GuideCertificates & Carbon Credits

Energy attribute certificates, from annual RECs and GOs to hourly granular tracking

Energy attribute certificates let a buyer claim the attributes of specific generation, such as its source and location. Europe uses Guarantees of Origin, North America uses RECs, and many other markets use I-RECs. Most still match certificates to consumption over a year, but hourly granular certificates are emerging for time-matched claims. This guide explains the systems, the lifecycle, Scope 2 reporting and where digital tracking adds value.

Reviewed 7 min read

On this page
  1. What an energy attribute certificate represents, and what it does not
  2. Guarantees of Origin, US RECs and I-RECs side by side
  3. From metered generation to a cancelled certificate
  4. How Scope 2 market-based reporting relies on certificates
  5. Granular certificates and round-the-clock matching
  6. A data architecture for hourly certificate tracking
  7. Where a ledger helps, and where the official registry stays authoritative
  8. A hypothetical data-centre operator matching hourly demand
  9. Questions and answers
  10. Sources

What an energy attribute certificate represents, and what it does not

Once electricity enters a grid, nobody can say which generator powered which socket. Energy attribute certificates solve the accounting problem by separating the attributes of generation, such as energy source, location, plant and production period, from the physical power. Each certificate usually represents one megawatt-hour of generation, and a buyer claims those attributes by cancelling or redeeming the certificate in a tracking registry.

That makes a certificate a claim instrument, not proof of physical delivery. It does not show that the generation was additional to what would have been built anyway, and an annual certificate does not show that the power was produced when the buyer was consuming. Those two gaps drive most of the current debate, and they are why buyers increasingly look at where and when certificates were produced, not only how many they hold.

Guarantees of Origin, US RECs and I-RECs side by side

AspectEU Guarantees of OriginUS renewable energy certificatesI-REC electricity certificates
BasisRequired by the Renewable Energy Directive, Directive (EU) 2018/2001, and issued by national issuing bodies1Created by state programmes and voluntary markets, tracked in regional systemsA voluntary international standard maintained by the I-TRACK Foundation3
RegistriesNational registries, many exchanging certificates through the European Energy Certificate System operated by the AIB2Regional tracking systems such as WREGIS in the western US, PJM-GATS and M-RETSA central registry with local issuers in each participating country
Typical useSupplier disclosure to consumers and corporate market-based Scope 2 claimsState renewable portfolio standards, voluntary purchases and Scope 2 claimsCorporate Scope 2 claims in markets without a national certificate system
Time resolution todayMostly production period by month, matched to consumption over a yearMostly monthly or annual vintagesMostly monthly or annual production periods
Transfer across systemsWithin the EECS hub between member registriesGenerally within the tracking system that issued themWithin the I-REC registry; not convertible into GOs or RECs

Rules differ by country and state, and some registries already support finer time resolution. Treat this as orientation and check the specific registry's rules.

From metered generation to a cancelled certificate

  1. Register the production device

    The generator is registered with the issuing body, with its technology, capacity, location, commissioning date and any support received.

    Output
    Device record

  2. Collect metered output

    Metering data, validated by the grid operator or an approved meter data provider, is reported to the registry for each production period.

    Output
    Validated production data

  3. Issue certificates

    The registry issues one certificate per megawatt-hour into the producer's account, stamped with device, period and attributes.

    Output
    Serialised certificates

  4. Transfer to the buyer

    Certificates move between registry accounts, usually alongside a power purchase agreement or a supplier contract.

    Output
    Transfer history

  5. Cancel for a named claim

    The certificate is cancelled or redeemed for a specific consumer, consumption period and location, which ends its life.

    Output
    Cancellation statement

  6. Report the claim

    The consumer uses the cancellation statements as evidence in market-based Scope 2 reporting and in any public claim.

    Owner
    Sustainability reporting team

How Scope 2 market-based reporting relies on certificates

The GHG Protocol Scope 2 Guidance asks companies to report emissions from purchased electricity in two ways: location-based, using average grid emission factors, and market-based, using the contractual instruments they hold. For an instrument to count under the market-based method it has to meet the guidance's eight Scope 2 Quality Criteria, which cover matters such as conveying a single claim, being tracked and cancelled on the reporter's behalf, and coming from the same market as the consumption4.

The guidance is under revision. A public consultation proposed keeping dual reporting while adding hourly matching and deliverability requirements to the market-based method, with load profiles, thresholds for smaller organisations, legacy treatment of existing contracts and phased implementation5. At the time of our last check the revision had not been finalised, so treat hourly matching as a direction of travel rather than a current requirement, and check the GHG Protocol's latest publication before planning around it.

