~..; NORTH DAKOTA , DEPARTMENT of HEALTH

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

Minnkota Power Cooperative

1822 Mill Road

P.O. Box 13200

Grand Forks, ND 58208-3200

Re: SCR Cost Estimate

Dear Mr. 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 of the following items so

that the final cost SCR numbers can be 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 of the catalyst

determined?

2) Anhydrous ammonia appears to be a less expensive reagent than urea for 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 whether the outage time includes the regular outage period.

4) The indirect capital costs associated with the project appear to be high. A detailed

explanation ofthe estimation method must be supplied.

5) Support must be provided for the cost ofnatural 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

Printed on recycled paper.

Division of

Waste Management

701.328.5166

Division of

Water Quality

701.328.5210
Mr. Graves· 2 January 11,2010·

6) More details, including calculations, must be supplied to justify the pressure drops and

parasitic loads associated with the SCR configurations.

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 original requests submitted to vendors and analyst suppliers

by Minnkota and its consultants. This must also include the description ofthe gas stream

that was supplied to the vendors.

8) Data must 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 must be justified.

9) A comparison ofthe SCR costs at the 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 of costs 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

steam for flue gas reheat purposes.

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 m3 per layer per reactor 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 catalyst volume.

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

explain this difference.

c) The capital costs for the "stand alone" SCR (p.3 of attachments to December 11, 2009

submittal) do not total correctly. Please check the 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 of attachments 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 ask that you supply the requested information by February 11,2010.

If you have any questions, please feel free to contact us.

Respectfully,

~7~~ Terry L. OClaIr, P.E.

Director

Division ofAir Quality

TLO/TB:csc

xc: Hans Buenning, EPA

Maggie Olson, Asst. Attorney General