Not every carbon project can supply CORSIA, and the reasons differ by type. Some fail on additionality, some on permanence, some on safeguards, and a great many on host-State authorisation regardless of their technical merits.
This is a type-by-type assessment of where the difficulties actually sit.
The Two Filters Every Type Faces
Before the type-specific issues, two filters apply universally.
Programme approval. The project must sit under a crediting programme the ICAO Council has approved, using a methodology that programme offers. If your activity has no methodology under an approved programme, it cannot supply, however good it is.
Host-State authorisation. The government must authorise transfer and apply a corresponding adjustment. This is type-agnostic in principle but not in practice — several governments authorise some project types and decline others, typically retaining the ones central to their own abatement pathway.
A project that clears both filters then faces the type-specific questions below. One that fails either does not get that far.
Grid-Connected Renewable Energy
The difficulty: additionality.
Solar and wind have become the least-cost generation option in many markets. That is excellent news for the climate and very bad news for the additionality argument, which requires demonstrating that the project needed carbon revenue to proceed.
Several programmes have narrowed or retired methodologies for grid-connected renewables in markets where they are commercially viable without carbon finance. Where methodologies remain available, they typically restrict eligibility to specific country contexts, technologies at an early deployment stage, or projects facing demonstrable barriers.
Where it can still work: Least developed country contexts, genuinely early-stage technologies, projects facing documented financing or regulatory barriers, and off-grid or mini-grid applications where the commercial case is weaker.
Realistic assessment: For a standard utility-scale solar or wind project in a market where renewables are competitive, expect difficulty. Approach with realistic expectations rather than assuming past success transfers.
Energy Efficiency
The difficulty: additionality and baselines.
Industrial and commercial efficiency measures often have short payback periods, which raises the same question — would this have happened anyway. Baseline construction is also harder than it looks, because efficiency improves over time for reasons unrelated to the project.
Where it works: Measures with genuinely long payback, interventions facing capital constraints or split incentives, and contexts where the technology is not common practice.
Additional issue: Overlap with domestic compliance schemes. Where a country runs its own energy efficiency trading mechanism, the same reductions may sit inside it, which complicates both authorisation and double-counting analysis.
Methane Avoidance
Landfill gas, wastewater treatment, biogas, coal mine methane.
The strengths: Additionality arguments tend to be cleaner, because the counterfactual is usually venting rather than a commercially attractive alternative. Permanence is not an issue — avoided emissions do not reverse. Methane's high warming potential means meaningful volumes from modest projects.
The difficulties: Regulatory additionality, where capture is already legally required. Measurement accuracy, since flow and concentration monitoring must be robust. And in some jurisdictions, overlap with waste sector regulation.
Realistic assessment: Among the better-placed types for CORSIA, subject to the regulatory additionality check.
Cookstoves and Household Energy
The difficulty: quantification and sustained scrutiny.
Improved cookstoves have enormous potential scale, strong development co-benefits, and a sustained record of methodological criticism. The contested elements are usage rates — how often stoves are actually used, and whether they replace or supplement the baseline stove — and the fraction of baseline biomass that is non-renewable.
Independent research has repeatedly found real-world reductions below crediting estimates for some methodologies. Programmes have responded by tightening requirements, and buyers have become more cautious.
Where it works: Projects with rigorous, independently monitored usage data, conservative assumptions applied deliberately, and a methodology reflecting current rather than historic understanding.
Realistic assessment: Viable but demanding. Conservative quantification here is not a formality, and a project designed to older assumptions will face buyer resistance even if technically compliant.
Afforestation, Reforestation and Improved Forest Management
The difficulties: permanence, baselines and tenure.
Permanence. Carbon in trees can be released by fire, disease, logging or drought. Buffer pools hold reserve credits against reversal, but buffer adequacy is under active scrutiny as losses accumulate in fire-prone regions. A buffer sized against historical risk may be undersized against current risk.
Baselines. Avoided deforestation baselines require projecting what deforestation would have occurred without the project — an inherently uncertain exercise that has attracted heavy criticism, with independent analyses finding some baselines substantially overstated.
Tenure and safeguards. The most common failure. Agreement from a government or a large landholder is not the same as free, prior and informed consent from the communities actually using the land. Disputes here have derailed otherwise sound projects.
Where it works: Clear tenure, robust and conservative baselines, adequate buffer contribution, and genuine community participation with documented consent.
Realistic assessment: High potential, high scrutiny, long timelines. Not a fast route to CORSIA supply.
Agriculture and Soil Carbon
The difficulties: measurement, permanence and aggregation.
Soil carbon is expensive and uncertain to measure, varies enormously across a field let alone a region, and can be released by a change in practice. Smallholder aggregation adds monitoring cost and complexity.
Where it works: Well-designed aggregation with statistically robust sampling, conservative quantification, and long-term practice commitments.
