About Renewable Gas Guarantees of Origin (RGGOs)

Understanding RGGOs and the information contained on RGGO Retirement Statements

Renewable Gas Guarantees of Origin (RGGOs) are unique identifiers issued by the GGCS for each kWh (rounded to the nearest whole number) of biomethane injected into the grid and registered with the Scheme (see below for details of RGGOs related to other types of green gas).

These RGGOs can be transferred from Producers to Traders in the GGCS Registration Database and then allocated to a gas consumer, either directly or via a green gas tariff.

When a gas consumer is allocated a RGGO they are matching the gas that they have withdrawn from a Distribution Network to a unit of green gas that was produced and placed into the same network. The RGGO will be retired and shown on a Retirement Statement (see below). They will then be unavailable to any other gas consumer.

RGGOs do not track the physical flow of green gas. However, gas consumers who are allocated RGGOs can make a claim to have consumed green gas (see below for more information on the relationship between RGGOs and physical gas flows).

What is in a RGGO?

RGGOs are composed of a code containing information on the green gas injected into the grid. An example is:

G     0001     BF     00000001     E     0211

The various aspects of the code are detailed below.


Indicates that the gas was “green”


Indicates the identity of the producer – see the producer information page for more information


Indicates biomass inputs into the gas production process (sometimes referred to as the feedstocks) and the classification of those feedstocks as products/co-products, residues, or wastes


Indicates which kWh the RGGO represents, out of the total kWhs injected in a quarterly or monthly consignment (based on the order in which they are retired)

Indicates the country in which the producer is located (United Kingdom, Netherlands, Germany etc)


Indicates the month and year in which the gas injection period ended

RGGO Retirement Statements

When an account holder retires RGGOs, a Retirement Statement is generated (also referred to as a Certificate) which allocates those RGGOs to a gas consumer or a particular gas tariff which a group of consumers are part of.

The statement contains a range of information and the table below can help you understand the different fields and the information they provide. N.b. the terminology may vary according to when the Retirement Statement was created.

RGGOs issued on:

The date that the Renewable Gas Guarantees of Origin (RGGOs) were issued within the Registration Database (note that if RGGOs are imported from another registry this will be the date they were imported and not when they were originally issued)

Date Created / RGGOs :

The date that the RGGOs were retired from the Registration Database and the Retirement Statement was created

Date Printed / Retirement Statement Downloaded:

The date that the Retirement Statement was downloaded from the Registration Database

Certificate issued to / RGGOs allocated to:

The identity of the gas consumer or green gas tariff that the retired RGGOs have been allocated to

Renewable Gas Guarantees of Origin:

The unique identifiers that represent kWhs of biomethane injected into the grid. Each Retirement Statement lists a range of retired RGGOs and this field shows the first and last kWh of that range

Injection Date:

For RGGOs issued before August 2020 this will show the month and year of the end of a three-month production period, where the end date of the production could be any date in the month shown. For RGGOs issued after August 2020, this will show the start and end dates of the production period. These dates are fixed within the UK subsidy scheme, the Non-Domestic Renewable Heat Incentive (NDRHI), and actual meter readings may be take +/- 3 days from the dates shown

Technology / Feedstock or Biomass Information:

Information on the biomass inputs (feedstocks) used in the production process. See here for more details on the biomass information displayed on a Retirement Statement

Injection Location:

The location that the green gas was injected into the Distribution Network (only shown on Retirement Statements downloaded before July 29th 2020)

RGGOs issued by:

The name and country of operation of the registry which issued the original RGGOs (only shown on Retirement Statements downloaded after July 29th 2020)


The amount of kWhs of biomethane injected into the grid that the RGGOs on the retirement statement represent

Production Support received:

Only shows on Retirement Statements listing RGGOs issued after August 2020. Production Support is a financial incentive given to the producer by a national government at the point they inject their biomethane. In the UK, Production Support is provided by the NDRHI or the Green Gas Support Scheme (GGSS). For more information, see the section on Production Support below

