The Role of Improved Forest Management for Carbon Dioxide Removal

Key Takeaways

• Marine carbon dioxide removal (mCDR) uses ocean-based processes—primarily ocean alkalinity enhancement (OAE) and direct ocean removal (DOR)—to capture and durably store atmospheric carbon dioxide (CO₂), without the land and freshwater constraints of terrestrial methods. 
• The ocean already absorbs roughly 29% of human-caused CO₂ emissions each year, according to the 2025 Global Carbon Budget, and mCDR technologies aim to safely enhance that natural uptake without worsening ocean acidification.
• For corporate carbon buyers and project developers evaluating mCDR, the Criteria for High-Quality Marine Carbon Dioxide Removal, developed by Microsoft and Relae, outlines standards to guide responsible mCDR deployment at scale.

Reducing carbon dioxide (CO₂) emissions alone is no longer sufficient to limit global warming to 1.5°C. To effectively address climate change, scientific consensus highlights the need to remove carbon dioxide already present in the atmosphere. Marine carbon dioxide removal (mCDR), a form of ocean-based carbon removal, offers a scalable solution by leveraging the ocean’s natural ability to absorb and store carbon, without the land and resource limitations associated with terrestrial carbon removal methods.

This guide explores the fundamentals of marine carbon dioxide removal, including how it works, the technologies involved, and its role in global decarbonization.

What Is Marine Carbon Dioxide Removal?

Marine carbon dioxide removal uses ocean-based processes to capture and store carbon dioxide from the atmosphere. mCDR techniques fall into two primary categories: 

• Biotic CDR, which includes using photosynthetic fixation, microalgae cultivation, and terrestrial biomass sinking, to capture and store carbon. 
• Abiotic CDR, which influences CO₂ concentrations and carbonate chemistry in the seawater to absorb atmospheric CO₂ without increasing acidity. There are two main abiotic mCDR pathways: ocean alkalinity enhancement (OAE) and direct ocean removal (DOR). 

How Does Marine Carbon Dioxide Removal Work?

Marine carbon dioxide removal functions via the air-sea gas exchange—a process by which the atmosphere and surface seawater maintain equal CO₂ concentrations—meaning a shift in one leads to a corresponding change in the other. This exchange allows the ocean to absorb or release CO₂ back into the atmosphere depending on concentration levels and factors like pH. 

Once absorbed by the ocean, CO₂ exists in several forms, including dissolved CO₂, carbonates, and bicarbonates, influencing the ocean's pH levels. As atmospheric CO₂ levels rise, the oceans absorb roughly 12 GtCO₂ annually, approximately 29% of anthropogenic CO₂ emissions. This increase is disrupting the natural CO₂ balance and contributing to ocean acidification. 

mCDR methods like ocean alkalinity enhancement and direct ocean removal use safe and controlled processes to increase the amount of CO₂ absorbed from the atmosphere while mitigating acidification.

Understanding Ocean Alkalinity Enhancement (OAE)

Ocean alkalinity enhancement (OAE) captures and stores atmospheric CO₂ as dissolved carbonates in the ocean by increasing the alkalinity of seawater using one of two primary methods:

• Adding alkaline minerals such as olivine or basalt to seawater.
• Using electrochemical methods to add alkaline compounds to seawater.

Both of these methods increase the alkalinity of seawater and, thereby, its capacity to absorb atmospheric CO₂ without acidification. 

OAE methods can also differ by location and the manner in which seawater interacts with alkaline substances and atmospheric CO₂. This interaction may occur in the open ocean or within a controlled mCDR project facility. Each approach involves trade-offs: open ocean methods tend to be less energy-intensive but present greater uncertainties and challenges in measurement, reporting, and verification (MRV).

Understanding Direct Ocean Removal (DOR)

Direct ocean removal (DOR), also called direct ocean capture (DOC), removes CO₂ dissolved in seawater using the controlled acidification of seawater in a closed system using one of two primary methods: 

• Electrochemical methods such as electrolysis of seawater or electrodialysis
• The addition of minerals like olivine and basalt. 

The acidified and CO₂ depleted seawater is neutralized to native pH and allowed to equalize with and remove atmospheric CO₂. Once removed, CO₂ can be safely stored using geologic storage with a durability of >1,000 years.

Key Benefits of Marine Carbon Dioxide Removal

Understanding how mCDR works highlights its potential to address climate challenges. Here are the key benefits that make it a critical tool in global decarbonization strategies.

• Scalable carbon removal without land constraints: Marine carbon dioxide removal does not require large land areas or significant freshwater resources, making it highly scalable.
• Harnessing the ocean’s natural carbon sink: The ocean absorbs about 25% of human-generated CO₂ annually. mCDR enhances this natural process, increasing carbon storage without accelerating ocean acidification.
• Diverse technological pathways for flexibility: Technologies like ocean alkalinity enhancement and direct ocean removal offer flexible solutions tailored to different environments and project needs.
• Global reach with a large surface area: Covering over two-thirds of the Earth’s surface, the ocean provides an expansive platform for mCDR technologies globally. 
• Potential to mitigate ocean acidification: Some mCDR methods, such as ocean alkalinity enhancement, not only remove CO₂ but also help restore ocean pH levels, supporting marine ecosystem health.

Challenges of Marine Carbon Dioxide Removal

While mCDR holds significant promise, it also presents challenges that must be addressed for responsible deployment.

• Technical scalability and efficiency: Scaling mCDR technologies to achieve meaningful carbon removal while maintaining energy efficiency remains a significant hurdle.
• Potential environmental impacts: Altering ocean chemistry may pose risks to marine ecosystems, with long-term effects still not fully understood.
• Measurement, reporting, and verification (MRV) complexity: Accurately measuring CO₂ removal and ensuring its durability requires advanced monitoring systems, which are still evolving.
• Regulatory and governance gaps: Clear global policies are needed to oversee mCDR deployment, manage environmental risks, and ensure accountability.
• Public perception and ethical considerations: Concerns around geoengineering and potential unintended consequences may impact public acceptance and policy support.

Deploying Marine Carbon Dioxide Removal 

As mCDR technologies evolve, effective deployment will rely on adaptive management practices to address technical, environmental, and regulatory challenges. This includes robust MRV systems for accurate CO₂ removal tracking and continuous ecosystem monitoring to mitigate potential risks to marine life. 

