Perspectives on peak demand: How is ERCOT peak electric load evolving in the context of changing weather and heating electrification?

Abstract

This analysis characterizes the past and future evolution of peak electricity demand in the Electric Reliability Council of Texas (ERCOT) service area and assesses how these trends may be driven by changing weather and heating electrification. To accomplish this, historical ERCOT demand data from 1997 to 2021 were utilized along with weather data for the days in which peak demand occurred and from a future climate scenario. The results inform resource planners on the relationship between peak heating and cooling load and ambient temperature and present peak demand growth scenarios for 2025 through 2050. We found that historically, summer peak demand growth has been generally stable and approximately linear with time. Conversely, the winter peak demand growth has been less consistent, varying much more around the broader trend. These phenomena are likely consequences of temperatures that were fairly constant on summer peak demand days, but varied widely on winter peak demand days. The erratic nature of winter peak demand is also likely caused by the fact that electrical heating equipment becomes increasingly inefficient at lower temperatures, as is demonstrated by the polynomial relationship identified between per capita winter peak demand and heating degree days. Additionally, historical winter peak demand was shown to be growing more quickly than summer peak demand. This phenomenon is likely the result of increases in electrical efficiency of cooling and increases in electricity consumption that result from the rising penetration of electrical heating equipment that replace gas furnaces. Future peak demand scenarios indicate that winter peak demand will remain more erratic and will sporadically surpass summer peak demand between 2025 and 2050. Thus, resource planners in ERCOT should place less certainty on winter peak demand projections and an increased level of winter preparedness on both the supply and demand sectors appears warranted for resource planners. These findings might foreshadow future resiliency challenges that other regions will face as electric heating equipment is deployed in place of boilers or furnaces for decarbonization purposes.