Granular certificates and round-the-clock matching

Granular certificates carry an hourly or finer production timestamp, so consumption can be matched against clean generation hour by hour rather than across a year. Buyers pursuing 24/7 carbon-free energy goals use them to show how much of each hour's demand was covered, and EnergyTag publishes a Granular Certificate Scheme Standard describing how such certificates can be issued, transferred and cancelled, including the double counting risks a scheme must address6.

The shift from annual to hourly multiplies the number of records and changes what has to be right. Meter data must be interval data, not monthly totals. Issuance has to run at that cadence. Storage needs careful treatment because a battery can shift energy between hours. And the claim depends on a matching engine whose rules are documented and auditable, not on a single annual total.

A data architecture for hourly certificate tracking

01Interval meter data02Device registry03Hourly issuance04Matching engine05Cancellation records06Claim and audit report
  1. Interval meter data

    Hourly or finer generation and consumption readings from validated meters.

  2. Device registry

    Generators, storage assets and consumption sites with their locations and grid zones.

  3. Hourly issuance

    Certificates issued per device per hour, or annual certificates split into hourly slices where the scheme allows it.

  4. Matching engine

    Allocates certificates to each hour of consumption by documented rules, including grid-zone limits.

  5. Cancellation records

    Each matched certificate cancelled for a named consumer, site and hour.

  6. Claim and audit report

    Hourly coverage, unmatched hours and the evidence trail behind each figure.

Conceptual data flow for granular certificate tracking. Component boundaries vary by registry and scheme; it is not a reference implementation.

Where a ledger helps, and where the official registry stays authoritative

  • If

    You need certificates recognised for regulatory disclosure, such as GOs

    Then

    Issue, transfer and cancel them in the official national registry, and treat any other system as a mirror.

    Only the designated issuing body's registry gives a certificate its legal standing.

  • If

    You run an hourly matching programme across sites, suppliers or registries

    Then

    Use a shared event log or ledger for matching results and cancellation evidence, reconciled against each registry.

    The hard problem is consistency across many parties and many hourly records, which shared, tamper-evident records handle well.

  • If

    You want to represent certificates as tokens

    Then

    Do it only with the registry's agreement and with the underlying certificates locked while tokens exist.

    Otherwise the token and the certificate can each support a claim, which is double counting.

  • If

    You buy annual certificates from a single registry for a single market

    Then

    Use the registry's cancellation statements directly; a separate ledger adds little.

    There is nothing to reconcile and the registry already provides the evidence auditors expect.

A hypothetical data-centre operator matching hourly demand

Questions and answers

Are Guarantees of Origin and RECs interchangeable?

No. They are issued under different legal and market frameworks, sit in different registries and generally cannot be transferred from one system to the other. The Scope 2 Quality Criteria also expect certificates to come from the same market as the consumption, so a US company cannot normally use European GOs for its US electricity, and vice versa.

Can energy certificates be tokenised?

Technically yes, but the token only supports a claim if the registry recognises the link and the certificate is locked while the token exists. Without that, cancelling the certificate in the registry and retiring the token on a ledger could each support a claim. Most of the practical value of ledgers here lies in reconciliation and evidence rather than in creating tradable tokens.

Is hourly matching required for Scope 2 reporting?

Not under the current GHG Protocol Scope 2 Guidance, which accepts certificates matched over the reporting period. A revision consulted on adding hourly matching and deliverability requirements to the market-based method, with phasing and exemptions. Check whether a final version has been published before setting procurement strategy, and note that some buyers already match hourly by choice.

What makes a certificate granular rather than ordinary?

Its production period. An ordinary certificate usually covers a month or longer, while a granular certificate is stamped with an hour or a shorter interval, so it can be matched against consumption in the same interval. Granular schemes also need rules for storage, for splitting certificates and for preventing an hourly certificate and an annual certificate being issued for the same output.

Sources

  1. Directive (EU) 2018/2001 on the promotion of the use of energy from renewable sources (recast) — EUR-Lex · checked 10 October 2026
  2. EECS: the European Energy Certificate System — Association of Issuing Bodies · checked 10 October 2026
  3. The International Tracking Standard Foundation (I-TRACK) — I-TRACK Foundation · checked 10 October 2026
  4. Scope 2 Guidance — GHG Protocol · checked 10 October 2026
  5. Upcoming Scope 2 public consultation: hourly matching and deliverability — GHG Protocol · checked 10 October 2026
  6. Granular Certificates Guide — EnergyTag · checked 10 October 2026

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