Collaborative efforts between scientists, policymakers, and project developers are key to establishing clear regulatory frameworks, optimizing technologies for efficiency and scalability, and building public trust. These practices ensure mCDR can be scaled responsibly while safeguarding ocean health. 

The Future of Marine Carbon Dioxide Removal 

As technologies like ocean alkalinity enhancement and direct ocean removal advance, their potential to deliver large-scale, durable carbon removal is becoming increasingly evident. Realizing this potential requires more than technological innovation—it depends on rigorous environmental monitoring, transparent reporting, and strong collaboration among project developers, carbon buyers, and policymakers.

Establishing clear, consistent standards for high-quality mCDR is essential to ensure both climate effectiveness and environmental safety. To support this, Microsoft and Relae have partnered to develop the Criteria for High-Quality Carbon Dioxide Removal. 

Frequently Asked Questions

What is marine carbon dioxide removal (mCDR)?

mCDR uses ocean-based processes, primarily ocean alkalinity enhancement and direct ocean removal, to capture and durably store atmospheric CO₂. It works by increasing the ocean's natural capacity to absorb CO₂ without increasing acidification.

How does marine carbon dioxide removal compare to land-based methods like direct air capture or reforestation?

Unlike land-based approaches, mCDR doesn't require large land areas or freshwater, and the ocean's size gives it significant scaling potential. It's earlier-stage than more established pathways, though, with measurement and environmental monitoring standards still maturing.

Is marine carbon dioxide removal proven and scalable today, or still emerging?

mCDR technologies have shown promising results in lab testing and early deployments, but confirming safety and effectiveness at a large real-world scale requires more monitoring data. It's best described as an emerging pathway with strong near-term momentum, not yet a mature, at-scale solution.

What should a company look for when evaluating a marine carbon dioxide removal project or credits?

Buyers should look for rigorous carbon MRV paired with equally rigorous monitoring of ocean ecosystem health (eMRV), transparent reporting, and adherence to established frameworks like the Criteria for High-Quality Carbon Dioxide Removal.

Key Takeaways

• Near-term role for carbon removals: The revised Science-Based Targets Initiative (SBTi) Corporate Net Zero Standard (CNZS) v2.0 proposes requiring or recognizing interim carbon dioxide removal (CDR) targets before companies reach net zero. This shift aims to scale up the CDR industry in line with climate science and ensure companies address residual emissions earlier rather than deferring action until their net-zero target year.‍
• Revised target frameworks and increased accountability: The draft standard introduces key changes, including separate targets for scope 1 and 2 emissions, enhanced scope 3 target-setting guidelines, and the recognition of market-based mechanisms for indirect mitigation of scope 3 emissions. It also requires companies to publicly disclose transition plans and assess implementation progress against targets.‍
• Potential for stronger action on removals: While the proposed updates are a step forward, the final standard should make near-term CDR targets mandatory rather than optional and should expand to include those for projected scope 3 residual emissions, not just scope 1. Without these stronger mandates, demand for early-stage CDR investments may remain limited, potentially slowing progress toward net-zero goals.‍
• Companies should prepare now: Businesses should start integrating CDR into their climate strategies now so they are equipped to navigate procurement of high-quality removal credits in the voluntary carbon market. Preparing ahead of the final CNZS v2.0 release will help companies align with science-based decarbonization pathways and demonstrate climate leadership.

What the Latest SBTi Update Means for Corporate Climate Action

On 18 March, 2025, the Science Based Targets Initiative (SBTi) released its draft Corporate Net Zero Standard (CNZS) v2.0, significantly updating its framework for corporate net-zero target setting for the first time since 2021. The draft proposes new approaches for companies to support carbon dioxide removal (CDR) in the transition to net-zero emissions, a move that could help scale the nascent CDR industry.

This release is part of a broader revision, with key proposed updates including:

• Requiring public disclosure of transition plans after companies set targets.
• Separating targets for scope 1 and 2 emissions.
• Enhancing the scope 3 target-setting framework using an impact-based prioritization process.
• Recognizing indirect mitigation (e.g., book-and-claim commodity certificates) for hard-to-trace scope 3 emissions.
• Defining a role for emissions removals in the transition to net zero.
• Providing options to recognize company leadership in beyond value chain mitigation (BVCM).
• Assessing corporate progress against targets to bolster accountability.

While formal recognition of removals in the transition to net zero is a positive step, stronger incentives will be needed in the final CNZS to ensure companies take meaningful early action on CDR. The draft standard is open for the first of two public consultations until 1 June, 2025, with a finalized version expected to launch in 2026.

What Remains the Same From the Current Standard?

SBTi’s framework remains focused on three core requirements for companies:

• Reducing emissions year-on-year to reach an approved science-based target (SBT) by 2050 or earlier.
• Investing in beyond value chain mitigation (BVCM) in the transition to net zero to support near-term global decarbonization efforts.
• Neutralizing remaining emissions from the net-zero year (achieved after at least 90% emissions reductions) and onwards with high-quality, permanent carbon removal.

Carbon credits representing emissions reductions and removals remain ineligible for meeting reduction targets within a company’s value chain (SBTs).

What’s New in CNZS v2.0 for Carbon Removals?

Until now, the SBTi encouraged companies to invest in CDR through mechanisms such as BVCM, but has not proposed requiring removal before their target net-zero year. As a result, organizations had little clarity or incentive to invest in CDR ahead of their net-zero target date, dampening near-term demand for carbon removal and delaying the industry's growth.

The new draft changes this by proposing three options for the V2.0 Standard that address the impact of residual emissions during the transition to net zero:

• Option 1 (requirement): Companies are required to set near- and long-term removal targets, including interim CDR milestones,¹ to address projected residual emissions.
• Option 2 (optional with recognition): Companies can set and receive recognition for removal targets to address projected residual emissions.
• Option 3 (flexibility of mechanism): Companies have the flexibility to address expected residual emissions either entirely through additional emissions reductions within their value chain, entirely through removals, or via a combination of both.

Notably, all three approaches apply only to residual scope 1 emissions.

