# Appendix 10.13

Table 10-16

Reference 10: Page 5 of "BART Determination for Stanton Station U nit 1" in Appendix B of Department BART Determination.Table 10-16

Reference 11: Page 6 of "BART Determination for Milton R . Young Station Units 1 and 2" in Appendix B of Department BART Determination.Table 10-16

Reference 12: Table 3-8 on page 18 of "South Dakota’s Regional Haze State Implementation Plan" and Tables 3.4-2 and 3.4-3 on page 39 of "Appendix C: Otte r Tail Power Company Big Stone Generating Station Unit 1"1

BART Determination 11/18/09 for Stanton Station Unit 1

I. Source Description

A. Owner/Operator: Great River Energy

B. Source Type: Electric Utility Steam Generating Unit

C. BART Eligible Units 1. Unit 1 boiler 2. Auxiliary Boiler 3. Emergency Diesel Generator 4. Emergency Fire Pump Engine 5. Materials Handling Equipment a. Unit 1 coal bunker b. Flyash silo

D. Unit Description

1. Unit 1: Generator Nameplate Capacity: 188 MWe Boiler Rating: 1,800 x 10 6 Btu/hr Startup: 1966 Fuel: North Dakota Lignite, PRB Subbituminous Firing Method: Wall-fired Existing Air Pollution Control Equipment: Low NO x burners and an electrostatic precipitator

2. Auxiliary Boiler: Boiler Rating: 38 x 10 6 Btu/hr Fuel: #2 fuel oil

3. Emergency Diesel Generator Rating: 10.35 x 10 6 Btu/hr Fuel: #2 fuel oil

4. Emergency Fire Pump Engine: Rating: 370 horsepower Fuel: #2 fuel oil

5. Materials Handling Equipment:

a. Unit 1 coal bunker Existing Air Pollution Control Equipment: Baghouse4

Therefore, the Department does not consider coal cl eaning or the K-Fuel process available or technically and economically feasible.

A circulating dry scrubber is not considered commer cially available by Great River Energy. However, the Department is including this as an available technology. Costs for a circulating dry scrubber are estimated based on c ost estimates included in other BART analyses.

The Department considers the Powerspan ECO technolo gy and the Pahlman Process not to be commercially available since no full size plant has been installed or is operating at this time. All other technologies or alternatives are c onsidered technically feasible.

Step 3: Evaluate Control Effectiveness of Each Rema ining Control Technology

The Department has calculated the baseline SO 2 emission rate when burning lignite by utilizing the highest calendar year average SO 2 emission rate of 1.81 lb/million Btu from 2000-2004 and multiplying this value by the highest heat input for any two consecutive years for the 2000-2004 period. This results in a baseline SO 2 emission rate as follows:

Heat input (2001) = 9.965 x 10 12 Btu

Heat input (2002) = 1.075 x 10 13 Btu

Average heat input = (9.965 x 10 12 + 1.075 x 10 13 ) / 2 = 1.036 x 10 13 Btu

Baseline SO 2 emission rate when combusting lignite coal = 1.036 x 10 13 Btu (1.81 lb/million Btu)(1 ton/2000 lb) = 9,376 t ons/year

The control effectiveness of all remaining control technologies are shown in the following table.

Alternative Control

Efficiency (%) Inlet Loading

(tons/yr) Controlled Emissions

(tons/yr) (lb/10 6 Btu)
Wet Scrubber 95 9,376 469 0.091
Circulating Dry Scrubber 93 9,376 656 0.127

SD/FF 90 9,376 938 0.181
Flash Dryer Absorber 90 9,376 938 0.1815

Alternative Control

Efficiency (%) Inlet Loading

(tons/yr) Controlled Emissions

(tons/yr) (lb/10 6 Btu)

Wet Scrubber with 10% bypass 86 9,376 1,313 0.263

DSI/FF 55 9,376 4,219 0.817
DSI/ESP 35 9,376 6,094 1.18

The cost effectiveness and incremental costs for th e various alternatives are as follows:

Alternative Emissions

Reduction (tons/yr) Annualized Cost

($)* Cost Effectiveness

($/ton) Incremental

Cost ($/ton) Wet Scrubber 8,907 13,180,000 1,480 4,179****

Circulating Dry Scrubber 8,720 14,220,000*** 1,631 10,638

SD/FF 8,438 11,220,000 1,330 850**

Wet Scrubber with 10% bypass 8,063 9,490,000 1,177 365

DSI/FF 5,157 8,430,000 1,635 2,789

DSI/ESP 3,282 3,200,000 975 ---

Note: Flash Dryer Absorber not included since it co sts more than a spray dryer with no additional emissions reduction.

* Costs provided by Great River Energy (except as noted). ** The incremental cost shown is the incremental co st of SD/FF compared to DSI/FF. *** The cost is estimated based on other BART analy ses. **** The incremental cost shown is the incremental cost of a wet scrubber compared to SD/FF.

Step 4: Evaluate Impacts and Document Results

Great River Energy has evaluated the energy and non -air quality effects of each option. The Department has determined that these effects wi ll not preclude the selection of any of the control equipment.6

Step 5: Evaluate Visibility Results

The two primary alternatives are a wet scrubber ope rating at 95% removal efficiency and a spray dryer operating at 90% efficiency. The effec ts on visibility for each of these two control options at the Theodore Roosevelt National Park, South Unit (TRNP-SU), Theodore Roosevelt National Park, North Unit (TRNP- NU), Theodore Roosevelt National Park, Elkhorn Ranch (TRNP-Elkhorn Ranch) and the Lo stwood Wilderness Area (Lostwood WA) are shown in the following tables.

