The biochar carbon methodologies and safeguards have dug in deeper and improved quickly over the last few years, closing gaps that early due diligence unearthed. Biochar has moved swiftly from a relatively niche carbon removal pathway to an increasingly important part of the durable carbon market. Its appeal is intuitive: biomass that might otherwise decompose or be burned is converted through pyrolysis into a more stable form of carbon, which can then be stored in soils or durable products. Beyond its appeal, biochar is also a useful case study in something broader: the role fair scrutiny and due diligence can play in helping a carbon market mature.

What questions did early biochar projects leave open?

A couple of years ago, some of the most important questions around biochar projects were still being tested in practice, and did not readily appear in the scope of carbon methodology requirements. Where exactly did the biomass come from? Was a claimed “waste” feedstock genuinely residual, or had it been diverted from another use? Could its origin be substantiated beyond supplier documentation?

Furthermore, the questions did not stop at the pyrolysis plant. Once biochar had been produced, where did it actually go? Was it applied or incorporated as intended? Could its final destination be demonstrated? Did local users understand the material and how it should be used?

In 2024, the European Commission was still convening technical work to identify best practices and challenges for biochar carbon removal certification. Research was also highlighting monitoring challenges once biochar enters soils, including how to distinguish credited biochar carbon from other soil carbon and avoid double counting.

These were not necessarily signs that biochar certification was fundamentally flawed. Standards already contained some controls around eligible biomass, production and storage. Rather, the industry was learning how those requirements translated into complex, real-world supply chains, and how to articulate them more robustly. But while the standards were still catching up, due diligence helped to catch these early issues and gaps.

What does early due diligence see that biochar standards don’t?

For Xilva, these questions became tangible during our assessments of biomass-based projects, including biochar. Our in-house forestry expertise means we are regularly asked to assess whether the surrounding forest landscape can sustainably provide the biomass assumed by a project, and to ground-truth that assessment and subsequently provide input into its traceability system. In this kind of work, looking beyond the project documents and certification standards proves valuable.

The questions it raises include biomass provenance and the reliability of supporting evidence: whether sourcing areas show signs of illegal logging, tree cover loss or fire, and whether traceability systems are reliable or opaque. Downstream, they include how the biochar will actually be used, whether local users properly understand its application, and whether the anticipated benefits will materialise in practice. These are the same early-stage questions that were still being asked of the market just a few years ago. 

A lack of transparency, or at least of publicly available data proving sustainable sourcing, has also drawn wider scrutiny. Organisations such as NewClimate Institute and Fern have investigated biochar carbon crediting and called for transparency behind biomass sustainability claims, and in June 2026 nine NGOs formally challenged the EU's adopted methodology that classifies biochar as a permanent carbon dioxide (CO2) removal method.

Xilva’s work also illustrates what independent due diligence can contribute to carbon markets, beyond carbon methodology requirements (improved or not).

This does not mean that certification standards are a failure. Instead, the takeaway is that due diligence takes a different, complementary role which holistically expands the assessment of a project to determine credibility. A carbon methodology has to create rules that can be applied consistently across many projects, and understandably there are boundaries around what a standard can reasonably assess. Due diligence, however, can move beyond these boundaries. It can interrogate the specific landscape, counterparties and operating reality behind an individual investment, providing for a greater sense of depth and grounding in the project’s context. 

In a young market, due diligence can therefore act as an early-warning system. It can identify issues before they have been fully translated into standardised requirements. It can encourage buyers and investors to think beyond the carbon credit and look at the greater environmental and social structures where project activities will inevitably leave their mark – structures which can and often are messy and complex to interpret and translate into risks, but where due diligence is exceptionally well-positioned to do so.

How have biochar standards and buyers responded?

Upgrades to the system over the last two years alone are notable. 

