Biochar - What it is and Why it's Important
Biochar is a high-carbon, fine-grained residue that is produced via pyrolysis; it is the direct thermal decomposition of biomass in the absence of oxygen (preventing combustion), which produces a mixture of solids (the biochar proper), liquid (bio-oil), and gas (syngas) products.
Gasifiers produce most of the biochar sold in the United States. The gasification process consists of four main stages: oxidation, drying, pyrolysis, and reduction. Temperature during pyrolysis in gasifiers is 250–550 °C (523–823 K), 600–800 °C (873–1,073 K) in the reduction zone and 800–1,000 °C (1,070–1,270 K) in the combustion zone.
Biomass burning and natural decomposition releases large amounts of carbon dioxide and methane to the Earth's atmosphere. The biochar production process also releases CO2 (up to 50% of the biomass), however, the remaining carbon content becomes indefinitely stable. The biochar becomes a long term carbon storage vessel once used an agriculture or industrial application.
Biomass power plants play a critical role in woody biomass management, and can produce power rain or shine. When the biomass used for power is transformed into biochar, it provides a pathway for fixing carbon and sequestering it in soils. Interestingly, this looks a lot like a form of Biomass Energy with Carbon Capture and Storage (BECCS), listed by the International Panel on Climate Change (IPCC) as a key technology for carbon drawdown.
“Biochar is one of a small set of carbon drawdown and utilization strategies identified by the Intergovernmental Panel on Climate Change (IPCC) as ready to deploy in our efforts to stabilize climate,” ~City of Boulder Senior Sustainability and Resilience Policy Analyst Brett KenCairn.
Sustainability for Hawai'i. Food, Farm and Forest Security.
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- California Energy Commission. “Biomass Energy in California. California Energy Commission, State of California, www.energy.ca.gov/biomass/biomass.html. (and here) https://www.energy.ca.gov/almanac/electricity_data/total_system_power.html