Unit 1 - Lignite Coal Combustion Delta Deciview 90 th Percentile SO 2
Year Unit 90% Reduction 95% Reduction Difference

2000 2001 2002 Average TRNP-SU

TRNP-SU TRNP-SU TRNP-SU 0.066 0.061 0.096 0.048

0.043 0.089 0.018

0.018 0.007 0.014

2000 2001 2002 Average TRNP-NU

TRNP-NU TRNP-NU TRNP-NU 0.080 0.089 0.097 0.062

0.061 0.072 0.018

0.028 0.025 0.024

2000 2001 2002 Average TRNP-Elkhorn Ranch

TRNP-Elkhorn Ranch TRNP-Elkhorn Ranch TRNP-Elkhorn Ranch 0.054 0.036 0.074 0.040

0.024 0.050 0.014

0.012 0.024 0.017

2000 2001 2002 Average Lostwood WA

Lostwood WA Lostwood WA Lostwood WA 0.118 0.160 0.088 0.094

0.139 0.078 0.024

0.021 0.01 0.019
Overall Average 0.0197 Unit 1 - Lignite Coal Combustion Delta Deciview 98 th Percentile SO 2
Year Unit 90% Reduction 95% Reduction Difference

2000 2001 2002 Average TRNP-SU

TRNP-SU TRNP-SU TRNP-SU 0.320 0.322 0.668 0.290

0.270 0.556 0.03

0.052 0.112 0.065

2000 2001 2002 Average TRNP-NU

TRNP-NU TRNP-NU TRNP-NU 0.458 0.385 0.595 0.369

0.334 0.516 0.089

0.051 0.079 0.073

2000 2001 2002 Average TRNP-Elkhorn Ranch

TRNP-Elkhorn Ranch TRNP-Elkhorn Ranch TRNP-Elkhorn Ranch 0.224 0.241 0.517 0.183

0.178 0.429 0.041

0.063 0.088 0.064

2000 2001 2002 Average Lostwood WA

Lostwood WA Lostwood WA Lostwood WA 0.340 0.526 0.410 0.320

0.449 0.341 0.02

0.077 0.069 0.055
Overall Average 0.064

Step 6: Select BART

There are no energy or non-air quality environmenta l impacts that would preclude the selection of any of the feasible control options. The incremental cost of greater than $10,600 per ton of sulfur dioxide removed for a cir culating dry scrubber compared to a spray dryer is considered excessive and a circulati ng dry scrubber is removed from further consideration as BART.

The unit has no existing air pollution control equi pment for removing sulfur dioxide and the plant is expected to have a remaining useful li fe of at least 20 years. The degree of visibility improvement achieved by selecting a wet scrubber operating at 95% control efficiency versus a spray dryer operating at 90% co ntrol efficiency does not exceed 0.028 deciviews (90 th percentile) or 0.112 deciviews (98% percentile) at any Class I area for the 2000-2002 time frame. Although the amount of visib ility improvement achieved by selecting a wet scrubber versus a spray dryer is sm all, the Department has placed the primary emphasis on the cost of each option. The i ncremental cost from a spray dryer to a wet scrubber is $4,179 per ton of SO 2 removed. The Department does not consider this8

incremental cost to be excessive. However, wet scr ubbing does have additional environmental impacts when compared to a spray drye r with a fabric filter as outlined below:

- A wet scrubber is estimated by GRE to use as much as 20% more water or approximately 15 million gallons per year of additi onal water. - It is assumed that a wet scrubber system will req uire additional on-site ponding. GRE has identified two potential areas on site that could be used for the additional ponding. The areas include the existing ash pile, which would have to be excavated and moved, or the abandoned ash disposal area adjacent to the river, which reportedly has geotechnical deficiencies. - Dry scrubbers are purported to achieve a higher m ercury control efficiency on lignite and PRB as compared to a wet scrubber. In addition, future mercury control requirements could result in high concentra tions of mercury in the ponds and prove problematic to discharge.

Based upon the additional environmental impacts and the fact that a wet scrubber will remove at best an additional 469 tons/year of SO 2 (with a small corresponding visibility improvement) beyond the control achieved by a spray dryer, the Department proposes BART as a spray dryer with a fabric filter.

The highest calendar year average SO 2 emission rate is approximately 1.81 lb/MM Btu for the 2000-2004 period when combusting lignite at Sta nton Station Unit 1. Utilizing a 90% control efficiency for the spray dryer and fabric f ilter results in an annual average controlled emission rate of approximately 0.181 lb/ MM Btu. Based upon historical SO 2 emissions data for spray dryers and fabric filters at North Dakota facilities, the Department has determined that an increase of 33% is warranted to adjust from an annual average SO 2 emission rate to a 30-day rolling average SO 2 emission rate. Multiplying the annual average emission rate of 0.181 lb/MM Btu by a facto r of 1.33 (an increase of 33%) yields a 30-day rolling average SO 2 emission rate of 0.24 lb/MM Btu. Therefore, BART for SO 2 when combusting lignite coal is an SO 2 emission limit of 0.24 lb/million Btu heat input ( on a 30 day rolling average) or a reduction efficiency of 90% (on a 30 day rolling average) on the inlet SO 2 concentration to the pollution control equipment.

B. Filterable Particulate Matter

Step 1: Identify All Available Technologies

New Baghouse New Electrostatic Precipitator (ESP) New Wet ESP Existing ESP

Step 2: Eliminate Technically Infeasible Options

All technologies are considered technically feasibl e.