Selective Catalytic Reduction

Selective catalytic reduction (SCR) technology is a proven and effective method to reduce nitrogen oxides (NOx), which are produced when coal is burned. NOx is a contributor to ground level ozone formation.

What is ground level ozone?

Ground level ozone is formed on hot, sunny days by chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs). Nitrogen oxides are released into the air from the burning of fossil fuels such as gasoline, oil and coal. The primary manmade sources of NOx are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fossil fuels. Motor vehicles in the U.S. are the largest source category for NOx emissions. Motor vehicles, gasoline vapors and chemical solvents are some of the major sources of the VOCs that contribute to ozone formation. Vegetation can also be a significant source of VOCs.

How does selective catalytic reduction technology work?

Prior to exhaust gas going up the smokestack, it passes through a catalyst where the NOx reacts with anhydrous ammonia and is converted to nitrogen and water.

What has Duke Energy done to address safety or environmental hazards associated with using selective catalytic reduction technology?

Anhydrous ammonia is a compressed, liquefied gas which is typically stored on site. It has the potential to become hazardous if released to the environment. To ensure the safety of our employees, the environment and the public, we have a comprehensive safety and emergency response plan at every station which stores anhydrous ammonia, to be put into action in the unlikely event of an accidental release. In addition, all of Duke Energy’s anhydrous ammonia systems are designed with redundant safety features and systems (leak detection, automatic shutoff valves, etc.) to further reduce the risk of an accidental release. Other sectors that use anhydrous ammonia include agriculture, chemical and pharmaceutical manufacturing, water and wastewater treatment, pulp and paper, and many more.