Road Map

Demand drives resource adequacy. Demand forecast information is a critical part of ensuring that a load-serving entity is resource adequate. If demand is expected to grow, either new resources or more energy purchases will be needed to meet demand. There are two types of demand important to resource planning.

Annual Demand: The amount of energy in MWh needed to serve an area over an entire year. It is typically divided into seasons because demand cycles are closely related to weather and seasonal patterns. Understanding annual demand, and its seasonal changes, helps in planning a resource portfolio.

Peak Hour Demand: The amount of energy in MW needed to serve an area during the peak hour of the day or year. Understanding trends in peak hour demand helps to identify changes that must be considered in resource planning.


The combined demand for all regions in the Western Interconnection is projected to grow from about 906 TWh in 2020 to around 972 TWh in 2029—just over a 7% increase. Each subregion in the interconnection is expecting load growth to varying degrees from 2020 to 2029. The combined peak hour demand for all regions in the Western Interconnection occurs in the summer and is expected to grow from about 162 MW in 2020 to over 176 MW in 2029, an increase of almost 9%.

Page Tip

Clicking a region on the map will change the charts to show that area's information. Clicking the same area again will switch the charts back to the overall Western Interconnection results.