On top of these approaches, SBTi has suggested two options for the minimum durability threshold of CDR purchases in their draft standard. Removals will either need to follow a ‘like for like’ approach,² where CDR storage must match the atmospheric lifetime of residual emissions, or a gradual transition approach, where carbon storage durability increases over time.

Why Mandating CDR Matters

Mandating near-term CDR reinforces the need for immediate climate action, ensuring that carbon removals complement emissions reductions rather than being deferred until the net-zero target year. The urgency of early CDR investment is clear:

• Limiting global warming to well below 2°C above pre-industrial levels requires removing billions of tonnes (gigatonnes) of carbon dioxide annually by mid-century.
• The CDR industry is in its early stages and requires sustained investment today to scale in time.
• If companies wait until their net-zero year to purchase CDR, the supply of high-quality removal credits is unlikely to be sufficient.

As part of the proposed removal targets in Option 1 (above), the CNZS v2.0 would require companies to gradually increase CDR purchases over time, ramping up to 100% of a company’s projected residual scope 1 emissions in the net-zero target year (<10% of baseline year emissions).³

What More Can Be Done?

The potential introduction of required removal targets would be a significant and welcomed step, reinforcing the importance of near-term CDR investment to support industry maturation and climate goals. However, mandatory near-term CDR targets represent only one of three potential pathways for the V2.0 standard. Moreover, neutralization of residual emissions on the path to net zero is only proposed for scope 1 emissions. While the SBTi provides clear rationale for this,⁴ SBTi should not let the complexity of projecting scope 3 emissions be a barrier to climate change mitigation. Scope 3 emissions represent the majority of emissions from SBTi-aligned companies. Furthermore, companies with high scope 3 emissions typically have a higher ability to pay compared to their industrial counterparts with high scope 1 emissions.

If interim removal targets are made optional, and scope 3 emissions remain excluded, the demand signal for near-term CDR will be limited. The public consultation (and advice of Expert Working Groups that SBTi is convening) will be essential in determining which proposed guidance matures into the final standard; consultation feedback can be provided here prior to June 1, 2025.

How Businesses Can Prepare for CNZS v2.0

Companies aligning with SBTi’s evolving guidance should begin to integrate CDR into their climate strategy now. This means:

• Understanding their residual emissions forecast and planning early investments.
• Developing a company-specific climate strategy to incorporate CDR into their sustainability roadmaps in tandem with plans to reduce value-chain emissions.
• Engaging early in the voluntary carbon market to implement these strategies and develop procurement processes to support high-quality removal projects.
• Ensuring credibility by selecting removal projects aligned with scientific best practices.

Conclusion: A Step in the Right Direction, But More Certainty Is Needed

The CNZS v2.0 draft represents a critical turning point for corporate climate action with options to formalize the role of early CDR investment through interim removal targets for signatories. However, SBTi must take a stronger stance in the final version of the revised standard by choosing to adopt requirements for near-term neutralization (rather than leaving this optional), including projected residual scope 3 emissions in near-term CDR targets, aligning durability requirements with climate science, and defining removal quality standards to ensure these efforts drive meaningful climate impact. Organizations seeking to align with this guidance should prepare by developing a comprehensive climate strategy that accounts for science-based decarbonization pathways and recognizes the role of early-stage investment in CDR solutions.

Key Takeaways

1. The decision to fund a project is determined by a holistic review of project development maturity. This applies across capital-intensive projects, including low-carbon power generation, carbon capture and storage (CCS) solutions, sustainable aviation fuel (SAF), and broader transition infrastructure build-out. Both technical and commercial workstreams must be developed in parallel to avoid project failure. 
2. Early scope decisions, such as site selection, core technology selection, and nameplate capacity, are cheap to make but become exponentially disruptive and costly to reverse. 
3. Independent challenge and verification is tangible evidence of a disciplined, well-managed capital development process. 

Bridging the Gap from Announcement to Delivery

Among project developers, a perception often persists: seeking external review signals a project in distress. In capital budgeting discussions, subjecting engineering scope and commercial assumptions to third-party interrogation can be misconstrued as a vote of no confidence in the primary delivery team.

In reality, the reverse is true. Across complex infrastructure, independent challenge is the disciplined stage-gate practice that protects capital by reconciling technical reality with commercial terms before designs are locked.

Independent Challenge Is a Sign of Strength, Not Doubt 

Across capital projects, and in particular within emerging low-carbon industrial infrastructure, the gap between announced projects and delivered assets remains stark. Data from the Mission Possible Partnership’s Global Project Tracker reveals that fewer than 17% of announced commercial-scale clean industrial facilities worldwide have reached Final Investment Decision (FID) or commercial operations, leaving more than 800 major decarbonization projects stalled in front-end development.

The causes of developmental paralysis are multifaceted. While macroeconomic interest rate shifts and global supply chain disruptions sit largely outside a developer's control, project definition and developmental discipline remain entirely manageable. Even amid external volatility, a project designed with resilience will have a far greater likelihood of success.

Independent review and assurance directly strengthen a project’s chance of success and overall value. Large global project delivery organizations have applied this discipline for decades by deploying independent teams to evaluate project readiness at every stage gate. For teams lacking a dedicated internal oversight organization, or those deploying first-of-a-kind facilities, third-party independent review provides the necessary rigor to facilitate project success.

Relae’s (formerly Carbon Direct) work with Stockholm Exergi is a clear example: independent assurance helped build funder and regulator confidence in a first-of-a-kind carbon removal facility with no direct precedent to benchmark against.

Why Projects Stall Between Announcement and FID 

Low-carbon infrastructure and net-zero industrial projects carry unique risks compared to the repeat delivery of established designs. Exciting new developments run a higher risk of falling victim to optimism bias or compressing development timelines to meet public announcement milestones.

It is a natural human tendency for project champions to focus on the upside during early development. However, early momentum must be balanced with processes that reintroduce industrial lessons, supply-chain realities, and operational resilience.

Front-End Loading (FEL) is a well-evidenced approach for improving capital project outcomes. Decades of benchmarking by Independent Project Analysis (IPA) show that approximately two-thirds of industrial megaprojects suffer capital cost overruns or schedule slippage of 25% or more, or encounter severe operational problems lasting more than two years post-startup. This pattern is repeating in low-carbon infrastructure: IPA’s analysis of 12 completed low-carbon projects found average cost escalation of 31% and schedule slip of almost 50%. Rigorous front-end definition remains the single strongest predictor of whether a project will achieve its cost and schedule targets. 

