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Published on August 03, 2022

High integrity for carbon removal credits

Companies looking to tackle the climate crisis by buying carbon credits after reducing emissions, have two choices: avoidance or removal credits. While avoidance credits avert emissions, removal credits represent carbon dioxide that is captured from the atmosphere and stored for the long term.

The IPCC has deemed removals unavoidable in order to prevent the worst climate scenarios becoming a reality. But not all carbon removal credits are created equal. As companies negotiate their journeys to net zero, how can they be sure that the carbon removal credits they buy are of high integrity? How can they guard against accusations of greenwashing in the future? Here we take a closer look at the processes behind Puro Standard’s verification system for biochar and other methodologies for carbon removal credits. We delve into the rigorous work that goes on behind the scenes before a CO2 Removal Certificate (CORC) for one metric ton of carbon dioxide removal can be issued.

The Puro Standard

The carbon markets require the integrity of certification via carbon standards. Puro Standard is the first standard for engineered removal methods in the voluntary carbon market. Before will issue CORCs to carbon removal suppliers, they must go through a stringent two-step verification  to confirm their process is carbon net-negative. Our aim is to increase trust that there is verifiable climate impact so we can unlock financial flows to the suppliers removing carbon.

Step one: LCA and laboratory-based evidence

Suppliers must provide either a Lifecycle Assessment (LCA) or an Environmental Product Declaration (EPD) to show their product or process absorbed more CO2 from the atmosphere than it emitted, and in most methodologies a laboratory test is required to determine the embodied CO2 in the material.

Biochar is a charcoal-like substance made by heating agricultural or forestry waste in a controlled process without oxygen, called pyrolysis. When suppliers complete the LCA for biochar, they must show all the emissions that arose from different stages of this process, from “cradle to grave”.

That means they need to detail the emissions from transporting the raw materials, converting them to biochar and then applying them, for example, to soil. The CORCs they are issued are equal to the lab-tested amount of CO2 sequestered by the biochar minus its lifecycle emissions. The carbon will remain stored for hundreds of years.

Suppliers of other carbon removal methodologies must complete the same LCA or EDP processes. CORCs issued for carbonated building elements, for example, must provide laboratory-tested evidence of CO2 removal from the chemical reaction during the hardening phase of the concrete-like building element. During the process, CO2 is chemically bound and mineralized permanently into the building element: it will never escape back into the atmosphere. Again, the number of CORCs issued is determined by subtracting the CO2 emissions generated by production from the CO2 stored in the building elements.

The same is true for suppliers who apply for CORCs based on biobased building elements. Under this methodology, the carbon captured by trees is locked into buildings for 50 years, and that is the contracted durability of the CORC. In reality, it is likely to stay there for much longer than that. Risk of reversal, for example in the form of fire, is accounted for in a 10% buffer during the CORC issuance.

Finally, suppliers who apply for CORCs issued for the geologically stored carbon methodology must show also show LCA evidence of their carbon capture processes, such as the direct injection of CO2 into deep geological formations.

Step two: independent verification

After suppliers have completed their LCAs or EPDs, their claims are audited by independent assessors trained by Auditors verify compliance to Puro Standard methodologies, which include carbon accounting formulas to establish the net carbon removal quantity for each method. The methodologies are created by working groups of scientists and industry carbon removal experts and overseen by’s external Advisory Board, chaired by Professor Myles Allen, of the University of Oxford, who was credited with first demonstrating the need for “net zero” CO2 emissions to stop global warming.

Besides quantification of net-negativity, other criteria and concerns that are audited are: durability, baseline, financial additionality, and social and environmental safeguards. works with four audit partners across Europe, the USA and Australia, including DNV GL, ELS and bio.inspecta and are currently setting up contracts with three others due to increased demand in other geographies. Auditors visit suppliers’ facilities and check compliance against the evidence the suppliers submitted and against the methodology set by the Puro Standard. Audit partners are all accredited organizations, usually by the relevant national energy ministries, to ensure high standards.

Puro Registry- transparency in the carbon removal market

For traceability, transparency and to avoid double counting, CORCs are issued in the Puro Registry where their complete lifecycle is recorded from issuance to retirement, as emphasized by the likes of the Integrity Council for Voluntary Carbon Markets and ICROA. In fact, anyone can go to to search for corporations that have made carbon removal claims based on CORCs and find the project information and retirement purpose.

What does the future hold?

As new methods for removing carbon from the atmosphere emerge, will develop new methodologies with external experts and our Advisory Board to establish carbon accounting formulas. Our most recent methodology sets out the criteria for measuring the carbon captured by Woody Biomass Burial and we are working on bringing to market an Enhanced Weathering methodology soon.

The voluntary carbon market is set to expand rapidly, so it is vital to maintain the highest verification standards and transparency of the carbon removal credits on offer.’s rigorous methodologies and two-step verification process, which includes audits by independent third-party partners, means customers fulfilling their net zero commitments can be confident that CORCs represent actual removal of carbon from the atmosphere.

If you, like us, think that removals are unavoidable and the only way to restore the balance of CO2 in our atmosphere, join us. Visit our marketplace of suppliers who are already producing CORCs and visit our Pre-CORC suppliers, projects that need offtake agreements to start or expand operations.

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