BlogWhy distributed biochar needs two methodologiesDate02 June 2026AuthorRoss Kenyon

On this pageWhy is everyone looking at distributed biochar?The problem with one credit for everythingTwo methodologies, two value propositionsWhy the co-benefits aren't a side storyWhat a buyer should take from this

Why is everyone looking at distributed biochar?If you've been following the CDR registry landscape lately, you may have noticed something: everyone is suddenly talking about distributed biochar. Rainbow launched a distributed biochar methodology last spring. This spring, two other registries each launched their own methodologies for distributed biochar. All this in a category that, for years, had been largely quite quiet. Registries are now recognizing distributed biochar as one of the largest sources of actually-delivered carbon removal, and the market infrastructure around it hasn't kept pace. Whether the timing is coincidence or convergence, the more interesting question is what the new methodologies actually change for buyers. And the answer, I think, is more than it appears.

The problem with one credit for everythingThe single biggest complaint Rainbow heard from distributed biochar developers was about differentiation. Under legacy options, a project running advanced closed kilns with camera-equipped dMRV, continuous temperature monitoring, and rigorous quality tracking receives the same credit as a minimal open-kiln operation with basic oversight.Erica Dorr, who leads methodology development at Rainbow, heard the frustration directly: "They say, 'We're doing such a better job. Our MRV and operations are a lot more expensive, but we struggle to justify a higher credit price because it's technically the same credit.'"That's a market failure worth naming. When a buyer can't distinguish between a high-investment project and a low-investment one, the incentive structure collapses. Developers who spend more on quality can't recover that cost, which means they either cut corners to compete on price or leave the market. The projects with the strongest claims end up subsidizing the weakest ones by sharing a label. It’s Gresham’s Law but for carbon credits.Gresham’s Law is a principle in economics that “bad money drives good money out.” If a ruler declares a fixed exchange rate between two coins (or declares by fiat that two coins of different metallic composition of different values must be accepted at the same nominal price), then people will only circulate the inferior money but hoard the quality money. Why would you give away a gold coin for the price of a silver coin if both have the same legal (and arbitrary) value? The answer is you wouldn’t. It distorts behavior around both assets to the detriment of each.Distributed biochar projects use farm residue (like cotton stalks and corn cobs) that would otherwise be openly burned or degraded in soil.

Two methodologies, two value propositionsRainbow's response was to build two separate methodologies—one for closed-kiln distributed biochar, one for open-kiln—rather than a single catch-all. The split is more than cosmetic, and it cuts both ways.Closed kilns give operators tighter control over pyrolysis, which translates to more consistent biochar quality and meaningfully lower methane emissions. That control also makes monitoring simpler and more reliable. For buyers who prioritize consistency and want to underwrite something that looks and feels closer to industrial biochar, a closed-kiln credit under a dedicated methodology lets them do that with clarity about what they're buying.But the story isn't just about closed kilns breaking away. Open-kiln distributed biochar has its own real strengths, and Rainbow's methodology is designed to surface them rather than treat open kiln as a lesser category.Open-kiln systems can scale faster, require dramatically less capital expenditure, and operate in contexts where closed-kiln infrastructure has less history and requires greater upfront investment (smallholder farms, remote agricultural communities). Critically, Rainbow's open-kiln methodology raises the bar on what has previously been available. It requires more measurements from integrated temperature sensors to prove biochar quality, drier biomass, stricter feedstock criteria. It avoids the potential gaming of using photos. It’s the first Rainbow methodology that mandates an external digital MRV system as a hard requirement, not an option. These are not the same open-kiln credits that have been available under legacy frameworks. Erica's team deliberately built something that separates the more sophisticated open-kiln operators from the full spectrum of artisanal biochar.Erica’s team at Rainbow came to this conclusion by noting that if they had to wait for all open-kiln projects to go to closed-kiln, we would lose years of climate action even though many of those open-kiln projects would add temperature sensors right away if they needed to. If we believe climate change is an urgent threat, we need to be able to find cases where the right balance between scale and quality can be advanced.The result is that both categories can price on proof. A closed-kiln developer competing with an open-kiln developer is no longer arguing about which one deserves a higher price for an identical-looking credit. And an open-kiln developer who has invested heavily in dMRV and quality controls is no longer lumped in with operators doing the bare minimum. They're selling different credits, backed by different methodologies, reflecting genuinely different risk profiles and cost structures. Each can make its case to a buyer on its own terms.Farm residue is converted into a soil amendment, which is then used by the same farms that supplied the feedstock.

Why the co-benefits aren't a side storyHere is where I think the CDR-native framing sometimes gets in its own way. If you evaluate distributed biochar purely through the lens of measurement certainty, it will always look weaker than industrial biochar. The MRV is harder, the variability is wider, and the process control is less absolute. That comparison is honest and it should be made.But it's also incomplete, and Erica pushed back on it when I raised it. If you compare distributed biochar to nature-based removal like afforestation, soil carbon, or improved forest management, the MRV risk profile of a well-run distributed biochar project looks strong enough. The comparison you reach for shapes the conclusion you draw.And then there's the question of what you're actually buying alongside the carbon removal. Distributed biochar generates diversified income for smallholder farmers in regions where agricultural livelihoods are precarious. It converts biomass that would otherwise be openly burned—causing local air pollution and losing all its potential value—into a soil amendment that improves degraded agricultural land. It operates at a scale of capital that is genuinely democratic: you don't need seven figures of capex to participate. These co-benefits are not a marketing wrapper on a CDR credit. For a lot of buyers, and for Rainbow's independent standard advisory board, they are the reason the voluntary carbon market was built in the first place.When Rainbow brought the distributed biochar work to its advisory board, Ludo Chatoux described their reaction: "They were super excited. They said if you can maintain high quality and scientific rigor while opening market access for these projects, it's amazing." Clément Georget, who leads product at Rainbow, framed the excitement more directly: it's about developing-country rural communities where farmers and agricultural lands matter more than anything. Where biochar makes sense for its agricultural benefit and carbon finance creates real incentives for participation.The price-discrimination story and the co-benefits story are, in the end, the same story. The reason it matters that open-kiln and closed-kiln projects can compete on their own terms. Now, the open-kiln projects with the strongest co-benefits—the ones operating in the places that need the carbon finance most—get priced out of a market they helped build.Distributed biochar generates diversified income for smallholder farmers in regions where agricultural livelihoods are precarious.

What a buyer should take from thisDistributed biochar is not going away. It's where a large share of delivered volume in the biochar market currently comes from. And the line between open-kiln and closed-kiln is not fixed, with some of the most experienced operators doing both. Carboneers, for example, has delivered over 100,000 tonnes of CDR and is now opening closed-kiln sites. Varaha, whose MRV work helped convince Rainbow to take distributed biochar seriously, is now deploying industrial reactors. Some of the best operators move with fluency between kiln and project types depending upon the commercial opportunities available to them. The question for buyers is no longer if they should engage with distributed biochar, but whether the methodology infrastructure exists to let them engage with confidence.Rainbow's bet is that the answer is now yes, but only if the market stops treating every distributed project as the same thing. Two methodologies, two credit types, each with requirements that exceed what came before. Buyers who care about quality now have a way to find it. And operators who have been quietly doing the harder version of this work finally have a way to prove it.