Biochar is a specialized form of charcoal that is produced using high heat (typically 300 C to 700 C) in low-oxygen environments. It is commonly used as a soil amendment (typically combined with compost) to increase agricultural crop yields and conserve nutrients and water, but researchers are discovering many other uses.
Biochar is not a single type of material, but rather the catch-all name for a wide spectrum of carbonized biomass made from different feedstocks, at different temperatures, using processes called pyrolysis or gasification that also produce a variety of other valuable byproducts such as process heat, producer gases, and pyrolytic fluids such as wood vinegar.
Much of the biochar produced today comes as a byproduct of renewable biomass energy generation, although it can be and is easily made almost everywhere on earth in earthen pits, simple kilns, or by altering agricultural burning techniques.
Biochar has a unique physical structure, with thousands of tiny pores that hold the nutrients and water for the plants’ roots to access and enjoy. In many ways it’s akin to a coral reef in the ocean, acting as a natural attractant, sanctuary, and incubator by creating infrastructure for billions of organisms to thrive.
Microscopic images of biochar’s pores. Truly a “condo” for microbes.
Biochar is placed into the soil by farmers….in their fields of crops, in orchards, in vineyards. The best time to apply it is with new plantings, but there are ways to add it using no-till nutrient application techniques in existing fields or orchards. Field tests have shown that the worse the soil’s characteristics are when the biochar is added to it, the more positive the impact will be on crop yields.
This form of highly stable (or recalcitrant) carbon can be made from many different sustainable feedstocks such as surplus forestry materials from mills, fuels reduction slash generated in high fire risk areas, vineyard, orchard and some crop residues, and from materials generated by tree services clearing utility rights of way. In general, the higher the density and lignin content of the feedstock the more biochar will be produced, so woody materials are most commonly sought after and used.
Biochar can be made by simply managing an open burn pile in a better way and extinguishing it to preserve the carbon. It can also be made in pits, in simple kilns, or in a vast array of sophisticated pyrolysis or gasification machines.
Biochars can also be made at lower temperatures from materials like manures that can possess special and unique properties, and we are just beginning to learn where biochars of different types might best be used in specific soils and with specific plants. Since biochar production and use is an important “waste” management tool with multiple benefits, we support creative uses and applications. However, we may discover that the conversion of materials like manures with significant nutrient and agronomic value may be better utilized in holistic management systems or composting streams rather than as feedstock for biochar.
We strongly believe that biochar should be made ONLY from sustainably managed sources, which is critical from both an environmental and business perspective, and that when sourcing biomass from forest environments great care must be taken to preserve and minimize damage to forest ecosystems.
While some rapidly growing woody biomass materials, such as that produced by small-holder bamboo farms in developing countries, are certainly better than cutting slow-growing trees to produce biochar, we encourage agricultural models that move away from mono-cropping and that embrace increased biodiversity and regenerative techniques as the models of the future.
There is more than enough misdirected and poorly managed biomass to provide material for a healthy, sustainable biochar industry in the coming decades. We are strong supporters of James Amonette’s “Climate Star” and Climate Action’s carbon credit initiative sthat seek to establish industry-wide standards for rating biochar’s carbon sequestration value.
We also well understand that biochar production is a regional activity and that hauling biomass over long distances is not viable from an economic or an environmental standpoint. So we support construction of regionally-located, biomass-to-biochar conversion centers organized by “carbonsheds” that would determine appropriate feedstock sources and technology sizes and types based on site-specific situations. Just as with distributed energy generation, we need a distributed network of biochar and compost operations (preferably integrated) that utilize local “waste” streams and minimize transportation costs and GHG impacts.
Once large volumes of biochar are available for commercial use, it can be used widely around the world by literally millions of farmers. Imagine the impact in Africa and Eastern Europe and Southeast Asia and Patagonia. In almost every country, biochar can be added economically in pasture land to improve grass production, to chicken coops to reduce odors and improve animal health, as well as in farms of all kinds. Cooperatives could be set up to share investment costs in conversion machines and/or simply teach low-polluting and low-investment biochar production techniques.
In many settings, we could get farmers and ranchers to “donate” their woody wastes to the biochar production unit operators and receive in exchange not cash but biochar. The same truck that brought the waste wood to the production site (assembly area) could be used to return bags of biochar to the same farmer. The world could shift from patterns of “slash and burn” agriculture to “slash and char” instead.