Publication date:	6 oktober 2008
More information:	Prof.dr.ir. R.J.F. (Rob) van Haren E-mail: rob@kiemkracht.com Phone: - Mobile: +31 (0)6-20182110 Expertise: arable farming

The Amazon Indians already knew it 7000 years ago: charcoal in all its forms is ideal for improving soil fertility, soil structure and soil moisture management. In the Amazon the ‘Terra Preta do Indio’ (Indian black earth) is well-known for its high stable crop yields. The Dutchman Wim Sombroek has devoted his entire scientific career to researching these soils. In one of his latest articles Sombroek discusses at length the possible win-win situation of increasing soil fertility through permanent storage of CO₂ (in the form of charcoal) in the soil. Charcoal is produced in many shapes and forms, both as a residue from low-tech slash & burn practices and cooking fires and as one of the many high-tech bio-based products from modern biorefinery clusters.
International Terra Preta researchers recently agreed to use the term Biochar to refer to charcoal destined for agricultural applications in the soil. Early in September the first International Biochar Initiative Conference was held in Newcastle (UK) (www.biochar-international.org). More than 225 attendees from 31 countries came together there to exchange ideas and knowledge and develop new plans. Leading research groups from Australia, the US, Germany and the United Kingdom presented the most recent scientific knowledge. Unfortunately no Dutch research groups were represented. Most contributions centred on the production of BioChar through low-temperature pyrolysis, a technique for using heat to break biomass down into charcoal, resinous fluids and gases. The fluids and gases can be used for transport fuel and the production of basic chemicals, while the BioChar can be fed back to the soil where its fertile properties lead to improved biomass and food production. BioChar production thus fits well with the ecological cycle and the modern biorefinery philosophy.

Pyrolytic installations are high-tech, but to my great surprise there was also an Italian inventor with a small pyrolytic cook stove that can be used for cooking food in developing countries. This cook stove has three advantages over a traditional cooking fire: it generates a great deal of heat with a small amount (handful) of fuel, it creates no soot and it produces BioChar. The production costs of the cook stove are about EUR 10-15, so its motto “… a million stoves to save the world” is no empty boast.

 BioChar still contains a lot of energy, so it also serves as a CO₂-neutral energy source. The question remains whether it is better to store BioChar permanently in the ground to promote soil fertility or to use it as a CO₂-neutral energy source: exergy or energy, in other words. Exergy refers to the amount of information (or organization) in relation to the environment and thus concerns the quality of the energy form. The exergetic value of charcoal for burning is low while its energetic value is high. The exergetic value of charcoal for improving the soil ecosystem is extremely high, while its energetic value is low. In my view, therefore, soil improvement is the most sustainable application for BioChar.

Adding BioChar to the soil is also a sustainable form of CCS (Carbon Capture and Storage) where the CO₂ stored in the form of charcoal can make a valuable contribution to the ecosystem. With the current CCS methods, CO₂ is put into disused underground gas fields at high energetic cost and without making any active functional contribution to a sustainable ecosystem and society. CCS of BioChar in the soil thus constitutes a highly viable alternative. The United Nations (UNCCD, United Nations Convention to Combat Desertification) wants to include BioChar Carbon Sequestration in the post-2012 climate change market mechanisms. This initiative even creates a tripleWin and triple-P situation: the permanent removal of CO₂ from the atmosphere, the sustainable improvement of soil fertility for food and biomass production and the award of Carbon Credits (CO₂ trading rights) for this application! In the coming years the BioChar idea will be worked out by the agriculture innovation alliance Kiemkracht in the framework of the self-fertilizing agriculture and climate-proof soil concepts.

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