Deep sea sub-sediment slurry injection for carbon removal

A method for carbon dioxide removal and long-term sequestration in marine sediments, characterized by a specific sequence of targeted natural processes, comprising:

• a. Deep Burial and Initial Oxic Degradation:
• The method begins with the injection of a slurry composed of ligno-cellulosic biomass and seawater into deep-sea sediments, initiating the first stage of biomass degradation under oxic conditions. This step is critical for breaking down complex macromolecules, such as lignin, using oxygen as the primary electron acceptor.
• b. Transition Through the Redox Cascade:
• As oxygen is depleted, the method ensures that degradation progresses through a sequence of less energetically favorable electron acceptors-nitrate, iron (III) oxides, manganese oxides, and sulfate-culminating in methanogenesis. This controlled progression slows down the degradation process, preserving the biomass for extended periods.
• c. Encapsulation and Anoxic Preservation:
• The method encapsulates the biomass within an anoxic layer of sediment, where limited oxygen exposure time (OET) and sediment compaction mimic natural conditions, such as those observed in the Bengal Fan, to effectively prevent further degradation of the organic carbon.
• d. Formation of Stable Carbon Compounds:
• During the redox cascade, the method promotes the formation of stable carbon compounds, including methane and CO2 hydrates, which become trapped within the sediment matrix, ensuring their long-term sequestration.
• e. Sediment Compaction and Limited Solute Diffusion:
• The method induces sediment compaction around the injected biomass, significantly limiting the diffusion of solutes and substrates, which further stabilizes the carbon and ensures its preservation for millions of years.
• f. In a certain embodiment, the Microbial Interactions and Chemical Additives:
• The method may incorporate specific microbial communities or chemical additives designed to steer the biochemical reactions towards the formation of highly stable carbon forms, such as biochar or carbonates, thus enhancing the permanence of carbon sequestration.