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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 

analysis of controls for sulfur dioxide, nitrogen oxides and particulate matter. This analysis 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 which may

reasonably 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 analysis and determination 

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.
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II. BART Analysis Summary

Dynegy submitted a BART analysis for the Danskammer Generating Station dated September 

30, 2010 and revised on November 2, 2010. The following emission source had previously been 

identified as BART-eligible and is therefore included in the analysis:

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 time over the last five years; 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 based on natural gas 

combustion.

A summary of the analysis’ findings for each pollutant are as follows:

 SO2

Dynegy reviewed a number of potential SO2 control options for Unit 4. All of these 

options are considered technically feasible. The control efficiencies and costeffectiveness (based on cost per ton of SO2 reduced) are presented for each option in the 

table below. Dynegy also presented cost-effectiveness data based on the projected 

capacity factor, which can be seen in Table 4-11 of the Dynegy report.

SO2 Control Option Control 

Efficiency (%)

Annualized Cost/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 $1,683
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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 yield 

additional power requirements as well. Dynegy modeled visibility impacts which span 

the range of the SO2 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 dollar-per-dv standpoint. Although they would be effective at reducing SO2

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, Dynegy has committed to lowering the 

current Title V permit SO2 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, installation of post-combustion 

controls, or any combination thereof. This BART compliance method will effectively

lower allowable SO2 emissions by 55 percent, or 6,602 tpy.

 NOx

The existing NOx controls for Danskammer Unit 4 are use of low excess air, combustion 

air manipulation, separated overfire air, burners out of service, and low NOx burners. 

The table below represents potential additional control options identified by Dynegy, 

along with the related control efficiency and cost effectiveness. Dynegy also presented 

cost-effectiveness data based on the projected capacity factor, which can be seen in Table 

4-3A of its report.
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NOx Control 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 NOx 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 various BART factors, Dynegy has committed to lowering of the 

current Title V permit NOx 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. 

Dynegy proposes to meet this new limit through optimization of existing Level II low 

NOx burners, co-firing with natural gas, installation of post-combustion controls, or any 

combination thereof. This BART compliance method will reduce the allowable NOx

emission level by 71 percent, or 3,301 tpy.

 PM

Particulate emissions are currently 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, Dynegy concludes 

that the current equipment should be accepted as BART. Dynegy also notes that the 
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emission reductions of NOx and SO2 (3,301 and 6,602 tons per year reductions in 

allowable emissions, respectively) will serve to reduce the secondary condensable 

particulates 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:

 SO2

The Department accepts Dynegy’s commitment to adopt a 0.5 lb/mmBtu SO2 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 

Dynegy to evaluate and implement potential options.

 NOx

The Department accepts Dynegy’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 impacts. A six-month extension past the BART compliance date 

(to July 1, 2014) is being granted to allow sufficient time for Dynegy 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.