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 and consumers to the unknown events are also on the rise.”

In filings to Washington and Idaho regulatory commissions this month, Avista projected less dependence on fossil fuel generation. The IRP indicated “adequate resources between owned and contractually controlled generation, when combined with conservation and market purchases,” to meet customer needs through 2025. 

In addition to gas-fired peakers, Avista said renewable energy, energy storage, demand response, energy efficiency and upgrades to existing hydropower and biomass plants were integral.

“Changing dynamics related to carbon emissions will continue to evolve future planning environments and any need for supply side resources,” the IRP noted. 

Earlier this year CEO Dennis Vermillion said climate change mitigation to minimize greenhouse gas emissions required a “holistic approach” that considered reliability of regional natural gas and electric energy systems, as well as cost impacts to customers.

In the IRP’s decarbonization section, Avista cited Oregon and Washington legislation that support utilities using renewable natural gas (RNG). 

“Avista views RNG and low carbon fuels as an important component of its corporate environmental strategy and decarbonization goals,” the IRP noted. “By utilizing waste streams to create green fuel, RNG and hydrogen both support Avista’s environmental strategy and will provide Avista’s customers with a new environmentally friendly, low carbon fuel choice, delivered via the existing gas system.”