Biochar projects for mitigating climate change: an investigation of critical methodology issues for carbon accounting

89 ISSN 1758-3004 10.4155/CMT.10.4 © 2010 Future Science Ltd Interest in biochar as a tool to fight climate change has led to the exploration of how biochar projects might use the stabilization of biomass carbon into carbonrich biochar, while capturing energy for mitigating climate change [1–6]. While greatly reducing our use of fossil fuels must be our primary focus, ‘safe levels’ of CO 2 in the atmosphere are thought by some to be lower than even present-day values, requiring significant draw-down of CO 2 , in which biochar might play a part [7]. In order for biochar systems for climate change mitigation to be developed, we must devise a methodology to evaluate how much carbon a biochar project could sequester over an appropriate timescale (permanence) and determine best practices for application to systems such as the Kyoto Protocol’s Clean Development Mechanism (CDM) [8]. This paper takes a step toward this task by reviewing some key methodological issues for implementation of biochar in climate change-mitigation projects, considering additionality and baseline establishment, permanence, leakage, measurement and verification, economics and development issues. Biochar projects & carbon markets Biochar is a carbon-rich organic material that results from the heating of biomass in the absence, or under a limited supply of oxygen. This process is known as ‘pyrolysis’ and it has been used to produce charcoal as a source of fuel for millennia [9,10]. Recently, interest has grown in understanding the potential of this process to improve soil health by adding biochar as an amendment to soil, in order to manage agricultural and forestry wastes, generate energy and store carbon [11]. Biochar is included in the spectrum of black carbon materials – the name ‘biochar’ is used here to distinguish it from charcoal created for fuel, and to denote its particular application in carbon-sequestering and emission-reducing projects as a soil amendment. A very wide range of methods can be used to produce biochar, from systems such as the industrial biochar production system, to biomass-fuelled cook stoves that produce biochar as well as heat for cooking [12]. Carbon offsets are based on the principle of efficiency in addressing climate change. In general, emissions are to be reduced at their source. However, for efficiency and Carbon Management (2010) 1(1), 89–107 Biochar projects for mitigating climate change: an investigation of critical methodology issues for carbon accounting