Throughout Earth history, one of the principal mechanisms by which atmospheric CO2 concentrations have declined from hothouse conditions is the burial of organic carbon in anoxic marine basins. Carboniferous’s Anoxic Biological Carbon Sequestration (ABCS) process is designed to safely accelerate the natural process of organic carbon burial by collecting and processing agricultural byproducts and storing them in deep, hypersaline, anoxic basins, our first being below the oxygenated ocean in the Gulf of Mexico.,
Our CDR approach is designed to maximize the efficiency of biomass preservation through both our choice of biomass sources and our targeted storage location. Most terrestrial biomass and crop residues are composed of lignin, cellulose, and other structural polymers that are relatively resistant to chemical and microbial breakdown. Some of these materials, like lignin, are particularly difficult to degrade in the absence of O2. Anoxia also slows the breakdown of terrestrial materials by restricting the activity of animals like worms that physically degrade biomass, and it reduces the energy available to microbes. Deep hypersaline anoxic basins take this effect even further, generally slowing metabolic rates and limiting life forms to extremophilic bacteria and archaea. Because of this terrestrial biomass storage in anoxic environments should represent an optimal scenario for efficient biomass preservation.
The sources of carbon for the ABCS process are crop byproducts, including sugarcane bagasse (the pulp remaining after sugarcane processing) and corn stover (stalks, leaves, etc.). These materials fix large amounts of carbon every year, with one tonne of dry terrestrial biomass embodying approximately 1.6t of CO2e. Currently, most non-grain biomass is tilled back into the soil to decompose, or burned, releasing the fixed carbon back into the atmosphere. Our approach mitigates the return of part of this biomass to the atmosphere.