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.
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.
A number of companies have formed to either create fertilizer or use modified machines to convert biomass into a liquid fuel such as methanol. The first U.S. biochar conference was held in Boulder, Colorado, two weeks ago, organized by the International Biochar Initiative industry group.
Tons of green waste
Biochar Systems, a joint venture created by BioChar Engineering and EcoTechnologies Group, has developed a mobile machine targeted at landowners or other organizations that generate a lot of "green waste," such as agricultural producers, nurseries, or land managers. The biochar can be used on-site as a soil amendment or moved and sold as a fertilizer, according to Fernando Migliassi, chief corporate development officer at EcoTechnologies Group.
The Bureau of Land Management will use one unit, which weighs 4,000 pounds and is 12 feet long, seven feet high, and five feet wide, to improve soil that has been damaged by mining, according to Biochar Systems. The North Carolina Farm Center for Innovation & Sustainability will use test a unit as well to see how agricultural waste can be converted into fertilizer.
The Biochar Systems Biochar 1000 costs $100,000 and is capable of turning out 1,000 tons of biochar a year.
Another unit will be tested by the Colorado State Forest Service to thin forests and treat the tons of wood infested by pine beetle into a soil amendment. Thinning forests manually is very expensive but the biochar machine could be a cheaper route.
"If this is feasible, it would allow us to manage a greater portion of forested lands that right now aren't cost effective," Joseph Duda, forest management supervisor for the Colorado State Forest Service told ClimateWire.
The U.S. produces 368 million tons of forest product waste a year and another 60 million tons a year of wood infested by the pine beetle, according to BioChar Engineering. Having a mobile unit reduces overall pollution as biomass doesn't need to be hauled for treatment at a centralized plant, according to the company.
But although it has potential to mitigate climate change, some people have warned against relying heavily on biochar as a carbon offset. The impact of biochar on land may have changed since the time thousands of years ago when people in Amazon region created charcoal, called terra preta.
"But despite its astounding potential, caution is warranted in implementing biochar on any sizeable scale. Though re-creating terra preta sounds simple, recent research suggests that modern-day soils may respond less well to the treatment and that the carbon may escape sooner than anticipated. On these questions alone, all of the evidence is not in," according to a recent editorial in the journal Nature Reports Climate Change.