The Claim at the Heart of the Biochar Market
Biochar is one of the fastest-growing carbon dioxide removal (CDR) pathways in the voluntary carbon market. In 2025, biochar carbon removal credits traded at premiums of $100–$350 per tonne CO₂e — multiples above standard avoidance credits — largely on the basis of one critical promise: that the carbon locked inside biochar will stay locked for at least 100 years.
But is that promise scientifically robust? And more importantly, how are the world’s leading carbon registries — Verra, Gold Standard, Puro.earth, Isometric, and the European Biochar Council (EBC) — actually verifying it?
As biochar production scales globally and corporate buyers commit hundreds of millions of dollars to long-duration CDR portfolios, the permanence question has moved from academic debate to a live commercial and regulatory risk. This article examines the science, the standards, and what project developers need to know in 2026.
What Does “Permanence” Actually Mean in Carbon Markets?
In carbon accounting, permanence refers to the duration for which carbon is removed from the atmosphere and prevented from re-entering as CO₂ or CH₄. For a credit to be counted as a genuine climate contribution under frameworks such as the IPCC Sixth Assessment Report pathways or the Oxford Principles for Net Zero Aligned Offsetting, the removal ideally needs to be measured in centuries, not decades.
For biochar specifically, permanence is a function of:
- Feedstock composition — the ratio of labile to recalcitrant carbon compounds in the input biomass
- Pyrolysis conditions — temperature, residence time, and reactor design directly control the degree of carbon aromatisation
- Post-application environment — soil chemistry, moisture, temperature, and microbial activity all influence how quickly biochar degrades in the field
- Physical stability — mechanical breakdown of biochar particles can accelerate oxidation
The scientific consensus, anchored in landmark studies including Lehmann et al. (2015) and more recent meta-analyses, suggests that highly aromatic, high-temperature biochar can persist in soils for hundreds to thousands of years. However, the keyword is can. Not all biochar is equal — and this is precisely where the methodological debate gets complicated.
How the Major Registries Approach Permanence in 2026
1. Isometric Biochar Methodology 1.3
Isometric takes a data-driven, conservative approach to permanence quantification. Under Isometric Biochar Methodology 1.3, projects must report the Mean Residence Time (MRT) of biochar carbon — a statistically derived estimate of how long carbon will remain sequestered under site-specific conditions. Isometric applies a permanence discount to the credited tonnes based on MRT modelling, meaning projects with lower-quality feedstock or lower pyrolysis temperatures receive fewer credits per tonne of biochar produced. This self-correcting mechanism is one of the more scientifically rigorous approaches in the market.
Isometric also requires hydrogen-to-organic-carbon (H:Corg) ratio testing — a proxy for biochar stability — with a mandatory threshold of H:Corg ≤ 0.7 to qualify for credits.
2. European Biochar Council (EBC) Guidelines
The EBC Guidelines set minimum quality thresholds that have become a de facto global standard for premium biochar. EBC certification requires an H:Corg ratio ≤ 0.7 and a minimum total carbon content of 50% (EBC-Carbon class). EBC-certified biochar is widely accepted as meeting the stability threshold required for long-duration CDR claims. The EBC framework also mandates detailed feedstock traceability and process monitoring — data that forms the foundation of any credible permanence claim.
3. Puro.earth Biochar CORC Methodology
Puro.earth issues Carbon Removal Certificates (CORCs) specifically for engineered carbon removal, including biochar. Their methodology requires projects to demonstrate a minimum 100-year permanence through a combination of H:Corg ratio testing, pyrolysis temperature verification, and field application documentation. Puro.earth has been particularly active in the Nordic and European markets and has issued tens of thousands of CORCs to biochar projects since 2020. In 2026, scrutiny on CORC quality has intensified as secondary market trading of Puro.earth certificates has grown significantly.
4. Verra VM0044 v1.2
Verra’s VM0044 v1.2, updated in 2024, introduced a significant new requirement: projects must now conduct a formal investment analysis to demonstrate additionality — meaning they must prove the carbon revenue is what makes the project financially viable. On permanence, VM0044 uses a combination of the Sequestration Permanence Tool and feedstock-specific emission factors. The 2024 errata and clarifications also tightened requirements around soil application monitoring, reflecting growing concern that field conditions post-application are insufficiently tracked under earlier versions of the standard.
5. Gold Standard PARC Methodology (GS4GG PAA M400-XX)
Gold Standard’s Production and Application for the Removal of Carbon via Biochar (PARC) methodology is the newest major entrant to the biochar credit space. PARC requires rigorous documentation of the entire biochar value chain — from feedstock sourcing through pyrolysis to field application — and applies permanence discounts based on site-specific soil and climate data. Gold Standard’s entry into biochar is significant: it brings the credibility of one of the oldest and most respected registries to a methodology space that has historically been dominated by newer, tech-first players like Puro.earth and Isometric.
Where the Science Is Still Contested
Despite the progress made by registries, several areas of genuine scientific uncertainty remain — and sophisticated corporate buyers and carbon market analysts are increasingly aware of them.
