Ofgem is open to relaxing rules around gas imports to drive greater competition.
The energy regulator has opened a call for input on proposals to raise the upper limit of the Wobbe Index, which measures the heat output of different fuel gases when burned.
The regulator’s open letter states that raising the upper limit of the Wobbe Index could enable Britain to import currently out-of-specification offshore natural gas without additional processing.
It states that doing so could also “result in a reduction in societal risks such as fuel poverty”.
The Wobbe Index is currently set at 51.41 MJ/m3.
It means that most imports of liquefied natural gas (LNG) into Great Britain must be ballasted with nitrogen to bring them in-line with the current Wobbe Index limits. This process increases the cost of imports and restricts sources of LNG.
A 2020 report by the IGEM Gas Quality Working Group suggested increasing the upper limit to 52.85 MJ/m3.
Ofgem’s letter adds: “The current evidence base and analysis of potential impacts is insufficient to support a change to the upper limit of the Wobbe Index however, Ofgem consider there is merit in further exploring the possibility of raising the upper limit of the Wobbe Index to widen the range of available gas to import and reduce, or even eliminate, the cost of nitrogen ballasting.”
Specifically, Ofgem states that there needs to be more evidence about the impact raising the limit would have on household appliances as well as further analysis on the impacts on a wider range of gas assets, for example National Gas Transmission.
The regulator also qualifies that the impact of introducing more carbon-intensive natural gas on net zero ambitions will need to be assessed.
Changes to the lower limit of the Wobbe Index have already been approved and from 6 April 2025 will reduce from 47.2MJ/m3 to 46.5MJ/m3.
Therefore, Ofgem states that “if there is to be consideration of raising the upper limit of the Wobbe Index, we are of the view that it would be necessary to provide evidence on the safe operational range of the Wobbe Index as a whole”.
The final decision on changing the Wobbe Index is ultimately taken by the Health and Safety Executive (HSE), which has previously said it is open to raising the upper limit if the safety case can be made.