Gas consumers who are allocated RGGOs via a Retirement Statement may seek to make associated claims within the carbon emissions they report.
There are various government and non-governmental reporting standards and disclosure systems for how these claims can be made and shown with an organisations carbon reporting.
The validity of such claims will be determined by any auditor and reporting scheme involved, such as the Science Based Target Initiative, the GRI or the CDP.
The GGCS has produced a number of guidance documents and reports to help market participants and consumers navigate the various schemes and systems in use.
It is also important to consider the emission factors published by the UK government here.
Consumers should be aware that any GHG values related to the production of green gas are calculated against the lower calorific value of a green gas, whereas the kWh represented by the RGGOs are the higher calorific value of the green gas. This discrepancy has arisen because of the historic practices within GHG calculations and the gas industry. Using the lower calorific value within GHG calculations ensures a conservative approach is taken to the level of GHG savings that are being made.
Calorific values are sometimes referred to as the “heating” value of a fuel or the Gross or Net measurement of its energy content. The UK government publishes figures on the Gross and Net energy values of all types of fuel here.
GGCS Retirement Statements will, either in the text at the bottom or within the main data fields, provide information on specific Sustainability Criteria that have been met. These criteria may include GHG thresholds and criteria on other topics e.g. land use for crop growth.
Non-Domestic Renewable Heat Incentive (NDRHI)
The most common criteria in use are those within the Non-Domestic Renewable Heat Incentive (NDRHI) operated by the UK government. The key aspect of these criteria is that the lifecycle emissions associated with the production of biomethane, up until the point of injection to the grid, are no more than 125.28 g CO2 equivalent per kWh.
Where products/co-products and residues are used then an actual calculation must be made. Where wastes are used then the producer is deemed to have met this threshold.
The capture of carbon dioxide (CO2) during the biogas-to-biomethane upgrading process is counted as a negative value within the lifecycle emissions calculation (lowering the value). This methodology does not require that the CO2 is stored and the most widespread use of this CO2 is currently in the food and drink industry.
More information the “Non-Domestic RHI Sustainability Self-Reporting Guidance” can be accessed via Ofgem’s website.
International Carbon and Sustainability Certification (ISCC)
Gas Producers may choose to become certified under the ISCC System of which there is more information on their website. If so, then they will be able to generate Proof of Sustainability (PoS) documents which will display calculated emissions factors.
These documents are outside the scope of the GGCS whoever the Scheme has a compliance process to guard against double counting – see GGCS Guidance Document 19 - Interaction of GGCS and ISCC - here.
The “naturemade star” sustainability criteria have been developed by the Association for Environmentally Sound Energy (VUE) in Switzerland. The criteria cover the entire process from production and delivery of the substrates to feeding the biomethane into the grid. More details can be found here.
No Sustainability Criteria Met
Where RGGOs are imported from registries outside the UK it is possible that neither the NDRHI or the ISCC Sustainability Criteria will have been met, however the GGCS will have taken steps to assure ourselves that the gas meets our Scheme Rule that we only issue RGGOs for “gas produced from a renewable source, that has lower GHG emissions from its production and consumption than an equivalent fossil fuel product.”