The role of F-gases in high-voltage

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F-gases: F-riends or F-oes?

Did you know that tennis balls used to be filled with sulfur hexafluoride (SF₆), a powerful insulating gas used in high-voltage equipment? While it might seem strange that the same gas that powers electrical grids was once used to keep tennis balls bouncing longer, it underscores the versatility of fluorinated gases (F-gases), a family of synthetic compounds. Of these, SF₆ has been a superhero of insulating gases in high-voltage power systems for the past decades, with its extraordinary abilities to insulate and dissipate heat. Sadly, some F-gases also happen to be "super greenhouse gases" with severe and powerful impact on the climate. 

In this blog, we'll clarify what F-gases are, explore the vital roles they play in high-voltage technologies, the environmental challenges they present, and debunk common myths surrounding their use. We'll also look at the innovations underway at Hitachi Energy aimed at mitigating their negative impacts, leading the industry to a more sustainable energy future. Visit this page to discover more about sustainable practices in high-voltage technology.

Understanding F-gases 

The "F" in F-gas stands for fluorine, an element known for its high electronegativity. This property, coupled with the presence of other elements like sulfur, makes some F-gases ideal for insulating and quenching electrical arcs in high-voltage equipment. In electrical equipment, such as switchgear, these gases serve to prevent electrical discharges, which can otherwise lead to power outages or even dangerous explosions.

SF₆, in particular, has been prized for its excellent electrical insulation and current interruption properties. This gas insulates by forming a barrier that makes it difficult for electricity to pass through, similar to how rubber insulates electrical wires. Furthermore, when arcs do form, SF₆ is highly efficient at absorbing the heat generated, helping to quickly extinguish the arc. These properties made the gas an industry favorite, with widespread use across the globe in high-voltage equipment. While SF₆ has been vital for the reliable operation of electrical grids, its role in global warming has sparked significant discussion and debate.

The distinctive properties of F-gases, the uniqueness of their chemical structures, and lack of alternatives in some instances, adds layers of nuances that are often overlooked. We can replace SF₆ but need some F-gases if we want to maintain the current reliability of the electrical grid. 

Curious to learn more? Listen to Power Pulse for a deep dive into the world of F-gases and their role in high-voltage technology.

The environmental impact of F-gases

SF₆ has an incredibly high global warming potential¹ (GWP) – about 24,300 times more than carbon dioxide - over a 100-year period. This means that even small amounts of SF₆ released into the atmosphere can effectively trap lots of heat, contributing significantly to global warming. To put this into perspective, SF₆ can remain in the atmosphere for thousands of years, making it one of the most persistent greenhouse gases.

The issue of per- and polyfluoroalkyl substances, where most F-gases formally belong, adds to the complexity of the environmental discussion. While SF₆ is a single compound, this is a large family of chemicals that is widely used in consumer products and high-tech industrial products. Because of their incredible persistence to wear, and resistance to heat, water, and oil, they are practically found everywhere. In high-voltage circuit breakers, they are valued for their ability to withstand temperatures as high as 19,000°C.

However, their durability also means many of these substances resist breakdown and decay in the environment and can be pollutants if they are not properly disposed. A subset of these compounds that are used in consumer products tends to move relatively quickly through the environment, making such contamination hard to contain.  

Debunking myths surrounding F-gases

Despite the valid environmental concerns surrounding F-gases, there are several misconceptions that need to be dispelled to create a balanced understanding of these chemicals.

• Myth 1: All F-gases are equally harmful.
  Not all F-gases have the same environmental impact. Some compounds have a much lower environmental impact. While SF₆ has an extremely high GWP, other F-gas mixtures may have much lower environmental footprints. For example, Hitachi Energy has developed an eco-efficient gas mixture used in its EconiQ^TM high-voltage portfolio, which includes C4-FN. This fluorinated gas decays within 30 years and breaks down into natural end products. This is a significant improvement over SF₆’s 1,000-year atmospheric life span².

• Myth 2: F-gases are easily replaceable.
  Replacing SF₆ and avoiding fluorinated gases altogether is not as simple as swapping out one gas for another. These gases are carefully selected for their unique properties, which combine insulating capacity and heat dissipation. Any replacement must maintain these critical safety features to ensure high-voltage systems function effectively. In many cases, alternative gases do not provide the same level of performance in isolation, which is why carefully formulated mixtures like those used in EconiQ are necessary.

• Myth 3: F-gases are harmful to human health.
  While problematic substances in consumer products do raise health concerns, using F-gases in high-voltage equipment does not pose any risk to human health. SF₆ is non-toxic for the human body, making it safe for use in electrical systems. The same is true for eco-efficient gas mixtures. It is all about the potential environmental impact, not about toxicity to humans. 

The search for sustainable alternatives

The high-voltage industry recognizes the urgent need to reduce the environmental impact of F-gases, particularly SF₆. Active efforts to develop and adopt more sustainable alternatives include:

• SF₆ alternatives: Several companies, including Hitachi Energy, are developing eco-efficient alternatives that provide the same insulation or cooling properties without harmful environmental effects or compromising safety and efficiency.

• Technological innovations: Innovations and processes can greatly reduce F-gas use. The integration of digital technologies with high-voltage switchgear allows for more precise monitoring and control, leading to enhanced performance, reliability, and sustainability.

• Regulatory frameworks: Governments and international organizations are implementing several policies and regulations to further reduce F-gas emissions, phase out the use of high-GWP F-gases, and improve recycling practices. 

The challenge with moving away from SF₆ is that the electrical infrastructure must stay efficient, reliable, and compact. Re-engineering circuit breakers and other components to work with alternative gases require significant R&D investment. However, the potential for reducing environmental harm makes this investment worthwhile.

Hitachi Energy’s EconiQ portfolio is a promising solution in this regard. By combining multiple gases in a precise mixture, EconiQ achieves the same insulating and heat-dissipating properties as SF₆ but with a 99% reduction in GWP. This breakthrough technology demonstrates that it is possible to balance environmental responsibility with the operational demands of high-voltage systems.

Conclusion: Striking a balance between safety and sustainability

As we move toward a more environmentally conscious future, the role of F-gases in high-voltage technology needs a nuanced discussion. While gases like SF₆ have been indispensable for ensuring the safety and reliability of our electrical systems, their environmental impact cannot be ignored. The good news is that the industry is evolving, with innovative solutions like EconiQ paving the way for more sustainable high-voltage applications. 

The future lies in continued research, stricter regulations, and a commitment to reducing harmful emissions. By understanding the complexities of F-gases and debunking common myths, we can make informed decisions that benefit both our electrical infrastructure and the environment.

Notes

^{1 Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (CO₂). GWP is 1 for CO₂.}

^{2 Based on the Sixth Assessment Report adopted by the Intergovernmental Panel on Climate Change}