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Glossary · Energy industry & energy transition

Granular guarantees of origin

Granular guarantees of origin Guarantee of origin Green power temporal matching 24/7 Carbon-Free Energy electricity labelling

Granular guarantees of origin certify electricity from a specific generation installation and, in addition, the short period in which it was generated. A conventional certificate says, for example: this megawatt hour comes from wind farm X. A granular certificate says: this quantity of electricity comes from wind farm X and was generated on 14 March between 2 p.m. and 3 p.m. In English they are usually called Granular Certificates (GC) or time-based Energy Attribute Certificates. The widely used voluntary standard of the organisation EnergyTag defines them as certificates for electricity generated in a period of one hour or less. A quarter-hourly resolution is therefore possible, but not mandatory.

The unit does not change as a result. It is still a quantity of energy, that is, kilowatt hours or megawatt hours. Only the allocation in time is new. Under EU law, a guarantee of origin applies by default to 1 MWh. Since the amendment by Directive (EU) 2023/2413 (RED III), this size can, where appropriate, be divided into fractions, provided they are multiples of 1 Wh. This matters for granular certificates, because a single installation often generates considerably less than one megawatt hour in an hour.

Distinction from conventional guarantees of origin

A conventional guarantee of origin is an accounting instrument. It allocates the environmental attributes of a quantity of electricity to a consumer. It is neither a supply contract nor proof that a particular electron has arrived at a particular customer. The certificate does state a generation period. In practice, however, this usually covers a longer period, and certificates are often set off against consumption over a calendar year, for example for electricity labelling. Whether generation coincided in time with consumption remains open. Granular certificates close this gap. They do not, however, track the electricity more precisely in physical terms. The separation between the physical flow of electricity and the attribute in the accounting remains.

This distinction is important because the term is often confused with physical direct supply. Even if a company procures matching certificates for every hour of consumption, the electricity in the grid continues to flow according to the laws of physics. Granular certificates therefore do not change the flow in the grid, but the precision of the accounting statement. Likewise, they differ from a power purchase agreement. Such a contract creates an economic relationship with an installation and can secure investments. The granular certificate, by contrast, documents the allocated quantity of generation in a specific time window. The two instruments can be combined, but they serve different purposes.

Legal and normative position

EU level, guarantees of origin: Under Article 19 of the Renewable Energy Directive as amended by RED III, at most one guarantee of origin is issued for each unit of energy produced. According to the recitals, Member States should, where appropriate, make it possible to issue certificates in fractions and with a timestamp closer to real time. This is expressly a discretionary provision. It does not give rise to an EU-wide obligation for hourly guarantees of origin or for hourly electricity labelling. How far a national registry already offers time-stamped certificates must be checked for each country individually.

EU level, renewable hydrogen: So far, hourly assessment becomes binding mainly for renewable fuels of non-biological origin, such as green hydrogen, where the electricity is drawn from the grid. Under Delegated Regulation (EU) 2023/1184, a match within the same calendar month is sufficient until the end of 2029. From 1 January 2030, the fuel must be produced in the same hour as the renewable electricity obtained under contract. Independently of this, temporal correlation is deemed fulfilled if the day-ahead price in the bidding zone is at most 20 euros per MWh. The Commission is to report on the effects by 1 July 2028. This legal framework concerns the accounting of such fuels, not the general marketing of green electricity to households or businesses.

Voluntary standards: EnergyTag's Granular Certificate Scheme Standard describes requirements for registries and issuing bodies for time-stamped certificates. In June 2025, EnergyTag accredited the first issuing bodies. The Danish transmission system operator Energinet issues granular certificates directly to generators. A platform provider generates hourly certificates by linking existing monthly certificates with hourly generation data.

