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New York State Department of Environmental Conservation 

Best Available Retrofit Technology Determination 

Facility Ravenswood Generating Station 

Location Queens, NY 

Queens County 

Permit ID 2-6304-00024 

Source Category Fossil-fuel fired steam electric plant 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 performed a BART 

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

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 summarizes the reasoning behind the Department’s BART determination, 

including the level of controls and emission limits that constitute BART for this facility’s eligible 

emission source(s). Each analysis and BART 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 this determination will be included 

with its official submission to the U.S. Environmental Protection Agency (EPA). 

The Department has modified this facility’s Title V permit to include the enforceable BART 

limits. The modifications were noticed in New York State’s Environmental Notice Bulletin on 

December 28, 2011. Upon completion of this public notice period, the modified permit was 

submitted to EPA for review on February 14, 2012. The final modified permit was issued on 

April 6, 2012. This permit is now being submitted to EPA as a revision to the New York 

Regional Haze SIP. 

 
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II. BART Analysis Summary 

TransCanada (TC) submitted a BART compliance plan for the Ravenswood Generating Station 

dated September, 2010. Ongoing discussions between the Department and TC resulted in a 

BART determination for NOx that differed from that of the initial plan; this alternative 

determination is described below. 

The following emission sources had previously been identified as BART-eligible and were 

therefore included in the analysis: 

Boiler No. 10 – Emission Unit U-00010; Emission Source ES10H/ES10R 

Boiler No. 20 – Emission Unit U-00020; Emission Source ES20H/ES20R 

Boiler No. 30 – Emission Unit U-00030; Emission Source ES30H/ES30R 

• Each of these units is a Combustion Engineering tangentially-fired boiler. Units 10, 20 

and 30 have the ability to fire natural gas or No. 6 fuel oil. Natural gas is primarily used, 

with occasional use of residual fuel due to reliability requirements. These units have 

maximum heat input rates of 4,204 mmBtu/hr, 4,171 mmBtu/hr, and 9,379 mmBtu/hr, 

respectively. Units 10 and 20 commenced commercial operation in 1963 while Unit 30 

began in 1965. All three units are equipped with close coupled overfire air (CCOFA) 

systems and low NOx burners (LNB) for NOx control, while SO2 emissions are limited by 

the use of low-sulfur fuel (0.3 percent by weight). 

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

• SO2

Due to the low-sulfur fuel oil standards contained in 6 NYCRR Part 225-1, the 

Ravenswood Generating Station has a permit condition which limits the maximum sulfur 

content of the fuel oil to 0.3 percent by weight for Units 10, 20 and 30. TC notes that this 

low-sulfur fuel is below the 1.0 percent sulfur limit in oil referenced by the Appendix Y 

guidance. TC therefore requests that the current use of low-sulfur fuel oil be considered 

BART for SO2. 

• NOx

TC initially developed a NOx compliance plan for BART based on a 100% oil-firing 

scenario. TC identified the combination of upgraded LNB with separated overfire air 

(SOFA) as cost-effective on a cost-per-ton basis. (Other options were ruled out by TC 

based on overall or incremental cost effectiveness.) Under this 100% oil-firing scenario, 

emissions were projected to drop from a baseline of 0.24 lb/mmBtu to 0.17 lb/mmBtu, a 

29% reduction. Modeling provided by TC demonstrated that the maximum visibility 

improvement at a Class I area would be 0.12 deciviews at over $21.6M/deciview. TC 

cited the modest visibility improvements and high cost-per-deciview in ruling out 

LNB/SOFA for BART purposes, but committed to installing them solely to comply with 

the Department’s upcoming NOx RACT requirements. 
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In actuality, these units are predominantly natural gas-fired. Recent data from the Clean 

Air Markets Division (CAMD) reveal that operations during 2009 and 2010 typically 

resulted in 30-day NOx emission rates of around 0.07 lb/mmBtu. Emission rates were 

occasionally higher during the winter months due to the oil-firing requirements that are 

necessary to maintain electric system reliability in New York City. The emission 

reductions and visibility improvements cited in TC’s September, 2010 report are 

therefore overstated. 

Whereas TC had committed to meeting NOx RACT requirements through the installation 

of LNB/SOFA, they later changed their compliance approach to the “fuel switching” 

option granted by 6 NYCRR Part 227-2.5(a). This provision requires the source to 

burner a cleaner fuel during the ozone season; the annual average NOx emission rate must 

still comply with the relevant limit contained in Part 227-2, which is 0.15 lb/mmBtu for 

these units. In addition to complying with NOx RACT through the fuel switching option, 

TC has proposed to comply with BART by establishing a separate, more stringent NOx

limit of 0.15 lb/mmBtu on a 30-day rolling average. 

• PM 

TC identified three potential add-on BART control technologies for PM in addition to 

switching to low-sulfur distillate oil. A fabric filter (baghouse) was ruled out because of 

the technical issues with installation on oil-fired units. The remaining options are 

summarized below along with projected control efficiencies and cost effectiveness. 

 
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PM Control Option Control

Efficiency (%)

Cost Effectiveness

($/ton)

Dry Electrostatic Precipitator (ESP) 99 $132,650

Wet ESP 99 $181,280

Switching to Distillate Fuel Oil 65 $174,970

Due to these excessive costs of controls, TC requests that current operations represent 

BART for PM on Units 10, 20 and 30. 

III. BART Determination 

The Department finds that the following shall constitute BART for the Ravenswood emission 

sources: 

• SO2

These units are primarily natural gas-fired, which yields negligible SO2 emissions, but are 

required to burn oil at times due to reliability concerns. The Department accepts the 

current No. 6 fuel sulfur limit of 0.3 percent by weight as BART for SO2. This is in line 

with the guidance provided by EPA for sulfur in fuel of 1.0 percent or less by weight 

(Appendix Y, Section IV.E.4, “SO2 limits for Utility Boilers”). EPA also notes in the 

BART rule that “the most appropriate control option for oil-fired EGUs, regardless of 

capacity, is to set limits on the sulfur content of the fuel oil burned in the unit” (70 FR 

39133). 

• NOx

The Department accepts TC’s conclusion that additional controls are not necessary given 

the magnitude of visibility improvement and cost of controls on a per-deciview basis. 

The maximum visibility improvement at the Lye Brook Wilderness area was 0.12 

deciviews at over $21.6M/deciview; the improvement decreases into the hundredths of a 

deciview for other high ranked daily visibility change days (8th-highest values correspond 

to visibility improvements of 0.01 to 0.05 deciviews). The Department also doesn’t feel 

that the addition of SNCR is necessary or appropriate, as minimal gains in NOx

reductions would result while likely driving the cost-per-deciview values even higher. 

The Department accepts the proposed NOx BART limit of 0.15 lb/mmBtu, based on a 30-

day rolling average. Although typical emission rates are below this level – commonly 

around 0.07 lb/mmBtu – the required use of oil to maintain electric system reliability 

demands some leniency in the limit. 

 
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• PM 

The Department accepts that current operations represent BART for PM. TC adequately 

demonstrated that potential control options were technically or economically infeasible. 

These units will retain the existing 0.1 lb/mmBtu particulate emission limit.