What New Eco-Friendly Alternatives Exist to SF₆ Gas in Substations?

For decades, SF₆ gas (sulfur hexafluoride) has been the preferred insulation and arc-quenching medium in gas-insulated switchgear (GIS). Its excellent dielectric strength and stability made it ideal for high-voltage applications.

But there’s a problem: SF₆ is the most potent greenhouse gas ever used in power systems—with a global warming potential (GWP) 23,500 times higher than CO₂ and an atmospheric lifetime of more than 3,000 years.

As climate regulations tighten, the power sector is moving toward eco-friendly alternatives. At VSS Power Engineering Services, we help clients modernize substations with sustainable and future-proof technologies.

1. g³ (Green Gas for Grid) – GE Grid Solutions

• Developed by GE and 3M, g³ is a mixture of fluoronitrile, CO₂, and O₂.

• 99% lower GWP compared to SF₆.

• Can be used in high-voltage GIS, circuit breakers, and gas-insulated lines.

• Already deployed in Europe in transmission substations.

2. AirPlus – Hitachi Energy (formerly ABB)

• Uses a mixture of fluoroketone (C5-FK) and synthetic air (N₂ + O₂).

• Almost zero GWP.

• Designed for medium-voltage switchgear, now scaling to higher voltages.

• Provides excellent insulation without compromising safety.

3. Vacuum Interruption + Solid Insulation

• Uses vacuum interrupters for switching and solid/dry insulation instead of gas.

• Eliminates greenhouse gas use completely.

• Widely applied in medium-voltage applications and expanding into higher voltages.

4. Clean Air (Siemens Energy)

• Insulating medium based on natural air (80% N₂, 20% O₂).

• Zero GWP and no chemical handling required.

• Suitable for both indoor and outdoor GIS.

• Already tested in harsh environments like offshore wind farms.

5. CO₂-Based Mixtures

• Research is ongoing into CO₂ blends with O₂ or N₂.

• These gases are non-toxic, widely available, and eco-friendly.

• Currently used in some medium-voltage switchgear prototypes.

Challenges of SF₆ Alternatives

While eco-gases are promising, they face challenges:

• Higher operating pressure needed in some cases.

• Adaptation of existing GIS designs.

• Initial investment costs are higher, though long-term savings balance this.

• Engineers need training to test, operate, and maintain new gas technologies.

The Road Ahead

By 2030–2035, many regions (EU, Japan, parts of the U.S.) plan to phase out SF₆ entirely. Eco-friendly alternatives like g³, AirPlus, Clean Air, and vacuum insulation will become the global standard.

Conclusion

The era of SF₆ in substations is ending. Eco-friendly gases and insulation systems—such as g³, AirPlus, Clean Air, and vacuum interrupters—are already proving to be safe, reliable, and climate-friendly solutions.