Clean Energy Commitment | APS Low-Carbon Economy Principles | Green Bond | Palo Verde Generating Station | Hydrogen | Solar Research & Development | Energy Storage | Coal Reduction | Carbon & Air Emissions | Sustainable Fleet | Sustainable Facilities

Updated: December 2020

Our Commitment: 100 Percent Clean Energy by 2050

We've set a bold, three-part goal to provide a clean energy future for our customers:

  • An aspirational goal to provide 100 percent clean, carbon-free electricity by 2050
  • A nearer-term 2030 target of achieving a resource mix that is 65 percent clean energy, with 45 percent of our generation portfolio coming from renewable energy
  • A commitment to end all coal-fired generation by 2031, seven years sooner than previously projected
Carbon Goal

Our clean energy plan will be guided by sound science and focused on achieving environmental and economic gains—all while maintaining affordable, reliable service for our customers.

Collaboration with customers, regulators and other stakeholders is key to our plan’s ultimate success. We look forward to working alongside those who believe in this vision to move forward together to keep Arizona clean, beautiful and thriving.

“We see incredible things ahead for Arizona and are excited to power our state’s future with electricity that will be 100% clean.” — Jeff Guldner, Chairman and CEO, Arizona Public Service

Pathways to 100 Percent Clean


Policy decisions

Support policy decisions that leverage market-based technology and innovation to attract investment in Arizona


Existing power sources

Near-term use of natural gas until technological advances are available to maintain reliable service at reasonable prices


Evolving market-based solutions

Participation in the Energy Imbalance Market provides access to clean energy resources while saving customers money



Electrification will drive a cleaner environment and more energy-efficient operations throughout the economy


Modernization of the electric grid

Continue to advance infrastructure that is responsive and resilient while providing customers more choice and control


Energy storage solutions

Storage creates opportunity to take advantage of midday solar generation and better respond to peak demand

APS Low-Carbon Economy Principles

APS’s transition to clean energy will contribute to a future low-carbon economy that will create new growth opportunities while providing environmental benefits. APS developed a set of principles to guide our path toward a low-carbon economy.

Read the APS Low-Carbon Principles.

Green Bond

In September 2020, APS issued its first-ever green bond. Through this green bond issuance, we were able to raise almost $400 million to support “green” projects, such as renewables and energy storage, energy efficiency programs, climate change mitigation and clean transportation. Green bonds allow APS to raise capital to support sustainable projects reflecting the strong commitment APS has made toward a clean energy future.

Palo Verde Generating Station

For the 28th consecutive year, Palo Verde was the nation’s largest energy producer, generating 31.9 million megawatt-hours (MWh) of carbon-free electricity in 2019. Palo Verde is the only generating facility in the United States to produce more than 30 million MWh in a year, a milestone the plant has achieved 11 consecutive years and a total of 15 times. APS operates the Palo Verde Generating Station and owns or leases 29.1% of the facility.

Nuclear energy works in concert with renewable generation. Without nuclear energy, carbon emissions would increase because of greater reliance on natural gas to fill the inevitable energy void. Because Palo Verde is producing energy at all hours – day and night – it supports the basic needs of customers when solar and wind are not available because of their intermittent nature. It can facilitate increased adoption of electric vehicles (EVs) and improve the environment by supplying zero-emission energy to charge EVs and large-scale batteries instead of relying on natural gas or coal-fired power plants to do the job.

Nearly half of Palo Verde’s output is dedicated to serving Arizona consumers. Electricity generated by the plant annually displaces more than 13.3 million metric tons of greenhouse gas (GHG) emissions that otherwise would have been produced, providing clean energy that powers about four million homes and businesses throughout the Southwest.

Additionally, as the nation’s only nuclear plant not located on a body of water, Palo Verde recycles more than 20 billion gallons of wastewater annually from surrounding municipalities to cool the plant. Learn more in our section on Water.

Read more about Palo Verde Generating Station on and in this article from AZ Big Media: Palo Verde – Inside the Nation’s Largest Nuclear Power Plant.”


Achieving our clean energy commitment will require continued advances in energy technology. One of the most promising emerging opportunities is the use of hydrogen. A substantial majority of the world’s industrially produced hydrogen creates carbon dioxide as a byproduct. However, when hydrogen is produced by electrolysis using clean electricity (such as nuclear, solar or wind energy), the resulting hydrogen is a carbon-free fuel. Producing hydrogen when there is an excess of carbon-free electricity effectively creates another energy storage technology for meeting peak demand with carbon-free energy. 

