New study reveals that early coal retirement, more clean energy investment would save over one billion for APS customers

May 4, 2021

Ellen Zuckerman, SWEEP | 609-610-2989
Maggie Field, Strategen Consulting | 630-251-1455


[PHOENIX, AZ] – A new study reveals that greater investment in clean energy, including energy efficiency, solar, and storage, and the retirement of the Four Corners coal-fired power plant in 2023, would save customers of Arizona Public Service Company (APS) more than $1.4 billion.

The study was released today by the Southwest Energy Efficiency Project (SWEEP) and conducted by Strategen Consulting, a leading energy modeling and research firm.

The report identifies the cheapest way for APS to meet its energy service needs over the next 15 years. Using data from APS, Strategen built a model of APS’ power system and determined the state’s cheapest, most reliable mix of energy options moving forward.

The study’s key findings include the following:

  • APS customers could save over $1.4 billion if the utility increases its investment in energy efficiency, retires uneconomic coal generation (i.e., the Four Corners Power Plant) by 2023, continues to invest in low-cost renewable energy and battery storage, and makes no new investments in fossil-fired resources.
  • APS’ cumulative carbon emissions over the next 15 years would be 50% lower under this Optimal Portfolio modeled by Strategen.
  • APS’ planning model includes artificial limits when it comes to energy efficiency investments and coal retirements. If these modeling limits are removed, significant additional cost savings and emissions reductions could be achieved.

“The results speak for themselves. APS customers stand to reap over one billion from greater investment in clean energy, including energy efficiency,” said Ellen Zuckerman, SWEEP’s Utility Program Director. ”We hope utility regulators take note and direct APS to do what’s in the best interest of Arizonans. As a first step, Commissioners should act immediately to approve and implement their Energy Rules.”

“Our model looked at all the options available to APS and identified the optimal energy portfolio, without the artificial limits APS included in its own analysis. Our findings demonstrate that there is a cheaper, cleaner path for Arizona’s energy future that includes major investments in energy efficiency, storage, and renewables,” said Edward Burgess, Stragen’s Senior Director.

To read the Strategen analysis, click here.

To read APS’ 2020 Integrated Resource Plan, click here.


The Southwest Energy Efficiency Project (SWEEP) is a public interest organization promoting greater energy efficiency in Arizona, Colorado, Nevada, New Mexico, Utah, and Wyoming. For more information, visit

About Stratgen Consulting
Strategen is a globally connected, impact-driven firm on a mission to decarbonize energy systems. For more information, visit