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.