Innovative Hydrogen Partnership. Arizona Public Service is one of three utilities chosen by the Department of Energy's Office of Nuclear Energy to participate in a hydrogen production project in partnership with Idaho National Laboratory. The goal of the project is to improve the long-term economic competitiveness of the nuclear power industry. The multi-phase project, planned for 2020 through 2023, will look at how hydrogen produced at the Palo Verde Generating Station may be blended with natural gas for use in gas-fired combustion turbines during times of the day when photovoltaic solar energy sources are not available and energy reserves in the southwest United States are low. Experience from the pilot project will offer insights into methods for flexible transitions between electricity and hydrogen generation missions in solar-dominated electricity markets, and demonstrate how hydrogen may be used as energy storage to provide electricity during operating periods when solar is not available.

Learn more about the Palo Verde & Idaho National Lab hydrogen partnership

Solar Research & Development

We are a national leader in solar energy, with more than 1.5 gigawatts of solar capacity producing energy for our customers in Arizona. Our customers can count on us for innovative solutions that will advance Arizona’s solar leadership, including ground-breaking research to evaluate how energy companies can bring the benefits of this clean, renewable resource and advanced technology to customers reliably and affordably. Solar is an important part of our increasingly clean, diverse energy mix that will continue to grow in the future. We are setting the course for a sustainable energy future that brings together clean energy resources including solar, advanced technology, customer choice and reliability for all customers.

  • State Ranking. Arizona ranks number 3 nationally for solar capacity
  • Solar Capacity. Our 1.5 gigawatts of solar capacity ranks number 5 among all U.S. investor-owned energy companies
  • Solar Portfolio. Our portfolio includes 10 APS-owned large-scale plants, more than 30 APS-owned small-scale plants, APS-owned rooftop solar systems and 6 power purchase agreements to buy solar power from third-party providers, totaling 550 MW. We have helped more than 103,000 customers install private rooftop solar on their homes, and we have assisted more than 300 schools and 32 government agencies install solar projects at their facilities across Arizona. Learn more about our Renewable Energy Portfolio.

We are pursuing numerous opportunities to advance Arizona’s solar leadership for the benefit of customers here and across the nation. Our engineers are developing and deploying innovative projects to understand solar’s potential for customers, including evaluating how solar interacts with energy storage and other advanced technologies.

Research from the award-winning APS Solar Partner program, Solar Innovation Study and Solar Communities program, among others, is being shared across the utility industry and with academic researchers, consumer advocacy groups and Arizona-based solar installers. The results are informing our company and the industry about how to bring the benefits of solar energy and advanced technology to customers reliably and affordably.

Energy Storage

We deploy a number of advanced technologies on our system, including energy storage. Storage can provide capacity, improve power quality, be used for system regulation and help defer certain traditional infrastructure investments. Energy storage can also aid in integrating higher levels of renewables by storing excess energy when system demand is low and renewable production is high, and then releasing the stored energy during peak demand hours later in the day and after sunset. We are utilizing grid-scale energy storage projects to benefit customers, to increase renewable utilization and to further our understanding of how storage works with other advanced technologies and the grid.

We currently plan to install at least 850 MW of energy storage by 2025, including 150 MW of energy storage projects under power purchase agreements. The additional 700 MW of APS-owned energy storage is expected to be made up of energy storage that will be added to our existing AZ Sun solar sites, along with current and future RFPs for energy storage and solar plus energy storage projects.

In April 2019, a battery module in our McMicken battery energy storage facility experienced an equipment failure, which prompted an internal investigation to determine the cause. The results of the investigation will inform the implementation of batteries on our system. We continue to evaluate the appropriate timing and path forward to support the overall capacity goals for our system and associated energy storage requirements.

Coal Reduction

We have permanently retired over 1,000 megawatts of coal-fired electric generating capacity. These closures, in addition to other measures taken by APS, have resulted in a total reduction of carbon emissions of 26% since 2005, which is equivalent of removing over 940,000 passenger vehicles from the road. In addition, we have committed to end the use of coal at our remaining Cholla units by 2025 and made an overall commitment to exit coal by 2031, which means we will close the Four Corners Power Plant seven years earlier than our original plan.

With all plant closures, we work closely with impacted employees and local communities to ease the transition and support long–term economic planning for a future beyond coal.

Learn more about our coal communities transition plan.

Carbon & Air Emissions

In 2019, total APS carbon dioxide emissions were 13,455,060 tons. This represents a decrease of 26% over total carbon dioxide emissions since 2005. In addition to carbon reductions, we are on the pathway to reduce nitrogen oxide (NOx) and sulfur dioxide (SO2) intensity by 93% and 89%, respectively. Since 2005, we have had an intensity reduction of 77% for NOx and 86% for SO2. This resulted from our commitments to reduce emissions and institute operational efficiency enhancements.

