Tens of thousands of times stronger at trapping heat than carbon dioxide, sulfur hexafluoride continues to be used as an insulation gas in switchgears worldwide. But now one Norwegian energy provider is leading a charge to eliminate it.
A few years ago it might have been in your running shoes, your window insulation or in your tires: sulfur hexafluoride or SF6 – the most potent greenhouse gas in the world, with a potential for global warming around 23,500 times greater than carbon dioxide. While manufacturers have since pulled SF6 from shoes, windows and tires, tons of it are still being used to insulate high-voltage switchgear in substations around the world. In Norway, however, BKK Nett, the country’s second largest power grid owner with 245,000 customers is spearheading a shift to eliminate the gas from their substations.
The company became the first to commission a Siemens Energy SF6-free gas-insulated switchgear (GIS) that replaces the greenhouse gas with treated air, called “clean air”, a pure mixture of nitrogen and oxygen with zero potential for global warming. “Our interest in SF6-free switchgear technology comes from a genuine commitment to sustainability and the practical need to avoid problems in the future,” says Jens Skår, Division Manager at BKK Nett. “Someone has to take the first step.”
BKK Nett’s decision came about due to another progressive project to provide renewable energy to cruise ships in Bergen Port. Bergen, the largest city in Western Norway, with colorful wooden houses, islands dotting the North Sea at its coast and massive mountains all around, has become an attraction for cruise ships – ships that would run their diesel engines while docked more or less round the clock to power their electrical systems.
As the number of ships increased, the engines generated more and more air pollution; smog formed and lingered around the mountains. The City of Bergen made the decision to invest in their regional power grid so cruise ships could use clean power. To provide the necessary grid infrastructure, BKK Nett had to upgrade its Koengen transformer substation in Bergen from 45-kilovolts to a 132-kilovolts operating level.
“When we started the project to rebuild the Koengen transformer substation, we knew of several suppliers developing environmentally-friendly technology,” says Skår, who has been in the energy industry for more than 30 years. “When evaluating all the offers, we stressed environmental impact – and Siemens Energy came out best.”
With an abundance of natural energy resources and a relatively small population, Norway has one of the most decarbonized power sectors – and ambitious climate targets. “Norway has a green heart,” says Andreas Albert, Senior Project Manager at Siemens Energy, “and we need people with green hearts to get new sustainable technology established in the market.”
Albert also points out that, despite initial costs, changing to a new technical solution often saves time and money. BKK Nett already benefits from no longer having to account and report SF6 at any of their substations using the SF6-free GIS, and maintenance will be easier and more cost efficient with only air to consider during servicing. Moreover, “the costs for technology that harms the environment will almost certainly rise,” says Albert.
“We anticipate that SF6 will eventually be banned or burdened by restrictions and penalty fees,” says Jens Skår. “So when making investments in capacity and substations in and around Bergen, we opted to eliminate SF6 from the equation – because we want to move towards sustainability and,” Skår adds, “we didn’t want to make a decision today that would embarrass us two years down the line.”
Today, two of BKK Nett’s substations have been rebuilt with the SF6-free GIS, with more to come. In Norway altogether, a total of ten substations are using the new switchgear. But there are still thousands of high-voltage substations around the world using millions of kilograms of SF6. As these facilities reach the end of their lifetimes and need rebuilding, or when entirely new facilities are being planned, they could benefit from the new technology. “Why use SF6,” says Albert, “when SF6-free switchgear performs the same function and reduces your impact on the environment?”
The SF6-free GIS, with zero global-warming potential, is a development based on upgraded switching and insulation technology that has long been proven in practice. And thanks to digital technology and the use of more flexible low-power instrument transformers (LPIT) rebuilds like the one in Bergen can be made in the same space as the old equipment. “We managed to make the change in Bergen,” says Skår, “despite having restricted space in our substations. The station has now been in operation for a year, and the experience is what we expected: problem-free.”
Over the next years, Siemens Energy will implement their clean air technology at higher voltages as well. “We’re putting a lot of money and effort into this project”, says Albert. “There are safety considerations and technical challenges to handle. But we’ll get there. Green technology is moving forward with increasing speed, and make no mistake, it’s the future.”