Operational and market challenges to the changing fleet of resources in California

This paper summarizes the California ISO´s renewable integration studies performed to quantify the operational challenges and need for flexible resources in the year 2020 as the fleet of resources transitions from flexible conventional resources to intermittent and variable resources under higher renewable penetration levels. California´s Renewable Portfolio Standard (RPS) requires that 33% of all energy consumed be met by renewable resources. In the same time period environmental policy will result in coastal once-through-cooled steam resources being retired or repowered. The result of these two environmental policies is a significant change in the operating characteristics and capability of the fleet. There will be an increase of supply variability and a decrease in the amount of flexibility to balance the system. The California ISO performed studies to quantify the flexibility requirements and fleet needs in order to maintain load and supply in balance. The presentation will: 1) describe the planning assumption, 2) explain the study methodology, 3) summarize results and conclusions and lastly suggest some areas of further study.