Sustainable Biochar to Mitigate Climate Change

Wednesday, August 11 2010

By producing biochar - a charcoal-like substance made from plants and other organic materials - up to 12 percent of the world's human-caused greenhouse gas emissions could be sustainably offset, which is more than what could be offset if the same plants and materials were burned to generate energy.

"Biochar offers one of the few ways we can create power while decreasing carbon dioxide levels in the atmosphere. And it improves food production in the world's poorest regions by increasing soil fertility," said Jim Amonette, a soil chemist at the Department of Energy's Pacific Northwest National Laboratory (PNNL).

Amonette worked with Dominic Woolf and Alayne Street-Perrott of Swansea University in Wales, UK, Johannes Lehmann of Cornell University in Ithaca, NY, and Stephen Joseph of the University of New South Wales, Australia. The study is the most thorough and comprehensive analysis to date on the global potential of biochar. The substance was first suggested as a way to counteract climate change in 1993.

Biochar is made by decomposing biomass like plants, wood, and other organic materials at high temperatures in a process called slow pyrolysis. Normally, biomass breaks down and releases its carbon into the atmosphere within a decade or two. But biochar is more stable and can hold onto its carbon for hundreds or even thousands of years, keeping greenhouse gases like carbon dioxide out of the air longer. Other biochar benefits include: improving soils by increasing their ability to retain water and nutrients; decreasing nitrous oxide and methane emissions from the soil into which it is tilled; and, during the slow pyrolysis process, producing some bio-based gas and oil that can offset emissions from fossil fuels.