📌 The biochar due diligence checklist no one sends you
Biochar is booming, but most buyers don’t ask the right questions. If you’re buying biochar, read this first.
Biochar demand is booming.
But biochar removal must be backed by robust and credible evidence.
Supply is constrained (each site caps at around 100,000 tonnes/year) and quality is all over the map. Top-tier credits sell out fast.
Done well, high-quality biochar is permanent, verifiable, and scalable. Done purely to capitalize on the boom, it’s a liability: questionable feedstocks, overstated permanence, or projects that can’t deliver at scale.
The carbon removal (CDR) market is still young, and quality signals are inconsistent. Registries and ratings agencies only go so far—they’re useful, but not necessarily comprehensive.
We can’t afford to wait for perfect standards. Biochar is the most accessible, fastest-growing carbon removal method available today. That makes due diligence more important than ever. If you're relying on a registry listing alone, you're taking a risk.
At Supercritical, we vet every biochar project against 118 data points so you don’t learn the hard way. If you’re assessing a new project yourself, these are the checks that matter most.
What really dictates biochar quality?
Before you run a deep due diligence process, you need to know what makes or breaks biochar quality. It comes down to six key variables:
✔️ Feedstock
What type of biomass goes into the pyrolysis reactor? It must be derived from biological materials, sustainable (e.g., waste biomass produced by existing activities or FSC certified), and abundant.
✔️ Permanence & Pyrolysis conditions
Pyrolysis conditions need to be high temperatures above 550°C to achieve lower H/Corg ratios and more stable carbon. This ensures the carbon stays locked away for 200+ years.
✔️ Monitoring, Reporting and Verification (MRV)
Credible projects prove permanence with lab tests and independent verification and ongoing monitoring and reporting (MRV). High quality MRV plans include continuous measurements and monitoring of process conditions and emissions.
✔️ Additionality
Whether this carbon removal would have happened without CDR investment and the economic viability relies on the sale of CDR credits. High-integrity projects show that the biochar wouldn’t have been produced and stored for climate benefit without carbon finance.
✔️ Co-benefits
What the project delivers beyond carbon removal. This can include social and environmental benefits, often linked to UN Sustainable Development Goals (SDGs). Look for measurable gains like improved soil health, crop yields, local employment, health benefits for local communities.
✔️ Delivery risk
Has the project identified and addressed risk factors that could result in credits not being delivered or delayed (e.g., feedstock supply chain).
⚠️ Before you start: The real risk of bad biochar
Not all “biochar” is the real deal. Without due diligence, buyers risk paying for low-grade charcoal, not engineered carbon removal.
Poorly produced or mislabelled biochar can do real damage:
It can contain harmful contaminants like polycyclic aromatic hydrocarbons (PAH), which are carcinogenic, or heavy metals that degrade soil health, especially in vulnerable regions.
It can break down quickly, releasing carbon back into the atmosphere long before the claimed biochar permanence.
It undermines trust in biochar as a CDR pathway, which could slow the scale-up the world urgently needs.
Most of this won’t show up on a glossy registry listing. And small shortcuts today become big climate, ecological, and legal risks tomorrow.
How do you check these variables fast? Start with these three critical questions.
1. What’s the feedstock, pyrolysis process, and application plan?
Why it matters:
These details make or break your carbon removal project—and the credibility of the credits you buy. They also determine whether the project delivers real climate impact (permanence and additionality) and tangible local benefits (co-benefits).
What to ask:
✅ Feedstock: Is it genuinely waste biomass? Certified sustainable? Is feedstock supply abundant enough to meet your contract volume for years to come? (Tip: FSC certification for forestry residue is a green flag.)
✅ Permanence and pyrolysis conditions: What temperature is the pyrolysis reactor running at (ideally above 550°C)? Is the H/Corg ratio independently tested and below 0.4? Higher temperatures and lower H/Corg ratios mean more stable biochar and more durable carbon storage. Check that analysis follows approved DIN norms or accredited lab standards.
✅ Application: How will the biochar be used or stored? Is it being mixed into soil, or other approved application, where carbon removal reversal is unlikely? The application mechanism should prevent biochar from being combusted later, releasing your carbon back into the atmosphere.
✅ Additionality: Would this project have happened without carbon finance? What’s the counterfactual? (e.g. Would this biomass still be processed this way to produce biochar without my investment? Or would it have been burned or left to rot, releasing CO₂ or methane?) Are there any regulations or policies that mandate biochar activity, or make biochar common practice? If so, the project would not be additional.
✅ Co-benefits: Does the project deliver verified social or environmental benefits, like improved soil health, increased crop yields, or community employment?
Red flags to watch for:
❌ Vague answers about feedstock sourcing
❌ No lab data on H/Corg ratio
❌ No clear plan for MRV of the project or how and where the biochar will be applied
❌ No justification for why carbon finance is necessary
❌ Vague, unsubstantiated or exaggerated claims about local or environmental benefits
If your supplier can’t explain exactly what they’re turning into biochar, how they’re producing it, and where it’s going after, find a new supplier.
2. How permanent is the removal, and who verifies it?
Why it matters:
Anyone can say their biochar locks away carbon for 100+ years. Proving it is another story. Permanence is non-negotiable for true carbon removal.
What to ask:
✅ Permanence claim: How many years do they claim the carbon stays stored? Is that backed by reliable lab tests (by accredited laboratories) and scientific literature (or just a marketing slide?)
