Avista Corp.’s four-state utility operations will rely more on natural gas peaking plants over the next five years in the absence of long-term energy storage, the Spokane, WA-based operator said in updated integrated resource plans (IRP).

With forecasts for higher retail and residential per-customer demand versus the 2020 IRP, Avista Utilities said it would return to “new natural gas-fired peakers because long-term energy storage is not yet available or as cost effective as initially estimated” for 2026 capacity needs.

Price volatility in the Pacific Northwest region is forecast to grow because of increasing subscribed transportation. The IRP also noted that as “weather events throughout the United States have continued to rise, the risk to energy providers, utilities...