Sustainability Criteria Met:

Different voluntary and regulatory schemes contain sets of sustainability criteria related to GHG thresholds, use of biomass types and its sourcing. More information about the ISCC and RHI sustainability criteria can be found here

Certificate Pin Number / Statement Pin Number:

Can be used here to verify a Retirement Statement

Green Gas Producer:

The details of the producer of the biomethane, whose gas injections the RGGOs listed on the Retirement Statement represent. Details will include: address of producer, type of gas produced, production process type, metering point, commissioning date, production capacity, if investment support was received

More information on producers is available here

Green Gas Supplier / Retirement statement generated by:

The details of the Trader which has retired the RGGOs listed on this Retirement Statement

Further information:

This text contains information on the carbon emissions associated with the biomethane production process and for RGGOs issued before August 2020 the nature of the support the UK government has provided via the RHI and the sustainability criteria met– for more information see here

Net vs Gross measurement of Green Gas production

The Net measurement method means that you calculate the number of RGGOs to issue by subtracting from the kWh of green gas produced any kWh of fossil gas used in the production process. For example, a biomethane plant may use natural gas (a fossil gas) to provide heat to its biogas-to-biomethane upgrading process. This is the method used in the UK to calculate payments under the Non-Domestic Renewable Heat Incentive (NDRHI) and Green Gas Support Scheme (GGSS) and is used by the GGCS to issue our RGGOs. It is also used by Vertogas in the Netherlands.

The Gross measurement method means that you issue RGGOs according to the total number of kWh of green gas produced without any subtraction for fossil gas used in the production process. Although, the fossil gas use will be factored into any calculation of the greenhouse gas emissions arising from the production of the green gas. This method is used by Energinet in Denmark, DENA in Germany, and AGCS in Austria.

Production Support

Production Support is a financial incentive given to a producer by a national government at the point they inject their biomethane. In the UK Production Support is provided through the NDRHI or the GGSS.

This type of support is sometimes referred to as a “feed-in-tariff”, as it is provided at the point energy is “fed-in” to a network.

It is essential that consumers are given clear information on whether the RGGOs they have purchased are for gas that has been supported financially by a national government. Where the core incentive to produce the biomethane was production support, then claims that a purchase of RGGOs has led to any additional biomethane production, above the amount incentivised by government support, should be carefully considered – see here for more information.

GGCS RGGOs include a label of “Production Support – Yes/No” which is visible to Producers and Traders when they transfer RGGOs within the Registration Database and to Consumers via the Retirement Statements they are provided.

There may be times where producers receive production support for only part of their production over a given period:

  1. When a producer chooses to claim NDRHI/GGSS for >100% of their production, making the unsupported kWhs available to be sold for use in the transport market and a RTFC claimed
  2. When a producer exceeds their agreed production capacity under the NDRHI or GGSS, in which case kWhs produced up until a certain volume will receive Production Support, but kWh produced over that volume will not. 
  3. When more than 50% of a producer’s annual production comes from crop inputs, they may be affected by a “crop cap” on their the NDRHI and GGSS payments. Note that in the terminology of the GGCS, the NDRHI and the GGSS, crops are referred to as “Product/Co-Product”.


The Production Support status for each kWh in examples 1 and 2 above is clear at the point that RGGOs are issued. However, under example 3, the “crop cap” scenario, the status of the Production Support payment is more complex.

The requirements of the “crop cap” are that producers should only receive Production Support payments for kWhs produced from crop if those kWhs represent below 50% of their total annual production.

However payments are always made after the end of a quarterly production periods for all kWhs of gas produced from crop.  Only at the end of an annual production period is it possible to calculate the number of kWhs that represent 50% of a plants production and any kWh produced from crops beyond that level. When that calculation is made the Production Support payments for kWhs beyond the “crop cap” are then repaid (by the producer to Ofgem) either via an actual repayment or a reconciliation with the NDRHI/GGSS payment due from Ofgem for the next quarter of production.

