Wisconsin Power and Light (WPL) plans to install a new Air Quality Control System (AQCS) on the coal-fired Unit 5 at its Edgewater Generating Station located in Sheboygan, Wisc.
The new AQCS will consist of a dry flue gas desulfurization (DFGD) system utilizing control equipment consisting of two circulating fluidized bed scrubbers (CFBS) and two baghouses to reduce SO2, plus other acid gas and particulate matter emissions.
“This initiative is being implemented to meet a consent decree agreement (Civil Action No. 13-cv-266 and 13- cv-265) with the Environmental Protection Agency (EPA) and Sierra Club entered by the Court on June 17, 2013,” noted an air construction permit document from the Wisconsin Department of Natural Resources. “The AQCS construction is expected to commence in the spring of 2014 and be complete summer of 2016.”
The DNR is currently taking public comment until Feb. 15 on the draft version of the air construction permit.
Hydrated lime will be added to the CFBS as the reagent for acid gas removal. The reagents and the reaction products, including calcium sulfate, calcium chloride and other salts, will result in additional particulate matter (PM) emissions. Two new baghouses in parallel will be installed to control PM.
The Edgewater power generating station is located on the edge of Sheboygan along the Lake Michigan shoreline. Edgewater Unit 5 currently burns a variety of low sulfur, subbituminous, Powder River Basin (PRB) coals. The maximum continuous heat input rate of B25 has been given as 4,366 million BTU per hour in the permit application. The Unit 5 boiler components, including combustion equipment, will not be physically modified as part of the AQCS installation.
With no change in combustion equipment and no change in type of coal burned, the emission rates of pollutants from combustion in boiler, in terms of pounds per million BTU, should remain the same, the DNR noted.
“During high load (430–385 MW) conditions, Unit 5 operates at or near capacity and will not be able to offset the auxiliary power consumed by the AQCS by increasing the fuel input. However since Unit 5 operates in a cyclical manner, at low load conditions (125 MW) the auxiliary power consumed by the AQCS can be offset by increasing the hourly heat input (fuel input) to the boiler,” said the October 2013 application, prepared for WPL by Stanley Consultants.
This project is part of broader Wisconsin Power and Light air plan
Alliant Energy (NYSE: LNT), which has WPL as a subsidiary, reported in its November 2013 Form 10-Q report that it is pursuing various clear-air initiatives for coal-fired capacity. In April 2013, WPL along with the other owners of the Edgewater and Columbia plants, entered into a Consent Decree with the U.S. Environmental Protection Agency and the Sierra Club to resolve claims relating to the coal-fired Edgewater, Columbia and Nelson Dewey plants, while admitting no liability.
In June 2013, the decree was approved by a federal court, thereby resolving all claims against WPL. Under the decree, WPL is required to install the following emission controls systems:
- Selective Catalytic Reduction (SCR) system for NOx control at Edgewater Unit 5 by May 1, 2013 (actually placed in-service in December 2012);
- SO2 scrubbers and baghouses at Columbia Units 1 and 2 by Dec. 31, 2014;
- Scrubber and baghouse at Edgewater Unit 5 by Dec. 31, 2016; and
- SCR system at Columbia Unit 2 by Dec. 31, 2018.
WPL is also required to fuel switch or retire Nelson Dewey Units 1 and 2 and Edgewater Unit 3 by Dec. 31, 2015, and Edgewater Unit 4 by Dec. 31, 2018. In addition, the decree establishes emission rate limits for SO2, NOx and particulate matter for Columbia Units 1 and 2, Nelson Dewey Units 1 and 2 and Edgewater Units 4 and 5. The decree also includes annual plant-wide emission caps for SO2 and NOx for Columbia, Edgewater and Nelson Dewey.
The Public Service Commission of Wisconsin issued a June 2013 final written order approving these air controls for Edgewater Unit 5. The estimated cost of the project is $413.7m, excluding allowance for funds used during construction (AFUDC).
Edgewater consists of three coal-fired units; Units 3, 4 and 5. They began operation in 1951, 1969, and 1985, and have nameplate generation capacities of 60 MW, 330 MW, and 380 MW, respectively. While Unit 5 was previously jointly-owned by WPL and Wisconsin Electric Power, Units 3 and 5 are currently owned exclusively by WPL. Unit 4 is jointly-owned by WP&L and Wisconsin Public Service Corp. (WPSC). All three units are operated by WPL.