Questions and answers on renewable gas measurement

What is the carbon intensity of a renewable gas?

Carbon intensity is the amount of greenhouse gases emitted across a fuel's entire life cycle per unit of energy delivered, expressed in grams of CO₂ equivalent per megajoule (gCO₂e/MJ).

It is not the same as origin. Two batches of biomethane can share the same feedstock and still have different carbon intensities: what changes is the plant's methane leakage, the energy the process itself consumes, how emissions are allocated between the gas and its co-products, and how biogenic carbon is accounted for.

It is calculated under the life-cycle assessment standards ISO 14040 and ISO 14044 and, where the scope is a product carbon footprint, under ISO 14067.

That is why the figure is only worth something if it can be audited: you have to be able to say which instrument each data point came from, how often it was read, what period it covers and what was done with the gaps.

What is I-TRACK(G)?

I-TRACK(G) is the international code under which the environmental attributes of biogas and biomethane are issued and transferred: for gas, the equivalent of energy attribute certificates in electricity.

The code splits the work into separate roles and requires them to be independent of each other: the party that registers the production facility, the body that issues the certificates, the LCA service provider that calculates carbon intensity, and the assurance service provider that reviews that calculation and signs a statement.

It also defines the Labelling Authority, the owner of a calculation methodology. The code states explicitly that the owner of the methodology and the accredited provider who submits it for usage may be different entities.

The Code Manager is Global Gas Tracking, and it is with them that LCA and assurance service providers are accredited.

Is a renewable gas attribute the same thing as a carbon credit?

No. An attribute certifies the characteristics of a unit of energy that was produced and delivered — origin, feedstock, technology, facility and carbon intensity — whereas a carbon credit represents a tonne reduced or avoided against a baseline and is retired as an offset.

The difference has practical consequences. The attribute belongs in the accounting of the energy a company consumes; the offset comes at the end, once there is nothing left to reduce.

It also changes the buyer's question: with an attribute, what matters is how clean the energy they bought is; with a credit, how much was reduced against a scenario that did not happen.

The corporate accounting rules for these instruments are still being written: the GHG Protocol's standard on actions and market instruments is under development, with public consultation expected in 2027.

How is destroyed biogenic methane measured?

With two instruments rather than an estimate: a flow meter on the line feeding the flare or the engine, and an analyser that reports what share of that gas is methane; the product of the two, read continuously, is the methane that reached the device.

That volume is converted to mass using the density of methane (0.716 kg/Nm³) and to CO₂ equivalent using its global warming potential.

There is no single potential, and it is worth saying so out loud: the Mexican authority requires 28 for methane in the National Emissions Registry, while international certificates use 27, the non-fossil methane value from the IPCC's sixth assessment report. The same measurement yields two figures depending on who the calculation is for, and the period has to be the same in both.

And a distinction that is often skipped: what the instrument measures is the methane that ENTERED the device, not the methane that was destroyed. How much was destroyed depends on that device's destruction efficiency, which is evidenced separately.

What does CAUDAL do, and what does it not do?

CAUDAL measures and assembles the evidence: it does not verify and it does not certify. Verification is done by an independent accredited body and the certificate is issued by the registry.

The platform connects to each facility's instrument, polls it every twenty minutes with no human intervention, stores every reading with its timestamp, closes the period and hands the file to the verifier and to the issuing registry.

That separation is not a limitation: it is the reason the evidence is worth anything. If whoever measures also certified, the number would be no use to anyone.

A meter that is down is not counted as zero production. The platform distinguishes three states — measuring, measuring zero, and no data — and says whose fault it is. What gets certified is the closed and reconciled period, not the latest reading.

What is dMRV?

dMRV is digital measurement, reporting and verification: the data is taken by the instrument and reaches the system with no one keying it in, timestamped and traceable, so that a third party can audit it afterwards.

The difference from conventional reporting is who writes the number. Under traditional MRV the producer declares it and it is reviewed once a year; under dMRV the number comes from the instrument and is recorded at the moment it was read.

What makes a dMRV auditable is not the frequency: it is being able to answer, reading by reading, which device it came from, when it was read, whether that device was calibrated, and what happened during the periods with no reading at all.

How is the CO₂ avoided by a facility's electricity calculated?

You multiply the megawatt-hours actually measured by the grid emission factor for the corresponding year: in Mexico, 0.444 tonnes of CO₂ equivalent per MWh for 2024, and 0.438 for 2023.

The factor is published by the authority and changes every year, so each month is converted with the factor of its own year. A multi-year total computed with a single factor is wrong, however small the difference looks.

When a year has no published factor yet, reporting uses the latest one in force and the screen says so: that is the rule the authority itself set, not a decision of ours.

And only what was measured in the period enters the total. A facility with no reading does not contribute zero: it does not contribute.

Does a renewable gas guarantee of origin state its carbon intensity?

In Spain, not necessarily: the guarantee of origin certifies origin, feedstock, technology and facility, while the carbon footprint field is optional.

At the same time the country has built mandatory demand: the royal decree promoting biomethane sets a quota on gas and LNG sales starting at 0.5 % in 2028 and reaching 6 % in 2035.

In other words, a mandatory market is being built on top of a certificate that says where the gas comes from but not how it performs. That field, which today travels empty, is the one a continuous carbon-intensity measurement fills.

It neither competes with the guarantee of origin nor replaces it: it completes it.

Does Mexico's National Emissions Registry recognise these attributes?

Reporting to the National Emissions Registry is an inventory — the establishment's direct emissions plus the indirect emissions from its consumption of electric and thermal energy — and the regulation does not provide for subtracting purchased certificates.

It does, however, open two doors. Article 8 allows the Ministry to set specific emission factors by resolution, and article 7 allows an establishment to propose alternative measurement or calculation methodologies where instruments are needed to guarantee accuracy; once approved they are published in the Official Gazette and become available to anyone in the same situation.

So the place where a renewable gas can show up in the report is not a subtraction of certificates: it is the emission factor used to report what was consumed. It is the same mechanism that already exists for electricity through the national grid factor.

Article 29 adds that the Ministry shall recognise certifications obtained through international registries or through bodies accepted in international carbon markets.

This is what the text in force says, read in the primary source. It is not a criterion issued by the authority.

What does Europe require of the gas it imports?

The EU methane regulation sets dates: from 1 January 2027 import contracts are subject to measurement, reporting and verification equivalent to the European regime; from August 2028 the importer must report the methane intensity of what it buys; and from August 2030 that gas must fall below a maximum value.

It covers natural gas, oil and coal, and those who import them. Biomethane is out of scope: a biomethane plant is not covered by that regulation, even where the company that also operates a natural gas network is.

For an exporter, traceability stops being good practice and becomes a condition of the contract: measure continuously, close the period, and hand the evidence to a third party who verifies it.