This week’s question was asked by a relative.

QUESTION: What is biochar?

The word “biochar” is a combination of the words, “biomass” and “charcoal.” Biochar is a charcoal-like substance made by burning organic material from forestry and agricultural wastes. It is a controlled process call pyrolysis. You might guess from the prefix “pyro” that burning or heat is involved.

The pyrolysis process involves any organic material such as leaf litter, dead plants or wood chips burned in a container with very little oxygen. The lack of oxygen prevents what we think of as normal burning. As the material smolders, there is very little release of contaminating fumes. The heat created during pyrolysis can be captured and used as a form of clean energy. The stuff looks like common charcoal − black but irregular in shape, not the smooth, perfectly formed bricks we use for barbecuing.

Biochar is porous, very lightweight, fine-grained and has a large surface area. About 70 percent of its composition is carbon and the remainder mainly nitrogen, hydrogen and oxygen.

Why the buzz about biochar? Biochar is under serious investigation as an approach to dealing with carbon release that has huge implications for global warming and climate change.

Biochar is hygroscopic which means it can attract and retain water and water vapor. It is porous and has a large surface area. Nutrients, phosphorous, and applied chemicals are retained for plant benefit. Less fertilizer leaches into the groundwater. Biochar is suitable as a habitat for many beneficial soil micro-organisms. In addition, biochar is highly favorable for acidic soils (low pH).

There are places in the world that would be very advantageous for this carbon sequestration. Brazil harvests million of tons of sugarcane. The sugarcane tops are normally burned in the field. Those huge bonfires contribute to greenhouse gases (carbon dioxide) and global warming. Why not put that carbon dioxide back into the soil? The thinking is that in a centralized system, all biomass in a region would be taken to a central plant for processing. Large scale plants not only produce biochar but include liquid (bio-oil) and gas (syngas). In more remote areas, groups of farmers could operate a lower-tech kiln. A truck equipped with a pyrolyzer could move from place to place to take care of biomass.

The International Biochar Initiative, the industry’s highest-profile trade group, describes the product’s effects this way: “This 2,000 year-old practice converts agricultural waste into a soil enhancer that can hold carbon, boost food security, and discourage deforestation. The process creates a fine-grained, highly porous charcoal that helps soils retain nutrients and water.” Furthermore, IBI notes, “The carbon in biochar resists degradation and can hold carbon in soils for hundreds to thousands of years, curbing greenhouse-gas accumulation in the atmosphere.”

One of the drawbacks to large-scale biomass production is lack of infrastructure, such as large processing plants. There are more than 120 companies already producing biochar or biochar-related products, including pyrolysis cook stoves. Most biochar operations are small scale. Most of the companies in the United States are located in New England and are producing biochar for farms and gardeners or selling pyrolysis equipment. Although the number of companies involved continues to rise dramatically — including firms in Europe, Australia, and Brazil — there has been little indication of a profitable business model to this point. But the future could be bright for biochar.

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Larry Scheckel is a retired Tomah High School physics teacher.


Tomah Journal editor

Steve Rundio is editor of the Tomah Journal. Contact him at 608-374-7785.

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