Sensitivity Run Specifications for CENRAP Consultation

Direction from the POG in March was to refine the cost basis of the control run 

specifications and to evaluate the differences between areas controlled under the Class I 

area Areas of Influence (AOI). The initial direction on the cost refinement was to look at 

the basis for the CAIR control cost assumptions and use those numbers for a lower 

bound. The general cost assumptions for BACT within the region were to serve as the 

upper bound. However, BACT costs can vary by pollutant and industry. Therefore a 

variation on the proposed methodology was employed. 

CAIR documentation refers to a $1,500 cost per ton level in the generation of CAIR 

control assumptions for SO2. The same information was not as readily apparent for NOx 

and therefore the $1,500 cost per ton assumption was used as a lower bound for both 

pollutants. 

A concern was expressed in the March meeting that limiting our strategies to the level 1 

AOIs for each Class I area would drop substantial portions of the CENRAP region from 

consideration. While these areas were not found to be the primary contributors to 

visibility impairment at the Class I areas in the original Alpine study they do nonetheless 

contribute. The following graphics illustrate the coverage area for the level 1 AOIs for 

sulfate and nitrate. 
Given the coverage area gaps in the level 1 AOIs the cost refinement evaluation was 

performed over the entire CENRAP region without respect to AOIs. 

The following bar chart was generated with the latest version of the Environ PSAT tool. 

The chart was generated for EGU and Non-EGU nitrate apportionment from CENRAP 

states. Note that, while outside the level 1 AOI, Northeast Texas is modeled to be a 

significant contributor, relative to the other States, to the worst 20% visibility days in the 

Caney Creek Class I area. The same can be found, though to a lesser degree about 

Kansas and Nebraska sulfate impacts on neighboring Class I areas, though both States 

fall outside the bounds of level 1 AOIs for Missouri, Arkansas, and Minnesota.

As the control run is intended to assist with the consultation process and provide more 

information on the effectiveness of reasonably achievable levels of controls, limiting 

controls to only the areas covered by level 1 AOIs may not provide the intended

information. 
Queries of the Alpine Geophysics control data set were generated to provide control 

assumptions for all sources that fell within a range of Q/5D of any CENRAP Class I area. 

The queries were generated for a range of maximum dollars per ton, starting at $1,500 up 

through $10,000 per ton. The following graphs illustrate the cost effectiveness curves for 

both pollutants.

The SO2 curve indicates that given the constraints on the data set, the effectiveness of 

increasing control cost begins to diminish after a maximum of approximately fourthousand dollars per ton. The NOx curve indicates that again, given the constraints on the 

data set, effectiveness of increasing control costs begins to diminish beyond the range of 

three to four thousand dollars per ton.
SO2 Cost/Ton

58,244

161,230

412,575

576,535

657,191

765,313

826,594

857,090

0

2,000

4,000

6,000

8,000

10,000

12,000

0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 800,000 900,000

Tons Reduced

Cost/Ton

NOx Cost/Ton

84,287

118,104

146,368

162,738

174,999

181,107

205,820

207,248

0

2,000

4,000

6,000

8,000

10,000

12,000

0 50,000 100,000 150,000 200,000 250,000

Tons Reduced

Cost/Ton
The State summary tables below assume a maximum cost of four thousand dollars per ton

with and without level one AOIs for those sources that fall within 5D of any CENRAP 

Class I area. 

Q/5D

NOx ($4,000/Ton with no restriction on AOI)

State Tons Tons Reduced Total Cost (2005 $) Average Cost/Ton

Arkansas Total 29,840 10,939 $16,063,479 1,468

Iowa Total 15,229 9,638 $21,152,980 2,195

Kansas Total 45,492 17,694 $28,654,098 1,619

Louisiana Total 37,285 30,617 $61,113,051 1,996

Minnesota Total 22,258 8,192 $17,530,083 2,140

Missouri Total 41,489 20,312 $29,217,934 1,438

Nebraska Total 27,751 13,159 $11,014,418 837

Oklahoma Total 49,127 24,423 $47,342,251 1,938

Texas Total 110,421 40,025 $72,892,326 1,821

Grand Total 378,892 174,999 $304,980,620 1,743

NOx ($4,000/Ton with AOI =1)

State Tons Tons Reduced Total Cost (2005 $) Average Cost/Ton

Arkansas Total 29,840 10,939 $16,063,479 1,468

Iowa Total 15,229 9,638 $21,152,980 2,195

Kansas Total 45,492 17,694 $28,654,098 1,619

Louisiana Total 37,285 30,617 $61,113,051 1,996

Minnesota Total 22,258 8,192 $17,530,083 2,140

Missouri Total 30,663 13,492 $13,835,584 1,025

Nebraska Total 21,414 10,811 $7,760,719 718

Oklahoma Total 44,140 20,825 $39,511,338 1,897

Texas Total 43,545 16,725 $29,774,281 1,780

Grand Total 289,867 138,934 $235,395,613 1,694

SO2 ($4,000/Ton with no restriction on AOI)