Corporate accounting: For greenhouse gas accounting under the GHG Protocol, that is, for Scope 2 market-based, a proposal was made in 2025/2026 to mandate hourly matching. As of autumn 2026, the position provides for two methods: one with hourly matching, deliverability and additionality, and the previous 2015 rules, which are to apply only until a cut-off date that is still open. This has not been finally adopted. A further consultation is planned for 2027, and a joint standard with ISO for the end of 2028. Until then, the 2015 Scope 2 Guidance applies.

Temporal matching and 24/7 carbon-free energy

Granular certificates are the data basis for temporal matching, that is, the matching of consumption and generation over time. With annual matching, it is enough to cancel over the year as many certificates as the electricity consumed. With hourly matching, every hour of consumption must be covered by generation in the same hour. The goal of 24/7 carbon-free energy goes furthest: consumption is to be covered by CO₂-free generation in as many hours as possible, ideally every hour. Without a timestamp, it is impossible to verify whether such a claim is accurate.

A simple example shows the difference. An office building consumes 1,000 MWh a year, including at night and in winter. If the operator buys 1,000 MWh of solar certificates, the annual balance is 100 percent green. In an hourly comparison, however, it turns out that the certificates fall mainly on summer middays. There, a surplus arises on paper, while at night and during a Dunkelflaute (prolonged period of low wind and sun) there is a gap. With hourly matching, surpluses from the midday hour cannot be transferred to the night hour. This is possible only if the energy was actually charged into a storage facility and withdrawn later, and this is proven under the rules of the relevant system.

Why time resolution matters

In the electricity grid, generation and consumption must be in balance at all times. Wind and solar power depend on the weather and the time of day. The value of a renewable kilowatt hour therefore also depends on when it is generated. Granular certificates make visible which gaps exist in procurement. An annual balance can often be met with cheap certificates. High hourly coverage, by contrast, requires a portfolio of different generation profiles, controllable low-CO₂ generation, load shifting and, where appropriate, storage. The certificate itself does not build an installation and does not shift load. It can, however, create price signals: certificates for scarce hours with a high residual load are likely to be more valuable than those for sunny midday hours. Whether such price signals actually steer investment depends on the interplay with wholesale markets, support schemes and grid regulation.

Typical misinterpretations

  • Guarantee of physical green electricity supply: Granular certificates make the temporal statement of the accounting more precise. They do not, however, replace an analysis of grid flows.

  • Proof of avoided emissions: A certificate that matches hourly does not prove that additional emissions were avoided. What matters for that is the additionality of the installation, the displacement of fossil power plants in the relevant hour and the spatial proximity of generation and consumption.

  • Granular means complete: An hourly resolution reflects neither grid congestion, redispatch and balancing group deviations nor local emission factors. The system boundaries, such as bidding zone, technology and installation age, should therefore be disclosed.

  • Hourly matching is already mandatory: Outside the rules for renewable fuels of non-biological origin from 2030, it is currently essentially voluntary in the EU. The proposals for the GHG Protocol have not yet been finally adopted.

Institutional prerequisites

Granular certificates are credible only if several prerequisites are met. Registries with clear rules for issuance, transfer and cancellation are needed, as well as reliable metering data with a resolution of at least one hour. Procedures against double counting are also necessary. A kilowatt hour may be allocated to only one consumer in an hour. This applies in particular where hourly certificates are derived retrospectively from existing monthly or annual certificates. In that case, the original certificates must be unambiguously cancelled as well. On the consumption side, genuine hourly meter readings are often lacking. Standards then partly allow load profiles, which again limits the precision of the statement.

Relationship to green electricity and electricity labelling

The term green electricity remains ambiguous as long as it is unclear what it means: physical supply, accounting-based procurement, regional proximity, additionality or temporal matching. Granularity clarifies only part of this, namely the time of generation. A certificate that matches hourly from an old, fully depreciated installation affects investment differently from a long-term contract that finances a new installation. Granular guarantees of origin thus make the electricity accounting more precise. Their limit lies where the better accounting is used, without further verification, to infer physical supply, additional climate impact or grid compatibility.

Sources

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Edited by eCMS on 12.11.2026 05:05

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