- Sulphur hexafluoride or SF₆ is the strongest known greenhouse gas with a global warming potential of 25200 and an atmospheric lifetime of 3,200 years.
- SF₆ is rapidly accumulating in the atmosphere, driven by the demand for SF₆-insulated switchgear in developing countries due to increased renewable energy installations.
- There is currently no regulatory framework to monitor, report and manage SF₆ in India and the country needs to develop a framework for SF₆ monitoring, reporting and phaseout.
The use of sulphur hexafluoride (SF₆) will grow exponentially as India expands its installed renewable capacity. As the country continues its journey towards the target of 500 GW of non-fossil fuel sources by 2030, mixed sources of energy will use more and more connections to the electricity grid and a rise in the number of gas-insulated electrical switchgear (GIS) that are needed to prevent serious accidents.
SF₆ is widely used across the power industry, from large power stations to wind turbines and electrical substations. In electronics, SF₆ is used in semiconductor devices found in computers, smartphones, consoles and batteries for electric vehicles.
SF₆ is also part of the “basket” of greenhouse gases under the UNFCCC and the Paris Agreement. With the enhanced transparency framework (ETF) under Article 13 of the Paris Agreement, all parties are supposed to prepare and submit National GHG (Green House Gas) inventory report of GHG emissions.
What is SF₆?
SF₆ is a stable colourless, odourless, synthetic fluorinated gas that makes effective insulating material for medium and high-voltage electrical installations. Around 80% of the SF₆ used globally is in electricity transmission and distribution. Medium- and high-voltage electrical equipment contains SF₆ to insulate the live electrical parts and to switch the flow of electrical current on and off.
It is the strongest known greenhouse gas, with a global warming potential (GWP) of 25,200 in a 100-year perspective and an atmospheric lifetime of 3,200 years.
Why should we be concerned about SF₆?
SF₆ is rapidly accumulating in the atmosphere, driven by the demand for SF₆-insulated switchgear in developing countries. Common emission sources of SF₆ include electrical transmission and distribution equipment, manufacture of electronics/semiconductors and the production of magnesium.
Almost 89% of SF₆ emissions are in the area of grid infrastructure/ transmission (switchgear and circuit breakers) while smaller amounts are used for magnesium, aluminium and semiconductors. The estimated SF₆ – global potential emissions (CO2eq) is around 5 GT from historic installation while each installed GW the current use of SF₆ is 40-66 t or 1.1 to 1.5 MtCO2eq cumulative emissions until 2050.
SF₆ emissions occur during all stages of the component lifecycle: manufacturing, operation, and decommissioning of equipment contribute the most to the emissions of the operational phase. However, 93% of leakages were caused by leakages during ordinary operations, while seven percent were caused in connection with component failure or breakdowns. High Voltage components are assembled on-site, which increases the risks of leakage and emissions. Moreover, the older the equipment, the higher the risk of leakages.
How are renewable energy and SF₆ linked?
Renewable energy installations are of main concern as they require more switchgear in the electricity grid than fossil fuels. It takes more solar panels and wind turbines to produce the same electrical output as a single thermal power station. So, as renewable power generation grows, the chances of increased emissions from SF₆ also grow.
Renewable technology also uses the SF₆ gas directly in the switchgear for wind turbines to prevent overloads. The switchgear associated with wind turbines can contain anywhere between 3 kg to 5 kg of SF₆. This is apart from the SF₆ used in the substations associated with the power transmission systems of wind farms.
“India is going to face a double whammy as it will be seeing maximum deployment of SF6 due to renewable expansion. It will be ironic as the world is moving away from SF₆ and finding alternatives, but we are pressed for time as maximum renewable installation will happen in the next 15-20 years,” said, Venugopal Pillai, Editor of T&D India—a monthly publication on the power transmission and distribution (T&D) sector.
What is the status of SF₆ in India?
SF₆ is mostly imported into India. There is a lack of publicly available data on total production, use growth rates and emissions of SF₆ in India. According to MMR Pvt. Ltd., a market research company, the India SF₆ market will see impressive growth of market size of 56.4 million US$ in 2020 to 88.80 million US$ in 2027 at a CAGR of 6.7%. As per Volza’s India Import data, India imported 600 shipments from China, Taiwan and the United States and is the largest importer of SF₆ in the world.
India, in its Third Biennial Update Report to The United Nations Framework Convention on Climate Change, reported magnesium production as the single estimated source of SF₆ for 2016, leaving aside all other sources such as leakages from electric switchgears, transmission and equipment. According to the latest data from The World Bank, India emitted 5772 thousand metric tons of CO2 equivalent in 2010 while NDC communication to UNFCCC reported just 100950 tonnes CO2 eq.
How is SF₆ monitored?
Indian public sector companies have proactively started monitoring data for SF₆ consumption, leakage and contribution towards GHG emissions. NTPC Ltd, India’s largest integrated power generator reported a 20250-tonne equivalent for emission from losses of SF₆ from energy production in its sustainability data trend for 2023.
