Not all of the biomethane fuelling UK trucks originates in the UK.  Some is injected into the European gas distribution network, and is matched with an equivalent amount extracted from the UK pipeline.  This process is known as mass balancing.

Last September, the DfT initiated a discussion on amending its guidance on the mass balancing of biomethane and it became clear that further work was required to:

  • expand the options to reflect the realities of how gas is traded
  • to ensure that suppliers of gas and those that verify their applications for RTFCs have clarity on how mass balancing should be evidenced, and
  • to ensure that methods employed are not equivalent to a “book and claim” approach, which is explicitly ruled out under the Renewable Energy Directive

“The mass balancing concept was evolved for liquid fuels,” explains Gaynor Hartnell, Chief executive of the RTFA.  “Mapping that principle over to gas, which can be transported in pipelines as well as ships, required further consideration.  We embarked on a process of exploring the detail and examining the range of approaches companies were taking.  Our objective was to bring greater transparency and ensure that all stakeholders involved were aware of which approaches would meet the DfT’s criteria.  The DfT was happy to work with us to take the time to ensure that the updated guidance is robust and comprehensive.”

The RTFA engaged the services of gas markets expert Sue Ellwood, in November last year.  Phase 1 of the work was completed, and the results presented to DfT in December.

The next stage of work has just commenced, as a joint DfT – RTFA project, and should be completed in April with the publication of updated guidance.  Industry participants include CNG Fuels, Gasrec, AirLiquide, BP and Decarbonise Fuel Limited.

Gaynor Hartnell continued,

“We’re expecting DfT will be communicating with industry stakeholders within the next couple of weeks, setting out how it intends to approach the mass balancing of biomethane delivered through gas pipelines and its intention to review the arrangements for imports of liquified biomethane.  It will also set out transitional arrangements, giving industry ample time to prepare, should any changes be necessary.

Biomethane is an important and growing fuel within the RTFO, and we welcome working with the DfT to ensure it continues play its role in decarbonising UK road transport.”

Background information

The use of biomethane to fuel vehicles can achieve savings in the region of 85% and above.

For an explanation of the benefits of biomethane in transport visit the Gas Vehicle Network’s website.

For a map of the location of gas filling stations visit

RTFA members supplying biomethane:

CNG Fuels develops, owns, and operates CNG Refuelling infrastructure and sources 100% Renewable Biomethane or Bio-CNG for its stations.  It is rolling out a UK-wide network of reliable and convenient refuelling facilities to service customers’ vehicle fleets and their off-grid energy needs.

Gasrec sells liquified and compressed renewable biomethane through publicly accessible refuelling stations in strategic locations or bespoke CNG and LNG refuelling facilities that it designs and builds for its customers. It is supplied in its own gas-powered tankers that deliver LNG direct to stations and CNG is supplied via the grid or by tanker (known as L-CNG) where a grid connection is not available.

Air Liquide both produces biomethane from organic waste at a network of anaerobic digestion facilities in the UK, and supplies it as a fuel for trucks and buses at a network of bio-LNG and bio-CNG fuelling stations.

Decarbonise Fuel Ltd works to decarbonise UK transport by generating a saving over fossil fuel using the RTFO scheme. It then passes on as much of the saving as it can to the transport user.