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New York State Department of Environmental Conservation 

Best Available Retrofit Technology Determination 

Facility Northport Power Station 

Location Huntington, NY 

Suffolk County 

Permit ID 1-4726-00130 

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 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 7, 2011. Upon completion of this public notice period, the modified permit was 

submitted to EPA for review on February 7, 2012. The final modified permit was issued on 

March 27, 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 

National Grid submitted a BART analysis for the Northport Power Station dated September 27, 

2010 to the Department. The following emission sources had previously been identified as 

BART-eligible and were therefore included in the analysis: 

Boiler No. 1 – Emission Unit U-00001; Emission Source ES001 

Boiler No. 2 – Emission Unit U-00002; Emission Source ES003 

Boiler No. 3 – Emission Unit U-00003; Emission Source ES005 

Boiler No. 4 – Emission Unit U-00004; Emission Source ES007 

• These four units are identical Combustion Engineering tangentially-fired steam electric 

boilers rated at 3,695 mmBtu/hr heat input. These units are primarily natural gas fired, 

with backup oil firing capability. 

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

• SO2

The Northport facility primarily burns natural gas, which results in negligible SO2

emissions. The facility is currently permitted to burn oil with a maximum sulfur content 

of 1.0 percent for Units 1 through 3, and 0.75 for Unit 4. National Grid commits to 

limiting the fuel sulfur content of Units 1 through 4 to 0.7 percent. National Grid notes 

that this low-sulfur fuel is below the 1.0 percent sulfur limit in oil referenced by the 

Appendix Y guidance. Aside from the economic aspects of switching to lower-sulfur oil, 

National Grid cites additional technical issues with the delivery methods which 

complicate lower-sulfur alternatives. 

This unit is required to burn oil at times, as required by local reliability rule I-R5 (the 

“minimum oil burn” rule) which states that “the NYS bulk power system shall be 

operated so that a loss of a single gas facility does not result in the uncontrolled loss of 

electric load within the Long Island zone.” For this reason the facility is unable to accept 

a permit condition limiting the amount of oil burned in order to further reduce SO2

emissions, as such a limit would detract from the operational flexibility needed to meet 

the reliability requirement. The amount of oil burned is a factor of load level and the 

number of units online, though real-time conditions may arise that require variations from 

the scheduled operation. 

• NOx

In 2006 and 2007, National Grid began the evaluation of NOx control technologies in 

anticipation of future regulatory requirements (i.e. the Clean Air Interstate Rule and 

revisions to NOx RACT regulations). The primary technologies evaluated were selective 

catalytic reduction (SCR), selective non-catalytic reduction (SNCR), and separated 

overfire air (SOFA). 
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SCR was the first add-on technology to be evaluated because it offers the greatest 

potential NOx reductions. One issue with SCR technology is that effectiveness degrades 

with non-steady state operation, and this unit is no longer a base load unit but rather a 

load following unit. Additionally, structural problems and physical constraints on each 

unit would impede construction—because space is limited at the Northport facility, the 

SCR units would potentially have to be suspended, also adding cost. Previous estimates 

put the cost of an SCR unit at $100M, but a more conservative value of $70M was used 

for the cost analysis. Based on a 100 percent capacity factor, the cost effectiveness of 

this unit would be $11,000 per ton of NOx reduced; based on actual load and emission 

forecasts for each unit, cost effectiveness would be approximately $27,000 per ton. 

 

SNCR was also investigated during this time period, and had been evaluated in the mid 

1990’s as well. The resulting finding was that SNCR produced benefits no greater than 

that of SOFA, with additional operational constraints. The ineffectiveness of SNCR 

(with vendor quotes of control efficiency no higher than 20 percent) was in large part due 

to the load-following operation of the boilers; SNCR is much more effective for base load 

units in which the temperature profile inside the boiler is held constant. 

National Grid is proposing SOFA as BART for Units 1, 2, 3, and 4, to be operating on 

each boiler by January 1, 2014. National Grid is committing to NOx emission rates of 

0.20 lb/mmBtu on oil and 0.10 lb/mmBtu on gas, for compliance on a 24-hour average 

basis. Because National Grid selected the most stringent NOx control option that was 

technically and economically feasible, they did not proceed with a visibility analysis. 

• PM 

Each of the four units at Northport is currently equipped with electrostatic precipitators 

(ESP). National Grid notes there is no feasible or cost-effective PM control technology 

available beyond an ESP for a natural gas-fired unit utilizing low sulfur oil as a backup 

fuel, and therefore request the current control be considered BART. 

III. BART Determination 

The Department finds that the following shall constitute BART for Northport Power Station 

Units 1 through 4: 

• SO2

The Department accepts National Grid’s commitment to lowering its permitted fuel 

sulfur limit from 1.0 to 0.7 weight percent for Units 1 through 4. 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). 
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It should also be noted that the Department is pursuing a regulatory revision to Part 225-1 

to lower the acceptable fuel sulfur limit to 0.5 percent statewide (not including New York 

City, Nassau County, and the lower Hudson Valley area, which are already subject to 

more stringent limits). This revision is tentatively scheduled to be effective for 2014. 

The Department has made owners aware of this upcoming requirement and indicated it 

may supersede BART limits such as the 0.7 percent limit recommended by National Grid 

for Northport Units 1 through 4. National Grid has committed to “comply with any 

future, more stringent requirements under Part 225-1.” 

• NOx

The Department accepts National Grid’s commitment to install SOFA on Units 1 through 

4 as BART for NOx. Other options were ruled out due to economic infeasibility (SCR) or 

lesser control efficiency (SNCR). National Grid is committing to NOx emission rates of 

0.20 lb/mmBtu on oil and 0.10 lb/mmBtu on gas, for compliance on a 24-hour average 

basis. 

• PM 

The Department accepts that no additional controls beyond the existing ESPs are 

necessary for compliance with BART for PM. The facility’s 0.1 lb/mmBtu particulate 

emission limit will remain in place.