BART Comments on Omaha Public Power District 

Nebraska City Station Unit #NC1

January 14, 2011

Omaha Public Power District’s (OPPD) Nebraska City Station contains one operating 650 MW 

coal-fired (Powder River Basin coal) boiler (NC1), with a second 660 MW coal-fired boiler 

currently permitted and under construction (NC2). Since NC2 has been permitted it is 

considered part of the electric generation capacity of Nebraska City Station and as such the two 

permitted emission units within Nebraska City Station generate more than 750 MW of 

electricity. Electric Generating Units within a 750 MW power plant which are greater than 

200 MW in size are subject to specific, presumptive control requirements for SO2 and NOx

emissions under the Environmental Protection Agency (EPA) Best Available Retrofit 

Technology (BART) Guidelines.1 Of course, the only unit within the facility that is subject to 

the presumptive requirements of BART is NC1. 

Even setting aside the presumptive requirements discussion for a moment, the SO2 control 

alternative of Spray Dryer Absorber (SDA) with fabric filter was assumed to meet a control level 

of 0. 10 lb./MMBtu, which is more stringent than the presumptive 0.15 lb./MMBtu control level. 

The $1,636 per ton of SO2 controlled using the SDA system is very reasonable. Many examples 

of proposed SO2 control for BART can be cited that far exceed $1,636 per ton. Some examples 

are Boardman, OR - $3,053/ton; Brayton Point, MA - $3,043/ton; Bridger, WY $2,551/ton; 

Canal Station, MA - $3,170/ton; Martin Drake, CO - $2,765; Johnston, WY - $4,743; Kincaid, 

IL - $4,274; Mystic Station, MA - $4,270; Silver Bay Power, MN - $7,309; Salem Harbor, MA -

$3,043; Stanton, ND - $2,006 and Taconite Harbor, MN - $5,300. The EPA BART Guidelines 

state, “A reasonable range would be a range that is consistent with the range of cost effectiveness 

values used in other similar permit decisions over a period of time.”2 In summary, $1,636 per 

ton for SDA with a fabric filter is reasonable and should be considered as BART for the NC1 

unit.

The $78.9 million cost per deciview of visibility improvement at Hercules Glades for 

installation of SDA with a fabric filter was considered by the Nebraska Department of 

Environmental Quality (NDEQ) to trump the reasonable cost per ton as a reason to reject this 

SO2 control alternative. Chapter 8 of the Regulatory Impact Analysis (RIA) the EPA prepared 

for the Regional Haze rule stated that high cost control measures that have only minimal effect 

on visibility improvement can be avoided. The functional words are “high cost control 

measures”. SDA with fabric filter was shown above to not be a high cost control measure. 

Correspondingly, this control alternative should not be dismissed solely on the basis of a higher 

cost of visibility improvement at only one Class I area. 

Further, the Clean Air Act, Section 169A(g)(2) states:

 

1

See 40 CFR Part 51, Appendix Y, Section IV.E.4 and 5.

2

Ibid., See Section IV,D.Step 4,f.
“. . . in determining best available retrofit technology the State (or the 

Administrator in determining emission limitations which reflect such technology) 

shall take into consideration the costs of compliance, the energy and non-air 

quality environmental impacts of compliance, any existing pollution control 

technology in use at the source, the remaining useful life of the source, and the 

degree of improvement in visibility which may reasonably be anticipated to result 

from the use of such technology.” 

This wording indicates that the various considerations listed are to be used for help in 

determining a “best” available retrofit technology from among the various alternatives being 

considered. It does not state that a questionable outcome for any particular consideration may 

result in the outright dismissal of all choices for selection of a control technology. 

There is a single conceptual idea presented in the EPA BART Guidelines from Section 

IV.D.Step 4, “Evaluate Impacts and Document the Results” to Section IV.D.Step 4.i, 

“How do I analyze non-air quality environmental impacts?” to Section IV.D.Step 5, 

“Evaluate Visibility Impacts” to Section IV.E, “How do I select the “best” alternative 

using the results of Steps 1 through 5?” The single concept is that these sections present 

methods for deciding which alternative control is the “best” alternative from among the 

technically feasible and cost feasible alternatives. These sections do not provide a means 

to entirely delete all alternatives from consideration.

