FERC last week denied CAISO’s request to waive Tariff requirements regarding “availability assessment hours” used to assess utilities’ compliance with resource adequacy requirements (ER17-2263).

The ISO uses availability assessment hours to measure the availability of generation during a predetermined time period of the day for each type of capacity. Resources that are available for 98.5% of the hours for a month are eligible for payments, while resources that are available for less than 94.5% for that month are subject to non-availability charges.

CAISO wants to keep its 2017 availability assessment hours for 2018, but that violates a requirement that the hours vary by season. The ISO requested the waiver to provide relief to demand response companies that had offered to provide capacity based on qualifying capacity values calculated under California Public Utilities Commission rules, which are the same as 2017, creating a conflict with CAISO rules.

FERC’s Oct. 24 order said the waiver request affects the availability assessment hours applied to all nonexempt resource adequacy resources and not solely the DR providers that require relief.

“CAISO does not provide a precise accounting of the demand response resources that require relief through this waiver request,” FERC said. “However, the number appears to be relatively small compared with the total number of resource adequacy resources subject to the availability assessment hours. In sum, CAISO has not shown that the small amount of resources requiring relief justifies or requires the proposed scope of the waiver CAISO requests.”

The commission said CAISO could submit a limited waiver request that directly addresses the problem of DR participation without creating undesirable consequences for the resource adequacy program.

— Jason Fordney