Crop residues scattered across farmlands globally hold the potential to combat climate change in an unexpected way. By converting these leftover crops into a charcoal-like substance called biochar, we can effectively store up to 7% of global greenhouse gas emissions for up to a century.
Typically, crop residues are either left to naturally degrade or burned, releasing emissions into the atmosphere. However, technology exists to transform this raw material into biochar through a process called pyrolysis.
By heating organic matter at high temperatures with limited oxygen, biochar is produced. Biochar has a much longer carbon-sealing capacity compared to fresh plant matter. This is particularly true when it’s incorporated into the soil.
While previous studies have highlighted the potential of biochar on a smaller scale, the global potential of agricultural waste at an industrial level has remained largely unknown.
In a study published in the journal GCB Bioenergy, a team of researchers analyzed a comprehensive dataset on international crop production and created a detailed map of agricultural residues across the world. The study focused on 34 crops that generate residues suitable for biochar production, including wheat straw, rice husks, and fruit peels.
If we were to utilize all this agricultural residue to produce biochar, the impact could be remarkable. Every year, biochar could remove one billion metric tons of carbon in the soil.
A significant portion of agricultural residue is not readily available for use, as it is lost during harvest or used as livestock feed and bedding.
When considering these factors, the potential carbon-locking power of biochar decreases to approximately 510 million tons per year, according to Anthropocene Magazine. Of this total, about 360 million tons would still be stored in the soil after a century.
Although this represents a decline, it still signifies a substantial amount, especially when viewed on a national level. For example, India (the third-largest emitter globally) could lock away 53% of its emissions by converting crop residues to biochar.
Even more conservative estimates indicate that we could potentially sequester at least 3% of worldwide emissions by leveraging biochar.
Businesses are also recognizing biochar’s powerful potential. In July, a group of Canadian and French companies announced that they would be building North America’s largest biochar plant in Port-Cartier, Canada. The plant will become operational next year.
The plant will ultimately sequester 75,000 tons of carbon per year. The owners of the plant will make money by selling carbon credits.
Image Source: Jake Nash