The Iowa Department of Natural Resources is taking public comment until Oct. 27 on draft air permit changes so Muscatine Power and Water (MP&W) can apply chemical additives to coal to reduce emissions at the Muscatine power plant.
MPW is planning to install a coal treatment system, identified as ChemMod, which will be used to reduce mercury and possibly emissions of other pollutants like NOx from the combustion of coal in its three boilers. The ChemMod system applies both a dry and liquid additive.
There was also an application to replace a fabric filter dust collector that is used to control emissions on the fly ash loadout and silo. All five of the permits to be altered were among the 51 permits issued to MPW in July 2013 with emission limits for PM2.5.
The maximum amount of ChemMod dry additive to be used at the facility is estimated at 5,850 tons per year. The maximum amount of ChemMod liquid additive to be used is estimated at 41,600 gallons per year.
MPW plans to install a storage silo and two day bins for the handling the dry ChemMod additive. The additive is primarily calcium carbonate and calcium oxide.
The modifications involve adding bypass conveyors and additional transfer points so that the dry and liquid additives can be applied to the coal, removal of coal crushing equipment associated with Unit 9, and the installation of two road segments to allow for truck delivery of the dry and liquid additives. Also, the existing fabric filter baghouse for fly ash handling equipment is being replaced by a new fabric filter baghouse.
Muscatine, in a July 30 statement about its board’s latest meeting, said about another emissions control project that had just gotten a board approval: “Approved capital expenditures for design, procurement, and installation of Powdered Activated Carbon (PAC) injection systems for Unit 9 ($1,800,000) and Unit 8 ($1,000,000) to reduce mercury emissions. The PAC injection system should allow the Units to meet emission reductions required by the Mercury and Air Toxics Standard (MATS). Compliance dates for the MATS rule is April 16, 2015, with the potential for a one-year extension as needed. Installation of the systems, subject to testing, design, and procurement, is scheduled to take place in May 2015 for Unit 8 and October 2015 for Unit 9.”
Muscatine plant affected by two different EPA rules
In a June 25 statement, Muscatine said that Brandy Olson, Director, Legal and Regulatory Affairs, reviewed highlights for a board meeting that month of the EPA’s Small Boiler MACT rule. This rule requires reductions of mercury and hazardous air pollutants from utility and industry boilers smaller than 25 MW. This regulation affects MP&W’s Unit 7 and the Auxiliary Boiler and has a compliance date of Jan. 31, 2016.
“There is the possibility of obtaining an extension of up to one year, but we have not encountered any issue to date that would justify seeking an extension under the Small Boiler MACT,” said Olson. “Although this regulation is currently in litigation, there seems little opportunity for a reversal of the sections that pertain to electric utility boilers.”
Olson also reviewed with the board highlights of MATS, which requires reductions of mercury and acid gas emissions from utility boilers greater than 25 MW. The compliance date is April 16, 2015. However, the EPA has encouraged state regulatory agencies to grant an extension of up to one year if the project timeline so necessitates.
Olson said that MP&W had conducted a Refined Coal (RC) test trial. The added chemicals alter the combustion characteristics of the coal such that mercury and NOx emissions are reduced. Management previously reviewed with the board the results of the RC test trial as part of the background information on the Powder Activated Carbon Demonstration Test Project. The results of the RC test trial indicated significant reductions in mercury emissions MP&W plans to enter into contracts for two turnkey RC treatment units, one for Units 7 and 8, and the other for Unit 9.
The Muscatine website shows that the power plant has a total nameplate capacity of 293.55 MW, broken down as:
- Unit 7 generator capacity – 25 MW
- Unit 8 generator capacity – 75 MW
- Unit 8A generator capacity – 18.05 MW
- Unit 9 generator capacity – 175.50 MW
U.S. Energy Information Administration data shows deliveries to the Muscatine plant earlier this year from the Black Thunder mine of Arch Coal (NYSE: ACI) and the Buckskin mine of Kiewit Mining, both located in the Wyoming end of the Powder River Basin.