Biochar: can charcoal really stop global warming?

In Australia, opposition leader Malcolm Turnbull has condemned the government’s climate policy as inadequate. Not because the targets are so low that, if agreed globally, they would almost certainly put us on track towards a greater than 2°C rise in global temperature. Nor because all of the targets could potentially be met not from real emissions reductions, but instead from ‘offsets’ abroad. Rather, his party (which, while in power, refused to take any action against climate change) now advocates that the country can achieve major reductions in emissions without any restrictions on coal burning. Instead they claim that targets could be met by applying large quantities of fine-grained charcoal to the soil. 

When biomass is exposed to high temperatures with little or no oxygen present (a process called pyrolysis) it yields two types of fuel that can be used for heat and power or be refined into transport biofuels. It also produces charcoal. Somewhere between 12 and 50 per cent of the carbon is retained in this charcoal, depending on the process. The more energy gained, the less charcoal produced. Bioenergy and ‘biochar’ (the name for charcoal used in soils) can be produced...

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