Independent Project Assurance Is Likely Your Best-Returning Spend

Key Takeaways

• The UK's new biomass Contracts for Difference framework will cut industrial wood pellet imports by slightly more than half starting in April 2027. As a result, US producers will be left competing for only 1.6 million GST, an 80% reduction in US-addressable volume, with no successor market locked in.
• US wood pellet producers who move now to upgrade sustainability credentials and build relationships in emerging markets will be best positioned to capture the next generation of demand; those who wait may find the most attractive offtake opportunities already structured around someone else's supply.
• Four domestic markets now present producers with new demand opportunities: cofiring, sustainable aviation fuel (SAF), low-carbon steel, and bioenergy with carbon capture and storage (BECCS). Of these, BECCS for data centers is the strongest structural fit: hyperscalers need clean firm power, pellet mills need offtakers, and the feedstock infrastructure is already in place.

The Demand Cliff Is Real, and the Timeline Is Short

A pellet made in southern Mississippi this morning will be burned in a UK boiler about four weeks later. North America is on pace to ship more than 9 million green short tons (GST) of pellets to the UK each year—making the UK the world's largest consumer of wood pellets since 2018. The US Southeast is at the center of that supply chain: 28 large mills, 13.5 million GST of production capacity, rail spurs, export terminals, and bulk carriers, built almost entirely around UK demand.

However, the UK's new low-carbon Contracts for Difference (CfD) framework caps biomass power generators at a 27% annual capacity factor starting April 2027, down from roughly 64% today. When run hours fall by half, pellet demand follows. Existing subsidies expire in the first quarter of 2027, and the new CfD runs only to March 2031 with no commitment beyond that. Plant closures in Arkansas and Washington state, along with reduced output in Canada, are already early signals of supply chain contraction.

The Math of Who Gets Squeezed

The math is stark. By the second quarter of 2027, total annual UK pellet demand drops to 4.9 million GST. Of that:

• Approximately 2.3 million GST goes to captive, integrated UK supply chains.
• Approximately 1.0 million GST goes to Baltic suppliers, whose shipping times of one week or less become a decisive advantage as UK plants shift from baseload to dispatchable operation.

That leaves US producers competing for only 1.6 million GST. If Baltic suppliers capture more, US wood pellet exports to the UK could be effectively eliminated by 2031.

Sustainability qualification is also tightening. The new CfD cuts the supply-chain emissions ceiling from 55.6 grams of carbon dioxide equivalent per megajoule (gCO₂e/MJ) to 36.6 gCO₂e/MJ. The framework assesses compliance mill by mill, not on a portfolio average. A cleaner mill cannot carry a dirtier sibling through the door.

The producers who understand this math now have roughly 18 months to position themselves for what comes next.

From Stranded Supply to New Markets

The US Southeast's wood basket is robust: abundant inventory, strong growth-to-removal ratios, and more available residues than ever. The infrastructure is in place. The question is whether the next generation of markets can be developed quickly enough to redeploy this supply before the infrastructure sits idle.

Four pathways stand out as the strongest options for redeploying US pellet supply: BECCS for data centers, low-carbon steel, SAF, and domestic cofiring. We have rigorously assessed the logistics economics, sustainability cases, and project development for each.

BECCS for Data Centers: The Strongest Structural Fit

BECCS as a power source for data centers is the most compelling match for the situation pellet producers now face. The timing, feedstock requirements, and buyer characteristics align closely in a way that few other emerging markets can match.

Hyperscalers, the large data center operators driving an unprecedented surge in electricity demand, are signing deals for nuclear, geothermal, and small modular reactors alongside natural gas and renewables. They are doing this because annual Renewable Energy Certificates (RECs) are no longer sufficient to compensate for their scope 2 emissions, and they need clean, firm generation that can be matched to load on an hourly basis.

BECCS delivers exactly that. The Louisiana Green Fuels project—advanced by Strategic Biofuels and Relae (formerly Carbon Direct)—illustrates the model: regionally sourced forestry residues and sawmill waste generate 75 megawatts (MW) of firm electricity while sequestering over one million tonnes of CO₂ annually in deep saline formations. An ample supply of wood pellets creates a strategic opportunity for similar projects to move forward with certainty around feedstock processing, logistics, and costs.

The remaining commercial barrier is deal structure, not technology. No data center operator has yet signed an agreement to purchase both the electricity and carbon removal credits from a single BECCS plant. As scope 2 accounting tightens and domestic pellet supply becomes more readily available post-2027, the conditions for structuring the first such deal are improving fast.

"Pellet mills and data center developers have complementary problems: mills need offtakers, and data centers need local, dispatchable, clean power they can match to load on an hour-by-hour basis. BECCS is one of the few technologies that could solve both at once, and hyperscalers have shown they are willing to back early-stage clean firm power when the asset makes sense."

—Douglas Bryan, Senior Power and Energy Systems Modeler

Low-Carbon Steel: Certification Frameworks Are Arriving

Wood-derived biocarbon has a long-established niche in steelmaking. Brazil produces roughly 10% of its steel and 30% of its pig iron using charcoal from managed eucalyptus plantations—a proof of concept for biomass as a metallurgical input, if not a direct template for US producers. The plantations measurably lowered groundwater in producer regions of Minas Gerais, and charcoal's mechanical weakness relative to fossil coke has limited the model's reach beyond Brazil.