Powergrid, being one of the largest transmission utilities in the world in its sustainability report 2019-21 reported the installed SF₆ gas of 2540368 kilograms in 2020-21. The Percentage Leakage (%) increased from 0.16 to 0.19 from 2020 to 2021, which translates to 11885089.61 tonnes of CO2 equivalent.
In developed countries, SF₆ is regularly monitored to immediately detect any SF₆ leakages, on an almost real-time basis while India still needs to make a lot of progress in SF₆ handling and monitoring.
Vishal Patil, Senior Consultant, WIKA India, part of WIKA Alexander Wiegand SE & Co. KG, Germany, a global market leader in pressure, temperature and level measurement technology, said that Indian grid companies have an internal mechanism to report SF6 leakage. The maximum threshold is 0.5 per cent per year, a guideline from the government. But this is neither documented nor published by any T&D companies but they maintain data internally.
Patil further informed that currently, all conventional gas density monitoring is happening in India. There is no cumulative assessment of SF₆ leakage but companies inform that they follow CIGRE Guidelines for SF6 management which prohibits the release of SF₆ in the environment. But beyond releasing in the environment, there is not much awareness about other aspects to prevent, avoid or monitor leakage, he says.
“The only way you can control SF₆ is through continuous online remote monitoring as this is an odourless gas. Competent authorities need to come up with a regulatory framework for mandatory continuous online minoring of SF₆ gas as the transmission for new renewable capacity will mostly happen at remote locations. A lot of leaks go undetected due to quality/policy control,” said Pillai.
What are the international regulations on SF₆?
Various countries have regulated or voluntary initiatives to monitor, report and phase out of SF₆. The U.S. Environmental Protection Agency (EPA) made mandatory the reporting of large SF₆ emissions in 2009. This was followed by the California Air Resources Board (CARB) and Massachusetts Department of Environment – two state environmental agencies – strengthening their own SF₆ regulation. California has also set a target of to stop buying any SF₆-insulated products by 2033. EU is strengthening F-gas Regulation 2014 for the SF₆ phase-out based on the availability of alternative technologies. In Europe, it is also mandatory to recycle, reclaim or destroy the SF₆ gas contained in electrical equipment (Regulation (EU) No 517/2014).
There are no SF₆ regulations in Asia that focus directly on transmission and distribution operators. But Japan’s switchgear OEMs and electric utilities created a voluntary action plan in the late 1990s and reported a substantial reduction in reduction in SF₆. In 2015 South Korea implemented a GHG Emissions Trading Scheme, which includes SF₆. China has also made moves away from SF₆. Using GIS, China is now considering new regulations or standards to further reduce SF₆ usage and emissions and created a dedicated working group.
What are the alternatives to SF₆?
At the moment, there is a large base of switchgear containing SF₆ and therefore technology for handling and monitoring this greenhouse gas becomes crucial. It would take at least 20 years to move towards an SF₆-free world. While SF₆-free technology is slowly making its presence felt in developed countries, it would take longer for it to be imbibed in the developing world. SF₆ will be phased out in batches – starting from medium voltage (MV) and gradually moving towards higher voltages.
Several alternatives are being considered for SF₆. These include the use of clean air, hydrogen, nitrogen, etc. But these are available mostly for medium voltage (MV) switchgear. Fluorine-free alternatives for HV switching with circuit breaker function exist up to 145 kV based on natural origin gasses (N2, O2, CO2) and a GWP < 1. Several companies are currently working to close the gaps for voltage above 145 kV. Hitachi Energy and GE unveiled the SF₆ free eco-efficient 420-kilovolt (kV) high voltage (HV) circuit-breaker in 2022. Hitachi and GE are also working on how to replace SF6 in exiting switchgear with other gas.
Stephan Jorra, Head of Siemens Energy transformer Factory in Dresden Germany said that Siemens is using Blue switching technology based on clean air (80% nitrogen + 20% oxygen) as SF₆ substitute, which has a GWP of zero and is 100% CO2 neutral. Circuit breaker and switchgears based on blue technology are also being manufactured at Siemens factory in Aurangabad, Maharashtra.
European nations are expected to take the lead in banning the use of SF₆ in MV applications. India therefore needs to develop a framework for SF₆ handling and phaseout with the first step to start monitoring and reporting SF₆ emissions.
Pillai further stated that alternatives to SF₆ exist but it’s going to take a lot of time at least 25-30 years for some action on SF₆ to happen in India. All mitigation action is coming from developed countries. Countries such as Germany will go completely SF₆ free by 2030. He further believes that in the next 15-20 years, we could have the technology to replace SF₆ in existing switchgear, and then we will not have to replace the complete infrastructure.
However, Patil informs that currently SF₆ free equipment is not mandated and the Indian government is projecting to introduce, by 2030 and beyond, for medium voltage SF₆ switchgear.
Banner image: Sulphur hexafluoride gas circuit breakers in a switchyard. Photo by Dingy/Wikimedia Commons.