Quantifying biochar’s benefits to drive finance, investment
February 3, 2023 By Kelli Barrett
Biochar’s capability as a large-scale carbon dioxide removal technology is massive. The carbon-rich solid material has a mitigation potential of at least one billion tonnes of CO2 per year by 2050, according to the Intergovernmental Panel on Climate Change.
Recently, the biochar sector received some help in scaling and delivering on its ability to store carbon. Verra, an independent organization that develops standards for use in the voluntary carbon market, released a methodology for quantifying emission reductions from the production of biochar and its use in soils and other emerging applications.
“This new methodology will catalyze biochar producers’ access to carbon finance and help the budding biochar industry continue globally, enabling biochar to serve as a meaningful carbon sink,” said David Antonioli, CEO of Verra.
Background and benefits beyond combating climate change
Biochar is created from biomass subjected to high heat and limited-oxygen environments. A substantial amount of biochar’s organic carbon will persist in soil and non-soil applications for centuries to millennia.
Biochar offers a range of agricultural benefits when used as a soil amendment, including enhanced nutrient and water retention, aeration, drainage, and microbial activity, which can all help increase crop yields and enhance soil health, especially in degraded agricultural soils. There are also numerous emerging non-soil end uses that show promise as low-emissions industrial products, such as in building materials, cement and asphalt.
How the biochar methodology works
It takes time and a rigorous process to develop methodologies for use in one of Verra’s standards programs. Verra provides a framework within which environmental NGOs and other groups can develop methodologies that help funnel finance in underfunded climate solutions, such as biochar.
The biochar methodology is applicable globally – except in wetlands. Essentially any user along the biochar value chain can develop a project in Verra’s Verified Carbon Standard Program.
Biochar is eligible to be used as a soil amendment on land, and in non-soil applications where long-term storage of the biochar is possible. Only biochar produced in high-technology production facilities is eligible to be used in non-soil applications.
Developing a project
The project activity entails installation and operation of a new biochar production facility where the project proponent must:
- Source waste biomass
- Produce biochar
- Ensure the biochar is utilized in eligible soil or non-soil applications
Project proponents should keep in mind that the designated end use for soil application is in the field (or other land area) where the carbon sink is created. Therefore, an intermediate mixing/blending step is not considered the final end use. In such cases, the application location for the final soil product containing the biochar must be indicated by the project proponents.
A range of thermochemical conversion processes that produce biochar are allowed, including:
- Biomass boilers
Torrefaction and hydrothermal carbonization are explicitly excluded.
Production facilities are classified into low-technology and high-technology facilities.
High technology facilities must:
- Recover or combust the greenhouse gasses produced during pyrolysis
- Use at least 70 per cent of the heat energy produced by pyrolysis (taking into consideration heat transfer inefficiencies)
- Have pollution controls, such as a thermal oxidizer or other emissions controls, that meet local, national, or international emission thresholds
- Measure and report production temperature
If these criteria are not met, the facility is classified as low technology.
To define 70 per cent heat waste utilization, the project proponent determines how to demonstrate this rule. Eligible determination will include schematic descriptions (e.g., through technical details) and quantification, i.e., by estimating potential flows of heat energy embodied in the biomass and biochar as well as the heat energy within the production system.
Feedstocks permitted for use
Feedstock must be purely biogenic waste biomass that would otherwise have been left to decay or combusted for purposes other than energy production in the baseline scenario, which is the projected GHG emissions that are calculated to occur in the absence of the proposed project activity.
Biosolids are allowed. However, all feedstocks must comply with relevant thresholds for heavy metals and other contaminants under relevant standards or guidelines (e.g., IBI or EBC) according to the biochar end-use application.
Purpose-grown feedstocks are not allowed under the current methodology. Using productive land areas to produce biomass aimed for biochar production could potentially compete with other sustainable development goals, such as food security, and lead to unintended land use change. While it is possible to demonstrate that these negative impacts are not met, it adds additional reporting and monitoring burden to projects. Therefore, only waste biomass is eligible under this current version. Verra intends to consider allowing purpose-grown feedstocks in a subsequent version of the methodology that appropriately addresses sustainability and other concerns.
Accounting for emissions reductions
The methodology uses a comprehensive monitoring and accounting framework that captures the GHG impacts in the three important stages of a biochar value chain: sourcing, production, and application (i.e., the use of biochar in soil or non-soil applications).
At the sourcing stage, emissions are conservatively set to zero since feedstocks are restricted to waste biomass that would otherwise have been left to decay or combusted.
Production stage emissions that are quantified include pre-treatment of biomass, conversion of biomass, and auxiliary energy use. Stable carbon content of biochar over a 100-year period is derived from the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories with the option to use project-specific emission factors from peer-reviewed literature.
Application stage emissions include emissions from processing biochar and utilization. Transportation emissions must be accounted for if exceeding 200km, according to procedures in the Clean Development Mechanism Tool 12.
Additionality, double counting and non-permanence
Additionality is an integral component to emission reduction projects. Project activity must cause reductions additional to what would have occurred without the project.
The biochar methodology uses a standardized activity method for determining additionality. The method stipulates that the total mass of waste biomass converted to biochar amounts to five per cent or less of the total mass of waste biomass available worldwide. Verra will undertake an interim reassessment of the penetration rate within three years of the approval and publication of the current version of the methodology. Such an assessment is required per VCS rules.
Double counting, where reductions are counted multiple times, is another big issue. Methodology developers integrated rigorous reporting and monitoring requirements from feedstock sourcing to biochar production through to end use in approved soil or non-soil applications to ensure double counting doesn’t occur.
Any nature-based approach to carbon removal must also address non-permanence, the risk that an unexpected event, such as fire, may cause a reversal of the achieved reductions.
To address non-permanence when using biochar, end-use monitoring and verification are required to demonstrate approved soil or non-soil uses in the biochar methodology. In practice this means that projects have to demonstrate where the biochar was applied into soils or which product (e.g., cement, building materials) it was mixed into. Once these approved end uses occur, it is virtually impossible to extract the biochar and burn it for energy. It is plausible that a warehouse fire could result in biochar combustion but since an approved end use could not yet be demonstrated, it would be impossible to achieve verification. Furthermore, risk of unintentional combustion (e.g., forest fire, grass fire) is mitigated by requiring that biochar is incorporated to a minimum 10-cm soil depth where risk of combustion of organic material is greatly diminished, and by requiring that biochar is mixed with other less flammable materials like clay or other minerals if it is surface-applied.
Find more information about the new biochar methodology at verra.org.
Kelli Barrett is a senior program officer in communications at Verra.
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