Current pilot projects use biomass in two roles. As a fuel, industrial trials have demonstrated 10% bio-coal co-injection without operational disruption, with reviews estimating that full replacement could cut blast-furnace CO₂ by around 27% per tonne of hot metal. As a reductant, biocoke is already being demonstrated at Outokumpu's pelletizing plant in Tornio, Finland. ArcelorMittal in Belgium and Tata Steel in India are running biomass pilots at tens of thousands of tonnes per year.

What makes this market worth serious attention now is the certification landscape. The Low Emission Steel Standard issued its first certifications in September 2025. The Global Steel Climate Council's Steel Climate Standard is under stakeholder review. In May 2025, Relae and Microsoft published Criteria for High-Quality Environmental Attribute Certificates in the Concrete and Steel Sectors. These frameworks allow producers to internalize carbon price and environmental attribute certificate (EAC) values, closing the cost gap against fossil coke that has historically constrained biocarbon demand.

Relae worked with Eramet, a global metals company pursuing biogenic materials as a substitute for fossil coke at its Norwegian smelters, to assess high-quality carbon dioxide removal methodologies and chart a path to generating and selling carbon credits from their decarbonization projects. Producers who align their sustainability credentials to these emerging standards now will be better positioned for offtake as commercial-scale demand grows.

"Steelmaker pilots and the first low-carbon steel certifications are opening green-steel offtake to wood pellets, though commercial-scale demand remains limited. The producers that thrive in this market will be those that reliably deliver pellets aligned with high-quality sustainability standards."

—Louisa Brotherson, Hybrid Decarbonization Scientist

Sustainable Aviation Fuel: Mandates Create a Durable Demand Signal

Wood-based SAF is technically feasible via gasification to syngas, followed by Fischer-Tropsch upgrading, a proven chemistry for converting syngas to liquid hydrocarbons. Yet, the commercial challenges are substantial: the International Civil Aviation Organization estimates capital costs exceeding US$1 billion for large facilities, and production costs of US$11–48 per gallon to distillate. 

The cautionary case is Fulcrum Bioenergy near Reno, Nevada, which attempted a Fischer-Tropsch process using municipal solid waste and appears to have failed due to a lack of rigorous pre-implementation testing and unrealistic timelines, a reminder that feedstock homogeneity matters enormously, and one area where pellets have a relative advantage.

Two structural dynamics make SAF worth serious attention despite those barriers. First, the European Union's (EU) SAF mandate, starting at 2% of jet fuel supply and ramping to 70% by 2050, carves out cellulosic biomass as the only qualifying feedstock once cooking oil supply is exhausted. The penalty structure in both the EU and UK creates strong demand regardless of SAF price: EU non-compliance penalties run roughly three times the price of SAF, and UK penalties can reach 13 times the cost of the fuel itself. Second, the alcohol-to-jet pathway offers a lower-capital entry point than Fischer-Tropsch, as demonstrated by Project Speedbird, a British Airways and LanzaJet collaboration targeting UK woody residues.

The near-term question is which routes have bankable offtake. Very few do yet, but the mandate structure suggests that window will shift rapidly.

"So far, facilities haven't scaled to the levels required to meet timeline demand. But the EU and UK mandate structures mean buyers are greatly incentivized to purchase SAF even at high prices, rather than pay non-compliance penalties."

—John Dees, Director, Fuels and Industrial Commodities

Domestic Cofiring: Achievable, but Not a Long-Term Anchor

Cofiring biomass with coal to produce electricity or heat is the most immediately achievable option. Most US coal-fired power plants could displace up to 10% of their input energy with raw or torrefied pellets, though plants would likely need fuel handling upgrades. Some state policies, such as Pennsylvania's Alternative Energy Portfolio Standards Act of 2004, support cofiring to meet renewable energy goals. However, there are no federal policies in the US that incentivize cofiring.

The case for cofiring as a long-term market is weak. The US coal fleet has contracted steadily for economic reasons—over 100 gigawatts (GW) of coal-fired capacity retired between 2015 and 2025—and biomass cofiring is unlikely to make a coal plant more cost-competitive. The Greenhouse Gas Protocol's scope 2 guidance does not permit buyers to procure a "strip" of electricity representing the biomass-fired fraction of output from a cofired plant; instead, buyers must accept the average total emissions from the plant in their scope 2 inventory, which limits the value proposition for corporate buyers seeking to demonstrate clean energy procurement.

The more interesting version of this pathway combines cofiring with carbon capture and storage (CCS), a combination that creates a deeper-abatement value proposition and the kind of firm, dispatchable power that corporate buyers increasingly need.

"Cofiring is a proven step toward modest emissions reductions from coal-fired electricity, but it's hard to make the economic case for it when compared to applications that command price premiums for deeper climate abatement."

—A.J. Simon, Director of Industrial Decarbonization

Sustainability Is Now the Qualification Gate

Each of these markets is more discerning about sustainable biomass sourcing than the UK power sector was a decade ago. That shift will not reverse.

US Southeast wood has real potential for high-integrity sustainability credentials, particularly in softwood residues. But it also carries downside risks when sourcing from natural stands. Through work with producers, buyers, and project developers across these markets, we have found that four questions now drive every serious procurement conversation:

1. Does the supply chain have verifiable governance and chain-of-custody transparency?
2. Does sourcing respect the rights of Indigenous Peoples and local communities?
3. Is the wood coming from regions where forest carbon stocks are stable or growing, and not from protected areas or primary forest?
4. Is sourced biomass a by-product of non-energy uses, and not the primary silviculture driver?