Puro.earth’s 2025 biochar methodology update strengthened and clarified requirements around responsible biomass sourcing and verified end-use applications, drawing on several years of certification experience. It has also worked through specific end-use challenges such as retail distribution, introducing additional safeguards around traceability, consumer guidance and reversal risk before allowing such pathways to generate credits.

Buyers have also raised their expectations. Microsoft’s carbon removal approach, for example, layers its own diligence on top of registry certification, looking across biomass sourcing, technology, lifecycle emissions, MRV, environmental and social impacts, and end use. The biomass sourcing guidance it has co-developed with Carbon Direct further expands the attention paid to sustainable sourcing.

Verra is continuing to revise VM0044, with proposed changes for version 2.0 covering areas including feedstock transport, monitoring of biochar properties, uncertainty, and safe storage and transport. 

Our review of eight active biochar methodologies similarly found that all now contain some form of feedstock sourcing or provenance requirement, although their depth and design vary.

It would be overstating things to suggest that any one due diligence exercise caused these market developments. Markets evolve through the accumulated work of project developers, scientists, standards bodies, buyers, auditors, civil society and investors. Taken together, biochar’s story shines a light on the proactive and well-meaning intent of the various actors in the market, and their ability to collectively respond when fair criticism and gaps are pointed out.

What biochar risks should buyers and investors still watch?

Although the market has responded strongly and rapidly, there is still room for healthy scepticism of project integrity beyond the boundaries set by carbon standards. Background checks, for example, remain difficult to standardise. A carbon methodology may tell an investor whether a project satisfies technical requirements, but not necessarily everything it should know about the ownership, governance, track record or reputation of the counterparties behind it.

Scale creates another challenge. A project may prove that today’s biomass is eligible, traceable and genuinely residual. But if its investment case depends on multiplying production, investors should ask whether the surrounding landscape can sustainably provide that volume year after year.

Traceability can tell you where today’s tonne came from, while due diligence should also ask whether the next 100,000 tonnes can credibly come from the same place. That means looking beyond individual supply contracts towards the wider supply area: competing biomass demand, sustainable removal rates, transport distances, changing land use and the pressures created by future growth.

Why is due diligence part of carbon market infrastructure?

The most encouraging lesson from biochar may therefore be the evolution itself. Early scrutiny identified issues around sourcing, provenance, end use and evidence. Encouragingly, standards responded, buyers developed additional requirements, and developers improved systems. Overall, expectations for project and carbon credibility rose. That is what a functioning integrity ecosystem should look like.

The value of due diligence is not simply that it can readily find evidence to reject poor project design, reputational risk or fatal flaws in delivery. At its best, it helps good projects become stronger, gives investors confidence to allocate capital, and identifies emerging risks before they become sector-wide problems.

If independent scrutiny has helped push the sector even slightly towards stronger sourcing, better evidence and more credible end use, that is a success. The continuing role of due diligence will be to keep asking the questions that standards cannot yet fully encapsulate, helping credible projects distinguish themselves and, in the process, helping shape the direction in which the wider carbon and nature markets develop.

Frequently asked questions

What is biochar carbon removal?

Biochar carbon removal converts biomass into a stable, carbon-rich material through pyrolysis and stores it in soils or durable products. Because the carbon resists decay for centuries, standards such as Puro.earth certify it as durable carbon removal.

Why does biomass sourcing matter for biochar carbon credits?

A biochar credit is only as credible as its feedstock. If biomass is not genuinely residual, is diverted from other uses, or comes from unsustainable or illegal extraction, both the climate benefit and the buyer's reputation are at risk.

What does biochar due diligence cover beyond certification?

Certification checks a project against a methodology's rules. Independent due diligence also tests whether the sourcing landscape can supply the biomass, whether traceability evidence holds up, how the biochar is really used, and who stands behind the project.

Are biochar standards strong enough today?

They have improved markedly since 2024: all eight active biochar methodologies Xilva reviewed now include feedstock sourcing requirements. Gaps remain around counterparty checks and whether supply landscapes can sustain growth, which is where project-level due diligence adds value.