The biochar process is carbon negative: it removes net carbon from the atmosphere. When a green plant grows it takes CO2 out of the air to build its body. All of the carbon in the plant came from CO2 taken out of the air, and returns to the air when the plant dies and decomposes.

When the biomass is pyrolyzed heated in the absence of oxygen it produces charcoal, which is called biochar when buried in the ground. Over 40% of the total carbon from the waste biomass is retained in biochar and permanently sequestered in the soil, effectively removing that carbon from the atmosphere. The carbon in a ton of biochar is equivalent to about 3 tons of CO2.

Biochar is not only a carbon sink, it increases soil fertility increasing cat-ion exchange and water retention capacity in soils, while reducing nutrient leaching and providing a "coral reef" for soil microorganisms thereby significantly increasing productivity and crop yield.

Biochar research was first inspired by the discovery of Terra Preta or black earth soils in the Amazon Basin, where an ancient civilization buried charcoal, transforming otherwise barren tropical soil into Terra Preta soils that are still incredibly fertile today.