Fluorocarbons & Sulphur Hexafluoride: Electrical applications

The gas SF6 (Sulphur hexafluoride) has proven to be essential in its main application in high and medium voltage switchgear stations and circuit breakers. Switchgear is a basic part of energy supply network. Many of today's technical, economic and environmental requirements for high and medium voltage switchgear can only be met by the use of SF6. About 70-80 % of the global SF6 production is used in this sector.

Gas insulated switchgears (GIS) using SF6 as an arc quenching and insulation medium provide considerable environmental advantages over air insulated switchgear (AIS) as clearly shown in a Life Cycle Assessment taking into account the complete chain including primary energy consumption, area requirement and contribution to global warming.

An earlier life cycle assessment (LCA)1 on high-voltage (110kV to 380kV) switchgear had demonstrated clear advantages from SF6 insulation technology in a power supply network This assessment was taking into account present practices of minimising leakage and handling losses and of recycling consistently SF6. This showed that the focus on the global warming potential (GWP) of SF6 (LINK) is misleading and that a global approach is necessary to fully appraise the total environmental benefits of SF6 in the systems in which it is used.

However, in medium-voltage (MV) applications this global performance of SF6 still needed to be demonstrated. Therefore, a LCA study was commissioned by a group of companies (equipment manufacturers, grid operators, producer) and subject to critical and independent peer-review.

The study covers MV (between 1 and 30kV) switchgear used in systems including transformer substations, ring-main units, consumer substations. Again and despite a high GWP, SF6 was shown to be environmentally preferable to alternative technologies. The results confirm also the need of a "system approach" to adequately evaluate the performance in such applications.

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Power supply fulfils an essential role in our economy. But what about the contribution of electriciy distribution grids to Germany's greenhourse gas emission burden? This new Life Cycle Assessment (LCA) study investigates the environmental profile of medium-voltage equipment, with a comparison between air-insulated and SF6-insulated switchgear.

Source
Mersiowsky I., "Life Cycle Assessment - SF6-GIS Technology for Power Distribution - Medium Voltage", November 2003.

1 Preisegger, Duerschner, Klotz, Koenig, Kraehling, Neumann, Zahn "Life Cycle Assessment - Electricity Supply Using SF6 Technology", IPCC workshop, Noordwijkerhout, September 1999

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