The power grid is underpinned by a single gas that is used to insulate a range of high-voltage equipment. The problem is, its also a super powerful greenhouse gas, a nightmare for climate change.Sulfur hexafluoride (or SF6) is far from the most common gas that warms the planet, contributing around 1% of warming to datecarbon dioxide and methane are much more well-known and abundant. However, like many other fluorinated gases, SF6 is especially potent: It traps about 20,000 times more energy than carbon dioxide does over the course of a century, and it can last in the atmosphere for 1,000 years or more.Despite their relatively small contributions so far, emissions of the gas are ticking up, and the growth rate has been climbing every year. SF6 emissions in China nearly doubled between 2011 and 2021, accounting for more than half the worlds emissions of the gas.Now, companies are looking to do away with equipment that relies on the gas and searching for replacements that can match its performance. Last week, Hitachi Energy announced its producing new equipment that replaces SF6 with other materials. And theres momentum building to ban SF6 in the power industry, including a recently passed plan in the European Union that will phase out the gass use in high-voltage equipment by 2032.As equipment manufacturers work to produce alternatives, some researchers say that we should go even further and are trying to find solutions that avoid fluorine-containing materials entirely.High voltage, high stakesYou probably have a circuit-breaker box in your homeif a circuit gets overloaded, the breaker flips, stopping the flow of electricity. The power grid has something similar, called switchgear.The difference is, it often needs to handle something like a million times more energy than your homes equipment does, says Markus Heimbach, executive vice president and managing director of the high-voltage products business unit at Hitachi Energy. Thats because parts of the power grid operate at high voltages, allowing them to move energy around while losing as little as possible. Those high voltages require careful insulation at all times and safety measures in case something goes wrong.Some switchgear uses the same materials as your home circuit-breaker boxestheres air around it to insulate it. But when its scaled up to handle high voltage, it ends up being gigantic and requiring a large land footprint, making it inconvenient for larger, denser cities.The solution today is SF6, a super gas, from a technology point of view, Heimbach says. Its able to insulate equipment during normal operation and help interrupt current when needed. And the whole thing has a much smaller footprint than air-insulated equipment.The problem is, small amounts of SF6 leak out of equipment during normal operation, and more can be released during a failure or when old equipment isnt handled properly. When the gas escapes, its strong ability to trap heat and the fact that it has such a long lifetime makes it a menace in the atmosphere.Some governments will soon ban the gas for the power industry, which makes up the vast majority of the emissions. The European Union agreed to ban SF6-containing medium-voltage switchgear by 2030, and high-voltage switchgear that uses the gas by 2032. Several states in the US have proposed or adopted limits and phaseouts.Making changesHitachi Energy recently announced its producing high-voltage switchgear that can handle up to 550 kilovolts (kV). The model follows products rated for 420 kV the company began installing in 2023there are more than 250 booked by customers today, Heimbach says.Hitachi Energys new switchgear substitutes SF6 with a gas mixture that contains mostly carbon dioxide and oxygen. It works as well as SF6 and is as safe and reliable but with a much lower global warming potential, trapping 99% less energy in the atmosphere, Heimbach says.However, for some of its new equipment, Hitachi Energy still uses some C4-fluoronitriles, which helps with insulation, Heimbach says. This gas is present at a low fraction, less than 5% of the mixture, and its less potent than SF6, Heimbach says. But C4-fluoronitriles are still powerful greenhouse gases, up to a few thousand times more potent than carbon dioxide. These and other fluorinated substances could soon be in trouble toochemical giant 3M announced in late 2022 that the company would stop manufacturing all fluoropolymers, fluorinated fluids, and PFAS-additive products by 2025.In order to eliminate the need for fluorine-containing gases, some researchers are looking into the grids past for alternatives. We know that theres no one-for-one replacement gas that has the properties of SF6, says Lukas Graber, an associate professor in electrical engineering at Georgia Institute of Technology.SF6 is both extremely stable and extremely electronegative, meaning it tends to grab onto free electrons, and nothing else can quite match it, Graber says. So hes working on a research project that aims to replace SF6 gas with supercritical carbon dioxide. (Supercritical fluids are those at temperatures and pressures so high that distinct liquid and gas phases dont quite exist.) The inspiration came from equipment that used to use oil-based materialsinstead of trying to grab electrons like SF6, supercritical carbon dioxide can basically slow them down.Graber and his research team received project funding from the US Department of Energys Advanced Research Projects Agency for Energy. The first small-scale prototype is nearly finished, he adds, and the plan is to test out a full-scale prototype in 2025.Utilities are known for being conservative, since the safety and reliability of the electrical grid have high stakes, Hitachi Energys Heimbach says. But with more SF6 bans coming, theyll need to find and adopt solutions that dont rely on the gas.