Realistic assessment: Methodologically immature relative to other types. Improving, but not the easiest path today.
Engineered Removals
Direct air capture, biochar, enhanced weathering, bioenergy with carbon capture.
The strengths: Additionality is rarely questioned — nobody does these without carbon revenue. Permanence is strong for geological storage. Measurement is generally more tractable than for biological systems.
The difficulties: Cost, which is high and reflected in price. Limited volume available. Methodology availability under approved programmes varies, and some approaches are ahead of the standards that would credit them.
Realistic assessment: Excellent integrity characteristics, constrained by cost and volume. Relevant for buyers wanting the strongest possible position, less so for meeting large obligations economically.
Industrial Gases
Historically significant, now largely restricted. Several methodologies were narrowed or retired after perverse incentive concerns — projects producing the gas in order to destroy it for credits. Current availability under approved programmes is limited.
Waste-to-Energy and Biomass
The difficulty: baselines and competing regulation.
Diverting waste from landfill to energy recovery can produce genuine reductions, but the baseline depends heavily on what would otherwise have happened to the waste, which is often governed by local regulation that is itself changing. Where landfill diversion is becoming mandatory, the additionality argument erodes.
Biomass energy raises a separate question — whether the feedstock is genuinely renewable and sustainably sourced. Methodologies require this to be demonstrated rather than assumed, and the demonstration is more demanding than developers often expect.
Where it works: Waste streams with a clearly documented landfill counterfactual, and biomass with verifiable sustainable sourcing and no land-use displacement.
Transport and Mobility
The difficulty: attribution and boundary definition.
Modal shift, electrification and efficiency projects in transport face a hard boundary problem — establishing that a particular intervention caused a particular change in behaviour or fleet composition, rather than coinciding with a trend driven by policy, cost or consumer preference.
Methodology availability under approved programmes is limited relative to the sector's emissions significance, and the attribution difficulty is the main reason.
Realistic assessment: Conceptually attractive, methodologically constrained. Not a straightforward path today.
Water and Sanitation
Safe water provision projects credit the avoided biomass burned to boil water. They share the quantification difficulties of cookstoves — usage rates, baseline behaviour, non-renewable biomass fractions — with the additional complication of establishing that treated water actually displaced boiling rather than supplementing it.
Development co-benefits are substantial and genuine, which supports voluntary demand. For CORSIA, where the buyer needs discharge rather than narrative, the quantification questions dominate and conservative assumptions are essential.
Ranking by Realistic CORSIA Suitability
Given the criteria as they currently stand, and assuming authorisation can be obtained:
Better placed: Methane avoidance from waste and wastewater; engineered removals where cost permits; efficiency in genuinely constrained contexts.
Workable with rigour: Cookstoves with strong monitoring and conservative assumptions; forestry with clear tenure and adequate buffers; renewables in least developed country contexts.
Difficult: Grid-connected renewables in competitive markets; soil carbon at present methodological maturity; industrial gases.
This ranking reflects the criteria and current scrutiny, not the intrinsic climate value of the activity. A grid-connected solar farm in a competitive market is a good thing to build; it is simply hard to argue it needed carbon revenue.
Choosing a Type as a Developer
Ask, in order:
- Will my host State authorise this type? If not, stop.
- Is there a methodology under an ICAO-approved programme? If not, stop.
- Can I defend additionality in this market, at this time, on current standards?
- Can I evidence permanence, if the reductions are storage-based?
- Can I produce the monitoring data over the project lifetime, in practice?
- Is tenure clear and consent documented?
- Do the economics work at my scale, or do I need to aggregate?
Failing at question one or two after spending on questions three through seven is the most common and most avoidable mistake in this market. See the supplier pathway.
Frequently Asked Questions
Are removals preferred over avoidance? For CORSIA, both are eligible if the criteria are met. Buyer preference exists but is weaker than in the voluntary market, where operators need discharge rather than a narrative.
Can a REDD+ project supply CORSIA? In principle, if the programme is approved, the baseline holds up, tenure is clear and the host State authorises. Baseline scrutiny in this space has been intense.
Is nuclear eligible? Methodology availability under approved programmes is the constraint, and it is limited.
What about blue carbon? Mangrove and coastal ecosystem methodologies are developing. Permanence and measurement remain challenging, and availability under approved programmes is narrow.
Does project location matter? Only through the host State's authorisation policy and through additionality, which is market-context dependent. There is no geographic eligibility rule.
Which type is fastest to market? Methane avoidance from existing waste infrastructure tends to be quickest, because additionality is clean, permanence is not an issue and monitoring is tractable.
Working on CORSIA? DSTechnoverse provides specialist CORSIA carbon credit services for aircraft operators, project developers and traders — eligibility screening, offsetting requirement calculation, unit sourcing and due diligence, corresponding adjustment support and registry execution. We are based in Indore, Madhya Pradesh and work with clients across India and internationally.
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