Biochar can enhance soil health, filter wastewater, improve thermal insulation, sequester carbon and more. Advantageous though it may be, biochar remains something of a well-kept secret. Here, let’s consider just one of biochar’s many virtues: its potential impact on the health of our climate.

Biochar is a charcoal-like material produced from organic matter during a process known as pyrolysis. The “feedstock,” whether wood chips, crop residues, manure or other biomass, is heated in a low-oxygen environment. Due to the restricted oxygen supply, the carbon in the organic matter does not oxidize and burn off as carbon dioxide. Instead, the carbon is converted into a stable, solid substance. Though this biochar resembles charcoal, the flammable hydrocarbons that enable charcoal to serve as a fuel have been cooked off.

Depending on the equipment, feedstock and temperature of the production process, pyrolysis can yield a range of byproducts. Among these are bio-oil and synthetic gas (syngas), which a well-engineered pyrolyzer can burn to create a self-sustaining reaction. Heat energy released during pyrolysis can also be recovered and used to fuel the pyrolyzer or for unrelated purposes, such as generating electricity. Finally, making biochar may produce greenhouse gas emissions, though in quantities that are minor relative to biochar’s environmental advantages.

Among the many potential benefits of biochar is its ability to mitigate climate change. For one thing, if biomass is left to decay, its unstable carbon is released into the atmosphere as the greenhouse gases carbon dioxide and methane. The stable carbon of biochar, however, resists decay, meaning that converting organic matter into biochar keeps carbon dioxide out of the air. Methane emitted during biochar production can be burned, thus fueling the pyrolizer and reducing the harmful climatic impact of this gas.

Biochar also benefits the environment when buried in the ground. As our next column will discuss, the appropriate use of biochar as a soil amendment improves the health of plant life. Stronger plants remove more carbon dioxide from the air than they otherwise would, so biochar actively contributes to carbon capture and sequestration.

Helping to counter climate change is just one of biochar’s many advantages. In two weeks, we’ll examine how it can help those who work the soil.

David Conwell belongs to the nationwide advocacy organization Citizens’ Climate Lobby and is a former member of Brunswick’s Sustainability Committee.