The GGCS accounts for this process in the following way, which we believe allows for the timely issuing RGGOs, in a way that minimises the risk of using the wrong Production Support label on a RGGO, and prevents any unfair gain by producers, traders, or consumers:

  • Waste and Residue RGGOs are not affected by the “crop cap” and repayments of Production Support.
  • At the end of an annual production period producers will provide GGCS with a calculation (as submitted to Ofgem) that shows if any kWhs of gas produced from crops were “beyond the crop cap” and if repayments to Production Support will be made.
  • If any kWhs have been produced beyond the cap, then GGCS will seek to ensure that in the final quarter of the compliance year the appropriate number of Product RGGOs are labelled as “Production Support – No”.
  • This is done with the acknowledgement that Production Support has been paid for those kWhs of production but will be repaid in approximately 3-months’ time (depending on the speed with which the next NDRHI/GGSS payment is made).


There is the potential that the number of Product RGGOs due to be issued in the final quarter of the annual production period is lower than the number of kWh for which a Production Support repayments are being made. In such cases the GGCS will seek to changed the Production Support label on RGGOs issued for the 3rd production quarter of the year according to the following principles:

  • Where those RGGOs are still being held by the producer they can be withdrawn and reissued with a “Production Support – No” label.
  • Where those RGGOs have been transferred to a trader (potentially moving through multiple accounts), have been retired and transferred to another registry or have been retired and allocated to an end consumer, no action will be taken. The producer, trader and consumers will have transacted those RGGOs based on Production Support labelling that was correct at the time and will not have gained any unfair value or advantage from the fact that the production support was repaid.

The GGCS may also change Production Support labels for RGGOs issued for the 2nd and 1st quarters, if appropriate, but corrections will only be made if Production Support repayment relate to those kWh. They will not be made in lieu of changes to Q3 RGGOs which were not possible because those RGGOs had been transferred and/or retired.

GGCS considers that the main detriment from failing to change the Production Support label from ‘Yes’ to ‘No’ is to the producer, who may have been able to secure a higher value for those RGGOs. Any producer wishing to avoid this potential loss of value should refrain from being issued with Product RGGOs, or to hold them in their account so they can be withdrawn and relabelled, until the end of an annual production period.

The GGCS will continuously review this policy and monitor the frequency with which Production Support labels are changed.

Contractual terms between producers, traders and consumers are outside the scope of the GGCS; however, we recommend that all parties account for the status of the Production Support label and any potential changes to that label within the terms they agree.

Is a Renewable Transport Fuel Certificate (RTFC) Production Support?

RTFCs have a market value determined by the need of certain fuel suppliers to fulfil the requirements of the Renewable Transport Fuels Obligation (RTFO). Producers are unlikely to be awarded an RTFC and sell it, but the payments made to them by counterparties for the delivery of biomethane that has not been awarded NDRHI or GGSS payments are enabled by the value derived from RTFC sales.

As these payments are not directly from a national government, or de facto government body, to a producer, for the injection of units of renewable gas, they are not considered to be “Production Support”. However, biomethane production that is sold to counterparties for RTFC claims is being driven by the RTFC value and not the RGGO value and any additionality claims should be made in that context.

For further information on this topic, you should contact the GGCS Scheme Administrator.

The wider context of the RGGO market

RGGOs are a type of Energy Attribute Certificate (EAC) which represent the environmental attributes of a unit of renewable energy and are traded separately to the energy they relate to.

In Europe, EACs that are used for disclosing to consumers the origin of the electricity they have been supplied are called Guarantees of Origin (GoO or GO) and are defined in Article 15 the European Union’s Renewable Energy Directive (RED). Outside of Europe, they may be called Renewable Energy Certificates (RECs) or International Renewable Energy Certificates (I-RECs).

While the RED only specified that GoO should be issued for renewable electricity, over the last ten years Schemes in the UK, Denmark, Germany, Finland, Netherlands, Austria, and Switzerland have started to issue EACs for renewable gases. You may hear these EACs being referred to formally and informally as Certificates, Green Gas Certificates, Biomethane Certificates or Gas GoO. As detailed on this page, the GGCS uses the term Renewable Gas Guarantee of Origin (RGGO).