✅ Monitoring and reporting: How is biochar production performance tracked over time (e.g., continuous monitoring of pyrolysis conditions)? Do they regularly sample biochar batches and verify soil application with third-party checks? Has their MRV plan been verified by a third-party? Are they using a trusted MRV provider?
✅ Verification: Which registry or standard are they using? Does it cover permanence properly? (Puro.earth and Isometric are considered solid minimum standards; anything that deviates from the scientific consensus, dig deeper.)
✅ Buffers and guarantees: What happens if actual performance falls short? Is there an insurance buffer or reserve to protect buyers from under-delivery?
Red flags to watch for:
❌ Claims of ultra-long permanence (beyond 200+ years) without lab data
❌ No registry listing
❌ Once-off monitoring
❌ No clear plan for carbon removal reversals
Permanence is the foundation of biochar’s climate value. If your supplier can’t prove it and protect it, walk away.
3. Can the supplier deliver—at scale, on time, every time?
Why it matters:
Sustainable feedstock and lab-verified permanence mean nothing if the supplier can’t reliably produce biochar and deliver carbon removal when you need it. Delivery risk is the hidden pitfall that trips up even the most mature buyers.
What to ask:
✅ Operational status: Is the facility up and running now, a pilot, or still a blueprint? How many tonnes have they delivered to paying customers to date? If it’s a new project that is not yet operational, does the team have relevant experience managing industrial-scale processes or equipment?
✅ Production capacity: Can they meet your required volume for spot or offtake contracts, today and in future years? Based on their current operation status, are their anticipated delivery timelines feasible or unrealistic?
✅ Pyrolysis equipment: What do they use (e.g., commercially available or bespoke machines)? Is it proven, maintainable, and scalable? If your supplier relies on uncertain, untested or unfinanceable equipment, the risk of production delays or shortfalls rises fast.
(Many UK-based biochar projects can only secure asset financing for high-end Pyreg machines, which cost around €2.5M and have an 18-month lead time. If the project is trying to secure finance from UK-based (and potentially other) institutions, they may not be able to finance Chinese-manufactured equipment, which limits options and raises delivery risk.)
✅ Feedstock security: Is there sufficient biomass supply secured for the life of your deal, or is it at risk of disruption? The project may have developed their own feedstock supply chain or established contracts with biomass feedstock suppliers.
✅ Exclusivity: Are these credits being sold on multiple marketplaces at the same time? (This can lead to double-selling risk and disputes.) Or have the credits been reserved for your deal?
✅ Governance and local risks: Are there any political, regulatory, or community issues that could halt operations or delivery?
Red flags to watch for:
❌ Big promises from a pilot plant using unproven pyrolysis technology
❌ No delivery history (or industrial track record)
❌ Feedstock supply that might run out
❌ Credits offered in too many places at once
In carbon removal, timely delivery is almost synonymous with credibility. If a supplier can’t show proof of performance, don’t bet your climate targets on their promises.
Quality questions today. Credible removal tomorrow.
Biochar is a powerful tool in the carbon removal toolkit, but only when buyers demand proof of quality and permanence.
Skip due diligence, and you risk paying for carbon that leaks back into the atmosphere, release of hidden contaminants that are harmful to the environment, and a market reputation that erodes right when we need trust to encourage scale-up.
At Supercritical, our Biochar Vetting Protocol checks every box for you. We score each project against 118 data points, from feedstock sustainability to lab-tested permanence, delivery track record, and real social and environmental safeguards. Only 18% of today’s biochar supply makes the cut.
Don’t guess. Don’t gamble. Use this checklist, share it with your team, and know exactly what questions to ask before you buy.
📄 [Download the Biochar Due Diligence Checklist PDF]
🔍 [Explore Supercritical’s fully vetted biochar projects]
What’s new at Supercritical?
🌇 London Climate Action Week: We hosted our first CDR Leadership Forum: a private, off-the-record gathering of buyers, suppliers, and standard-setters shaping the future of carbon removal. Here’s a recap of what came to the surface. Thanks to Reilly O'Hara (Google), Stuart Leckie (Capgemini), Stacy Kauk, P.Eng. (Isometric), Marcelo Pereira Holters (Exomad Green), Elias Azzi (Puro.earth), Harris Cohn (Charm Industrial), and Mai Bui (Supercritical) for joining us.
📘 New report: How to structure a good biochar offtake. Our latest guide unpacks what a high-quality biochar offtake should look like and how to avoid the pitfalls.
🧠 Latest articles and insights
The next biochar: Emerging solutions buyers should watch. Biochar is booming, but it can’t do all the heavy lifting. To reach net zero, we need scalable, affordable methods with real permanence. This article breaks down three promising contenders that could follow in biochar’s footsteps.
Why large-scale non-native monoculture plantations fail Supercritical’s vetting. This piece breaks down what credible nature-based solutions look like, and where (if anywhere) commercial forestry can play a legitimate role in carbon removal.
The carbon removal procurement journey: How to buy high-quality credits for your net-zero goals. We break down each step of the carbon removal buying journey, from shortlisting and vetting to negotiating and managing credits post-purchase.
🚀 Coming soon: Our first BECCS project goes live. Biochar has been leading the charge, but BECCS is the biggest CDR category globally. Our first BECCS project is about to launch on the Supercritical marketplace, offering buyers access to one of the most permanent and scalable removal solutions. Watch this space.
📘 Coming soon: The Carbon Removal RFP Playbook – Our upcoming PDF guide for buyers who want to build a better procurement process.