We reduce our environmental impact by closing older, less-efficient coal units and upgrading environmental controls on newer units. Selective catalytic reduction (SCR) technology currently is employed at six of our power plants. As noted above, installation of two new SCRs at the Four Corners Power Plant in 2018 resulted in an 88% NOx reduction at that facility.

Learn more about our air emissions trends.

CDP Recognition. We believe it is important to disclose our carbon management strategies and GHG emissions to customers, investors and other stakeholders. Through significant demonstrable action on climate change risk, Pinnacle West is leading on corporate environmental ambition, action and transparency worldwide. Pinnacle West has been recognized for leadership in corporate sustainability by global environmental non-profit CDP, securing a place on its prestigious A List in 2019 and 2020 for tackling climate change. CDP collects and analyzes environmental data and benchmarks companies for investors to use in financial decisions. CDP’s network of investors represents more than $106 trillion in assets. 

In 2020, Pinnacle West is the only U.S. electric utility to earn an A score for Climate and the only U.S. electric utility to earn A scores in both the Climate and Water categories. We were recognized for our actions to cut emissions, mitigate climate risks and contribute to a low-carbon economy. Our scope 1, 2 and some of scope 3 GHG emissions reported to CDP are third-party verified.

In addition, we submit a comprehensive annual report of our GHG emissions to the Environmental Protection Agency (EPA) as required by federal law.

Read our news story and learn more about our CDP responses and documents.

To measure our overall carbon reduction—not just decreasing emissions from generation but also throughout our company operations—we use a carbon-avoidance metric. This reflects actions taken company-wide, including retiring coal units, installing renewable generation and energy efficiency, increasing our building and operating efficiencies, and pursuing fleet electrification.

In 2019, we avoided 5.1 million metric tons of carbon. Since 2015, we have avoided 23.1 million metric tons of carbon dioxide emissions that otherwise would have been emitted had we not taken actions to reduce the emissions. That is equivalent to removing over five million automobiles from the road.

Sustainable Fleet

In July 2020, we set a goal of transitioning 30% of our light-duty vehicles and equipment (comprised of forklifts, all-terrain vehicles, golf carts and light-duty passenger vehicles) to electric by 2025 with an aspirational goal of achieving a 100% clean, carbon-free fleet by 2050.

Our transportation fleet’s conversion to more fuel-efficient vehicles and electrification continues through market research and updates to our electrification strategy. We are monitoring medium and heavy-duty options and will adopt them once there is more commercial availability. Through this ongoing conversion and by using our fleet more efficiently, we are working to reduce both carbon emissions and operating costs.

APS has also adopted idle-mitigation technology as part of a standard package offered on all trouble trucks, allowing workers to run laptops and air conditioning without keeping the vehicle running. In addition to reducing our carbon footprint, this decreases noise when working in residential neighborhoods. Our Odyne bucket trucks use less fuel and have quieter operations than traditional diesel or gasoline engine trucks by using battery-assisted drivetrain and electric power takeoff (ePTO) technology while operating the bucket. We are currently evaluating the new idle-mitigation technology for adoption in our larger trucks.

Sustainable Facilities

Our commitment to reduce our environmental footprint through sustainable practices is evident throughout APS facilities. Our corporate headquarters in Phoenix has earned seven ENERGY STAR labels for energy efficiency from the EPA. Over the past 11 years, we have improved energy efficiency at this facility by approximately 25%. Overall, our facilities have received 12 ENERGY STAR labels. Sustainability strategies are embedded within our standard architectural and engineering specifications when managing changes to our buildings or constructing new space. We work to improve energy efficiency throughout our facilities by replacing obsolete building systems and equipment with more energy-efficient systems and equipment.

While eco-friendly buildings are core to our sustainability efforts, we are also looking toward the future with a vision for how we will work tomorrow. The Workplace of the Future initiative was launched in 2019 to create a flexible strategy that will transform our workspace to support the evolving needs of our business and employees. Grounded in research and employee feedback, three guiding principles form the foundation of our vision for the Workplace of the Future.

The first project from this initiative is the APS Work Café, located in our corporate headquarters, which was opened in early 2020. It provides a combination of working, meeting and dining areas that bring people together in a modern, engaging, employee-centric atmosphere. The design incorporates many sustainable elements including the use of natural lighting, LED lighting fixtures and sustainably sourced furniture. The next project is a renovation of an entire floor that houses part of the IT organization. Construction will be completed by the end of 2020. We will monitor and measure the effectiveness of the implemented strategies and incorporate what we learn in future projects.

Going forward, along with our Workplace of the Future effort, proactive assessments of the health and use of our buildings, utilization of the most current technologies as we renovate, reusing materials where possible and further replacing ozone-depleting technologies will guide our decision-making. We will continue to design, construct, operate and maintain our new and remodeled facilities to ENERGY STAR standards and LEED principles.

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