California proposes phasing out the use of SF6 in GIE and further reducing allowable GHG emissions from such equipment.

By Aron Potash and Kimberly D. Farbota

California Air Resources Board (CARB) staff recently published a discussion draft (Draft Amendments) of potential changes to the current Regulation for Reducing Sulfur Hexafluoride Emissions from Gas Insulated Switchgear (SF6 Regulation).

Key proposed changes to the SF6 Regulation include:

  • Phasing out sulfur hexafluoride (SF6) gas-insulated equipment (GIE)
  • Further reducing allowable emissions from GIE
  • Expanding the regulation to encompass greenhouse gases (GHG) other than SF6

CARB held a workshop in Sacramento on February 25, 2019, during which staff presented an overview of changes proposed in the Draft Amendments and answered stakeholders’ questions. During the workshop, staff stated that CARB would like to hear any questions or concerns stakeholders may have about the Draft Amendments.

CARB is accepting public comments through March 11, 2019.

The SF6 Regulation and GHG Emissions

SF6 is the most potent GHG, with a global warming potential (GWP) tens of thousands of times higher than carbon dioxide. Electrical transmission and distribution equipment, which use SF6 as an insulator, are the primary source of SF6 emissions in California. Equipment subject to the SF6 Regulation are found at many renewable energy facilities that do not otherwise emit GHGs, such as wind, solar, hydropower, and geothermal facilities. Assembly Bill 32 (2006) (AB 32) requires that the State reduce GHG emissions to the 1990 level by 2020, and the SF6 Regulation was adopted as an early action measure under AB 32 due to the high GWP of SF6.

The current SF6 Regulation came into effect in 2011, setting an annual emission rate limit for SF6 as a percentage of a GIE owner’s cumulative SF6 nameplate capacity. Allowable emission rates under the SF6 Regulation started at 10% in 2011, decreasing by 1% per year until 2020, after which point the allowable emission rate remains constant at 1%.

Senate Bill 32 (2016) (SB 32) requires the State to reduce GHG emissions further to 40% below the 1990 level by 2030. Pursuant to SB 32, CARB staff are exploring opportunities to achieve additional cuts in GHG emissions. Accordingly, CARB is also evaluating a revamp of the SF6 Regulation in order to decrease GHG emissions.

Proposed Changes to the SF6 Regulation in the Draft Amendment

  • Phasing out the use of SF6 in newly acquired GIE. Staff proposes to prohibit the acquisition of new SF6 GIE. The phase-out schedule, developed based on CARB staff communication with GIE manufacturers, will be tied to the voltage class of equipment.
Voltage (kV): ≤ 145 145 < kV ≤ 245 > 245
Potential Phase-Out Date: January 1, 2025 January 1, 2029 January 1, 2031
  • Adding a “technical infeasibility exemption.” Staff proposes to include an exemption that would allow for acquisition of SF6 GIE — after the above phase-out dates — only if a GIE owner can demonstrate to CARB that: (1) non-SF6 GIE meeting the specifications for the particular project are unavailable, (2) available non-SF6 GIE cannot meet size requirements, (3) available non-SF6 GIE are incompatible with existing equipment, wiring, or connectors, or (4) available non-SF6 GIE are not suitable based on safety or reliability requirements.
  • Moving to an emissions limit, instead of the current emission rate limit, and lowering allowable emissions. The Draft Amendments propose changing the current emission rate limit to an absolute emissions limit. Individual emissions limits will be established based on each GIE owner’s MTCO2e capacity in 2019, or the first year in which the GIE owner’s capacity exceeds a de minimis level. The emissions limits will then be reduced over time by a set of decreasing multipliers. The owner-specific limits cannot be increased, even if a GIE owner adds new GIE. The MTCO2e limit will apply beginning in data year 2020, and is intended to incentivize the transition to low-GWP or zero-GHG technologies.
  • Adding a threshold for complying with the emissions limit. The Draft Amendments also propose a new threshold such that the emissions limit is only applicable to GIE owners whose average capacity is ≥5,500 MTCO2e. CARB expects that the emissions limit will apply to approximately 99% of the State’s GIE capacity, but given the threshold, more than half of all current GIE owners will not be subject to the emissions limit.
  • Adding a process for adjusting the nameplate capacity of GIE. CARB reports that GIE owners have requested a nameplate capacity adjustment process because the SF6 capacity information provided on nameplates is sometimes inaccurate. CARB staff is soliciting input from stakeholders, particularly with respect to which GIE owners should be allowed or required to determine revised nameplate capacity values, and what method will be permitted to perform the adjustment.

The proposed changes to the SF6 Regulation would require GIE owners to further reduce SF6 emissions starting in 2020, and to eventually replace all SF6 GIE with alternative technology. These changes would apply to both traditional and renewable assets across the electricity transmission and distribution sector. Affected entities would be well served to engage with CARB during the rulemaking process in order to ensure that any concerns are appropriately addressed.