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 biomethane producers to account holders in the GGCS 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When a gas consumer is allocated a RGGO they are matching the gas that they have withdrawn from a Distribution Network to a unit of green gas that was produced and placed into the same network.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 be 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’s 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.

G     Indicates that the gas was “green”
0001 Indicates the identity of the producer – see the producer information page for more information
BF 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
00000001 Indicates which kWh the RGGO represents, out of the total kWhs injected in a quarterly consignment
Indicates the country in which the producer is located (England, Wales, Scotland or Northern Ireland)
0211 Indicates the month and year in which the gas injection quarter 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 to 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
Date Created / RGGOs Retired: The date that the Renewable Gas Guarantees of Origin (RGGOs) were retired from the GGCS system and the Retirement statement created
Date Printed / Retirement Statement Downloaded: The date that the retirement statement was downloaded from the GGCS system
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 you will see here the first and last kWh of that range
Injection Date: Gas is registered with the GGCS in quarterly consignments and this tells you the month in which the quarter ended. For example if the RGGOs on the Certificate represent gas injected between April 2016 and July 2016, then July 2016 will show in this field
Technology / Feedstock or Biomass Information Information on the biomass inputs (feedstocks) used in the production process. See here for more information on the technology/feedstock information displayed on a retirement statement  
Injection Location: The location that the green gas was injected into the Distribution Network (not shown on Retirement Statement downloaded after July 29th 2020)
RGGOs issued by: The name and country of operation of the registry who issued the RGGOs (only shown on Retirement Statement downloaded after July 29th 2020)
Amount: The amount of kWhs of biomethane injected into the grid, that the RGGOs on the retirement statement represent
Certificate Pin Number / Statement Pin Number: Can be used here to validate a Certificate
Green Gas Producer: The details of the producer of the biomethane, whose gas injections the RGGOs listed on the Certificate relate to. More information on producers is available here
Green Gas Supplier / Retirement statement generated by: The details of the Account Holder who 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 the nature of the support the UK government has provided via the Renewable Heat Incentive – 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 (RHI) 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.

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).

The Second RED has now been published 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, in time for mid-2021.

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, and 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 gases 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 injected and withdrawn from the GDN, NTS or iGTs and makes no distinction to whether the gas was from a fossil or bio source. Like RGGOs the wholesale gas market is unrelated to the physical movement of particular quantities of gas within the network. The structure and rules of the wholesale gas market and supply to consumers are too complex to describe here, but Ofgem provides a useful summary on its website.

According to the conventions of greenhouse gas reporting and consumer disclosure for green tariffs it is the RGGOs which represent the environmental attributes of the biomethane and 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 to.

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 biomethane 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 is able to 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 of its RGGOs for biomethane injected into the UK Gas Distribution Network.

GGCS also issue 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. RGGOs for biopropane have technology/feedstock identifier beginning with C, for example CA, CB, or CD, which is to indicate that the green gas is:

BioLPG from Hydrogenated Vegetable Oils

For further information please visit their website.

As further types of green gas such as bio-SNG (Synthetic Natural Gas) and green hydrogen begin to enter the market we will create new technology/feedstock identifiers.

Founder Partners and Associate Members:
British Gas
Thames Water
Milton Keynes Council
National Grid
CNG Services Ltd