Researchers in South Korea have developed a new method that can turn wet spent coffee grounds into biochar in approximately 90 seconds. The process, detailed in a study published in the Chemical Engineering Journal, uses a technique called flame plasma pyrolysis (FPP) to rapidly convert the coffee waste without requiring a pre-drying stage.
The innovation addresses a primary challenge in repurposing spent coffee grounds, which typically have a high moisture content of around 55%. According to the research, the intense heat from the plasma flame vaporizes the internal moisture almost instantly. This creates a rapid pressure buildup inside each particle, triggering what the researchers describe as a "popcorn effect" that results in a highly porous biochar structure.
This method effectively turns moisture from a barrier into an asset, eliminating the costly and energy-intensive drying step common to other conversion processes. While the study was conducted on a small lab scale using 30-gram samples, its authors suggest the technology could be scaled for industrial use. The findings contribute to the growing interest in biochar as a circular solution for coffee waste and as a soil amendment for carbon sequestration on farms.