Texas Staff Updates Estimate of ERCOT Capacity Used for Small Fish Swim Free Rule

Staff of the Public Utility Commission of Texas have filed an updated estimate of installed generation capacity in ERCOT.

The amount of installed generation capacity is a factor in determining (1) the 20 percent limit on installed generation capacity established in PURA § 39.154 and (2) the 5 percent wholesale market power exemption established in P.U.C. Subst. R. 25.504(c).

For purposes of the 20% limit, the estimated total installed generation capacity is 90,765 MW.

For purposes of the 5% exemption, the estimated total installed generation capacity is 84,007 MW.

Staff reported that there were three changes in methodology this year that affect the total capacity estimates:

1. Capacity values for Coastal Wind units were revised from 56% to 55% to be consistent with the Summer Peak Average Capacity Contribution Percentages used by ERCOT in the 2015 CDR. The values for Non-coastal units were not changed.

2. Capacity to be retired in the next 12 months will not be removed from the calculation of installed capacity. Staff reviewed the Order for Adoption of Subst. R. 25.401 in PUC Project No. 21081 and concluded that the Commission intended to include the capacity of generating units that may be retired in the future in the determination of installed generation capacity. For 2016, this means that the capacity of Silas Ray GT5 (10 MW) and the Frontera units (524 MW) are included in the ERCOT installed capacity even though ERCOT expects those units to be retired during the year. Consistent with this change in methodology, staff removed the "New Retirements" worksheet from the spreadsheet file.

3. An "Adjustment" tab was added to the spreadsheet file to be used in unique circumstances where the formulas in the Current Capacity tab do not result in the proper determination of capacity for a given generating unit(s). For 2016, adjustments were made to include the capacity of the Silas Ray GT5 unit, the Frontera units, and the Notrees Battery Storage facility.

Staff considered one other methodology issue but concluded that no changes were necessary. For purposes of the CDR, ERCOT assigned a zero capacity value to the Notrees Battery Storage facility "because the facility provides regulation reserves in the Ancillary Services market and is not available to deliver energy on a sustained hourly basis." However, PURA Section 35.152(a) provides that, "Electric energy storage equipment or facilities that are intended to be used to sell energy or ancillary services at wholesale are generation assets," Staff noted. Therefore, the 33.7 MW capacity value for Notrees Battery will continue to be included in the determination of ERCOT installed capacity.