Abstract
SF₆ has been the dominant insulation gas in high-voltage switchgear for decades, but its extreme global warming potential, 23 500 times that of CO₂, makes its continued use unsustainable. The EU’s revised F-gas Regulation and Green Deal mandate a complete phase-out of SF₆ in new transmission equipment by 2032, creating an urgent need for alternatives.
The Horizon Europe-funded MISSION project is developing three SF₆-free technologies: 1 420 kV HVAC live‑tank vacuum circuit breaker using N₂/O₂ insulation with pilots planned in Norway and France under contrasting climate conditions. 550 kV HVDC gas-insulated switchgear with N₂/O₂ insulation for compact offshore and onshore installations and undergoing long-term testing in Germany. Ultra-fast 12 kV MVDC circuit breaker, air-insulated and based on mechanical LC commutation, demonstrated as a near-commercial prototype in a relevant environment. In addition to hardware development, MISSION conducts scientific research on N₂/O₂/CO₂ mixtures, including high-pressure breakdown tests, partial discharge detection, and advanced modelling to predict insulation performance. System-level studies assess grid resilience and environmental impact, confirming significant emission reductions with accelerated phase-out strategies. MISSION receives funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No. 10113584.