As highlighted in the CDR 2.0: Five Pillars of Successful Project Deployment and Delivery report published by Relae, projects falter when developers push ahead without stress-testing the full delivery framework. Stage gate reviews are the mechanisms that evaluate the total project concept and underlying business case. They are most effective when executed as independent cold-eye evaluations prior to each funding gate, identifying and mitigating vulnerabilities long before final investment decisions are reached. 

What Funders Need to See at Each Gate 

Different stages of project development rely on distinct capital sources, each requiring specific proof points before deploying funds.

Before FEED Funding: Justifying the Engineering Spend

Front-End Engineering Design (FEED) is a major financial commitment, typically costing between 2% and 4% of total project capital cost. The funders backing this stage are usually the developer’s own balance sheet equity, strategic partners, or public grant programs. Before allocating millions of dollars to detailed engineering, these funders need confidence on the fundamentals:

• A technically sound process concept, confirmed utility balances, and an energy integration scheme that fits the site.
• Secured site control, clear zoning pathways, and no environmental fatal flaws that could derail permitting.
• Documented availability of required feedstocks, water and power, paired with demonstrable interest from target off-takers.

Before FID: Proving Bankability and Commercial Closure

As a project approaches FID, the funding audience shifts to conservative commercial lenders, infrastructure funds, and binding offtake counterparties. These capital providers are not underwriting strategic vision; they are underwriting long-term operational cash flows and debt service. Depending on the project and financing structure, capital providers may require:

• A high-confidence capital cost estimate (AACE Class 2 or Class 3) backed by frozen Piping and Instrumentation Diagrams (P&IDs), firm equipment quotes, and a realistic execution schedule with clear critical paths.
• Bankable engineering, procurement, and construction (EPC) structures that clearly allocate risk, include performance guarantees and enforceable liquidated damages.
• Fully executed, binding offtake and feedstock agreements, along with non-appealable permits and completed utility interconnection agreements, with remaining conditions clearly understood.
• An objective, third-party challenge review that assesses operational viability and distinguishes an executable engineering plan from an aspirational concept.

Commercial and Technical Co-Development: The Stage-Gate Method in Practice

A project rarely fails because of an isolated mechanical issue or a purely commercial misstep; failure happens when technical decisions and commercial terms are negotiated in silos and decisions are made without understanding of the wider implications. 

We see this disconnect play out in several ways, including: 

• Sizing capacity before testing market demand: An engineering team may size a facility to maximize thermodynamic efficiency and economies of scale, only for the commercial team to discover buyers will only commit to half that volume. The developer is left with an oversized, unbankable design requiring fundamental rework. 
• Setting product specifications before negotiating offtake: Process engineers frequently design systems around standard vendor packages. However, when downstream transport, processing, or storage networks enforce strict purity standards, the facility faces costly equipment redesigns. This issue has materialized directly within European CCS networks. Open-access offshore storage operators, such as Norway's Northern Lights project, established strict cross-border CO₂ specifications requiring tighter moisture and impurity thresholds than originally designed for. 
• Locking Electrical Loads Prior to Interconnection Verification: As detailed in Relae’s analysis of physical infrastructure bottlenecks, scale is rarely constrained by capital availability; it is dictated by electrical transmission queues, substation headroom, and 24/7 firm power availability. Freezing electrical demand before verifying utility interconnection timelines risks stranding engineering work on an asset that cannot connect to the grid. 

How Relae Stress Tests Projects at Each Gate 

Independent reviews at each stage-gate improve success rates by stress-testing assumptions before presenting to lenders, infrastructure investors, or corporate buyers. Relae reviews projects across five categories using the TECOP framework:

• Technical: Verifying technology readiness levels (TRL), mass and energy balances, plot plan constructability, and operational availability under real-world conditions.
• Economic: Capex benchmarking, operating contingency adequacy, utility tariff sensitivities, and financial model cash-flow resilience.
• Commercial: Offtake agreement structures, feedstock contracts, contracting boundaries, EPC contract structures, and counterparty creditworthiness.
• Organizational: Owner's team capabilities, internal stage-gate governance, contractor oversight mechanisms, and execution capabilities. 
• Political: Statutory permitting status, regulatory durability, carbon market policy exposure, and local community social license.

The TECOP framework is relevant for evaluating delivery risk across all project types, see more in Relae’s Criteria for High-Quality Carbon Dioxide Removal, Delivery Risk Appendix.

What makes this approach effective is sitting on both sides of the table. Having completed over 250 deep-dive technology reviews, 900+ project evaluations, and advised on more than $6 billion in industrial project finance, Relae has extensive experience evaluating the considerations important to institutional funders and buyers.

The Value of Early Independent Project AssuranceIncorporating independent review should be standard practice for modern infrastructure delivery. Because funders will perform their own rigorous diligence regardless, conducting an independent evaluation early enables developers to address vulnerabilities proactively and present a more resilient business case.

Commissioning an independent team for a cold-eye review during early project formation can be a  cost-effective way to identify potential risks before they become expensive to address. Catching an unworkable process assumption, an oversized capacity plan, or a misaligned commercial interface during pre-FEED costs a tiny fraction of what it takes to fix those issues during construction

Ultimately, independent challenge is not an admission of doubt, but the disciplined stage-gate practice that protects capital by reconciling technical reality with commercial terms before designs are locked, signaling to partners, and your future funders that your project is built to deliver. 

To dive deeper into the frameworks that support successful projects, read Relae's white paper: CDR 2.0: Five Pillars of Successful Project Deployment and Delivery and take a look at project assurance in action through our Stockholm Exergi Case Study.

Frequently Asked Questions

What is independent project assurance?

Independent project assurance is a structured review of a capital project by a team that sits outside the project’s delivery organization. Reviewers test the engineering scope, cost estimate, schedule, commercial agreements and permitting position against what funders will require at the next stage gate. The developer receives a clear list of gaps, risks and proposed mitigations prior to presenting the project to lenders, investors or buyers.