Producers who can answer yes to all four, and support those answers with data, are more likely to access these emerging markets. Those who cannot will find it harder to compete for offtake.

For a detailed framework on how these principles translate into contract language and certification requirements, see the 2025 Sustainable Forest Biomass Sourcing for CDR: A Buyer's Guide.

The Window Is Open, but Not Indefinitely

The US Southeast wood basket is well-positioned for the markets described here. The infrastructure is in place. What producers still need to build is the market positioning, sustainability documentation, and offtake relationships to go with it.

The producers who move now will have a meaningful head start. Those who wait for certainty may find that the most attractive offtake opportunities have already been structured around someone else's supply.

Learn more about Relae's work on SAF mandates, steel decarbonization, and sustainable biomass sourcing. 

Frequently Asked Questions

What happens to US wood pellet exports when the UK's new biomass rules take effect?

Starting April 2027, the UK's signed Contracts for Difference agreement caps subsidized biomass generation at a 27% capacity factor, roughly half of today's levels. That's expected to cut total UK pellet demand to about 4.9 million GST a year, leaving only around 1.6 million GST available to US exporters.

Is BECCS for data centers a proven market, or still emerging?

The underlying technology is credible, and the Louisiana Green Fuels project already demonstrates it at commercial scale. However, the deal structure isn't yet proven. No hyperscaler has signed a single contract for both electricity and carbon removal credits from one BECCS plant, so this market is emerging rather than established.

How does low-carbon steel demand compare to sustainable aviation fuel as a market for pellet producers?

Steel offers nearer-term certification frameworks (the Low Emission Steel Standard began issuing certifications in 2025) but limited commercial-scale volume so far. SAF has a stronger long-run demand signal thanks to EU and UK blending mandates and steep non-compliance penalties, but requires far higher capital investment to enter.

What should a wood pellet producer look for when evaluating a new market?

The four sourcing questions that now gate access across all these markets are: verifiable chain-of-custody, respect for Indigenous and local community rights, sourcing from stable or growing forest carbon stocks (not primary forest), and biomass that's a by-product of non-energy uses rather than the primary driver of harvest.

Key Takeaways

• CORSIA, the program intended to address international aviation emissions, is currently the world’s largest international compliance carbon market, with approximately 200 million tonnes of eligible emissions units (EEUs) expected to be retired for Phase 1 (2024-2026) compliance. 
• Airlines have already begun retiring significant volumes of credits (clean cookstoves and jurisdictional REDD+) toward their Phase 1 obligations ahead of the January 2028 compliance deadline, signaling that the industry is treating CORSIA as a binding policy mandate.
• In addition to the four already approved, a record 25 carbon standards have applied for eligibility to supply credits under Phase 2 (2027–2035), pointing to a diversifying pipeline of credits.
• Legal enforcement of CORSIA at the national level remains uneven. A handful of jurisdictions, including the EU, Japan, Brazil, New Zealand, and Canada, have established compliance regimes, but it is unclear whether other major aviation markets will implement domestic enforcement requirements by 2027.
• As CORSIA matures alongside other compliance and voluntary frameworks, strategic engagement increasingly depends on understanding where eligibility overlaps and where the most value can be found.

Introduction to CORSIA 

The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) was established and is managed by the International Civil Aviation Organization (ICAO)—a specialized agency of the UN—and provides a compliance mechanism to reduce emissions from international aviation that do not fall within a single country’s contributions to the Paris Agreement. For years, CORSIA generated more commentary than activity—airlines weren’t required to offset a single tonne of CO₂ emissions (tCO₂) during the pilot phase (2021–2023). That is changing; in early 2026, Singapore Airlines and Japan Airlines retired significant volumes of carbon credits against their Phase 1 (2024–2026) obligations. Increasing authorization announcements showcase the eligible supply steadily entering the market, and 25 carbon standards have applied for Phase 2 (2027–2035) eligibility. As CORSIA becomes an active compliance market, this article explains how the program works, what is driving the current trends, and what to watch as Phase 1 draws to a close.

Who is Covered by CORSIA Phase 1 and Phase 2?

Because emissions from international aviation are not tied to any individual nation, the International Civil Aviation Organization (ICAO) adopted CORSIA in 2016 to complement the Paris Agreement framework and address these emissions. CORSIA applies to international airlines operating flights registered between participating countries. 

• During Phase 1, offsetting obligations apply only to routes between the 130 countries that have voluntarily opted in. 
• From Phase 2, participation becomes mandatory for all 193 ICAO member states, except for those below the aviation activity threshold or classified as Least Developed Countries, Small Island Developing States,  or Landlocked Developing Countries—although they can voluntarily participate. 

Several major aviation markets, including China, that are not participating in Phase 1 will be required to do so from 2027. 

Offsetting Obligations

Airlines are required to offset the portion of their emissions that exceeds the program’s baseline on routes subject to offsetting. The key input is the annual Sectoral Growth Factor (SGF), which reflects how much annual emissions on covered routes have grown above the baseline (set at 85% of 2019 emissions). In simple terms, each airline's offsetting obligation is calculated by multiplying its CORSIA-regulated emissions by the SGF.

