1 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 Retr ofit Technology (BART) rule under 40 CFR Part 51 and Appendix Y, and the New York State BA RT regulation as codified under 6 NYCRR Part 249. These requirements affect an emission s ource which fulfills the following criteria:

1. Falls within one of 26 sp ecific 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 ot her 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 particul ate matter. This analysis took into account such factors as the cost of c ontrols, energy and non-air quality environmental impacts of compliance, any existing pollution co ntrol technology in use at the source, the remaining useful life of the source, and the de gree of improvement in visibility which may reasonably be anticipated to result from the use of such technology.

This document summarizes the reasoning be hind the Department’s BART determination, including the level of cont rols 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 Ne w 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 submitt ed to EPA as a revision to the New York Regional Haze SIP.2 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 theref ore 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 E ngineering tangentially-fired steam electric boilers rated at 3,695 mmBtu/hr heat input. Th ese units are primarily natural gas fired, with backup oil firing capability.

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

• SO 2

The Northport facility primarily burns natura l gas, which results in negligible SO 2 emissions. The facility is currently permitte d 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 per cent. 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 i ssues 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 th at “the NYS bulk power system shall be operated so that a loss of a single gas facility does not re sult in the uncontrolled loss of electric load within th e Long Island zone.” For this reas on the facility is unable to accept a permit condition limiting the amount of o il burned in order to further reduce SO 2 emissions, as such a limit would detract from the operational flexibility needed to meet the reliability requirement. The amount of o il 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.

• NO x

In 2006 and 2007, National Grid began the evaluation of NO x control technologies in anticipation of future regulatory requirements (i.e. the Clean Air Interstate Rule and revisions to NO x RACT regulations). The primary t echnologies evaluated were selective catalytic reduction (SCR), selective non- catalytic reduction (SNCR), and separated overfire air (SOFA).3 SCR was the first add-on technology to be evaluated because it offers the greatest potential NO x reductions. One issue with SCR tec hnology is that effectiveness degrades with non-steady state operation, a nd this unit is no longer a ba se 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 suspe nded, 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 percen t capacity factor, the cost effectiveness of this unit would be $11,000 per ton of NO x reduced; based on actual load and emission forecasts for each unit, cost effectivene ss would be approximately $27,000 per ton.

SNCR was also investigated dur ing 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 additiona l operational constraints. Th e ineffectiveness of SNCR (with vendor quotes of control efficiency no high er 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 NO x emission rates of 0.20 lb/mmBtu on oil and 0.10 lb/mmBtu on ga s, for compliance on a 24-hour average basis. Because National Grid selected the most stringent NO x 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 curren tly equipped with electr ostatic precipitators (ESP). National Grid notes there is no feasible or cost-effective PM control technology available beyond an ESP for a natural gas-fire d unit utilizing low su lfur oil as a backup fuel, and therefore request the curr ent control be considered BART.

III. BART Determination

The Department finds that the following sha ll constitute BART for Northport Power Station Units 1 through 4:

• SO 2

The Department accepts National Grid’s co mmitment 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, “SO 2 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).4 It should also be noted that the Department is pursuing a regulatory revision to Part 225-1 to lower the acceptable fuel sulf ur limit to 0.5 percent statew ide (not including New York City, Nassau County, and the lower Hudson Va lley area, which are already subject to more stringent limits). This revision is te ntatively 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 requi rements under Part 225-1.”

• NO x

The Department accepts National Grid’s comm itment to install SOFA on Units 1 through 4 as BART for NO x . Other options were ruled out due to economic infeasibility (SCR) or lesser control efficiency (SNCR). National Grid is committing to NO x emission rates of 0.20 lb/mmBtu on oil and 0.10 lb/mmBtu on ga s, 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.