When should a developer commission an independent project review?

Periodically throughout the project development process - at a minimum before each major funding gate, but smaller reviews are also beneficial at earlier stages when key concept and technology decisions are being made. A review before Front-End Engineering Design (FEED) tests whether the process concept, site and supply of feedstock, water and power justify the engineering spend. A review before Final Investment Decision (FID) tests whether the cost estimate, EPC structure and binding agreements will satisfy lenders. Site, technology and capacity decisions are cheap to change in pre-FEED and expensive to reverse once detailed engineering starts.

What does an independent project review assess?

Relae structures its reviews around the TECOP framework, which covers five risk areas: technical (technology readiness, mass and energy balances, constructability), economic (capex benchmarking, contingency, financial model resilience), commercial (offtake, feedstock and EPC contracts), organizational (owner’s team capability and stage-gate governance) and political (permitting, regulatory durability and social license). Reviewers also check that technical and commercial decisions are aligned, because projects often fail where the two are developed in silos.

How does an independent project review differ from lender due diligence?

An independent project review applies a holistic approach identifying not only gaps, but also opportunities to add value and strengthen the business case. Lender and investor due diligence is often purely looking at risks and gaps, prior to committing capital. Lender diligence protects the funder and reports its findings at a point when changes are costly and can delay financial close. A developer-commissioned review takes place earlier, so the project team can fix weaknesses in scope, cost or contracts before funders see them.

Key Takeaways

• Biochar is the fastest-growing durable carbon removal method in the voluntary carbon market, accounting for 93% of all durable removal volumes contracted in the first quarter of 2026 alone.
• Scientists still have an incomplete understanding of biochar durability in soils, and there is some uncertainty regarding biochar's ultimate climate impact.
• Biochar carbon removal crediting must reflect conservative, science-based estimates of durability to safeguard against overcrediting.
• Relae’s (formerly Carbon Direct) detailed analysis highlights the key scientific issues affecting biochar soil durability to better inform credible carbon removal.

Biochar Is Gaining Momentum in Carbon Removal

Biochar has entered the spotlight as a scalable climate solution. It is being adopted for its carbon storage potential and agricultural co-benefits. Commercial uptake of biochar has expanded dramatically since 2019 and continues to accelerate, due to the voluntary carbon market. In the first quarter of 2026 alone, 2.3 million tonnes of total durable carbon dioxide removal (CDR) have been contracted, with biochar accounting for 93% of that volume, driven substantially by a single Microsoft-Liferaft deal for one million tonnes. Established and emerging CDR registries have developed biochar protocols and are certifying biochar carbon credits.

In addition to CDR, biochar can bring numerous co-benefits when it is applied to soil. These benefits include improved water and nutrient retention, pH adjustment, and pollution remediation. In agricultural and forage systems, improvements in soil quality following biochar application can lead to enhanced plant growth. Biochar also promotes rural economic development and can be a part of a circular economy that stewards its resources judiciously.

As purchases of biochar credits grow, a central question has not yet been fully answered: How durable is biochar carbon storage, and what are the best methods to assess this? This blog explores the science of biochar durability, also known as permanence, and how credible science can inform the carbon removal market.

What Is Biochar and How Is It Made?

Biomass heated in an oxygen-deficient environment produces biochar, a solid, carbon-rich material. In the near or full absence of oxygen, that process is called pyrolysis. Biochar can be produced from various kinds of biomass, including agricultural or forest residues, construction debris, organic waste, seaweed, and more. Biochar is also gaining attention for its potential as an ingredient within engineered materials, such as cement.

Biochar achieves CDR by durably storing carbon dioxide (CO₂) that was removed from the atmosphere via photosynthesis and plant growth. Carbon stored in living plants will stay stored during the plant’s lifespan. Once it dies, a plant’s biomass decomposes, cycling most of the stored carbon back into the atmosphere. By introducing technological interventions into this carbon cycle, such as using pyrolysis to produce biochar, the carbon that nature captured via photosynthesis can be stored longer than it would have been otherwise. Pyrolysis converts some of the carbon from biomass into chemical compounds with a higher resistance to environmental degradation. How much carbon converts to these more recalcitrant forms depends on the type of biomass used and the heating conditions, including temperature and time. After biochar is produced, the highly recalcitrant fraction of carbon can be stored for long periods of time, as long as the biochar does not combust.

Common methods of biochar production include:

• Industrial pyrolysis systems: Modern pyrolysis systems heat biomass in a low or no-oxygen environment, creating biochar and gaseous compounds known as synthesis gas. Synthesis gas is typically combusted in a controlled system to provide heat for the system. Low air emissions can be achieved for these systems, which is important to maximizing the environmental benefits of biochar production.
• Modular pyrolysis systems: Smaller, transportable pyrolysis units serve farm-scale or decentralized production. Unlike open kilns, these systems retain temperature control and sensor-based monitoring similar to industrial pyrolysis, and some use autothermal designs that recycle non-condensable gases for heat rather than relying on an external energy source. This makes them a middle option for smaller producers seeking more process control and emissions oversight than open-kiln methods allow, without the capital cost of a large, fixed industrial plant.
• Kon-Tiki kilns: This is a less complex and, therefore, more widely deployable method of biochar production. However, air pollution from this method is likely to be higher than from industrial pyrolysis and can be significant enough to undermine the carbon benefits of biochar production. In Kon-Tiki kilns, biomass is burned in an open-top, conical kiln. Biomass is continually added to the process and finally quenched with water.
• Trench mounds: Trench production is one of the simplest forms of biochar production and is used often by smallholder farmers. Biomass is buried in a trench, covered, and combusted to produce biochar. Air pollution from tench mound production is likely to be significant and even higher than from Kon-Tiki kilns.  

How Biochar Durability Is Quantified

Durability, or permanence, is a key metric used to quantify carbon removal from biochar; it describes the amount of carbon that remains stored in biochar for 100 years or more after it is applied to soil.

Quantifying durability relies on experiments and models to project permanence. There are a number of established and emerging approaches to evaluating biochar recalcitrance to chemical decomposition and storage permanence. Most of these are based on short-term incubation experiments in laboratories, where scientists seal biochar in a container with other organic matter and measure carbon changes over a period of weeks to months. These approaches typically treat biochar as having multiple pools of carbon that differ in their ability to resist decomposition.