The Priming Effect
When biochar is applied to soil, it can stimulate microbial activity in ways that accelerate the decomposition of existing soil organic matter — a phenomenon known as the priming effect. In some soil types and climatic conditions, this net loss of native soil carbon can partially offset the sequestration benefit of the biochar itself. Most current methodologies account for this to some degree, but field monitoring data at scale remains limited.
Physical Fragmentation
Over time, biochar particles can fragment through physical processes — tillage, freeze-thaw cycles, wetting and drying — reducing particle size and potentially increasing surface area available for oxidation. Long-term field studies tracking biochar particle integrity beyond 10 years remain relatively scarce, creating genuine uncertainty in multi-decade permanence projections.
Climate Change Feedback Loops
Ironically, one of the least-discussed risks to biochar permanence is climate change itself. Rising soil temperatures and shifting precipitation patterns alter the microbial and chemical environment in which biochar persists. Permanence estimates calibrated on historical climate data may not hold under the warming trajectories projected for 2050–2100 — the very period during which much of the claimed 100-year sequestration is meant to occur.
What This Means for CDR Project Developers
For project developers, the permanence debate translates into three concrete operational imperatives in 2026:
- Quality over quantity: Optimise pyrolysis conditions for maximum carbon aromatisation, even if this means lower biochar yield per tonne of feedstock. High H:Corg ratio biochar commands premium credit prices and faces less discount under MRT-based methodologies.
- Continuous monitoring: Static, point-in-time lab testing is no longer sufficient for leading registries. Projects need to implement ongoing monitoring of pyrolysis parameters — temperature, residence time, feedstock moisture — using calibrated sensors and tamper-proof data logging. This is where digital MRV infrastructure becomes a competitive advantage, not just a compliance cost.
- Field application traceability: Knowing where biochar was applied, in what quantities, and under what soil conditions is increasingly required for credit issuance and will become mandatory for all major registries within the next 12–24 months. Projects without structured application records face material credit invalidation risk.
The Role of AI-Native DMRV in Resolving the Permanence Verification Gap
The permanence problem is, at its core, a data problem. Registries cannot credibly verify 100-year permanence claims without continuous, high-quality, tamper-resistant data from the point of production through to long-term field monitoring. Manual reporting workflows — spreadsheets, periodic audits, PDF submissions — are fundamentally inadequate for this task.
This is why AI-native Digital Measurement, Reporting and Verification (DMRV) infrastructure is becoming a structural requirement for credible biochar CDR projects. A robust DMRV system captures pyrolysis parameters in real time, generates automated quality flags when H:Corg proxies fall below threshold, maintains an immutable audit trail from feedstock to credit issuance, and produces registry-ready evidence packages that dramatically reduce the cost and time of third-party verification.
At Goenvi Technologies, our AI-native DMRV platform is purpose-built for exactly this workflow — integrating directly with our patented CTDT pyrolysis hardware (Patent No. 437310, July 2023; Rotary Reactor Indian Patent No. 592630, June 2026) to capture the sensor data that underpins credible permanence claims. With 14+ commissioned plants converting biomass, MSW, and plastic into biochar and fuel, we are building the operational dataset that the next generation of biochar permanence science will rely on.
The Buyer’s Perspective: Due Diligence in 2026
Corporate buyers — particularly those operating under SBTi Net Zero Standard Version 2.0 or subject to CSRD mandatory disclosure — are applying significantly more rigorous due diligence to CDR purchases in 2026 than they were just two years ago. Key questions sophisticated buyers are now asking include:
- What is the measured H:Corg ratio of this specific production batch?
- What permanence discount has been applied by the registry, and what is the net credited permanence?
- Is there a continuous monitoring system in place, or are credits based on periodic spot checks?
- What is the chain of custody from feedstock to field application?
- Has the project undergone independent third-party verification under a recognised standard (EBC, Puro.earth, Isometric, VM0044, or PARC)?
Projects that cannot answer these questions with structured, auditable data are increasingly being passed over in favour of those that can — regardless of price.
Conclusion: Permanence Is Provable — But Only With the Right Infrastructure
The question is not whether biochar can lock carbon for 100 years. The science strongly suggests it can — under the right production conditions, with the right feedstocks, applied in the right environments. The question is whether project developers can prove it to a standard that satisfies regulators, registries, and increasingly sophisticated corporate buyers.
In 2026, that proof requires more than a laboratory certificate. It requires a continuous, integrated data chain — from pyrolysis sensor to registry submission — that makes permanence claims auditable, defensible, and tamper-resistant at every step. The projects that invest in this infrastructure today will not only command premium credit prices; they will be the projects that survive the coming wave of registry scrutiny and buyer due diligence.
The permanence problem is solvable. The question is whether you have the tools to solve it.
Want to see how Goenvi’s AI-native DMRV platform supports biochar permanence verification from pyrolysis sensor to registry submission? Book a technical demo with our team →
