Friday, December 23, 2022

What actually is biochar?

I have read many times about biochar and how environmentally beneficial it is, particularly as regards greenhouse gases and climate change. But I've never really understood what biochar actually IS, and how it is so environmentally beneficial.

So, what is biochar?

Biochar is a black carbon-rich charcoal-like substance, produced from burning organic materals like wood, manure, argicultural and forestry waste at ultra-high temperatures, through a process known as pyrolysis. 

The resulting material is lightweight, porous and fine-grained, with a large surface area and a very high absorption capacity, which can capture contaminants and volatile compounds, which are attracted to the surface of the biochar and become attached to it. Contaminants chemically bind with the biochar and are thereby stopped from entering the environment.

It has been known for centuries that biochar helps crops grow by improving soil fertility, soil structure, water retention and drainage, while also adding nutrients to the soil, thereby reducing the need for chemical fertilizers and pesticides. It is also a very useful substance for decontaminating water and wastewater.

But it is biochar's potential for carbon removal that is attracting attention in recent years. As biomass turns into biochar, carbon gets locked inside as a stable solid and so is not released into the atmosphere. Biochar sequesters more carbon than it produces, resulting in a "carbon negative" system, which is a very valuable property in today's climate crisis. Energy crops like switchgrass and miscanthus, or corn or other agricultural and forestry residues, which would otherwise be just waste or (worse) a source of planet-warming methane, can be converted into biochar in an energy-efficient process. 

Win-win: a sustainable solution that also improves our soil in the process.

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