The wet scrubbers and selective catalytic reduction (SCR) technologies that Duke Energy has installed on many of its coal-fired power generating units to control sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions provide a unique and successful co-benefit of removing a significant amount of mercury. When burning eastern bituminous coal, this co-benefit can realize up to a 95% reduction in stack mercury emissions.
Duke Energy works tirelessly to keep its generating units in compliance with EPA mercury limits. Over the last 13 years, Duke has partnered with the Electric Power Research Institute (EPRI), U.S. Department of Energy and other utilities and technology suppliers to understand what mercury-control technologies work best for our generating units.
Mercury control research that Duke has been involved in includes:
- In 2003, 2004 and 2005, Duke Energy partnered with the U.S. Department of Energy to test the performance of impregnated carbon injection on a hot-side electrostatic precipitator at the Cliffside and Buck steam stations.
- In 2004, Duke Energy tested the mercury removal capability of a pilot wet limestone scrubber at the Marshall Steam Station.
- In 2004, Duke Energy worked with the Electric Power Research Institute (EPRI) to test the performance of impregnated carbon injection on a cold-side electrostatic precipitator at Allen Steam Station.
- In 2006 and 2007, Duke Energy funded a study to review existing mercury continuous monitors on the market to determine which monitor would provide the most accurate and reliable service to provide a standard for the coal-fired fleet.
- Duke Energy partnered with EPRI to study the impacts on native carbon from combustion and flue gas temperatures impacts related to mercury capture.
- In 2009, Duke Energy partnered with EPRI to study the impacts on mercury control using dry sorbent injection (DSI) in conjunction with powdered activated carbon (PAC) on its Gallagher bag-house equipped generating unit.
- In 2009 and 2010, Duke Energy provided comments to the EPA to ensure an effective Information Collection Request (ICR) program to help formulate the EPA Mercury and Air Toxics (MATs) Rules.
- From 2010 to 2013, Duke Energy partnered with various suppliers to test and determine a path forward for the use of sorbents and other products introduced to the market that would work well with existing unit operating parameters to facilitate compliance with all requirements of the EPA MATs rule.
- From 2014 to 2016, Duke Energy installed and commissioned mercury control equipment and technologies for compliance with the EPA MATs rule.