As of July 2021 the second version of RED (REDII) has come into force and expands the scope of GoO to cover all kinds of renewable energy including renewable gas. The directive must be applied at the national level by EU member states and those wishing to align themselves with the EU GoO system. The UK government is not currently planning to align itself with RED II.

For further information on this topic, you should contact the GGCS Scheme Administrator.

RGGOs, the physical green gas, and the wholesale gas market

When a gas consumer buys a RGGO (or its equivalent in another country) they are matching the gas that they have withdrawn from a Distribution Network (a network) to a unit of green gas that was produced and placed into the same network.

Aside from the units of biopropane that GGCS track within the network of bottles and tankers operated by Calor Gas Ltd, the network that RGGOs relate to is the system of pipeline gas transportation in the UK (the GDNs, NTS and iGTs), and the pipeline network this is connected to in Europe. The type of green gas they represent is biomethane.

While RGGOs must link producers and consumers of gas that are part of the same network, they do not represent the physical movement of a green gas from injection point to withdrawal point. This is because once a green gas is injected into a network it mixes with all the other gas within the network and it is impossible to track the actual molecules as they move within the pipes according to local conditions of demand and supply.

Neither do RGGOs relate to units of gas traded on the wholesale market. The wholesale market is for the trading of units of gas within the GDN, NTS or iGTs (the grid) and makes no distinction to whether the gas was from a fossil or renewable source or what its green credentials are e.g. GHG emissions arising from its production and combustion. The structure and rules of the wholesale market are too complex to describe here, but National Grid, who are the System Operator, provide a comprehensive explanation here.

According to the conventions of green house gas reporting and consumer disclosure for green tariffs it is the RGGOs which represent the environmental attributes of the biomethane, and a wholesale gas contract has no standing with regards to if gas can be sold as “green”.

RGGOs are traded separately from wholesale gas and almost all claims of green gas use are made on the basis of generic gas supplied from the wholesale market, matched to RGGOs which link the customer back to the green gas injection.

However, in some cases, gas shippers and gas suppliers may coordinate their RGGO and wholesale gas activity if they see value in doing so.

For example:
Biomethane Producer A injects biomethane into the grid. It transfers the RGGOs it has been issued to its Gas Shipper, who is responsible for arranging entry for the physical units of gas into the wholesale market.

The Gas Shipper then has ownership of both the wholesale gas and the RGGOs and it sells both to a Gas Supplier serving the SME market.

The Gas Supplier then retires the RGGOs, allocating them to one of its SME customers and this is matched, within their internal systems, to the wholesale gas they have purchased from the Gas Shipper that represents gas injected by Biomethane Producer A.

The actual molecules of biomethane have mixed with the other gas in the network, but both the RGGOs and the wholesale gas contracts show a chain of custody between the biomethane producer and a gas consumer.

What kind of green gas does a RGGO represent?

GGCS can issue RGGOs for any type of green gas which meets our Scheme Rules requirement to be "a gas produced from a renewable source, that has lower GHG emissions from its production and consumption than an equivalent fossil fuel product". It must also meet the quality requirements of the Distribution Network it is injected into.

To date the Scheme has issued almost all its RGGOs for biomethane injected into the UK Gas Distribution Network.

As further types of green gas such as bio-SNG (Synthetic Natural Gas) and green hydrogen begin to enter the market we will update our Registration Database and create guidance for how RGGOs related to these gases can be issued, traded and retired.

GGCS also issues RGGOs for bio-propane injected into Calor Gas Ltd’s Distribution Network of bottles and tankers. These RGGOs are transferred and retired in a distinct area of the GGCS Registration Database and cannot be allocated to non-Calor customers.

It is clearly shown in the relevant Retirement Statements that the RGGOs are for biopropane and not biomethane.

For further information, please visit Calor Gas Ltd’s website.

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