For example, an airline that emits 1 million tCO₂ on covered routes in a year when the SGF is 10%, would have an offsetting obligation of 100,000 tCO₂. An airline that emits 500,000 tCO₂ in the same year would have an obligation of 50,000 tCO₂. The actual 2024 SGF was 15.4%, exceeding the baseline and triggering offsetting obligations for the first time since the COVID-induced reduction in international aviation activity. 

Beginning in 2033, CORSIA’s offsetting formula combined the SGF with an individual component that accounts for each airline's own emissions growth. The individual weighting starts at 15% in 2033 (with an SGF weighting of 85%) and rises to 45% by 2035 (SGF 55%). This progressively ties each airline’s obligations to its own emissions trajectory rather than sector-wide trends alone.

Airlines can also reduce their obligations by reporting the use of CORSIA Eligible Fuel (CEF). In order to qualify as CEF, Sustainable Aviation Fuel (SAF) must meet ICAO’s certification criteria. Offsetting remains a lower-cost option than sustainable fuel procurement, and CORSIA obligations are currently not influential drivers of CEF/SAF uptake compared to supply mandates, such as ReFuelEU Aviation. However, these dynamics will evolve as CORSIA matures and SAF prices continue to fall. 

CORSIA Eligible Carbon Credits: Phase 1 and Phase 2 

To determine the eligibility of carbon crediting standards and credits issued under those standards, ICAO's Technical Advisory Body (TAB) reviews applications and recommends approval to the ICAO Council, subject to restrictions on methodologies, vintages, and more granular project elements. Currently, no standard is approved without exclusions. Credits eligible for use under CORSIA are known as Eligible Emissions Units (EEUs).

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TAB broadly excludes some project types across standards, including large-scale grid-connected renewable energy projects and most project-level REDD+ activities. The exclusions reflect TAB's assessments of baselines, safeguards, and quantification gaps. However, these assessments are not static; ICAO updates its determinations as the evidence base improves. For example, in 2025, TAB approved certain direct air capture (DAC) and biochar pathways for the first time.

A record 25 carbon standards—certifying projects from emissions avoidance to engineered carbon dioxide removal (CDR)—have applied for Phase 2 eligibility in the 2026 assessment cycle, reflecting the scale of the opportunity. The International Air Transportation Association (IATA) projected a demand of 170–236 million EEUs for Phase 1 alone; developers are eager to serve this growing market. Assessment results are expected in October 2026.

Article 6 and Corresponding Adjustments

The biggest bottleneck for eligible supply has been requirements relating to Article 6.2 of the Paris Agreement. CORSIA requires that EEUs carry a host country Letter of Authorization (LoA) confirming that the host country will not count the underlying mitigation toward its Nationally Determined Contribution (NDC). This prevents double counting between CORSIA and national emission inventories, but it also means eligible supply depends on host country authorization, not just meeting methodological requirements. Authorized credits are called Internationally Transferred Mitigation Outcomes (ITMOs). 

To manage the risk that a host country fails to apply the promised corresponding adjustment, projects must secure legally enforceable insurance policies that either provide replacement EEUs or funds to secure them. Several providers have been approved to insure EEUs registered by Gold Standard and Verra. 

Insurance requirements do not apply when the host country has already confirmed the corresponding adjustments in its mandatory Paris Agreement reporting. For example, in March 2026, Madagascar submitted a Biennial Transparency Report (BTR) and annual information report that reflect the application of corresponding adjustments to CORSIA-eligible clean cookstoves credits listed on the Verra registry. According to Verra, BTR accounting is the “highest level of assurance” that ITMOs will not be double counted. 

The Enforcement Challenge

With the authorization bottleneck loosening, market attention is turning to demand. Critically, ICAO has no direct enforcement power; for CORSIA to work, participating countries must pass laws requiring airlines to comply with its requirements. Under CORSIA rules, airlines must retire their Phase 1 EEUs by January 2028, but most are not yet subject to legal sanctions for failing to comply. Where regulations do exist, it remains unclear whether penalties will be stringent enough to matter, or whether they will be enforced at all.

Where legal enforcement of offsetting requirements does exist, it varies by design. For example, in Brazil, failure to comply attracts a penalty of BRL 50/tCO₂ (US$10/tCO₂) and an administrative fine. Meanwhile, the Canadian Aviation Regulations impose administrative fines capped at CAD 25,000 (US$18,000) per infraction, but there is no specific fine for each tCO₂ not offset. However, the absence of a statutory penalty framework does not necessarily mean compliance will not be enforced. For example, New Zealand manages CORSIA participation through an administrative Memorandum of Understanding with Air New Zealand, rather than a dedicated legal regime (though this will change from 2027). Similar informal arrangements may be more common than the legislative record suggests.

According to 2024 data, US-based airlines account for around 15% of CORSIA-covered emissions. However, there is no indication that the federal government will implement CORSIA penalties under the current administration. It is unclear how non-compliance by a major economy will impact market confidence or enforcement by other governments, but uncertainty about US participation in multilateral climate programs is not new. 

