Ocotillo Modernization

APS is modernizing the Ocotillo Power Plant in Tempe. The project will create a cleaner-running, more efficient plant using advanced technology. APS intends to install five combustion turbines powered by natural gas. Two existing 1960s-era units will be removed.
The project is critical to the Phoenix metro area and provides several benefits. It supports service reliability, improves the plant’s appearance, is better for the environment, creates construction jobs and adds additional tax revenue to the local economy.


  • Update on Ocotillo Project
    Update on Ocotillo Project
  • Ocotillo Modernization Project
    Ocotillo Modernization Project

Ocotillo Modernization Snapshot



APS takes big-picture look at Arizona's energy future in 15-year forecast

Integrated Resource Plan highlights increasing flexible resources and grid investment to continue providing clean, reliable and affordable electricity

April 12, 2017
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APS requests first rate review in five years

Proposal enables continued investment in reliability, clean energy, innovation

June 01, 2016
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Public comment session planned for Jan. 19

The Maricopa County Air Quality Department will hold a public comment session for the Ocotillo Modernization Project air permit on January 19 in Tempe.

December 21, 2015
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Public comment session set for April 7

The Maricopa County Air Quality Department will hold a public comment session for the Ocotillo Modernization Project air permit on April 7.

April 01, 2015
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Ocotillo Earns Recognition from ADEQ

The Arizona Department of Environmental Quality selects Ocotillo Power Plant as a charter member of its state Voluntary Environmental Stewardship Program.

March 19, 2015
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What is the project timeline?
Demolition of the five large oil storage tanks, which are no longer in use, is planned for summer 2016. Construction on the new units would begin in 2017 and be completed by summer 2019. Removal of the old units would begin in 2019.
Why upgrade the Ocotillo plant?
The Ocotillo plant is critical to maintain service reliability in the Phoenix metro area because of its location. We can also improve an existing plant without changing its overall footprint. The planned new units are also more responsive – they can start up and begin delivering electricity in less than six minutes and reach full power in 10 minutes. The old units can take six hours or more just to start.
What will be the environmental benefits?
Replacing the obsolete steam generators with much newer, proven, cleaner technology will greatly improve the plant’s efficiency. The new units will decrease the plant's water-use and emission rates. They will also improve the plant's overall noise conditions.
How tall will the new structures be?
The plant currently has four 178-foot stacks, while the upgraded plant is planned to have five stacks about half as tall. This would significantly reduce the plant’s visibility from several locations. 

What economic benefits will the project provide?
It will create local jobs – we expect the project to require an average of more than 100 jobs during construction. Total property taxes for the upgraded plant are expected to increase to about $8 million by the fifth year of operation. APS currently pays about $600,000 in total property taxes for Ocotillo.

How can I get involved in the project? 
APS is committed to a transparent public process. In addition regularly providing updates on this page, we held a public open house to provide information and take comment, and we have participated in public forums for government agencies that provide oversight of various project components.

View more FAQs about the Ocotillo modernization project.