Net-zero emissions electricity grids: farewell to SF6?

The realization of net-zero emissions electricity grids is one of the key issues formulated in the European Green Deal . The contribution of SF6 (a fundamental gas in HV technology) emissions to the worldwide CO2 equivalent emission is in the order of several tenths of percent, which is the equivalent exhaust of approximately 100 million combustion engine automobiles . Moreover, given the 3,200 years of atmospheric lifetime of SF6 (against CO2: 300 –1000 years), reduction of SF6 emission is even more effective than compensating it with CO2 reduction elsewhere.

As a result, industry is investing heavily to develop SF6-free equipment. Alternatives to SF6 in T&D equipment are either based on natural-origin gases (GWP < 1) or consist of a mixture of CO2, O2 and a small fraction of fluoronitriles (C4-FN) or fluoroketones (C5-FK). They serve mainly two functions, which are crucial for the sustainable transformation of power grids: electric insulation or switching and electric insulation with a pressurized gas , which KEMA Labs (the CESI Testing, Inspection and Certification Division) can offer testing in quality assurance and design verification on.

Indeed, the multitude of new products can be confusing to system operators. In a poll at the CIGRE conference 2021 , 80% indicated to plan installation of SF6-free GIS within 5 years, but 72% did not decide yet on a technology. 87% Indicated that the state of technology and experience is insufficient. The willingness to phase out SF6 is clear, but the road towards it seems not clear yet.

However, the industry is taking SF6 reduction very serious, as the recent publication of ambitious roadmaps towards SF6-free switchgear up to 550 kV demonstrates. System operators take their share in decarbonization by installing equipment, thereby stimulating the development of reliable “green” products, building up an experience database and mitigating the risk of carbon taxation in the future.  

In this respect, KEMA Labs has already achieved an extensive test experience in our high-power Laboratories , which includes:

• Switchgear from 15 different manufacturing sites
• Up to 145/170 kV @ 50 kA three-phase synthetic
• Mostly R&D tests, no type-test certificate issued
• Short-circuit (all duties), capacitive, shunt reactor, bus transfer, MV internal arc

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