Study warns against hyping carbon-fixing biochar

cnet news
November 29, 2010 9:22 AM PST
by Martin LaMonica

Of all the approaches to cutting carbon emissions, making charcoal and putting it in the ground as fertilizer would seem one of the least controversial. But a report published today offers words of caution around expecting too much from biochar.

Biochar, also called man-made charcoal, is made by decomposing plants and other organic materials into charcoal through pyrolysis, or slowly burning biomass at high temperatures with no oxygen. The resulting biochar can be used as a soil fertilizer, a technique used by ancient civilizations in the Amazon.

Unlike naturally decomposing organic materials, biochar holds onto carbon dioxide for hundreds or even thousands of years. For that reason, it's been touted by everyone from Virgin CEO Richard Branson to environmentalist James Lovelock as a promising method for fixing carbon dioxide in the ground. Biochar has also attracted detractors in the past few years who say that growing plants to create biochar would be a "false solution" to climate change.

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