State Tons

Tons 

Reduced

Annualized Cost 

($2005)

AVERAGE 

COST/TON

Arkansas Total 64,543 58,088 $141,702,592 2,439

Iowa Total 123,996 111,596 $297,860,477 2,669

Kansas Total 19,078 17,170 $50,742,099 2,955

Louisiana Total 66,364 59,165 $106,975,459 1,808

Minnesota Total 8,950 8,033 $24,035,119 2,992

Missouri Total 181,493 161,624 $385,099,041 2,383

Nebraska Total 16,229 14,606 $10,605,556 726

Oklahoma Total 46,638 36,542 $93,684,930 2,564

Texas Total 212,005 190,366 $418,329,434 2,197

Grand Total 739,295 657,191 $1,529,034,707 2,327
SO2 ($4,000/Ton with AOI =1)

State Tons

Tons 

Reduced

Annualized Cost 

($2005)

AVERAGE 

COST/TON

Arkansas Total 64,543 58,088 $141,702,592 2,439

Iowa Total 118,082 106,273 $279,767,078 2,633

Louisiana Total 66,364 59,165 $106,975,459 1,808

Minnesota Total 8,012 7,189 $21,791,726 3,031

Missouri Total 143,241 127,464 $309,199,655 2,426

Nebraska Total 16,032 14,429 $10,134,192 702

Oklahoma Total 46,638 36,542 $93,684,930 2,564

Texas Total 165,379 148,403 $282,820,262 1,906

Grand Total 628,290 557,552 $1,246,075,894 2,235

The following State summary tables again assume a maximum cost of four thousand 

dollars per ton with and without level one AOIs for those sources that fall within 20D of 

any CENRAP Class I area. 

Q/20D

NOx ($4,000/Ton with no restriction on AOI)

State Tons Tons Reduced Total Cost

Average 

Cost/Ton

Arkansas Total 25,432 7,757 $8,815,243 1,136

Kansas Total 6,647 5,318 $12,271,745 2,308

Louisiana Total 4,687 4,140 $3,064,019 740

Minnesota Total 4,858 806 $1,413,275 1,753

Missouri Total 16,152 7,533 $10,571,431 1,403

Oklahoma Total 24,658 11,872 $18,375,364 1,548

Texas Total 33,200 11,390 $19,121,087 1,679

Grand Total 115,635 48,815 $73,632,164 1,508

NOx ($4,000/Ton with AOI= 1)

State Tons Tons Reduced Total Cost Average Cost/Ton

Arkansas Total 25,432 7,757 $8,815,243 1,136

Kansas Total 6,647 5,318 $12,271,745 2,308

Louisiana Total 4,687 4,140 $3,064,019 740

Minnesota Total 4,858 806 $1,413,275 1,753

Missouri Total 12,655 5,653 $6,286,970 1,112

Oklahoma Total 20,975 8,926 $11,624,171 1,302

Texas Total 28,648 10,634 $17,628,563 1,658

Grand Total 103,902 43,234 $61,103,986 1,413
SO2 ($4,000/Ton without respect to AOI)

Max Cost/Ton $4,000 Tons Tons Reduced Total Cost Average Cost/Ton

Arkansas Total 64,543 58,088 $141,702,592 2,439

Iowa Total 61,393 55,254 $149,243,419 2,701

Kansas Total 8,999 8,099 $18,131,435 2,239

Louisiana Total 60,290 53,844 $100,467,964 1,866

Missouri Total 168,658 151,792 $359,647,907 2,369

Nebraska Total 16,032 14,429 $10,134,192 702

Oklahoma Total 38,102 28,860 $82,593,436 2,862

Texas Total 183,658 165,292 $385,002,887 2,329

Grand Total 601,675 535,658 $1,246,923,832 2,328

SO2 ($4,000/Ton with AOI=1)

State Tons Tons Reduced Total Cost Average Cost/Ton

Arkansas Total 64,543 58,088 $141,702,592 2,439

Iowa Total 61,393 55,254 $149,243,419 2,701

Louisiana Total 60,290 53,844 $100,467,964 1,866

Missouri Total 133,596 120,237 $290,804,516 2,419

Nebraska Total 16,032 14,429 $10,134,192 702

Oklahoma Total 38,102 28,860 $82,593,436 2,862

Texas Total 138,992 125,093 $254,181,389 2,032

Grand Total 512,948 455,804 $1,029,127,508 2,258

Separate spread sheets for NOx and SO2 detail the control assumptions for each dollar 

level. Both the Q/5D and the Q/20D method focus on only the largest emitters. 

However, for SO2, Q/20D limits controls to primarily EGUs.

In summary, using the $4,000/ton threshold provides maximum reductions without 

sacrificing cost effectiveness. The Q/5D threshold spreads the burden of control across 

more contributing industries and provides more information for possible controls for the 

consultation process.