What is SF6?
SF6, or sulphur hexafluoride, is a man-made gas that is an extremely good electrical insulator and current interrupting medium. The gas is mainly used in high-voltage switchgears in the electric power grid .
However, SF6 is also the most potent greenhouse gas known. One kilogram of SF6 released to the atmosphere does as much harm as 23 tonnes of CO2 emissions . Therefore, it’s important that we reduce leaks and other emissions from high-voltage components as much as possible, as well as develop alternative, SF6-free technologies.
Monitoring Norwegian SF6 emissions
Every year, Norwegian electrical utilities and industrial companies that have equipment containing SF6 are required to report their inventory (gas in both switchgear and on stock) and emissions to the Norwegian Environment Agency. This is organised by SINTEF Energy Research on the instructions of and in co-operation with the Norwegian Gas Insulated Substation (GIS) User Group .
According to these reports, high-voltage components in the Norwegian grid currently contain over 300 tonnes of SF6, and the annual emissions in recent years have been between half a tonne and one tonne. Compared to other countries, this is extremely low: only a few tenths of a per cent of SF6 escape from Norwegian installations into the atmosphere every year.
Alternatives to SF6
For several years, research scientists at SINTEF Energy Research have worked with finding the best environmentally friendly alternatives to SF6, with the long-term goal of phasing out use of this gas . Among the solutions being considered are various fluorinated gas compounds , air, CO2, and new uses of vacuum interrupter technology .
It is likely that different technologies will be needed for different voltage levels and applications, but this development is expected to take time. In addition, switchgears have a typical service life of approximately 40 years, which means that a lot of equipment containing SF6 will continue to operate in the Norwegian grid for many years to come.
Information about SF6
SINTEF Energy Research has also taken on the task of educating decision makers and the public about SF6. Due to misinformation spread by the media, there are many myths circulating about the gas. Research Scientist Maren Istad and her colleagues at SINTEF Energy Research and NTNU discuss some of the myths in this article.
In 2017, Chief Scientist Magne Runde was invited to give a lecture on the development of alternatives to SF6 at a conference hosted by The Norwegian GIS User Group, wherein he outlined some of the most promising possibilities. This was then followed by a panel debate with representatives of some of the companies that will adopt these new solutions.