While these experiments offer insights into decomposition dynamics, they have two significant limitations. First, these approaches do not measure biochar decomposition and durability in the real world (e.g., after biochar is applied to agricultural soils), meaning they do not capture the effects of actual soil and other environmental factors. Research has shown that different soils can strongly influence decomposition rates. Second, the short duration of these experiments means there is significant potential for error in extrapolating the results to time periods of centuries and beyond.

Why Quantifying Durability Accurately Is Critical

Biochar CDR certification methodologies use a range of approaches to quantify permanence. Most commonly these are based on biochar’s chemical composition, namely the hydrogen-to-organic-carbon ratio (H/Corg). Models that correlate H/Corg with projected permanence, from decay models applied to biochar decomposition experiments, are used to calculate a permanence factor. Other quantification methods include measuring the random reflectance of biochar to estimate the amount of highly recalcitrant carbon in biochar.

The risks of inaccurate durability estimates for carbon removal buyers are significant. Overestimating durability can lead to ineffective CDR spending, reputational risk from overstated climate impact, and delayed progress on net-zero and compliance goals. Buyers need to understand and engage with durability estimation methods to ensure they are procuring high-quality biochar credits.

Why Underground Coal Isn't a Valid Durability Comparison

Recent research proposes a new approach to quantifying biochar durability. The authors assert that random reflectance—a parameter developed in the field of organic petrology (the study of organic matter in rocks)—can be used to characterize durability. Using a component of coal (known as "inertinite") as an analogue for biochar, they propose a benchmark random reflectance of 2% as an "inertinite benchmark" for biochar. They argue that the entire fraction of biochar that meets that benchmark will degrade over approximately 100 million years. This is a large departure from other estimates of biochar durability, and we believe this to be at odds with more conservative models.

There are several reasons to doubt this method. The coal-biochar analogy is inadequate because coal buried underground is not exposed to the same degradation conditions as biochar in soil. Underground coal has lower exposure to oxygen, water, and ultraviolet light, all of which are plentiful in surface soils. Each of these is associated with well-understood decay mechanisms. Furthermore, the process of geologic burial dramatically changes the physical structure of organic matter. Additionally, the permanence factor that the reflectance method allows (i.e., up to 100% carbon retention over extremely long time scales) contradicts experimental evidence that some carbon loss will occur over years or decades.

Subsequent research from the same authors has since recommended pairing random reflectance analysis with H/Corg rather than relying on either alone. This is a refinement of the original approach meant to support more reliable quantification of biochar durability and avoid overcrediting CDR from biochar.

Where Biochar Science Is Headed Next

Biochar stability science will keep advancing. Research into biochar degradation pathways in soil will continue to refine permanence models and inform the relevance of coal analogues. Long-term field measurement studies, with a high density of in-soil sampling to quantify persistence over time, should be a near-term priority that biochar CDR projects can contribute to. Additional studies should investigate pathways to increase durability and rigorously develop modern isotopic, spectroscopic, and chemical techniques for enabling robust assessments of biochar durability.

Crediting Biochar Means Getting Durability Right

Biochar is a promising solution for both soil health and climate impact. Nevertheless, carbon removal certification protocols will need updating as the science of biochar durability evolves. Relae cautions against excessively generous claims of biochar CDR durability, in both permanence factor and timeframe, given the important uncertainties outlined above.

Protocols should not outpace science in terms of permanence assessment, and crediting should stay rooted in an understanding of what drives biochar permanence that is backed by science, including production conditions (e.g., high temperatures) and biochar composition (i.e., low H/Corg). At a time when investment in biochar is booming and the science of biochar is evolving, the voluntary carbon market must keep pace.

Frequently Asked Questions

Is biochar carbon negative?
Biochar can provide net carbon dioxide removal when the amount of carbon durably stored exceeds the emissions associated with producing, transporting, and using the biochar. Plants capture CO₂ from the atmosphere through photosynthesis and store that carbon in biomass. Left alone, most of that carbon returns to the atmosphere within years to decades as the biomass decomposes or burns. Converting biomass to biochar stabilizes a portion of that carbon into forms that can stay stored for centuries or longer, delivering a net removal once those production emissions are accounted for..

Is biochar considered an engineered, hybrid, or nature-based carbon removal solution? Biochar is considered a hybrid carbon removal solution because it combines natural carbon uptake through photosynthesis with a technological intervention. Biomass first removes and stores atmospheric carbon as it grows, and pyrolysis then converts a portion of that biomass carbon into more stable forms that keep carbon from returning to the atmosphere for longer periods.

How do carbon removal registries currently estimate biochar's durability? Registries use decay models based on biochar's ratio of hydrogen to organic carbon (H/C_org ratio), which correlates with how resistant the biochar is to microbial breakdown, combined with environmental factors where biochar is applied, like soil temperature, moisture, and application context, to estimate what fraction of the carbon remains stable (i.e., not converted back to CO₂) over a defined timeframe. Methodologies typically also require third-party lab testing of feedstock and pyrolysis conditions to substantiate durability claims. Some registries and methodologies also incorporate random reflectance as part of durability quantification, although the scientific basis for using reflectance to estimate long-term biochar durability remains under debate.

How long does biochar actually store carbon? 

Biochar does not have a single storage lifetime. Some of its carbon decomposes relatively quickly, while more stable fractions can remain stored for centuries or longer, depending on the biochar’s properties and the conditions where it is stored. Because these estimates rely on models rather than direct observation, carbon crediting has to balance two risks: crediting more durability than actually exists, and being so conservative it undercredits real removals and threatens project viability.

Key Takeaways

• Relae (formerly Carbon Direct) has conducted over 900 comprehensive, rigorous reviews of carbon removal (CDR) projects around the world. But fewer than 10% meet our standard for high-quality. In today’s market, scientifically-credible CDR supply is scarce.
• To identify high-quality projects, buyers and investors previously had to commission numerous deep diligences, which often made it a lengthy and complex process, not well-suited to most market participants. 
• The Diligence Collection changes that paradigm by giving you direct access to existing comprehensive analysis on a curated set of high-quality CDR projects. The hard work of identifying high-quality projects is already done, allowing you to move faster, spend less, and procure with more confidence.

