Isometric's New Accelerated Weathering Module
This article is an automatically translated version of the original Japanese article. Please refer to the Japanese version for the most accurate information.
This is a newsletter from sustainacraft Inc.
Methodology Updates is a series focusing on carbon and biodiversity credit methodologies. This article introduces a new module recently released by Isometric for enhanced weathering type projects: the "Enhanced Weathering in Closed Engineered Systems" (EW-CES) module.
EW-CES presents a novel method for sequestering carbon through the weathering of mineral feedstock in closed, controlled environments. Unlike nature-based enhanced weathering approaches (EW-Ag) that rely on spreading feedstock on agricultural land, this module focuses on the quantification and storage of carbon dioxide in engineered environments where variables such as mineral composition and reaction kinetics can be strictly managed. This approach supports controlled research environments for weathering kinetics and sensor development, and by promoting more rigorous quantification of downstream carbon loss, it may offer a solution to some of the MRV (Measurement, Reporting and Verification) challenges faced by enhanced weathering projects in outdoor agricultural settings.
This article will first provide background by outlining the current mainstream Enhanced Weathering in Agriculture (EW-Ag) projects and their MRV challenges, then introduce how EW-CES aims to address these issues. We will also consider the relationship between EW-Ag and EW-CES.
Background
Scientific Basis and Strengths of Enhanced Weathering in Agriculture (EW-Ag)
Enhanced weathering (EW) is a carbon removal approach that accelerates naturally occurring geochemical processes for carbon sequestration. Silicate and carbonate minerals in rocks (e.g., basalt, limestone) break down over time through a chemical process called weathering, reacting with ambient CO₂ and water. This process converts CO₂ into bicarbonates, which are eventually transported to the ocean where they can be stored as dissolved inorganic carbon (inorganic carbon dissolved in water) for tens of thousands of years. In an agricultural context (EW-Ag), this process is implemented by spreading finely crushed rock (typically basalt) on agricultural land, where it reacts with CO₂ in the soil and atmosphere, aided by moisture, plant roots, and microbial activity.
EW-Ag offers several advantages as a carbon sequestration method compared to other Nature-based Solutions (NbS) approaches. First, EW-Ag is characterized by its high permanence. While stored carbon in afforestation or soil organic carbon projects can be re-released due to fires, diseases, or changes in land use, EW-Ag permanently removes CO₂ on geological timescales through mineral carbonation. This means it is easier to avoid the reversal risk common to many NbS. This point is also shared with biochar, which we introduced in a previous newsletter.
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Second, EW-Ag is considered to have less resource competition compared to other project types. Firstly, because it can be applied to existing agricultural land, the risk of land use conflict is low, and consequently, its impact on food security is considered minimal. As a result, leakage risk, such as the displacement of deforestation to other areas, is also reduced. Additionally, EW can improve soil health and crop yields by replenishing essential nutrients and reducing soil acidity, potentially even enhancing food security. While these advantages are shared with biochar, from the perspective of feedstock competition, the minerals used as feedstock for EW-Ag are (at least currently) considered to have significantly milder feedstock competition with other activities compared to biomass, which is the feedstock for biochar.
Third, EW-Ag has lower implementation barriers compared to Agricultural Land Management (ALM) projects. In EW-Ag projects, feedstock application can be integrated into routine farming practices, meaning farmers do not need to significantly alter their traditional practices. In contrast, ALM projects often require farmers to permanently change farming practices to additionally sequester carbon in the soil.
Challenges of Enhanced Weathering in Agriculture (EW-Ag)
While EW-Ag holds significant potential as a Carbon Dioxide Removal (CDR) strategy, several challenges must be addressed to ensure the creation of high-quality Carbon Credits. The most crucial among these is the difficulty in MRV for the amount of CO₂ removed through the weathering process. Here, we introduce three key points: heterogeneity of reaction rates, limited in-situ measurement equipment and analytical costs, and uncertain downstream behavior.