Clearing the Air: How TEP Is Reducing Emissions While Powering a Growing Community
Page summary
Tucson Electric Power is improving air quality and reducing emissions through cleaner energy resources, battery storage, modernized power generation and environmental stewardship while supporting Southern Arizona’s growing energy needs.
As Southern Arizona adds new residents, businesses, and economic opportunities, Tucson Electric Power is working to ensure that growth is supported by cleaner energy resources, modern technology, and responsible environmental stewardship.
Those efforts are delivering measurable results. Since 2019, TEP has reduced carbon dioxide (CO2) emissions by approximately 42 percent, driven by significant investments in renewable energy, energy storage, and more efficient power generation.
As of late 2026, our energy portfolio includes more than 1,000 megawatts (MW) of solar and wind power. These systems are supported by 550 megawatts (MW) of battery energy storage that helps us make the most of our renewable energy.
All these zero-emission resources have a real impact on air quality. Over time, they’ve reduced TEP's overall emissions intensity, meaning fewer emissions are produced for every megawatt-hour (MWh) of electricity delivered to customers.
Made in Tucson
These new systems are supported by the upgraded H. Wilson Sundt Generating Station, our largest local power plant. Over the past 15 years, TEP has modernized the plant and replaced older equipment with cleaner, more efficient technology.
One major milestone was achieved in 2015, when we suspended the use of coal at a unit that now operates exclusively on natural gas. Five years later, we replaced two older units with highly efficient reciprocating internal combustion engine (RICE) units equipped with advanced emission controls.
The results have been significant. Compared with average levels from 2011 through 2015, emission intensity from these units has been reduced by more than 60 percent for nitrogen oxides, 30 percent for carbon dioxide, and 90 percent for sulfur dioxide.
Behind those improvements is the work of employees across the company, including environmental professionals who help ensure compliance with federal, state and local air quality requirements. To ensure compliance with strict air permit requirements, TEP continuously monitors emissions and submits reports to regulatory agencies.
Beyond Generation
Environmental stewardship extends to every part of our business. For major construction projects, TEP obtains fugitive dust permits and employs controls to reduce dust emissions. Those efforts are particularly important in Arizona, where windblown dust can be a significant contributor to particulate matter levels.
We also support environmental initiatives through employee engagement and community partnerships, including our employee-led green team, UNS ECOS (Employees Creating Opportunities for Sustainability). TEP works with partners to transform trimmings generated through our vegetation management program into high-quality compost and contribute to tree-planting efforts that help strengthen Southern Arizona's urban canopy and green spaces through our Trees for You program.
Together, these activities support a broader community success story.
Air quality in Pima County remains among the best in the region. With the exception of particulate levels in the Rillito monitoring area northwest of Tucson, the county currently meets the health-based National Ambient Air Quality Standards for all monitored pollutants. That achievement has been maintained despite population growth and other regional air quality challenges.
While no single organization can take credit for that success, it reflects the combined efforts of local governments, businesses, residents and public agencies working toward the same goal. At TEP, that means continuing to invest in cleaner energy resources, operating responsibly, and finding new ways to reduce environmental impacts while maintaining the reliable service our customers depend on every day.
"Protecting air quality is part of our commitment to powering our community's future," said Catherine Schladweiler, Director of Environmental Services & Sustainability. "As we continue to add clean energy resources and modernize our system, we're helping ensure Southern Arizona remains a great place to live, work and raise a family."
