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UniSource to Issue All-Source Request for Proposals for Additional Energy Resources

UniSource Energy Services will seek new wind and solar generation, energy storage systems and other resources such as energy efficiency with an All-Source Request for Proposals (ASRFP) it plans to issue on Tuesday, April 19. The due date for proposals is expected to be July 1, 2022.

The ASRFP will target resources to support UniSource’s 2020 Integrated Resource Plan (IRP), which calls for increased use of owned or contracted generating resources and reduced dependence on wholesale market energy purchases. The IRP also describes UniSource’s plan to supply 50 percent of its energy to retail customers from renewable resources by 2035, taking advantage of reductions in the cost and improvements in reliability for wind, solar and storage technologies.

"We're looking for cost-effective resources that can help us maintain reliable service to our customers while building a cleaner energy grid with lower emissions," said Susan Gray, UniSource’s President and Chief Executive Officer. “We’re especially interested in resources that are consistently available during the late afternoon and early evening hours of summer, when customers' energy needs are greatest.”

In its request, UniSource will seek bids for all resource types, including:

  • Up to 170 megawatts (MW) of renewable and energy efficiency resources. This could include new wind and solar generating systems and new energy efficiency initiatives, including demand response programs that reduce usage during periods of high energy demand.
  • Up to 150 MW of "firm capacity" resources that can be called on at any time, including energy storage systems designed to provide at least four hours of continuous energy every day during the summer for UniSource to dispatch as needed. This also could include demand response programs that provide incentives to customers who curtail energy usage at specific times of the day and year when usage is typically highest.

UniSource will review proposals this summer and announce successful proposals near the end of this year. UniSource is seeking resources that will commence service as soon as May 1, 2024 but no later than May 1, 2025. Projects with combined technologies are eligible for consideration.

The ASRFP process is being supported by 1898 & Co., with independent monitoring services provided by Sargent & Lundy. More information, including bidder registration and ASRFP material, is available at

UniSource customers’ energy needs are growing, with new peak energy demand records set in both 2020 and 2021. UniSource is working to meet those needs with an increasingly clean energy resource mix. UniSource’s 2020 IRP describes the company’s plans to procure a robust mix of renewable resources, efficient natural gas generation and new customer opportunities for energy efficiency and managing peak energy demands.

In February 2022, the Arizona Corporation Commission reviewed and acknowledged UniSource’s 2020 IRP, noting its use of ASRFPs to secure future resources and providing guidance on development of future resource plans.

UniSource provides natural gas service to more than 165,000 customers in northern and southern Arizona. It also provides electric service to more than 100,000 customers in Mohave and Santa Cruz counties. For more information about UniSource, visit UniSource and its parent company, UNS Energy, are subsidiaries of Fortis Inc. (TSX/NYSE: FTS), which owns utilities that serve more than 3 million customers across Canada and in the United States and the Caribbean. For more information, visit


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