What to Watch

• Global enforcement: As Phase 2 approaches, the prospects for CORSIA enforcement in key aviation markets will become clearer. China, which has not participated in the voluntary phase and has raised objections to CORSIA’s design on grounds of fairness, presents an uncertain picture for domestic transposition. The UK government has consulted on a draft legal amendment that would penalise non-compliance for UK airlines at £100/tCO₂ (US$130/tCO₂), but has not published updates since February 2025. 

• EU Emissions Trading Scheme (ETS) update: In July 2026, the European Commission proposed to expand the ETS to address emissions from flights departing the European Economic Area (EEA) to destinations within 5,000 km. To avoid double charging emissions also regulated under CORSIA, the Commission proposed to deduct CORSIA costs from airlines’ ETS obligations. While the Commission flagged concern about the stringency of CORSIA eligibility criteria, the proposed rules would not impact demand for Phase 1 EEUs. Still, it is worth watching for future restrictions on which credits EU airlines can use for CORSIA, whether in Phase 1 or 2. 

• Supply financing vehicles: The LEAF Coalition—which purchases credits verified under the CORSIA-eligible ART TREES standard—has signed over US$1.5 billion worth of purchase agreements with host countries. The Forest Carbon Partnership Facility (FCPF) and BioCarbon Fund Initiative for Sustainable Forest Landscapes (ISFL), both CORSIA-approved for Phase 1 in early 2026, have built jurisdictional REDD+ pipelines across dozens of countries. As projects mature, it will be worth watching how issued credits are marketed across compliance and voluntary channels.

Strategic Considerations

Avoided emissions credits dominate early CORSIA supply—and consequently demand—principally from avoided deforestation and clean cooking projects. As there is no regulatory premium for higher-cost CDR, this is not surprising. But as the market matures and supply diversifies, airlines are likely to begin differentiating on geography, co-benefits, and environmental performance. Corporate interest is growing in projects that abate non-CO₂ superpollutants, due to their outsized near-term climate impact. As many of these projects are based in countries actively issuing LoAs, this may soon translate into a supply of superpollutant EEUs. Some airlines are reluctant to procure aggressively now, anticipating the upcoming availability of higher-quality credits.

Credits that hold value across multiple frameworks could carry a strategic premium. A credit also eligible for Singapore's carbon tax, Switzerland's CO₂ Act, or SBTi claims may offer more durable demand than one tied to a single use case. While specific requirements vary significantly, we are beginning to see convergence around broad principles, such as the need for Article 6 authorization for credits used in compliance markets tied to NDCs. Procurement and project development strategies could begin to favour credits that confer wider market optionality. 

The precondition for all of this is policy stability. Longer-term offtake agreements, portfolio strategies, and meaningful investment in project development depend on confidence that CORSIA rules will hold. Efforts to soften emissions regulations in response to energy price shocks are now testing this confidence, from proposed changes to soften the EU ETS to Singapore's deferral of its SAF levy. Tracking price signals, enforcement developments, and authorization trends will be essential for identifying firm demand and where the opportunities lie.

Conclusion

Effective engagement with CORSIA requires more than developing quality projects. It means understanding methodological eligibility requirements, navigating Article 6.2 authorization processes, tracking a network of overlapping national regulations, and staying ahead of a rapidly evolving market landscape. Relae (formerly Carbon Direct) brings together policy, market, and scientific expertise to help clients on all of these fronts.

Frequently Asked Questions

Which carbon credits can airlines use for CORSIA compliance?

CORSIA Eligible Emissions Units (EEUs) must be issued by crediting standards approved by ICAO's Technical Advisory Body. Every approved standard currently has exclusions on certain methodologies and project types, so eligibility is granular rather than blanket. EEUs must also have a host country Letter of Authorization confirming a corresponding adjustment under Article 6.2 of the Paris Agreement.

Is CORSIA actually enforceable?

In all phases, CORSIA obligations are legally binding when a country writes them into domestic law. Countries participating in Phase 1 are expected to do this, but not all have, and enforcement remains uncertain in several key aviation markets (e.g., the United States). Even where enforcement exists, penalty regimes vary significantly in stringency and design. 

How does the July 2026 EU ETS proposal affect CORSIA?

The European Commission's proposal to expand ETS coverage to more flights does not reduce demand for CORSIA credits. While it would lead to overlap between flights covered under CORSIA and the ETS, as proposed, airlines could have CORSIA costs effectively deducted from their ETS allowance obligations. However, the Commission has signalled continued scrutiny of CORSIA's effectiveness, which could shape future limits on the credits EU airlines are allowed to use.

Key Takeaways

• The Greenhouse Gas (GHG) Protocol’s Actions and Market Instruments (AMI) proposal would formally recognize market-based instruments across emissions scopes for the first time, within Statement 2.
• The proposal substantially expands opportunities for companies to report lower emissions from purchasing market-based instruments for low-carbon fuels (LCF), such as book-and-claim environmental attribute certificates (EACs) for sustainable aviation fuel (SAF) and renewable natural gas (RNG).
• Companies purchasing or already holding market-based instruments for SAF, RNG, and other low-carbon fuels should begin mapping those instruments to the AMI’s proposed reporting structure now, before the standard is finalized.

The Current Reporting Problem With Low-Carbon Fuels

A low-carbon fuel is defined as a fuel whose lifecycle greenhouse gas (GHG) emissions are lower than those of a relevant, use-case-specific fossil fuel baseline. Most LCFs used today are created from biogenic sources like agricultural residues, used cooking oil, or landfill gas, and their use often results in reduced GHG emissions due to the fact that the CO₂ they release during use is biogenic and not fossil.

