Biochar To The Rescue

Biochar, a type of charcoal made by slowly burning waste biomass under low-oxygen conditions, could become an unheralded way to help mitigate climate change. The carbon-based material could also assist in cleaning up abandoned industrial, mining, agricultural, and landfill sites, known as brownfields, and restore them for agricultural and other uses. Those are the conclusions of a study carried out by an international team led by Jingchun Tang of Nankai University, in China, that reviews biochar’s properties and applications (J. Biosci. Bioeng. 2013, DOI: 10.1016/j.jbiosc.2013.05.035). Scientists, engineers, and environmental advocates have been developing large-scale processes to turn materials such as wood chips, food waste, and animal manure into biochar as a way to permanently remove CO₂ from the global carbon cycle. The recalcitrant material is stable for centuries. Thus it is ideal for sequestering fossil-fuel-generated CO₂ that is absorbed by plants during photosynthesis—burying biochar is like coal mining in reverse. Like compost, the carbon in biochar can serve as a soil conditioner to restore fertility, enhance microbial activity, and improve water retention. Like activated carbon, the material adsorbs heavy metals and organic pollutants, trapping them in place so they aren’t taken up by plants and don’t migrate in groundwater. “Biochar clearly presents an important opportunity to reduce the impact of harmful pollutants in the environment and bring back into use huge areas of unproductive land,” says David Brown, chief executive of the Institution of Chemical Engineers, a global professional society.