves are made primarily out of carbon. Carbon is nature's building block, you could say.
But you might be thinking, how can burning something--like when making biochar--be good for the environment? And furthermore, how can burning something reduce levels of CO2 in the air? It seems counterintuitive, I know.
But try thinking back to your high school class in Earth Science: many elements of nature are cyclical and carbon is no exception. Trees and plants draw in carbon dioxide from the air and use the sun's energy to build their elaborate structures. They grow and continue to pull more and more CO2 out of the air. In a relatively short period of time the tree is going to die from natural or man made causes. It will most likely either burn or rot away. If burned, like in a forest fire, just about all the carbon will be released quickly back into the air as carbon dioxide. If it decomposes the carbon will also be released back into the air as CO2 over a small number of years. The cycle then starts over with the CO2 being pulled out of the air by new growing trees and plants.
Making biochar is a way to take some of the carbon out of the cycle explained above. By burning some of the tree's wood without exposing it to oxygen, a process called pyrolysis, the wood turns to charcoal instead of ash, leaving pure black carbon. This carbon is changed to a very stable solid state without being returned to the air in its gaseous form of CO2. This carbon, or biochar, can then be put into soil, locking it away for up to a thousand years or more.
In this way, making and using biochar results in less carbon dioxide in the atmosphere and more locked up in the ground. Oil and gas reserves deep in the earth were nature's ways of sequestering excess CO2 for the last several million years. We now have the ability to make up for some of that oil and gas that's been sucked out of the ground and burned for the last hundred plus years. Today with biochar, we can start putting carbon back in the ground where it belongs.
Till next time,
Comments will be approved before showing up.
Gore's book Our Choice pointed out some ways in which the climate change problem might be solved, with biochar being one piece of the puzzle.