Consumers of LCFs face a reportability problem. Many buyers track LCF purchases through market-based instruments such as book-and-claim and mass balance EACs. These instruments unbundle environmental claims from physical molecules to facilitate investment in LCFs when direct provision of the molecule is infeasible. However, the current GHG Protocol only permits the use of market-based tools for electricity-based emissions. 

Currently, companies cannot recognize the emissions benefit of an LCF purchase unless they physically receive and combust the fuel. Given that sustainable aviation fuel, renewable natural gas, and other LCFs typically flow into shared pipeline and distribution infrastructure rather than being delivered to buyers as distinct physical molecules, direct delivery is often not achievable in practice. This limitation constrains demand growth in the voluntary market.

The value of LCFs to voluntary buyers is the sustainability claim attached to the molecule, not the molecule itself. Without a credible reporting framework for market-based instruments, buyers struggle to justify LCF procurement. Producers, in turn, may face a market where buyer reluctance limits commercial opportunities for scale-up. Non-reportability inhibits one of the few available levers to incentivize voluntary investment in climate solutions.

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How Does the AMI Proposal Address Non-Reportability?

The Actions and Market Instruments (AMI) proposal introduces a four-statement reporting framework, with all four statements relevant to elements of LCFs. Together, these statements give organizations across the LCF value chain a standardized way to account for LCF procurements in their sustainability reports, whether those procurements are physical or through market-based instruments.

• Statement 1 covers the physical GHG inventory and is the traditional GHG Protocol inventory as it exists today. Companies that physically receive and combust LCFs recognize the lower GHG emissions here.
• Statement 2 proposes a market-based GHG inventory for all emissions scopes. For the first time, this will allow companies to report the carbon intensities of book-and-claim and mass balance EACs for LCFs within a GHG Protocol-aligned inventory. This is a shift from the current framework, which relegates market-based instruments for LCFs and other products, along with carbon credits, to a supplemental section outside of the core emissions inventory. By bringing these purchases into the inventory itself, Statement 2 puts market-based LCF claims on a more equal footing with the emissions companies already report.
• Statement 3 covers beyond value chain interventions as well as GHG emissions reductions/avoidance reported relative to a baseline counterfactual (e.g., the domain of carbon credits). Avoided methane emissions upstream from RNG use is one LCF-relevant example that might live here. 
• Statement 4 captures non-GHG indicators and could include things such as the quantity of an LCF procured or produced. This rounds out the story an organization tells about how LCFs fit within their operations and value chain.

How the AMI Proposal Applies to Specific Fuel Types

Two important LCFs are impacted by the current GHG Protocol guidance and offer an example of the significance of the AMI proposal. 

1. SAF is a biobased or synthetic drop-in substitute for conventional jet fuel. 
2. RNG, generally produced from organic wastes, is a drop-in substitute for conventional natural gas. 

Both are typically delivered through existing infrastructure. SAF is typically blended into a common fuel supply. RNG is often injected into the broader gas network. The buyer typically does not have a direct physical link to the molecule’s consumption, but rather an indirect claim on molecules injected into a common system.

Current GHG Protocol guidance disallows using and reporting market-based LCF emissions factors within corporate scope inventories. If finalized as proposed, the AMI proposal’s Statement 2 would open the aperture for companies to report the lower emissions from purchasing SAF or RNG market-based instruments. Here’s how that might work.

SAF: Reporting Across the Value Chain

When an airline physically receives and burns SAF in its aircraft, the lower combustion emissions are reflected in its Statement 1, scope 1 emissions inventory. This is reported the same way as conventional jet fuel.

The picture changes when airlines use market-based instruments. Many airlines purchase scope 1 SAF certificates that are decoupled from the physical fuel and tracked via book-and-claim or mass balance EACs. Under the AMI proposal, the lower emissions factors of these instrument purchases would be reflected in an airline’s Statement 2, scope 1 emissions inventory.

Corporate buyers face a parallel situation. Companies that purchase scope 3 EACs from SAF suppliers or through airline programs to address employee travel would reflect these lower emissions factors in their Statement 2, scope 3, category 6 emissions. Legitimate Statement 2 claims provide additional incentive for corporate climate action to address travel emissions.

RNG: Reporting Across the Value Chain

As with SAF, an organization that physically receives and combusts RNG can reflect the lower emissions in its Statement 1, scope 1 emissions inventory. 

More often, RNG is injected into the shared gas network and claimed by users through book-and-claim or mass balance certificates rather than physical delivery. Statement 2 introduces a reporting opportunity for RNG EAC purchasers to report lower scope 1 emissions. Lower emissions from RNG consumption could also be passed through as reduced scope 3 emissions for consumers of products associated with RNG consumption.

RNG carries an additional nuance. Some RNG projects may also claim to have avoided methane emissions (e.g., dairy manure methane emissions avoided by way of diversion to RNG). This type of methane avoidance attribute, typically tracked in the realm of carbon credits, would have a home within Statement 3, subject to additional disclosure requirements. Companies evaluating RNG certificates should understand which claims belong in which statement.