Relae Sets the Bar for High-Quality CDR

Since 2020, every year Relae has released an updated version of the Criteria for High-Quality Carbon Dioxide Removal in collaboration with Microsoft. The Criteria set the standard for scientific rigor across nine CDR pathways and across six technical dimensions. Using this standard, the Relae team has conducted diligence on over 900 CDR projects across 63 countries. Our diligence has been used for over 50% of all tonnes contracted through announced CDR offtake agreements worldwide, including diligence for the majority  of tonnes from Microsoft’s announced offtakes. This gives Relae a uniquely deep understanding of the CDR market; and importantly, it has highlighted that high-quality projects in the voluntary carbon market are scarce. 

Quality Is the Central Challenge in CDR Procurement 

Only 10% of the projects that Relae has assessed meet our high-quality criteria. This means that without rigorous, scientific assessment, buyers and investors run real risk of exposing themselves to delivery shortfalls, financial loss, and reputational damage. 

This presents a series of challenges to buyers and investors interested in procuring or investing in CDR. Conducting diligence on CDR projects is time-intensive, complex, and requires deep expertise. Building the internal capacity to rigorously evaluate a wide variety of CDR projects isn’t practical for most actors. But conducting the in-depth diligence required to procure or invest confidently requires real commitment, especially when a significant proportion of the projects diligenced may not be high-quality. Finding the needle in the CDR haystack isn’t easy.

The Case for Curated CDR 

The Diligence Collection directly addresses these challenges by providing self-serve access to diligence on a curated set of high-quality CDR projects vetted by Relae. Every project has already been evaluated against the Criteria for High-Quality Carbon Dioxide Removal, the science-based benchmark jointly established by Relae in collaboration with Microsoft. The Collection includes projects reviewed on behalf of Microsoft and other major buyers, and more broadly reflects our diligence work across the market.

With the Diligence Collection, you're not starting from scratch. Instead, you're starting from a shortlist of some of the highest-quality CDR opportunities available, with robust scientific diligence to back them up. The bottleneck that's slowed procurement for so many organizations is no longer a concern.

The Collection offers two levels of diligence, matched to the level of scrutiny your commitment warrants:

1. Desk review: An executive-level assessment using available project documentation, enough to make an informed shortlisting decision or purchase.
2. Deep diligence: A comprehensive technical evaluation covering project design, operational risk, technology assessment, policy landscape, and community impacts, reflecting the same methodology that's informed the procurement programs of Microsoft and other major buyers.

Both tiers include the option to commission an updated evaluation as your needs evolve.

What Rigorous CDR Diligence Involves 

The depth of Relae’s diligence sets the Diligence Collection apart. Our desk review process involves conducting detailed assessments to evaluate projects against 6 quality principles: social harms, benefits, and environmental justice; environmental harms and benefits; additionality and baselines; measurement, monitoring, reporting, and verification; durability; and leakage. The result is a comprehensive report that assesses projects against these criteria, highlighting the project's overall quality, strengths, and weaknesses in a clear, succinct way that supports decision-making. 

Many of our reports dig even deeper. Our deep diligences assess both a project’s quality and its delivery risk. To evaluate delivery risk, we assess projects across 5 elements: technologic, economic, commercial, operational, and political. Deep diligence is conducted over 3-4 months, which includes weekly back-and-forth with the supplier and a site visit to understand all of the nuances of the project and validate developer claims on the ground. The resulting report not only documents a project's strengths and weaknesses, but also outlines risk mitigation measures and recommends improvements over time. 

Broader Access, Stronger Market 

Forward offtake demand in the CDR market has historically concentrated among a handful of large buyers, and as our 2026 State of the Voluntary Carbon Market report notes, diversifying that pool is essential to enabling the next generation of CDR supply. The Diligence Collection is built to support exactly that. By making the scientific rigor behind the world's largest CDR transactions available through a self-service platform, it opens credible procurement to organizations at any stage of purchasing. More buyers accessing high-quality, de-risked projects means more capital flowing to suppliers, more projects able to scale, and a more resilient market that doesn't depend on a small number of actors to function.

High-quality CDR supply is scarce, and the best projects are in high demand. The Diligence Collection gives you the foundation to act efficiently and with confidence, without starting from zero.

[cta]

Frequently Asked Questions

Who Can Access the Relae Diligence Collection?

The Diligence Collection is available to approved subscribers, including CDR buyers and investors seeking to more efficiently evaluate carbon removal projects. To preserve the independence and integrity of the Collection and protect proprietary diligence insights, access is not available to project developers or rating agencies.

How Is the Relae Diligence Collection Different From a Rating Agency or Market Intelligence Platform?

Most rating platforms optimize for quantity; we optimize for quality. Our process includes pathway-specific risk assessments and, in many cases, site visits from our in-house scientists, engineers, and technical experts—the same multidisciplinary team and judgment behind our own portfolio decisions and the procurement programs we support directly. The Collection also includes projects diligenced before they've received external ratings, giving you visibility into promising opportunities at the pre-commercialization stage.

Does Inclusion in the Relae Diligence Collection Mean Relae Endorses a Project?

Inclusion means a project was evaluated through our scientific diligence process and, at the time of review, met our Criteria for High-Quality Carbon Dioxide Removal. It reflects a positive diligence outcome based on the information available during the review and the project's stage of development at that time. As projects and market conditions evolve, we recommend considering whether updated diligence or additional evaluation is appropriate for your specific procurement or investment objectives.

Can I Request Diligence on a Project That Isn't Already in the Collection?

Yes. You can commission us to diligence a specific project based on your procurement or investment priorities. Whether it's later added to the Diligence Collection depends on a few factors beyond just meeting our quality bar, including consent from you as the commissioning buyer and approval from the project developer.

