UK networks back split from Europe on SF6

Mirroring the hard stance that has been taken on SF6 in electrical switch gear in Europe would threaten the UK’s net zero ambitions, electricity networks have warned.

SSEN Transmission’s carbon reduction lead Joshua Msika said that the Scottish transmission operator’s entire business strategy is focussed on investing in its network.

This investment will enable renewable generation that will account for around a sixth of the UK’s decarbonisation needs to connect to its network.

He said the company has an SF6 avoidance policy that means it is installing non SF6 gases wherever technically viable, despite a host of associated risks and increased costs.

However, the transmission operator currently favours synthetic alternatives such as C4FN as the development timescales for natural origin alternatives, which have a global warming potential (GWP) of zero, would challenge its ability to deliver the necessary investment for net zero on time.

Similarly at distribution level, UK Power Networks’ head of asset strategy Sophie Motte said fulfilling the operator’s commitment to install SF6 alternatives at certain voltages was “a challenge” due to long lead times, as it has also made a commitment not to be a barrier to the transition to net zero.

SF6, which has been used to insulate electrical switchgear since the 1960s, is 23,500 times more powerful as a greenhouse gas than carbon dioxide. The European Union has set out a phased approach to banning SF6 in new installations, while network operators are tackling leakage rates from its existing installations.

“The GWP of the synthetic gases that we are looking at is generally around 400, so that is still a 98% reduction over SF6. Both options represent a massive improvement over SF6,” said Msika.

“You would have to leak 60 times more C4FN gas in order to have the same impact as an SF6 leak. Even though they are both F gases, their impact is completely different.”

The direction of the UK’s transition away from SF6 gas, and the speed at which network operators must make that change, has become less clear since the European Union revealed that it was planning to extend its F-gas ban to also cover fluoronitriles in October last year, which are used in the synthetic alternatives the UK industry has been trialling in readiness for a ban.

While the UK government is in theory free to set its own regulations on F-gases, the UK industry heavily relies on EU manufacturers for electrical switchgear, with many suppliers already announcing moves towards natural origin-based products.

Think tank Sustainability First, which has been pushing for action on SF6 in the electrical industry, has said that it would be “for regret” if, over time, the UK ends up with lower climate and environmental standards for electrical switchgear than the EU, but that in the short-term the UK should prioritise enabling net zero.

It held a webinar to discuss the implications for the industry of the changing regulatory environment at the end of last month.

As well as threatening net zero, Msika warned that the EU’s high ambition in ruling out everything except natural origin gases immediately is counterproductive, as it is actually forcing networks to rely on SF6 for longer.

“C4FN’s time is now as the gas insulated substations that we are building now can either be 100% C4FN or one of its alternatives, or it has to be a mix of clean air and SF6, as we need a certain amount of SF6 still to do the things clean air can’t do.

“From a carbon perspective that is not a good outcome as we are increasing the amount of SF6. In the pursuit of natural origin gases we could be missing the opportunity that C4FN presents in the immediate and short-term.”

In the long-term SSEN Transmission is “seriously considering” moving to air insulated substations wherever possible as they are less complex and easier maintain, although this will mean substations will need a substantially bigger footprint.

While this is an option in Scotland, for fellow transmission operator National Grid, larger substations would be difficult to accommodate given the shift to distributed generation has already increased the size of many of its substations.

Sustainability First associate Judith Ward said the priority for the UK industry should be working together to create a standardised and independent evaluation framework for lifetime greenhouse gas emissions of the different options, as this may allow for the continued use of synthetic options through the EU Eco Design Directive.

This would allow new equipment to be installed where the total life-cycle greenhouse gas emissions are shown to be lower than equivalent equipment, but Ward warns this should not be left to manufacturers to prove.

“Several manufacturers are producing lifecycle analysis, but I think if we want to really understand if fluoronitrile is a way forward or is dead then I think we need to have confidence in an evaluation framework.

“Maybe this could be done through an innovation project with the right people involved. I really think that this is something we as the UK could make a contribution on.”

Others in the industry speaking at the event believe the Department for Energy Security and Net Zero should provide a tool for comparing the whole carbon lifecycle of different transformer options to allow “everybody to be on the same page” and understand the space implications of different policies.