# ~..; NORTH DAKOTA

, DEPARTMENTofHEALTH ENVIRONMENTAL HEALTH SECTION Gold Seal Center, 918 E. Divide Ave. Bismarck, NO 58501-1947 701.328.5200 (fax) www.ndhealth.gov



### January 11,2010

John Graves, P.E. Environmental Manager MinnkotaPowerCooperative 1822 Mill Road P.O. Box 13200 Grand Forks, ND 58208-3200 Re: SCR CostEstimate DearMr. Graves: 

# FILE

The Department and the U.S. Environmental Protection Agency have reviewed the "NOx 

### Best Available Control Technology Analysis Study

- Supplemental Report" for Units land 2 at the M.R. Yqung 

### Station as well as the supplementary information dated December 11,2009. Based on the information submitted to date, there are several preliminary questions regarding the information presented. Although you addressed several of the concerns in our meeting of December 21, 2009, we ask that you provide a written response to all ofthe following items so thatthe final cost SCRnumbers canbe fully analyzed: 1) How were the SCR reactors sized and the catalyst volume determined and what target NOx 

### control efficiency was used to size the catalyst? How was the cost ofthe catalyst determined? 2) Anhydrous ammonia appears to be a less expensive reagentthan ureafor the SCR system due to local availability. A justification must be supplied for selecting urea over anhydrous ammonia. 3) Support must be provided for the catalyst cleaning/replacement outage periods. This should include an explanation of the method used to estimate the outage time and clarification whetherthe outage time includes the regular outageperiod. 4) The indirect capital costs associated with the project appear to be high. A detailed explanation ofthe estimationmethod mustbe supplied. 5) Supportmustbeprovidedfor the costofnatural gas and electricity.

Environmental Health Section Chief's Office 701.328.5150 Division of Air Quality 701.328.5188 Division of Municipal Facilities

701.328.5211 Printedon recycledpaper. Division of Waste Management 701.328.5166 Division of Water Quality 701.328.5210Mr. Graves· 2 January 11,2010·
6) More details, including calculations, must be supplied to justify the pressure drops and parasitic loads associated withthe SCRconfigurations. 7) All vendor correspondence related to SCR reactor sizing, catalyst volume, NOxcontrol efficiency, catalyst cost, catalyst replacement schedule, and catalyst guarantees should be provided. This includes the originalrequests submitted to vendors and analyst suppliers by Minnkota and its consultants. This must also include the description ofthe gas stream thatwas suppliedto the vendors. 8) Datamust be provided for the temperature gradient ofthe regenerative heat exchanger to justify the reheat calculations. This must be provided for both LDSCR and TESCR. The 600°F temperature for the reheated flue gas mustbejustified. 9) A comparison ofthe SCRcosts atthe M.R. Y!-lung Station versus PSE&G Mercer Station and We Energies Oak Creek Station should be provided or an explanation why such a comparison is not possible or inappropriate. We recognize that each plant has unique characteristics and there will be some design differences from plant-to-plant, but those differences. should not necessarily· dismiss making a general comparison ofcosts unless there are unique or extenuating circumstances which would preclude a general cost comparIson. 10) Provide additional clarification and technical justification regarding Minnkota's determination that the units at MRYS are boiler limited and cannot generate additional steamfor flue gas reheatpurposes. 1"1)There appear to be several discrepancies in the documents that must be addressed including: a) The catalyst volume for Unit

### 2 (PA-23) is listed as 256 m3per layerperreactor or 512 m3 per layer. This is 4:'5 times more than Unit 1 yet Unit 2 is not twice as large. Please verify the Unit 2 catalystvolume. b) The reheat for Unit 2 for TESCR is listed as 48.11 MMBtulhr per reactor and for LDSCR is 45.55 MMBtulhr per reactor. The differential between TESCR and LDSCR is much less than for Unit 1 (60.3 MMBtu/hr and 31 MMBtu/hr)' Please explainthis difference. c) The capital costs for the "stand alone" SCR(p.3 ofattachments to December 11, 2009 submittal) do not total correctly. Please checkthe numbers and revise the documents as necessary. d) The flue gas reheat burners and fans appear to be included in both the "SCR system equipment" and "Auxiliaries" cost estimates (see pA ofattachments to December 11, 2009 submittal, footnotes 1 and 3). Please check this and revise the documents as necessary.

### Mr. Graves 3 January 11, 2010

We

# askthatyou supply the requested information by February 11,2010. Ifyouhave any questions, please feel free to contactus. Respectfully,

# ~7~~ Terry L. OClaIr, P.E. Director Division ofAir Quality TLO/TB:csc xc: Hans Buenning, EPA Maggie Olson, Asst. Attorney General