An ancient technique to fertilize soil by creating charcoal from plant waste is being revived to tackle some of today’s environmental problems.
The latest company to pursue manmade charcoal, called biochar, is Biochar Systems, which has developed a biochar-making machine that can be pulled by a pickup truck. Two customers–a North Carolina farm and the U.S. Bureau of Land Management–will be begin testing the units this fall.
The unit, called the Biochar 1000, is designed to convert woody biomass, such as agricultural or forestry waste, into biochar, a black, porous, and fine-grained charcoal that can be used as a fertilizer. It uses pyrolysis–slowly burning biomass in a low-oxygen chamber–to treat 1,000 pounds of biomass per hour, yielding 250 pounds of biochar.
The Biochar 1000 converts agricultural wastes to charcoal, which is then added to soil, a process that enriches soil and removes carbon from air. (Credit: EcoTechnologies Group)
There still isn’t a well established market for selling biochar, but there’s growing interest among researchers in the process as a way to cut greenhouse gas concentrations. The United Nations has proposed classifying biochar as a carbon credit for sequestering carbon from the atmosphere.
When forestry or agricultural waste are converted into biochar and put into the soil, the carbon that would have been released through decomposition is held in the soil for hundreds or potentially thousands of years, say proponents.