Ever since I read about terra preta in the book 1491, I have been intrigued by its potential for increasing agricultural production and sequestering carbon. Now there is an International Agrichar Initiative that is looking to implement it on a large scale.
The first meeting of the International Agrichar Initiative convened about 100 scientists, policymakers, farmers and investors with the goal of birthing an entire new industry to produce a biofuel that goes beyond carbon neutral and is actually carbon negative. The industry could provide a "wedge" of carbon reduction amounting to a minimum of ten percent of world emissions and possibly much more.This 7,000 year old Amazonian technique could now be used to improve farming conditions in China and Australia.
Agrichar is the term not for the biomass fuel, but for what is left over after the energy is removed: a charcoal-based soil amendment. In simple terms, the agrichar process takes dry biomass of any kind and bakes it in a kiln to produce charcoal. The process is called pyrolysis. Various gases and bio-oils are driven off the material and collected to use in heat or power generation. The charcoal is buried in the ground, sequestering the carbon that the growing plants had pulled out of the atmosphere. The end result is increased soil fertility and an energy source with negative carbon emissions.
One reason for the excitement is agrichar's potential to address a range of problems from poor soil fertility to waste disposal to rural development. About half the world's population relies on charcoal for cooking fuel, and the production of charcoal drives deforestation in Africa and other places. Smoky, inefficient charcoal kilns pollute the air with noxious gases that harm health and heat the planet.
An effort to replace these kilns with modern, efficient pyrolysis units would relieve the pressure on forests by reducing waste and adding the ability to use any source of biomass, including agricultural waste products such as rice hulls. The ultimate objective is to produce enough charcoal to have some left over to bury and increase soil fertility, leading to a bootstrapping effect where increased yields provide both more food and more biomass for energy.
Robert Flanagan, an entrepreneur working in China, had a different view. There are 700 million farmers in China, he pointed out. China could quickly deploy a small, village-level pyrolysis unit he is developing, and because labor is cheap, spreading the agrichar on fields would be affordable even without a large energy harvest.via Energy Bulletin
Several farmers attending the conference were primarily interested in the increased yields possible with agrichar. Australia has some of the poorest soils in the world - 75 percent of Australia's soils have less than one percent carbon.