Application to Other LCFs and Market-Based Instruments

While SAF and RNG are two of the more prominent examples, the AMI proposal is relevant to all LCFs including renewable diesel and marine fuels. The emissions associated with market-based instrument purchases for these fuels would belong in Statement 2.

The proposed framework may also cover market-based instruments aimed at lower emissions conventional fuels, e.g., natural gas production that has taken measures to reduce fugitive methane emissions far below industry averages. Companies purchasing certificates of this type would theoretically report the reduced upstream natural gas emissions rates in Statement 2, scope 3, category 3.

Three Steps Companies Can Take Now to Prepare 

The AMI proposal is still in development. A public request for information on the initial white paper recently closed. A draft standard is in development, with a formal public consultation planned in Q3 2027. Companies that act early will be better positioned when the standard takes effect. Steps will vary depending on where in the fuels value chain an organization sits, but could include:

1. Map exposure. Identify where the organization sits in the LCFs value chain and what fuels it is currently procuring and consuming. This will help to better understand where the largest fuels-related emissions hot spots are in the current GHG inventory.
2. Record current instruments and assess quality. Catalog the instruments the company is currently producing or procuring. Understand where these instruments may sit within the AMI’s proposed four-statement framework and assess their quality against emerging eligibility criteria.
3. Engage with the process. The GHG Protocol is still defining eligibility and quality criteria for LCF instruments. Organizations can monitor interim developments from the AMI Technical Working Group. Companies with active programs have a real stake in how those criteria are written.

Frequently Asked Questions

How would the AMI proposal change the way low-carbon fuels get reported?

The core shift is the introduction of Statement 2, a new market-based GHG inventory. For the first time, companies would be able to report the lower emissions from purchasing market-based LCF instruments, including book-and-claim and mass balance EACs, within a GHG Protocol-aligned inventory. This applies to all LCFs, including SAF and RNG, and can be reflected in scope 1 or scope 3 inventories depending on where the organization sits in the LCF value chain.

Is the AMI proposal finalized, and what should companies do now?

No, the proposal is still in development. A public request for information on the initial white paper recently closed. A draft standard is in development, with a formal public consultation planned in Q3 2027. In the meantime, companies holding SAF, RNG, or other LCF instruments should map their exposure across the value chain, catalog existing instruments against the proposed four-statement framework, assess quality against emerging eligibility criteria, and monitor GHG Protocol AMI updates.

‍What should a company look for when evaluating a SAF or RNG certificate?

Buyers should confirm which claim a certificate actually conveys and where it would sit in the AMI’s proposed framework. For example, a lower-emissions carbon intensity claim belongs in Statement 2 whereas an avoided-methane claim falls under Statement 3. Buyers should also assess the instrument against the AMI's emerging eligibility and quality criteria to reduce the risk that a purchase won't qualify under the final standard. Relae (formerly Carbon Direct) has published a comprehensive set of criteria for high-quality low-carbon fuels that buyers can use as a starting point, until AMI’s eligibility and quality criteria are finalized.

Key Takeaways

• Buyers have been navigating the low-carbon fuels (LCF) market without a map.  The LCF market is expanding rapidly, but standards, definitions, and quality claims vary widely across regions, certification schemes, and regulatory systems, leaving voluntary buyers without a holistic framework for evaluating what they procure.
• Certifications cover some of the picture, not all of it. Existing certification schemes provide valuable assurance but vary in scope and rigor, and few, if any, were designed specifically with voluntary market buyers in mind. 
• The 2026 criteria give buyers a legible quality framework. The 2026 Criteria for High-Quality Low Carbon Fuels bring together key sustainability considerations across six principles, including social and environmental integrity, carbon accounting, additionality, feedstock sourcing, and leakage, giving buyers and producers a legible, living framework to navigate procurement decisions with confidence.

Verifying Quality Is Challenging in the Current Low-Carbon Fuels Market

For airlines, logistics companies, and large corporations with hard-to-abate transportation emissions, low-carbon fuels (LCFs) have become an important part of the decarbonization toolkit. Yet it remains difficult for procurement teams to answer a fundamental question: what does high-quality procurement actually look like? 

Standards, definitions, and sustainability claims vary widely across regions, certification bodies, and regulatory programs. The result is a market where quality is difficult to verify, certifications are difficult to compare, and the gap between a fuel's claims and its actual sustainability profile can be hard to close. Sustainable production will be especially critical as the market scales, because low-carbon fuel systems are deeply embedded in land, agriculture, forestry, and communities. 

The 2026 Criteria for High-Quality Low Carbon Fuels are designed to close this gap, giving voluntary buyers a consistent framework to evaluate the quality of what they procure and identify where additional diligence is still needed.

What Is a Low-Carbon Fuel?

For the purposes of the criteria, a low-carbon fuel, or LCF, is defined as a fuel or energy source whose lifecycle greenhouse gas (GHG) emissions are lower than those of a relevant, use-case-specific fossil fuel alternative. In this case, we are referring to the physical biofuel and its associated environmental attributes. 

While LCFs may be produced through biological, synthetic, or other non-fossil pathways, the 2026 edition focuses on biofuels for transportation, which currently represent the majority of LCF production and use. 

Understanding the Complex LCF Regulatory and Certification Landscape

The LCF market sits at the intersection of multiple regulatory and voluntary markets. In the US, this includes compliance programs such as the Renewable Fuel Standard (RFS) and state-level Low Carbon Fuel Standards (LCFS). Europe, the United Kingdom, Canada, and many other nations host comparable programs, often with specialized regulatory regimes for various transport sectors, e.g., aviation or maritime. 