This position then addresses the NDEQ concern that both SO2 control alternatives, the 

wet scrubber and SDA will require obtaining water rights that may be detrimental to 

stream flows in Nebraska. The EPA BART Guidelines state, “. . . where you or the 

source owner can show that unusual circumstances at the proposed facility create greater 

problems than experienced elsewhere, this may provide a basis for the elimination of that 

control alternative as BART.”3 First, this provides a good basis for selecting SDA over 

the wet scrubber. Second, SDA should be the selected alternative for BART, because 

NDEQ likely cannot show that water availability in Nebraska is more acute than in many 

other Western states which have installed SDA or other SO2 controls that require 

additional water. 

OPPD made judgments on cost per deciview based upon only the most impacted Class I area, 

Hercules Glades. We continue to believe that it is appropriate to consider both the degree of 

visibility improvement in a given Class I area as well as the cumulative effects of improving 

visibility across all of the Class I areas affected. It simply does not make sense to use the same 

metric to evaluate the effects of reducing emissions from a BART source that impacts only one 

Class I area as for a BART source that impacts multiple Class I areas. And, it does not make 

sense to evaluate impacts at one Class I area, while ignoring others that are similarly 

significantly impaired. If emissions from Nebraska City Station are reduced, the benefits will be 

spread well beyond only the most impacted Class I area, and this must be accounted for. 

NDEQ proposes to require that OPPD meet the NOx presumptive emission limit of 

 

3

Ibid., See Section IV,D.Step 4,i.2.
0.23 lb/MMBtu by installing retrofitted Low NOx Burners (LNB) combustion control technology 

to complement the existing over-fire air system (OFA) at an estimated cost of $136 per ton and 

$4.6 million/deciview of visibility improvement. OPPD proposes no additional NOx, SO2 or 

particulate matter (PM) BART controls. OPPD cited the reasons for no additional controls were 

excessive cost per deciview for Selective Catalytic Reduction (SCR) for NOx control, excessive 

cost per deciview for a spray dryer absorber (SDA) for SO2 control and “negligible impact” on 

visibility for PM control alternatives.

The addition of SCR to the proposed LNB/OFA results in $2,706 cost per ton of NOx control. 

This is considered as a reasonable cost. Some other examples of proposed BART using SCR 

include Boswell Energy Center, MN - $3,201/ton; Healy, AK - $3,374; Jim Bridger, WY -

$2,298; and Boardman, OR - $3,096. This alternative was discarded on the basis of excessive 

cost per deciview ($82.4 million/dv at Hercules Glades). The same arguments that were 

discussed above for SDA apply to installation of LNB/OFA/SCR as BART.

Page 7 of the 2007 OPPD BART Analysis document indicates that cost estimates were 

developed following guidance provided in the January 2002 OAQPS Control Cost Manual, using 

“limited vendor data obtained from various vendors in 2003” and then “scaled-up” to the present. 

Since it has been almost eight years since the 2003 vendor cost estimates were made, OPPD 

should obtain current cost estimates for all alternatives rather than simply scaling old 2003 

information to the present. Current vendor cost estimates may be quite different and the errors of 

scaling could be large. In an effort to make OPPD’s results for all control alternatives

comparable to the universe of other companies’ BART determinations, cost calculations based 

on use of the most recent OAQPS Control Cost Manual should be performed.

4

Regarding PM control through continued use of the existing electrostatic precipitator (ESP), it 

should be noted that the EPA BART Guidelines provide that upgrades/improved operation 

should be considered as a BART alternative. The addition of collection fields should be 

considered as an upgrade as indicated in the EPA BART Guidelines.5

Section 3.1 of the 2007 OPPD BART Analysis document attempts to make a case that certain 

visibility improvements are “well below the minimum perceptible dV change”. It is incorrect to 

dismiss a control strategy on the basis that the resulting improvement is not perceptible or 

significant. EPA states in the preamble to its BART Guidelines that, “Even though the visibility

improvement from an individual source may not be perceptible, it should still be considered in 

setting BART because the contribution to haze may be significant relative to other source 

contributions in the Class I areas. Thus, we disagree that the degree of impairment should be 

contingent upon perceptibility. Failing to consider less-than-perceptible contributions to visibility 

impairment would ignore the CAA’s intent to have BART requirements apply to sources that 

contribute to, as well as cause, such impairment.”6

 

4

Ibid., See Section IV.D.Step 4.a.5. 

5

Ibid., See Section IV.D.Step 3.4.

6

See 40 CFR Part 51, Appendix Y. The U.S. Environmental Protection Agency finalized its BART Guidelines on 

June 15, 2005, and published the preamble and final rule text in the Federal Register on 

July 6, 2005. The rulemaking action added Appendix Y to Part 51, titled “Guidelines for BART Determinations 

Under the Regional Haze Rule.” See Preamble, 70FR30129, middle column.