Sulfur hexafluoride (SF6) is a non-toxic gas used in various industrial processes - and has global warming potential of 23,900, the most potent of the Kyoto gases. The gas is often used as an insulator given its extremely stable properties. SF6 is widely used in utility electrical transmission and (to a lesser extent) distribution equipment - especially gas-insulated switchgear and circuit breakers. SF6 in this equipment can leak over time, and is often intentionally vented during routine maintenance and decommissioning of old equipment. By eliminating leaks and removing/reusing SF6 before maintenance and decommissioning, power companies can avoid significant GHG emissions.
QT can help companies assess what their SF6 leaks are and what equipment (leak detection and recycling) would be most appropriate to reduce those emissions. Even a few metric tonnes of avoided emissions is a potentially significant CDM project.
To avoid emissions of SF6 utilities can undertake the following actions:
Recycle: When old transmission equipment is replaced or repairs are made on existing equipment, SF6 is commonly released directly into the atmosphere. Since the gas is non-toxic and relatively cheap, many utilities around the world are under no legal or financial obligation to recapture the gas for reuse. Each piece of equipment using SF6 contains a manufacturer's specification including the exact amount of SF6 used in each piece of equipment. SF6 recycling equipment is also able to verify the exact quantities of recycled SF6. Such information will be recorded in inventories and will assist in the establishment of emission reductions from the project.
Eliminate Leaks: SF6 leaks from electrical transmission equipment are relatively common. Over time as equipment loses SF6, it becomes more prone to failure and at times results in system-wide power interruptions. New technologies have become available that allow SF6 leaks to be quickly detected, accurately quantified and fixed before equipment fails. Unfortunately, as noted above, in many cases even when leaks are identified, utilities without leak reduction expertise simply recharge the SF6 as fast as it leaks out.