Tackling SF6 on the electricity networks

SF6 is a highly potent, long lived greenhouse gas with a global warming potential (GWP) 25,200 times that of carbon dioxide. Widely deployed over many decades in electrical switchgear, including in electricity networks, it is effective as an electrical insulator and in preventing short-circuits. As highlighted in a Utility Week report last year, all GB networks are committed to reducing their SF6 emissions over the next five years. This is particularly important on the high-voltage transmission networks, which (primarily due to their scale) account for 93% of SF6 leakage.

GB networks have been actively working with manufacturers to trial different SF6-free solutions. However evolving EU Regulations are both increasing the urgency and adding to the challenge given that the previously piloted alternatives are now themselves coming under scrutiny.

The commitment to reduce SF6 emissions sits alongside unprecedented demand for network growth and system reinforcement in the next five to 10 years to enable us to reach the goal of a de-carbonised power system by 2035. Wider conversations are needed as the networks look to navigate through these competing tensions.

Despite Brexit, the new EU F-Gas Regulation will have a big impact on the equipment options open to the GB networks given that EU-based manufacturers continue to play a lead-role in our switchgear market.

The near final EU Regulation, agreed between the European Council and Parliament and published in October, introduces an outright ban (within the EU) on installing new switchgear equipment that contains SF6, with backstop dates (out to 2032) depending on voltage, and new rules around spare parts and use of SF6 for top-ups. A new development in this latest version of the Regulation is that fluoronitrile gas in switchgear is similarly banned.

Globally, there are effectively two categories of alternatives to SF6 in switchgear – those using a synthetic gas (such as fluoronitrile) and those based on natural origin gases (like oxygen).

The synthetic gas products are closest in performance to SF6. Hence they offer a readily used like-for-like alternative (including for retro-fill of existing equipment) and have been the main focus of the GB trials. They do have some global warming potential, but, in blended form this is a small fraction of that of SF6.

In addition, and of growing concern at EU level, the synthetic gases also fall into the broad category of PFAS (“forever chemicals”) which are pervasive, break down slowly in the environment and carry health and environmental risks.

While the natural origin gas equipment is safe for both the environment and health it typically requires more space in terms of its physical footprint (in particular at transmission level) and is not suitable in every case. There are also GB specific products (particular voltages or types of equipment) which are unlikely to be a priority for global manufacturers.

The regulation does have time-limited procurement derogations where suitable alternatives are not yet available to EU network companies but it is still unclear how these derogations will work in practice and what the implications will be for the switchgear market that GB networks rely on.

The regulation also has a derogation around eco-efficiency and life-cycle carbon impacts of switchgear which may leave options open on continued use of fluoronitrile blends. While it is right to look at the overall carbon impacts of different solutions including the embodied carbon involved in new or larger equipment, there is no widely agreed methodology for calculating these impacts – and there needs to be. Manufacturers of fluoronitrile products, like Hitachi who welcomed the derogation, will now be working hard to satisfy the Commission that their products do indeed satisfy these emission life-cycle requirements.

In parallel it is expected that the EU Regulation will encourage all major manufacturers to look to develop natural origin gas products although there are technical challenges with active switching equipment at higher voltages.

The situation in the UK

For the UK, Defra’s aim in regulating F-Gases is to meet successive UK carbon budgets and the UK’s 2050 net-zero target. With the EU F-Gas Regulation now clear, Defra will consider how this might be reflected in GB legislation. In so doing, it will be vital for Defra and DESNZ to coordinate and chart a route that balances the requirement to radically reduce new uses of both SF6 and fluoronitriles in GB equipment with the need for the networks to plan, procure and massively invest over the next five to 10 years to deliver on the network growth necessary to meet the 2035 target.

There are also increasingly pressing questions for the UK to consider on PFAS chemicals. The EU is looking at introducing a blanket ban on all PFAS products given their potential health and environmental impacts (already proven for some PFAS) and following the precautionary principle. Such a ban would rule out the use in switchgear of synthetic gas-based alternatives to SF6. While policy in this area is at an early stage the uncertainty is already impacting the switchgear supply chain. Again, Defra will consider how far to mirror any EU PFAS ban for the UK, noting that, post Brexit, the UK is generally looking at a more risk-based approach to chemicals regulation. Early work by both Defra and the EU to examine the actual impacts of the main PFAS compounds used as SF6 alternatives in switchgear should be a priority.

Stringent regulation on F-Gases and PFAS is key to the longer-term aim of driving the market in safe switchgear alternatives and supports the networks longer term commitments on eliminating SF6. It would be for regret if, over time, the UK ends up with lower climate and environmental standards for electrical switchgear than the EU. Nevertheless, faced with long lead-times on equipment procurement plus higher costs, GB networks have understandable concerns about how to square near-term supply chain challenges for F-Gas free equipment with securing delivery of hugely increased network capacity in accelerated timescales.

Given these tensions and trade-offs our view is that there should be two near-term priorities for the network companies: placing a laser-like focus on reducing SF6 leakage rates, and at the same time collaborating with manufacturers to support the development of natural origin gas solutions.

Continuing to innovate and share knowledge across networks is key to making progress on SF6 leakage rates. A greater emphasis on monitoring and digitalisation would open opportunities for AI and other tools to predict and better manage leakage – and allow more informed decisions about longer term pathways.

There is also a need for Ofgem to be more proactive and, for the next price control (RIIO ET3), to put in place stronger incentives on leakage reduction and require greater transparency from the transmission networks. It is notable that, for distribution, the ED2 Annual Environmental Reports require much more detail on SF6 assets and interventions undertaken than is required on transmission – a discrepancy we should not have to wait until ET3 to address.

Finally, with the EU direction of travel now clear, we need a wider GB debate involving networks, manufacturers, policy makers, environmental and other stakeholders on how transmission networks in particular should balance the trade-offs in their investment decisions over the next 5-10 years against important near-to-medium term targets for F-Gas reduction.

This article was first published in Utility Week’s latest Digital Weekly issue. The article draws on a Grid Edge Policy report “Green Grids” written by Maxine Frerk, Judith Ward and Janet Wood. Sustainability First is hosting a webinar to discuss the report on 24 January 2023.