6.1.3 Use-Limited Resources
Since the nature of Use-Limited Resources prevents them from being available every hour of every day, Use-Limited Resources of Reserve Sharing LSEs are subject to supplemental rules and guidelines.
6.1.3.1 Use-Limited Resource Registration
CAISO Tariff Section 40.6.4.1
For a resource to be considered a Use-Limited Resource, the applicable Scheduling Coordinator must provide the CAISO with an application requesting registration of the specifically identified resource as a Use-Limited Resource. Hydroelectric Generating Units are exempt from the requirement to register as a Use-Limited Resource and will be automatically designated by the CAISO as a Use-Limited Resource. The Use-Limited Resource application is posted on the CAISO Website at:
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This application includes specific operating data for the unit and supporting documentation including, but not limited to:
A detailed explanation of why the unit is subject to operating limitations
Historical data showing attainable MWh for each 24-hour period during the preceding year. Data should include environmental restrictions and other factors as applicable.
Any additional data requested by CAISO in order for CAISO to understand the operating characteristics of the unit
Although the CAISO intends to review applications individually, the following table provides general non-binding guidelines regarding the scope of Use-Limited status. The definition of a Use-Limited Resource is “a resource that, due to design considerations, environmental restrictions on operations, cyclical requirements, such as the need to recharge or refill, or other non-economic reasons, is unable to operate continuously on a daily basis, but is able to operate for a minimum set of consecutive Trading Hours each Trading Day.” Note that under the CAISO tariff, contractual limitations on the availability of Resource Adequacy resources, do not qualify a resource for Use-Limited status.
Resource-Type / Use-Limited (Yes/No)Gas-Fired (Steam) / No
Gas-Fired (Combined Cycle) / No
Gas-Fired (GT with limited fuel storage) / Yes
Gas-Fired (GT without limited fuel storage) / No
Gas-Fired with environmental restrictions that constraint its operation / Yes
Hydro-Large Storage / Yes/No - although Hydro with large amount of storage may have more flexibility to generate on demand and thus may not be use-limited in a manner similar to a run-of-the river, downstream water flow and water-release needs and other environmental conditions may dictate output so as to warrant Use-Limited status
Hydro-Small Storage/Small Conduit / Yes
Hydro-Run of the River / Yes
Wind / Yes
Solar / Yes
Nuclear / Yes
QF / Yes
Resource with Contractual Limitation that Limits Availability / No
The CAISO may allow a Resource Adequacy Resource that is subject to temporary or seasonal environmental restrictions imposed by federal or state law or regulation to be designated as a Use-Limited Resource for the period in which the restriction applies. Temporary environmental Use-Limited Resource status will begin on the start date of the restriction and end on the end date of the restriction, and may include a partial month or full month for Resource Adequacy purposes. A Resource Adequacy Resource may request temporary environmental Use-Limited Resource status by submitting the application required by this section and including a detailed explanation of the temporary or seasonal environmental restriction that is the basis for its request. As with annual Use-Limited Resource status, a contractual limitation or economic reason will not qualify a Resource Adequacy Resource for temporary environmental Use-Limited Resource status.
Within five days of the receipt of the application, the CAISO responds to the Scheduling Coordinator as to whether or not the CAISO agrees that the resource is eligible to be a Use-Limited Resource. If CAISO determines the facility is not a Use-Limited Resource, the Scheduling Coordinator may challenge that determination in accordance with CAISO ADR Procedures.
6.1.3.2 Use-Limited Use Plan
CAISO Tariff Section 40.6.4.2
In accordance with the schedule set forth in Exhibit A, the Scheduling Coordinator provides a proposed annual use plan for the following year for each Use-Limited Resource that is a Resource Adequacy Resource for the following year. The proposed annual use plan delineates on a month-by-month basis the total MWhs of Generation, total run hours, expected daily supply capability (if greater than four hours) and the daily energy limit, operating constraints, and the timeframe for each constraint. CAISO discusses the proposed annual use plan with the Scheduling Coordinator and suggests potential revisions to meet reliability needs of the system. If revisions are agreed upon, the Scheduling Coordinator then submits its final annual use in accordance with the schedule in Exhibit A. The Scheduling Coordinator is able to update the projections made in the annual use plan in optional monthly updates to the annual Use Plans. Scheduling Coordinators for hydroelectric Generating Units will be able to update use plans intra-monthly as necessary to reflect evolving hydrological and meteorological conditions. The annual use plan must reflect the potential operation of the Use-Limited Resource at a level no less than the minimum criteria set forth by the Local Regulatory Authority for qualification of the resource. The annual use plan must reflect the potential operation of the Use-Limited Resource at a level no less than the minimum criteria set forth by the Local Regulatory Authority for qualification of the resource. Resources that are approved for temporary environmental Use-Limited Resource status must submit a use plan that reflects the time-limited nature of the use-limited status. Such resources will not be considered as Use-Limited Resources during the balance of the year.