Isometric has certified the Biochar Storage in Subsurface Mines Module. The module outlines requirements for projects that store biochar in existing subsurface mines and is designed to be used alongside the Biochar Production and Storage Protocol.
Certification follows a comprehensive 30-day public consultation that included feedback from buyers, suppliers, and leading academics. Full details on how Isometric addressed feedback are available in the consultation summary.
Subsurface mines provide an ideal environment for durably storing biochar. Buried deep underground in sealed chambers, biochar is kept under stable, low-oxygen conditions at a consistent temperature, protecting it from biological and chemical breakdown.
This environment also provides practical advantages to both project developers and mine operators. Mines are often backfilled throughout their operating life and again once mining ends. Backfilling increases structural stability and is often required for mine closure. This lets project developers repurpose existing mine infrastructure for carbon removal while still meeting the mine's backfilling and closure requirements.
Mine environments vary widely, with different rock types, groundwater conditions, and structural stability. To account for this, the module sets specific requirements for each type of host rock, requiring project developers to characterize the surrounding rock and groundwater, and to demonstrate that the engineered barrier sealing the biochar is durable over the long term.
Under the module, certificates can be issued with a durability of 1,000 years. This is based on two things: the fraction of the biochar that will remain stable over that timeframe, and the storage environment's ability to keep it protected from oxygen, water, and microbial activity over the long term.
The module was developed in line with the Isometric Standard, through collaboration between Isometric's in-house Science Team and reviewers from the independent Science Network of more than 500 academic experts.
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