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This letter from the Energy & Environmental Research Center (EERC) in Grand Forks addresses several recent articles regarding the use of selective catalytic reduction (SCR) technology for NOx control in power plants that utilize North Dakota lignite. Throughout the history of the North Dakota coal-fired utility industry, combustion systems have been designed with larger passages to accommodate the high-sodium ash and minimize the effects of troublesome deposits. SCR technology requires that gases flow through tight passages in order to contact the gas stream with porous catalyst surfaces; this is in contrast to selective noncatalytic reduction (SNCR) that removes NOx but adds no additional flow constraints.

The North Dakota utility industry has decades of experience operating its systems successfully on lignite and was rightfully concerned with the potential for plugging in an SCR system. To evaluate this potential, the coal-fired utility industry commissioned a study with researchers at the EERC. The study indicated that SCR technology is not a good candidate for cyclone-fired power plants fueled with North Dakota lignite.

In a Bismarck Tribune story on July 21, 2011, titled “State has two-fronted battle with EPA,” federal attorney Brenda Morris was referenced as contending that North Dakota’s determination that SNCR technology is the best available control technology over SCR for North Dakota lignite is based on results from a poorly designed pilot test. However, the outcome of said study (i.e., the plugging of the catalyst) is definitely not indicative of a poorly designed program. The study demonstrates that SCR is not appropriate for cyclone-fired power plants burning North Dakota lignite.

The tests were designed by a group consisting of SCR catalyst vendors, utilities, the U.S. Department of Energy, the Electric Power Research Institute, and the EERC. The team of industry-leading experts who conducted these tests utilized state-of-the-art techniques and solicited input from those highly regarded in the field of study and industrial applications. The science indicates that installing an SCR system on a cyclone-fired power plant burning high-sodium North Dakota lignite will simply not work. The North Dakota utility industry should not be required to invest hundreds of millions of dollars in a technology that will force plant shutdowns and fall far short on NOx control. The current state of technology dictates that the clear answer to address U.S. Environmental Protection Agency concerns is SNCR.

Sincerely,

John Harju, Associate Director for Research
Mike Holmes, Deputy Associate Director for Research
Jason Laumb, Senior Research Manager Energy & Environmental Research Center