Ocean Storage of Biomass: Call for Input

Puro.earth is a carbon removal crediting platform that certifies durable carbon removal and issues CO2 Removal Certificates (CORCs) for each net tonne of CO2 removed and stored for hundreds or thousands of years. Our CORCs are issued and retired in the public Puro Registry, enhancing transparency in carbon markets.

We are excited to announce the public consultation for our new Ocean Storage of Biomass (OSB) Methodology. We have worked with a diverse group of experts over the last year to explore opportunities in marine carbon dioxide removals, specifically focusing on biomass deployment. The contributions by the working group have been invaluable.

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Overview of OSB

OSB is an innovative approach to long-term carbon removal that leverages unique marine environments. The methodology focuses on depositing sustainable biomass into permanently oxygen-depleted (anoxic) ocean basins where natural seafloor conditions allow for durable CO2 storage. These carefully selected anoxic marine zones are characterized by dense, stratified water layers that effectively seal carbon-containing biomass in deep, oxygen-depleted bottom layers.

Figure: A schematic illustration of the overall process of deploying terrestrial biomass into an anoxic storage.

The process is limited to lignin-rich terrestrial biomass—plant materials that naturally resist decomposition in low-oxygen conditions. By placing these materials in scientifically verified storage sites within national maritime jurisdictions, carbon can be sequestered for 1,000+ years. Strict site selection criteria, requiring location-specific ecological data, and supported by advanced oceanographic modeling and robust monitoring practices, ensure effective durable storage of carbon.

The fundamental goal is to create a stable, long-term carbon storage solution that mimics natural conservation processes in the deep sea. By leveraging the unique physical and chemical characteristics of anoxic marine basins, this methodology offers a promising pathway for removing atmospheric carbon.

Key Benefits of OSB

The OSB methodology provides potential co-benefits aligned with Sustainable Development Goals (SDGs):

1. SDG 14.c: Enhancing the conservation and sustainable uses of oceans and their resources by implementing international law as reflected in the United Nations Convention of the Sea.

2. SDG 11.6: Reduced adverse environmental impact of cities (related to agricultural and biogenic waste).

3. SDG 9.4: Improved sustainability of industries (with increased resource-use efficiency).

Environmental and Social Considerations

1. The methodology introduces safeguards and monitoring processes for effectively managing environmental and social risks.

2. The limitations on eligible biomass sources and strict storage site selection criteria aim to avoid negative impacts.

3. Scientifically robust characterization of the marine ecosystem, as well as efficient communication with relevant local stakeholders, are key factors in ensuring the safety of operations.

Please note that when the requirements set in the methodology are followed, negative impacts to people or the environment can be effectively avoided, minimized, or mitigated.

Period of Consultation

The public consultation will be open 15 January – 5 February 2025. We welcome feedback from all stakeholders during this period. Your input is invaluable to our methodology development process, ensuring transparency and informed decision-making.

Consultation Documentation

Please download the consultation documents and submit your feedback to [email protected] using the provided form:

• Puro Ocean Storage of Biomass Methodology, Edition 2025 Version 1 (Draft)

• Public Consultation Feedback Form

Your insights and expertise will help us refine and improve this groundbreaking methodology for durable carbon removal. We look forward to your participation in shaping the future of ocean-based carbon storage solutions.

Webinar

A webinar was held January 22nd to cover key aspects of the process. To access the webinar recording, click here and enter the following passcode: Vw^d9Qb=

Frequently Asked Questions

What is an anoxic basin?

In the context of this methodology, anoxic basins are considered as permanently oxygen-depleted marine basins, where oxygen-depleted bottom waters do not mix with oxygen-containing surface waters. Importantly, these non-mixing conditions are created by physical barriers, such as vertical basin walls, and high water-density differences that keep the heavier water at the bottom. These conditions must be stable to ensure the safety and durability of the storage over time.

What is permanence on stored carbon based on?

Carbon from biomass is lost when bacteria and microbes decompose it. They need oxygen to live. Oxygen-free areas in the ocean do not support most life forms, although microbes and bacteria may thrive in those conditions. Decomposition of lignocellulosic biomass in anoxic (oxygen-free) basins is generally negligible, since most of the released carbon will stay in the bottom waters. Permanence is maintained over time since the oxygen-free bottom waters have limited to no mixing with other ocean currents.

When both the biomass eligibility and the storage site criteria set in this methodology are met, the 1,000-year permanence is possible.

What is the risk for carbon losses and/or reversals?

• Carbon losses are known and accounted for in the methodology. Losses may occur when decomposition products of the biomass (such as CO2, nitrous oxide, and methane) mix with the surface waters and return to the atmosphere. However, losses are expected to be extremely low due to the properties of eligible anoxic basins.

• Carbon reversals are unaccounted-for events where stored carbon is released back into the atmosphere. The methodology minimizes this risk with stringent rules, supporting the Puro Standard General Rules in the unlikely event of reversals.

How are environmental risks assessed and avoided or mitigated?

By limiting the scope of the methodology to lignocellulosic, terrestrial biomass in anoxic basins, many environmental risks are avoided, minimized, or mitigated. The methodology requires a comprehensive Environmental Risk Assessment and specifies key environmental risks that must be monitored. Robust, science-based monitoring and reporting criteria ensure that risks are managed effectively.

Why is this methodology limited only to terrestrial biomass?

While marine biomass, such as seaweed, holds promise as a feedstock for carbon removal, certain challenges remain—particularly with carbon accounting and ecosystem risks. The methodology will be updated as new scientific evidence emerges.