Isometric has published the draft Biomass Storage in Subsurface Mines (BSSM) Module for public consultation. This module sets out requirements and procedures for storing sustainably sourced waste biomass in existing subsurface mines and is designed to be used alongside the Subsurface Biomass Carbon Removal and Storage Protocol.
Under typical conditions, waste biomass—such as cotton stalks or sawdust—decomposes over time, releasing the carbon dioxide it captured during photosynthesis back into the atmosphere. This decomposition can be slowed or even halted by removing or reducing the factors that enable it—such as oxygen or moisture—locking away the carbon contained in the biomass.
Subsurface mine chambers provide a promising solution for durably storing waste biomass. Their depth maintains stable temperatures naturally, and their enclosed design allows for the creation of low-oxygen conditions needed to slow or halt decomposition. Additionally, the use of existing chambers avoids the need to build completely new infrastructure.
This module has been designed for both mines that are currently in operation and those that have closed or are closing. The robust storage and monitoring requirements included in the draft BSSM Module will enable the issuance of carbon removal certificates with a durability of over 1,000 years.
Carbon removal supplier Rewind provided extensive feedback during the development of the module and aims to generate carbon removal certificates from its DMS Georgia project under it.
Ram Amar, Co-Founder and CEO of Rewind, said:
“Rewind focuses on science-led, permanent, and energy efficient carbon removal. Our biomass storage projects in disused mines combine the carbon capture efficiency of plants with the scale and permanence of existing underground voids.
“Being science-led brought us to work with Isometric. It's been a pleasure to support the development of this new module and we look forward to applying it to our DMS Georgia project."
The module was developed in line with the Isometric Standard, through collaboration between Isometric’s in-house Science Team and reviewers from Isometric’s independent Science Network of more than 400 academic experts and practitioners.
Comments are welcome from buyers, suppliers, and scientists during the 30-day public consultation period, ending on February 16, 2026. Follow this link to contribute.
