California Air Resources Board Caps Utilities’ Sulfur Hexafluoride Emissions

Under California’s Global Warming Solutions Act, AB 32, the Air Resources Board (ARB) is required to create strategies to lower the state’s overall greenhouse gas (GHG) emissions. Recently, ARB issued a notice to regulate electric utilities’ emissions of the most potent GHG, sulfur hexafluoride (SF6).

Electric utilities use small amounts of SF6 to insulate high-voltage switchgear systems because the gas resists the flow of electric current. However, SF6 emissions are many times more toxic than the more prevalent carbon dioxide. In fact, SF6 has 23,900 times the global warming potential of carbon dioxide. To remove one pound of SF6 is equivalent to removing 11 tons of carbon dioxide. Current estimates show that California’s electrical utilities emit 80% of the SF6 in California annually. (ARB issued regulations that went into effect earlier this year for the semi-conductor industry and other non-electrical uses that are also sources of the gas.) While the US EPA has been managing a voluntary SF6 emissions reduction program for electrical utilities, ARB’s regulation is the first mandatory program nationwide.

ARB’s newest SF6 regulation goes into effect on January 1, 2011. The rule establishes a step-down allowance of the maximum allowable SF6 emission rate. In 2011, the maximum allowable emission rate will be 10%, stepping down one percent each year until 2020 when there will be a 1% maximum allowable emission rate. Emission rates will be determined by dividing a utility’s annual pounds of SF6 emissions by the utility’s average switchgear system’s (designed) capacity to contain SF6. Available reduction techniques include updating equipment, leak detection and repair, and manual collection and recycling by certified workers, but ARB officials say that detection and maintenance will be the most common means to reduce SF6 emissions.