The North Dakota Public Service Commission plans a Sept. 25 hearing on a June application from Montana-Dakota Utilities for an Advance Determination of Prudence to install and operate additional filterable particulate control equipment on the coal-fired Lewis & Clark plant located near Sidney, Mont.
The project includes the installation of a baghouse with modifications to the existing mist eliminator at the Lewis & Clark Station. The project is required to meet non-mercury metal emission limits in the U.S. Environmental Protection Agency’s Mercury and Air Toxics Standards (MATS), which take effect in April 2015.
Montana-Dakota said it will be submitting a request to the Montana Department of Environmental Quality for a one-year extension of the April 2015 deadline to install the required pollution controls.
Montana-Dakota is a division of MDU Resources Group (NYSE: MDU).
The baghouse installation will also require the demolition of an abandoned chimney. Sargent & Lundy LLC, a consulting engineering, design and analysis company, was retained by Montana-Dakota to evaluate emission control technology strategies that would provide a cost effective means to address the controls necessary for Montana-Dakota to meet the requirements of the MATS Rule.
Lewis & Clark is a single-unit, 50-MW lignite-fired facility that has been in operation since October 1958. It is an integrated system resource supplying about 12% of the integrated system energy requirements in 2012 and representing 9% of the required capacity credits for the integrated system.
Lewis & Clark is currently equipped with multiple-cyclone mechanical particulate collectors, as well as a flooded wet disk particulate scrubber. The flooded wet disk scrubber is primarily designed for particulate matter pollution control but also removes SO2 from the flue gas. For mercury control, the unit currently uses fuel additives as well as activated carbon injection.
Montana-Dakota conducted an internal review of a potential fuel switch to natural gas in 2012 and 2013, but opted for new air controls.
The capital outlay for the project is estimated to be $26.1m (2013 dollars). This cost estimate is considered to be a conceptual cost estimate with an accuracy of ± 20%. The total cost of the project, including applicable loadings and Allowance for Funds Used During Construction, equates to approximately $27.7m based on the most recent project estimate and timeline for construction. North Dakota’s share of the addition required for Lewis & Clark is approximately 71% ($19.7m).