1 **New York State Department of Environmental Conservation Best Available Retrofit Technology Determination**  Facility Danskammer Generating Station Location Newburgh, NY

Orange County Permit ID 3 - 3346 - 00011 Source Category Fossil - fuel fired steam electric plants of

more than 250 mmBtu/hr heat input **I. Introduction** The above referenced facility contains at least one emission source that falls under the requirements of the federal Best Available Retrofit Technology ( BART ) rule under 40 CFR Part 51 and Appendix Y, and the New York State BART regulation as codified under 6 NYCRR Part 249. These requirements affect an emission source which fulfills the following criteria: 1. Falls within one of 26 specific source categories, 2. Was not in operation prior to August 7, 1962 and was in existence on August 7, 1977, or underwent reconstruction between August 7, 1962 and August 7, 1977, and 3. Has a potential to emit (collectively , with other emission sources at the facility which fulfill items 1 and 2) of 250 tons per year or more of any visibility- impairing pollutant. In accordance with BART requirements, each BART - eligible facility must perform a BART anal ys is of controls for sulfur dioxide, nitrogen oxides and particulate matter. This anal ys is takes into account such factors as the cost of controls, 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 wh ich may reasonabl y be anticipated to result from the use of such technology. This document reflects the Department’s determination of what level of controls constitutes BART for this facility ’s BART - eligible emission source ( s ) . Each anal ys is and determin ation was submitted to the Federal Land Managers (FLMs) for their review in accordance with Regional Haze State Implementation Plan (SIP) requirements. Comments received from the FLMs on each determination will be included with its submission. The Department is now working to expeditiously modify this facility’s Title V permit to include the enforceable BART limits. Specific parameters and limits that are used as the technical bases of BART determinations, such as sulfur limits, the installation of controls, and operational limitations, will be incorporated into each facility's permit in enforceable conditions. These permit modifications will be submitted to the U.S. Environmental Protection Agency (EPA) as SIP revisions once complete.2

**II. BART**  **Analysis Summary** Dy negy submitted a BART analy sis for the Danskammer Generating Station dated September 30, 2010 and revised on November 2, 2010 . The following emission source had previousl y been identified as BART - eligible and is therefore included in the anal ys is: **Boiler No. 4**

– Emission Unit U - D0004 ; Emission Source SD004  Danskammer Unit 4 is a 235 megawatt Combustion Engineering tangentially coal - fired steam generating boiler. The unit began commercial operation in 1967 (pressurized coal firing), but was converted to residual oil firing and gas firing in 1970. The unit operated on oil until a reconversion to coal in 1987. The unit retains the capability to burn all three fuels , although oil has not been combusted at any t ime over the last five ye ars; coal is the primary fuel . The heat input rating is 2,512 mmBtu/hr based on combustion of coal, 2,004 mmBtu/hr when combusting No. 6 oil, and 2,397 mmBtu/hr ba sed on natural gas combustion. A summary

of the analysis’ findings for each pollutant are as fol lows:

 SO 2 Dy negy reviewed a number of potential SO 2 control options for Unit 4. All of these options are considered technicall y feasible. The control efficiencies and cost effectiveness (based on cost per ton of SO 2 reduced) are presented for each option in the table below. Dy

negy also presented cost - effectiveness data based on the projected capacity factor, which can be seen in Table 4 - 11 of the Dy negy report. **SO2 Control Option Control**  **Efficiency (%) Annualized C**  **ost/Ton**

**(Based on PTE)** Lime - Based Spray Dryer FGD w/ Baghouse 91.50 $1,840 Circulating Dry Scrubber FGD w/ Baghouse 93.00 $2,629 Wet Limestone FGD 94.30 $1,959 Dry Sorbent Injection Unmilled Trona 30.00 $850 Dry Sorbent Injection Milled Trona 40.00 $503 Gas Cofiring (35%) 34.98 $2,049 Gas Cofiring (60%) 59.97 $2,072 Gas Firing (100%) 99.95 $2,110 Alternative Coal - PRB Triton 41.64 $2,614 Alternative Coal - Indonesian 76.14 $5,002 Alternative Coal - Chinese 52.57 $1,237 0.9 lb/mmBtu limit for Coal Combustion 18.18 $0 0.5 lb/mmBtu emission limit 54.55 $1,6833

