frequently asked questions

What is a switchgear?

Switchgear are an essential component of electricity grids. They are essentially a large fuse which protects one part of the grid from faults that may occur in another. The two main types of switchgear used today are air insulated (AIS) and gas insulated switchgear (GIS). GIS is frequently used in areas of high population density. Today's industry standard for GIS uses the synthetic gas sulfur hexafluoride (SF6). 

 

What is SF6?

Sulfur hexafluoride (SF6) is a synthetic gas which is used as an electrical insulating medium due to its dielectric properties which prevent electrical arcing during normal operation. SF6 is extremely damaging to the environment and is considered the world's most potent greenhouse gas by the Intergovernmental Panel for Climate Change (IPCC) due to its high global warming potential. The IPCC AR5 states that SF6 has a global warming potential 23,500 times higher than CO2.

What does global warming potential mean?

Every greenhouse gas has a different global warming potential. The GWP compares the amount of heat trapped by a certain mass of gas compared to a similar mass of carbon dioxide over a 100 year period. This is called the CO2-equivalent (CO2-e). 

Source:

Myhre, G., et al. 2013: 663. "Chapter 8: Anthropogenic and Natural Radiative Forcing." In: "IPCC, Climate Change 2013: The Physical Science Basis." Cambridge University Press: London and New York. Available here.

Why is SF6 so bad?

SF6 has an estimated atmospheric lifetime of up to 3,200 years (1)Unlike carbon dioxide, which is recycled into oxygen by plants and trees, it is a synthetic gas with no natural sink. Despite this, SF6’s use in the electrical industry is forecast to grow by around 50%, from 2005 levels, by 2030 (2)

Source:

(1) Diggelmann, T., et al. 2016. ‘An alternative to SF6 in electrical switchgear’. EE Publishers. Available here.

(2) Rhiemeier, J.M., et al., 2010: 29. ‘Update on global SF6 emissions trends from electrical equipment – Edition 1.1 Ecofys Emission Scenario Initiative on Sulphur Hexafluoride for Electric Industry (ESI-SF6)’. Ecofys Germany GmbH. Available here.

How much SF6 gas do we produce?

 

Global annual SF6 production is currently around 8,000 tonnes (1). Over 80% of SF6 is used in the electrical industry (3).

Source:

(1) Damsky, B., 2016: 1. ‘EPRI’s SF6 Management Program’. U.S. Environmental Protection Agency' (U.S. EPA). Available here.

(2) Powell, A.H., 2002: 6. ‘Environmental aspects of the use of Sulphur Hexafluoride’. ERA Technology Ltd. Available here.

How much SF6 is released into the atmosphere?

 

Based on atmospheric data, global SF6 emissions were 8,100 tonnes in 2012 (1) which equates to the annual SF6 production actually being emitted. This is the equivilant of the annual greenhouse gas emissions of approximately 100 million cars (or 40 million extremely thirsty American cars (2)).

Regarding the 100 million cars, the average emissions of new cars is around 118g/km (3). As cars have an average mileage of 15,000km, this means that the average car emitts 1,777kg. If one considers SF6 emissions (which is equivilant to 184,680,000 tonnes of CO2), they are equivilant to around 100 million cars.

Despite the existence of SF6-handling practices that try recycle and reuse the gas, no completely effective disposal method has been developed meaning that it can be expected that all of the SF6 that has been or will be produced will eventually end up in the atmosphere (4)

Source:

(1) Dunse, B.L. et al., 2015: 20. "Australian and global HFC, PFC, Sulfur Hexafluoride,
Nitrogen Trifluoride and Sulfuryl Fluoride Emissions". CSIRO. Available here.

(2) EPA (United States Environmental Protection Agency)., 2017. ‘Greenhouse Gas Equivalencies Calculator’. U.S. Environmental Protection Agency (U.S. EPA). Available here.

(3) EU Commission, 2018. 'Reducing CO2 emissions from passenger cars'. ​European Commission. Available here.

(4) Dervos, C.T., and Vassiliou, P., 2000: 138. ‘Sulfur Hexafluoride (SF6): Global Environmental Effects and Toxic Byproduct Formation’. Journal of the Air & Waste Management Association, 50:1, 137-141. Available here.

Why isn't there a ban on SF6?

Switchgear is a vital part of electricity grids and until now there has been no viable alternative to SF6 gas insulated technology. As public awareness grows and regulators become increasingly conscious of SF6’s environmental effects, the industry will likely come under greater scrutiny.

 

SF6 is among the so-called F gases that were addressed by the Kyoto Protocol of the United Nations Framework Convention on Climate Change (UNFCCC) in 1997. Following the Kyoto protocol, the EU introduced an F gas regulation in 2006 (revised in 2014) to combat the environmental damage caused by F gases. This regulation will be reviewed once again in 2020.

 

The EU Parliament has adopted a low carbon roadmap to 2050, which mandates the banning of F gas technology as soon as clean alternatives become available.

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