These regulatory markets coincide with and often intersect voluntary markets, which contain a multitude of standards and certifications. For producers, this creates a complex landscape of market options. For buyers, it creates a signal problem: a fuel may carry one or more certifications, comply with one or more regulatory programs, and still leave meaningful sustainability questions unaddressed.

Several organizations, including the Roundtable on Sustainable Biomaterials (RSB) and the International Sustainability and Carbon Certification (ISCC), have developed widely used standards for LCFs. These certifications assess supply chains from feedstock to end use and provide important baseline assurance. 

However, they were developed with different primary audiences in mind and can vary in scope and rigor. Few existing schemes were designed to serve as a comprehensive sustainability reference for voluntary market buyers evaluating what a given fuel's certification covers and where gaps may still exist.

Simplifying High-Quality Procurement for Voluntary Buyers 

The 2026 Criteria for High-Quality Low Carbon Fuels are not designed to replace or compete with existing certification schemes. Rather, they consolidate key sustainability considerations from across the landscape of existing frameworks into a single, legible reference built specifically for voluntary market decision-makers.

The criteria apply across the full LCF supply chain, covering not only fuel producers but also fuel blenders, aggregators, and certificate traders. This LCF systems view encompasses the full set of production, certification, and procurement arrangements through which LCFs are generated and claimed. This reflects the reality that sustainability outcomes in this market are shaped by many actors, not just at the point of production.

The criteria distinguish between requirements that must be met (minimum thresholds for quality and integrity) and considerations that should be addressed, reflecting best practices and aspirational standards. This distinction is intentional: the criteria set a floor while leaving room for market participants to demonstrate quality in ways appropriate to their specific context. 

The criteria are organized around six core principles that together define what high-quality LCF production and procurement looks like. 

Six Principles for Procuring High-Quality Low-Carbon Fuels

1. Social harms, benefits, and environmental justice: preventing new harms to communities, reducing existing ones, and ensuring equitable distribution of benefits
2. Environmental harms and benefits: minimizing impacts on air, soil, water, and biodiversity
3. Carbon accounting: accurately quantifying lifecycle GHG emissions using credible methodologies and tracking environmental attributes to prevent double-counting
4. Additionality: demonstrating that voluntary market support enables outcomes that would not otherwise occur
5. Feedstock sourcing: ensuring responsible and equitable sourcing practices and requiring end-to-end chain-of-custody documentation traceable to the point of generation
6. Leakage: assessing and mitigating activity-shifting and market leakage associated with the LCF system

Where a fuel's existing certification or regulatory program adherence already addresses one or more of these core principles, that coverage should be disclosed to the buyer by the producer. Buyers can then use the criteria to identify where certification coverage aligns with quality expectations, and where supplemental diligence is needed.

A Living Framework for a Market in Motion  

The LCF market will continue to evolve as policy frameworks are shifting, certification systems are maturing, and new production pathways are emerging. The 2026 edition reflects the current state of the LCF market and is intended as a living resource, with future updates possible as the market develops and new science emerges. Future editions may expand to cover synthetic LCF pathways, renewable natural gas, and sector-specific considerations such as maritime fuels.

For buyers navigating voluntary LCF procurement, the criteria offer a practical starting point: a framework to evaluate what existing certifications cover, identify where additional diligence is needed, and build procurement decisions on a consistent quality foundation. For producers, they provide clear guidance on what a sustainability demonstration looks like for voluntary market buyers.

Read the 2026 Criteria for High-Quality Low Carbon Fuels to learn more about how the criteria apply to your procurement strategy or production system.

Frequently Asked Questions

What is a low-carbon fuel?
A low-carbon fuel is a fuel whose lifecycle greenhouse gas emissions are lower than a comparable fossil fuel alternative for the same use case. The 2026 LCF Criteria focus specifically on biofuels for transportation, which currently make up most LCF production and use.

What do the 2026 Criteria for High-Quality Low Carbon Fuels cover?
The criteria are organized around six principles: social harms, benefits, and environmental justice; environmental harms and benefits; carbon accounting; additionality; feedstock sourcing; and leakage. Together they give buyers and producers a consistent way to evaluate what high-quality LCF production and procurement looks like.

Do the LCF criteria replace existing certifications like RSB or ISCC?
No. The criteria aren't designed to replace or compete with existing certification schemes such as the Roundtable on Sustainable Biomaterials (RSB) or the International Sustainability and Carbon Certification (ISCC). Instead, they consolidate key sustainability considerations from across those frameworks into a single reference so buyers can see what their certification already covers and where supplemental diligence may be needed.

Who do the LCF criteria apply to across the supply chain?
The criteria apply across the full LCF supply chain, not just producers, but also feedstock suppliers, fuel blenders, aggregators, and certificate traders, reflecting that sustainability outcomes are shaped by many actors, not only the producer.

What's the difference between the "must" and "should" requirements in the LCF criteria?
"Must" requirements set minimum thresholds for quality and integrity that need to be met, while "should" considerations reflect best practices and aspirational standards market participants can work toward. This sets a floor while leaving room for participants to demonstrate quality in ways suited to their specific context.

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.

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.