### Preliminary **BART Comments on Omaha Public Power District (OPPD) Nebraska City Station Unit #1** 

This facility

c ontains 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 Guidelines 1

. The status of the plant capacity should be resolved by

c ommunication between the State and U.S. EPA.
OPPD proposes to meet the NO x presumptive emission limit of 0.23 lb/MMBtu by installing retrofitted Low Nitrogen Oxide (Low

- NO x) 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 SO 2 or PM BART controls. Respectively, the reasons for no additional controls were excessive cost per deciview for SCR f or NO x , excessive cost per deciview for spray

dryer absorber (SDA) scrubber for SO 2 and “negligible impact” for particulate matter.

In section 2.1.3 , OPP D states an argument that the cost of materials is rising so rapidl y 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 OPP D 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 co st estimates were developed following guidance provided in the January 2 002 OAQPS Control Cost Manual, using “limited vendor data obtained from various vendors in 2003” and then “scaled

-up” to the present. Inan effort to make OPP D ’s results for a SDA scr ubber 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 desulfurizati on technologies can achieve SO 2 removal efficiencies of 90 to 95%. H owever, in costing the selected SO 2 control technology, an SDA scrubber, a removal efficiency o f onl y 81.6% was used (see Table 2)

. The discrepancy should be explained or a more realisti c removal efficiency should be used. In addition, s everal 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 s o that the costof visibility improvement (e.g., cost per deciview improvement) from a given control technology

c an be compared to the universe of similar controls in all other BART anal ys es (as OPPD did in Table 10) in an effort to judge reasonableness. O PPD should evaluate the visibility

i mprovement efficiency o f SDA for SO 2 and SCR for NO x 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 Guidelines 2 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 Iareas. 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 de ciview 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 SO 2 control) by reflecting the above procedural changes in the OPP D BART determination may result in a reasonable cost per deciview improvement in addition to the already- acceptable cost per ton for SO 2 control.
Particulate matter controls were dismissed on the basis of “negligible impact” of PM. However, relativel y 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 Protectio n 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. T he rulemaking action added Appendix Y to Part 51, titled “Guidelines for BART Determinations Under the Regi onal Haze Rule.” See Section IV.E.5.

2 Ibid, see Preamble, 70FR30129, middle column.