Preliminary BART Comments on Omaha Public Power District (OPPD)

Nebraska City Station Unit #1

This facility contains one operating 650 MW coal-fired (Powder River Basin coal) boiler 

with a second 660 MW coal-fired boiler currently under construction. It appears that

facility, as now permitted, is considered a 750 MW or greater power plant and is required 

to meet the presumptive emission limits for emission units found in the BART 

Guidelines1. The status of the plant capacity should be resolved by communication 

between the State and U.S. EPA. 

OPPD proposes to meet the NOx presumptive emission limit of 0.23 lb/MMBtu by 

installing retrofitted Low Nitrogen Oxide (Low- NOx) combustion control technology “as 

necessary” to complement the existing overfire air system at an estimated cost of 

$166/ton (see Table 5) and $5.4 million/deciview (see Table 9). OPPD proposes no 

additional NOx, or SO2 or PM BART controls. Respectively, the reasons for no 

additional controls were excessive cost per deciview for SCR for NOx, excessive cost per 

deciview for spray dryer absorber (SDA) scrubber for SO2 and “negligible impact” for 

particulate matter.

In section 2.1.3, OPPD states an argument that the cost of materials is rising so rapidly 

that cost estimates may be too low. It seems that they attempted to reflect this in 

Appendix A where project costs are outlined, by adding an arbitrary “contingency” cost 

of 25% to the calculated costs. This adjustment was not explained or justified and 

seemed to unreasonably expand estimated costs. For example, the OPPD cost estimate 

for an SDA scrubber and filter baghouse is $1,759/ton, but without the 25% contingency 

the cost may be closer to $1,319/ton. Either cost falls within a reasonable BART range. 

Page 7 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. In an effort to make 

OPPD’s results for a SDA scrubber comparable to the universe of other companies’ 

BART determinations it would be instructive to recalculate the numbers based strictly on 

use of the OAQPS Control Cost Manual. 

Section 2.2.1 correctly states that all of the flue gas desulfurization technologies can 

achieve SO2 removal efficiencies of 90 to 95%. However, in costing the selected SO2

control technology, an SDA scrubber, a removal efficiency of only 81.6% was used (see 

Table 2). The discrepancy should be explained or a more realistic removal efficiency

should be used. In addition, several regenerative FGD processes are identified in Section 

2.2.1, but none were subjected to BART steps 2 (technical feasibility) or 3 (evaluating 

control effectiveness). Each of these control technologies must be evaluated.

Section 2.5 evaluates visibility impacts by incrementally adding emission controls to 

arrive at an additive deciview impact as each pollutant is added. However, the visibility

improvement of each pollutant control should be evaluated individually so that the cost 
of visibility improvement (e.g., cost per deciview improvement) from a given control 

technology can be compared to the universe of similar controls in all other BART 

analyses (as OPPD did in Table 10) in an effort to judge reasonableness. OPPD should 

evaluate the visibility improvement efficiency of SDA for SO2 and SCR for NOx

separately. 

Section 3.1 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 Guidelines2that, “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.” However, it is 

recognized that a minimal deciview change can lead to objective documentation of 

excessive cost per deciview of visibility improvement which is a legitimate argument. 

Taking into account the results obtained (particularly for a SDA scrubber for SO2 control) 

by reflecting the above procedural changes in the OPPD BART determination may result 

in a reasonable cost per deciview improvement in addition to the already-acceptable cost 

per ton for SO2 control. 

Particulate matter controls were dismissed on the basis of “negligible impact” of PM. 

However, relatively inexpensive improvements/upgrades on the existing electrostatic 

precipitator should have been considered and only dismissed upon a showing of 

excessive cost.

1

See 40 CFR Part 51, Appendix Y. The U.S. Environmental Protection Agency finalized it’s 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 Section IV.E.5.

2

Ibid, see Preamble, 70FR30129, middle column.