Nature Reports Climate Change: The bright prospect of biochar

Feature

Nature Reports Climate Change
Published online: 21 May 2009 | doi:10.1038/climate.2009.48

The bright prospect of biochar

Enthusiasts say that biochar could go a long way towards mitigating climate change and bring with it a host of ancillary benefits. But others fear it could do more harm than good. Kurt Kleiner reports.

Jim Fournier wants to help save the planet, though in a most unlikely way: by burning biomass. At the forefront of a carbon-sequestration technology that proponents say offers a rare 'win-win-win' environmental opportunity, Fournier's company Biochar Engineering in Golden, Colorado, manufactures machines that turn biomass into charcoal, or biochar.
Spread on soil, biochar can keep CO₂ out of the atmosphere while improving soil fertility and boosting productivity. In addition, gases released in the charcoal-making process can be used to make biofuels that are more sustainable than those currently on the market. "Char happens to be the one thing that represents a solution to all of these factors together. It's a unique opportunity," Fournier says.

But while enthusiasts are pushing to have biochar recognized as an official means of offsetting greenhouse gas emissions, others remain cautious. At best we know too little, say critics, and at worst using biochar to sequester carbon could ultimately lead to unintended consequences, including the destruction of virgin forests to make way for plantations.

"Biochar certainly has potential," says David Wardle, a soil scientist at the Swedish University of Agricultural Sciences in Uppsala. "But it's premature to be already including it in carbon accounting. Maybe it really is an answer. But we don't know that yet."

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Most biochar-making technologies use heat produced by the biomass itself to form the charcoal. …