Key Takeaways

• The Nasdaq Carbon Issuance Calendar, a new data platform, provides carbon removal buyers and suppliers with standardized information on future offtake availability, indicative pricing, and project maturity. The platform was developed in collaboration with Relae, formerly Carbon Direct.
• The Carbon Issuance Calendar addresses the fragmentation and transparency problems of the voluntary carbon market by centralizing standardized project data and embedding our scientific diligence framework, built over 900 project reviews, giving buyers delivery-risk insight that no registry or marketplace offers today.
• The Carbon Issuance Calendar is an important early step, not the whole journey: it shows buyers what durable tonnes exist and allows them to compare projects with apples-to-apples data. 
• Buyers can move from the Carbon Issuance Calendar into technical diligence, contracting, and project assurance with Relae’s advisory team. Suppliers can register to connect with buyers who are ready to engage.

Carbon Removal Project Data Has a Visibility Problem

If you're sourcing durable carbon removal credits, you may run into a familiar wall: project data scattered across dozens of developer websites, presented in inconsistent formats, with no easy way to compare one project against another. If you're a project developer, you face the mirror image of that problem: fielding individual requests for proposals, with no central place to showcase your available tonnes.

Get this wrong, and buyers may end up counting on carbon removal that never shows up - the delivery risk bugbear.

Between 2022 and 2024, high-durability engineered carbon removal made up just 2 percent of all carbon credit issuances. They remain in short supply, particularly the high-quality supply corporate buyers need. The gap is set to widen: our 2026 State of the Voluntary Carbon Market report found that more than 80% of the 2030 high-durability carbon removal projects are at risk of stalling and failing without additional offtake and financing commitments.

The Nasdaq Carbon Issuance Calendar, developed by Nasdaq in collaboration with Relae, offers an important first step toward addressing this information gap.

What Is the Nasdaq Carbon Issuance Calendar?

The Carbon Issuance Calendar is a centralized, accessible dashboard where carbon removal buyers and suppliers view standardized project data: future credit availability, indicative pricing, and project delivery status, all in one place. 

The Nasdaq Carbon Issuance Calendar combines structured, developer-provided project data with project maturity assessment informed by Relae’s assessment framework and technical diligence. This helps users understand future CDR availability, indicative pricing, and potential project delivery risk through a single platform.

This expertise didn't appear overnight. It comes from sitting across the table with developers, stress-testing their science, mapping their delivery timelines against reality, and helping them show up to buyers as credible partners. The result is a track record that gives the framework embedded in the Carbon Issuance Calendar its depth. It's a starting point, built for buyers and suppliers to find each other on the basis of consistent, comparable information, using international class financial and information infrastructure.

How Buyers Should Use the Nasdaq Carbon Issuance Calendar

Today, if you're trying to procure durable carbon removal credits, you have no single place to start. You have to visit individual developer sites, request information through scattered channels, and compare projects that present data in entirely different formats before diligence has even begun. In many cases, you are comparing apples to oranges - different kinds of CDR projects with different durabilities, risks, and overall quality. 

The Carbon Issuance Calendar provides a central starting point. You can view future credit availability, compare indicative pricing across projects, and begin assessing options without contacting each supplier one by one.

More importantly, the Carbon Issuance Calendar frames the data. Our scientists developed a delivery-oriented lens, built from reviewing over 900 carbon removal projects, drawing on the same rigor behind our Criteria for High-Quality Carbon Dioxide Removal, which we develop annually with Microsoft.

How Suppliers Reach Buyers Through the Carbon Issuance Calendar

If you're a project developer, the Nasdaq Carbon Issuance Calendar tackles visibility, one of the most persistent barriers to market access. You can list available tonnes, display indicative pricing, and reach a global audience of corporate and financial buyers at no cost.

The timing matters. Many first-of-a-kind engineered carbon removal projects are preparing to break ground and need bankable offtake agreements to secure financing before they can do so (a key aspect of CDR 2.0). Our analysis of approximately 140 high-durability carbon removal project developers found scale-up plans for 30 million tonnes of supply per year. Reaching that potential will take real demand: committed forward offtake, increased project equity investment, and access to lending. 

Register now: you'll be positioned to connect to buyers actively looking to engage.

How Does the Carbon Issuance Calendar Differ From a Carbon Credit Registry or Carbon Removal Marketplace?

The Carbon Issuance Calendar solves a distinct, early-stage problem. It gives buyers and suppliers a centralized place to find each other and compare options against standardized information, something neither a registry nor a marketplace is built to do.

For a closer look at how registries differ and what you should weigh when navigating them, read our Navigating Carbon Credit Registries report.

Scientific Diligence Turns Visibility Into Confidence

Standardized data tells you what exists. Scientific diligence tells you what's worth pursuing. 

Relae’s scientists do that work every day. Our experts apply rigorous pathway-specific criteria to live projects, evaluating delivery risk and status, and identifying where questions remain is the core of what we bring to the carbon removal market.

The Carbon Issuance Calendar puts an accessible version of that expertise at the top of the procurement funnel. It’s for everyone in the market - you don't need to be a carbon removal scientist to use it. This snapshot allows you to compare projects against each other, giving you a meaningful starting point before deeper diligence begins. 

Want to go deeper on a specific project? Relae’s technical diligence team picks up right where the Carbon Issuance Calendar leaves off.

What Carbon Removal Projects Are on the Carbon Issuance Calendar Today?

The Carbon Issuance Calendar currently features engineered and hybrid carbon removal projects: direct air capture, biochar, enhanced rock weathering, and bioenergy with carbon capture and storage. These high-durability pathways offer permanence on the order of hundreds to thousands of years.

Many of these projects are at an inflection point: they’re ready to scale but dependent on committed offtake to unlock financing. The Calendar serves their needs, and the buyer’s needs, together.

Nature-based carbon removals have their own criteria and market dynamics. They may appear in a separate segment of the Carbon Issuance Calendar down the line.

From the Carbon Issuance Calendar to Completed Carbon Removal Procurement

If you're building or refining a carbon removal procurement strategy, the Carbon Issuance Calendar is the right place to start. 

From there, you can choose to work with the Relae advisory team to support every later stage: technical diligence on specific projects, contracting and negotiation support, ongoing project assurance, and access to curated carbon credit sourcing. The Carbon Issuance Calendar surfaces the market; we help you navigate it, connecting you with the right developers, on the right terms, with the scientific confidence to move forward.

Moving from commitment to delivery takes structural change across the market, too—our CDR 2.0 white paper lays out the five pillars we see as essential to getting engineered and hybrid carbon removal projects built and delivering.