Resource adequacy assessments for this power plan differ from past assessments in three significant ways. First, the Council has chosen to use climate change projections of temperature and precipitation to forecast future electrical demand and river flows. These data are a better predictor of future conditions than assuming a repeat of observed historical conditions (which were used for past assessments). Second, the low cost of renewable resources along with clean-air laws and renewable portfolio standards across the Western states are expected to result in a significantly high amount of renewable resource acquisition. Third, because of the expected higher levels of renewable generation, and for other considerations, it was necessary for the Council to enhance its adequacy model to represent hourly operations more accurately. It was especially important to implement more hourly-specific hydroelectric system constraints.
The fundamental objective of power system operations is to continuously match the supply of energy from generators to customers’ electrical demand. This involves proper long-term planning to ensure that the power supply has sufficient generating capability, and that the transmission system can deliver that power within an acceptable range of frequency and voltage.
Because our region is electrically connected to the rest of the West, policies and decisions outside the region will have an impact on our power supply. Clean air laws and policies across the West are leading to large investments in renewable resources (in particular, solar generation), which will create increasing amounts of surplus generation in Western electricity markets. A large and often inexpensive market supply will change the dispatch and fuel use of existing regional electric generators, which can create challenges to maintaining adequacy. With the anticipated fast pace of development for renewable resources and the announced retirements of generating resources outside the region, analysis shows the effects of shifting market dynamics to be approaching quickly.
The Council’s objective to provide an adequate, efficient, economic, and reliable power supply is becoming more challenging as more and more generation from existing fossil-fuel-based thermal resources is being displaced by renewable (and variable) energy resources. In the future, the region and the rest of the West will need to rethink how system capacity needs are measured and how different resources provide those needs.
Resource adequacy plays an essential role in both the development and implementation of the Council’s power plan. A needs assessment, which identifies future capacity and energy deficiencies, is a vital part of the process to develop the Council’s resource strategy. Once the plan is adopted, the Council’s annual adequacy assessment provides an early warning of potential near-term (three-to-five year) supply shortfalls and gives utilities time to implement appropriate measures outlined in the plan or to take other mitigating actions. A more detailed narrative about these assessments can be found in the “Resource Adequacy Overview” section.
The adequacy assessment, relating to the previous power plan’s resource strategy, was not explicitly used to develop the 2021 power plan, however, it was informative as to the state of the existing power supply. During plan development, results from both the adequacy assessment and the needs assessment were released concurrently, which may have led to some confusion regarding what data were specifically used to develop the resource strategy. Additionally, some advisory committee members and stakeholders were uncomfortable with the adequacy assessment and recommended further review of the adequacy model. To address these concerns, the Council will continue its review of the adequacy model after the release of the plan and has added related work items to the plan’s R&D section.