A LONG investigative report by journalist Phil McKenna and published by Inside Climate News on Sept. 20 began with this intriguing lead: “China’s electric grid has a dirty secret: Despite leading the world in renewable energy expansion, it is also the largest emitter of the planet’s most potent greenhouse gas.”
Since China is also one of the world’s most prodigious producers of fossil fuel-generated electricity, you might think at first that the culprit is something familiar, such as emissions of carbon dioxide (CO2) or methane (CH4). However, the greenhouse gas in question is not actually associated with electricity generation at all, but rather transmission and distribution equipment.
It is called sulfur hexafluoride (SF6), and it is a gaseous synthetic chemical (meaning it does not occur naturally in the environment) used as an insulator in high-voltage circuit breakers, switches, and other equipment. SF6 is excellent for this kind of application, and has been used for decades because it is stable to the point of being virtually indestructible, nontoxic, and nonflammable.
It is also probably the most potent greenhouse gas known, 24,300 times more effective at trapping heat on an equivalent-mass basis than CO2, or about 80,632 times more potent on an equivalent-volume basis. Once released into the atmosphere, SF6 remains for about 1,000 years. Because it is a strong, stable molecule, it essentially only degrades through being hit by cosmic rays, which is a slow process.
China’s government researchers and environmental watchdogs have known about the potential problem for years. In 2014, two papers published by the Renmin University of China in Beijing concluded that SF6 is “a significant potential threat to the global environment.” Nevertheless, the Chinese government has yet to move to regulate SF6, in spite of its Ministry of Ecology and Environment recently stating that electric utilities in China could recycle 90 percent of their waste SF6 gas. They do not, however; more recent estimates put the recycling rate at closer to 30 percent.
This is a problem because China is responsible for about half of global SF6 emissions, which have decreased everywhere else but doubled in China between 2011 and 2021, the last year for which there is reliable data. In 2005, global SF6 emissions measured about 20 million metric tons-equivalent (MMe) of CO2. Currently, they are at about 80 MMe, and on their current trajectory, will be close to 170 MMe by 2030, with the increase almost entirely attributable to China.
The reason for this is quite simple. China is expanding and upgrading its transmission and distribution grids at a furious pace to absorb its massive build-out of solar and wind power (along with additional capacity in more conventional coal and nuclear generation), investing something on the order of $70 billion a year (about P4.3 trillion) for the effort. To put that in context, the approved capital expenditure for the National Grid Corp. of the Philippines (NGCP) for a five-year period (2023 to 2027) was P375 billion. Obviously, there is a bit of a difference in scale, but even if one accounts for that, China’s grid development spending outpaces the Philippines’ by about six times.
Recycling equipment and the process of using it is, quite frankly, more costly than just buying replacement SF6 gas when equipment is repaired or replaced, and so the common practice is to just vent the gas. After all, it is essentially harmless except for its greenhouse gas properties, so there is no immediately obvious risk to just dumping it.
Critics of China’s business-as-usual practices point out that the investment in recycling systems is a fraction of a percentage of the amount being invested in grid development, and fully depreciates after about 10 years or so. Europe has enforced SF6 recycling since the late 1990s, and while utilities naturally groused about this initially, by now it has been completely integrated into work processes. If those of us old dogs from the pre-Montreal Protocol auto industry, a more set-in-our-ways mindset than you are ever likely to encounter elsewhere, could get used to recycling air conditioning coolant, then transmission and distribution utilities can certainly figure out how to recycle SF6 without presenting unmanageable costs or process steps.
After I had read the Inside Climate News article and some of the supporting research, I reached out to both the NGCP and Meralco to ask if either of them had addressed the SF6 question, but as of filing time, I have not received any information. To be fair, it was a technical question, the answer for which had to come from engineering people, and I did not give them a lot of time to get back to me. Nonetheless, it is an issue that should be addressed because it is only going to get bigger as we develop our own energy systems to accommodate greater amounts of renewable energy, more electric vehicles, and more tech-centered industries.
ben.kritz@manilatimes.net
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