Although the FGD options are cost - effective and have high control efficiencies , there are many non - air quality environmental concerns (Table 4 - 13), and these units would yi eld additional power requirements as well. Dy negy modeled visibility

impacts which span the range of the SO 2 emission reductions resulting from these control options, and presented these results as Table 4 - 14. These results show FGD as being cost -prohibitive from a dol lar-per- dv standpoint. Although they would be effective at reducing SO 2 emissions, high levels of gas firing/cofiring were ruled out due to the extreme price volatility and potential reliability

impacts on the electrical grid. Indonesian coal was ruled out due to its lower heating content, which would require more coal to be shipped and result in more waste products. The next most effective option is the 0.5 lb/mmBtu emission limit. Based on consideration of the various BART factors, Dy negy has committ ed to lowering the current Title V permit SO 2 emission limit from 1.10 lb/mmBtu to 0.50 lb/mmBtu ( on a 24 - hour average basis) effective July 1, 2014 . Dynegy

will meet this new limit through the use of alternate coal, co - firing with natural gas, installati on of post - combustion controls, or any combination thereof. This BART compliance method will effective ly lower allowable SO 2 emissions by 55 percent, or 6,602 tpy .  NO x The existing NO x controls for Danskammer Unit 4 are use of low excess air, combustion air manipulation, separated overfire air, burners out of service, and low NO x burners. The table below represents potential additional control options identified by Dy negy , along with the related control efficiency and cost effectiveness. Dy negy also presented cost - effectiveness data based on the projected capacity factor, which can be seen in Table 4 - 3A of its report.4 **NOx C ontrol Option**  **Control Efficiency (%)**  **Annualized Cost/Ton**

**(Based on PTE)** SCR 83 $3,151 SNCR 35 $41,345 Hybrid SCR/SNCR 60 $3,353 SNCR Trim 27 $44,891 Alternative Coal - PRB Triton 40 $7,126 Alternative Coal - Indonesian 21 $47,753 Alternative Coal - Chinese 38 $4,509 Gas Cofiring (35%) 14 $13,647 Gas Cofiring (60%) 24 $13,647 Gas Firing (100%) 40 $13,647 Gas Firing (100%) - 0.12 lb/mmBtu 71 $ 6,088 Gas Firing (100%) - 0.08 lb/mmBtu 81 $6,824 Gas Reburn 50 $9,815 FGR 8 $943 FGR + SNCR 36 $1,707 FGR + SCR 91 $2,012 FGR + Hybrid SNCR/SCR 63 $3,105 0.3 lb/mmBtu limit for Coal Comb. 29 $0 0.12 lb/mmBtu emission limit 71 $6,088 Although control options involving SCR create large NO x emission reductions at reasonable cost, SCR must be ruled out from a technical feasibility standpoint due to the ammonia handling issues and other non - air quality environmental impacts. As discussed previously , high levels of gas firing must be ruled out due to high price volatility and electrical system reliability concerns. The next most effective option is the adoption of a 0.12 lb/mmBtu limit. Based on consideration of the vario us BART factors, Dy negy has committed to lowering of the current Title V permit NO x emission limit from 0.42 lb/mmBtu to 0.12 lb/mmBtu (24 - hour average during the ozone season, 30 - day average otherwise) effective July 1, 2014. Dy negy proposes to meet this new limit through optimization of existing Level II low NO x burners, co - firing with natural gas, installation of post - combustion controls, or any combination thereof. This BART compliance method will reduce the allowable NO x emission level by

71 percent, or 3,301 tpy .  PM Particulate emissions are currentl y controlled through a cold side electrostatic precipitator (ESP) . Based on Danskammer’s 2009 annual emission statement, the average control efficiency is 99.98 percent. Due to this very high control efficiency , Dy negy concludes that the current equipment should be accept ed as BART. Dy negy also notes that the5

emission reductions of NO x and SO 2 ( 3,301 and 6,602 tons per year reductions in allowable emissions, respectivel y) will serve to reduce the secondary condensable particulate s emitted from this unit and the resulting visibility impact on Class 1 areas. **III. BART Determination**  The Department finds that the following shall constitute BART for the Danskammer Generating Station Boiler No. 4 :  SO 2 The Department accepts Dy negy ’s commitment to adopt a 0.5 lb/mmBtu SO 2 emission limit , from the existing 1.1 lb/mmBtu permit limit, for compliance with BART. More effective options were ruled out due to technical infeasibility , additional non - air quality environmental impacts and high dollar-per- deciview values. A six - month extension past the BART compliance date (to July 1, 2014) is being granted to allow sufficient time for Dy negy to evaluate and implement potential options .  NO x The Department accepts Dy negy ’s commitment to adopt a 0.12 lb/mmBtu NOx emission limit , from the existing 0.42 lb/mmBtu permit limit, for compliance with BART. More effective options were ruled out due to technical infeasibility and additional non - air quality environmental imp acts. A six - month extension past the BART compliance date (to July 1, 2014) is being granted to allow sufficient time for Dy negy to evaluate and implement potential options.

 PM The Department accepts the current use of an ESP with a control efficiency in excess of 99 percent as BART for PM.