April 18, To Whom It May Concern:

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1 April 18, 2005 EPA Docket Center (EPA/DC) Environmental Protection Agency Mailcode 6102T 1200 Pennsylvania Ave., NW Washington, DC Attn: Docket ID No To Whom It May Concern: The State and Territorial Air Pollution Program Administrators (STAPPA) and the Association of Local Air Pollution Control Officials (ALAPCO) are writing to submit these comments on the U.S. Environmental Protection Agency s (EPA s) proposed Standards of Performance for Stationary Combustion Turbines (Turbines NSPS Proposal) as published in the Federal Register on February 18, 2005 (70 Federal Register 8314). The proposed Turbines NSPS would apply to new stationary combustion turbines greater than or equal to one megawatt (MW) that commence construction, modification or reconstruction after February 18, STAPPA and ALAPCO welcome EPA s proposal to update the Turbines NSPS to reflect the significant advances in the design and control of emissions from stationary turbines and the increased knowledge of the severity of health and environmental effects from emissions of nitrogen oxides (NO x ) and sulfur dioxide (SO 2 ). I. Background Section 111 (b)(1)(b) of the Clean Air Act (CAA) requires EPA to promulgate NSPSs for sources and, at least every eight years, review and, if appropriate, revise these NSPSs. An NSPS will apply to any new stationary source, no matter where in the United States it is located. 1 As EPA notes in its proposal, it promulgated the NSPS for stationary gas turbines in (See Turbines NSPS Proposal, p.8316.) The CAA defines standard of performance as follows: The term standard of performance means a standard for emissions of air pollutants which reflects the degree of emission limitation achievable through the application of the best system of emission reduction which (taking into account the cost of achieving such a reduction and any nonair quality health and environmental 1 CAA 111(a)(3) provides that the term stationary source means any building, structure, facility, or installation which emits or may emit any air pollutant. 1

2 impact and energy requirements) the Administrator determines has been adequately demonstrated. CAA 111(a)(1). In other words, an NSPS should reflect the emission reductions achievable by applying the best system of emission reduction that has been adequately demonstrated, taking into account costs and any nonair quality health and environmental impact and energy requirements. As noted in Clean Air Law and Regulation, the EPA Administrator has the authority to determine that a technology has been adequately demonstrated, even if the majority of sources are not utilizing it. 2 Furthermore, the technology-forcing nature of the statute [and] a determination that the industry is moving uwaveringly toward a particular standard or system can be sufficient to support an EPA determination on NSPS. 3 In short, the NSPS for turbines has not been revised since 1979 and may not be revised again in decades, the technology for controlling emissions has progressed significantly, the healthbased air quality standards have changed substantially to reflect our evolving understanding of the substantial health effects of NO x and SO 2 and the NSPS will apply to any new source across the United States. Accordingly, since the Turbines NSPS will set an important benchmark for controlling air pollution from stationary turbines that will stand for years to come, it should limit air pollutant emissions aggressively. II. Specific Comments on EPA s Proposal A. Nitrogen Oxide Limitations for Natural Gas-Fired Turbines EPA is proposing the following limits for NO x emissions for turbines: Natural gas-fired turbines below 30 megawatts (MW) meet an emission limit of 1.0 pound per megawatt-hour (lb/mw-hr), and Natural gas-fired turbines greater than or equal to 30 MW meet an emission limit of 0.39 lb/mw-hr). STAPPA and ALAPCO believe, based on a review of technology determinations made by its members and limits set on turbines emissions by its members, 4 that the NSPS limits being proposed by EPA are not stringent enough. Given the added control possibilities for combinedcycle turbines in particular, we recommend that EPA adopt the following limitations: Simple cycle turbines 30 MW or larger 9 parts per million (ppm) limit (translated to lb/mw-hr), Simple cycle turbines under 30 MW a lb/mw-hr figure equivalent to ppm, 2 Elliott P. Laws, The Regulation of Stationary Sources, in Timothy Vanderver Jr., editor-in-chief, Clean Air Law and Regulation (Bureau of National Affairs, 1992) (149, 166 footnote 118), citing generally National Lime Ass n v. EPA, 627 F.2d 416 (D.C. Cir. 1980). 3 Id. 4 See National Turbine Spreadsheet, compiled by EPA Region 4 staff, available at 2

3 Combined cycle turbine an emission limit that reflects application of selective catalytic reduction (SCR) technology (a lb/mw-hr equivalent to ppm), regardless of size, and Simple cycle turbine converted to combined cycle turbine the same emission limit as a combined cycle turbine. 5 On page 8318 of the Turbines NSPS Proposal, EPA states that its proposed NO x limits for natural gas-fired turbines can be met without the use of add-on controls. Given that most states require SCR for combined-cycle turbines, 6 the proposed NSPS limits for combined-cycle turbines should reflect this level of control in order to ensure continued attainment of air standards and that these new turbines not contribute to air quality problems in other areas. That the standard should be stronger is reflected in EPA s analysis on p.8322 that zero NO x reductions will result from its proposed NSPS even with a projected 355 new turbines being installed over the next five years. STAPPA and ALAPCO strongly believe that the NO x emission limit for combined cycle turbines should reflect the use of add-on controls; however, if EPA nevertheless decides to set the NSPS based on no add-on controls, we offer the following comments: NO x limits for small natural-gas fired turbines (p. 8319) if actual NO x emissions are significantly lower than the manufacturer guarantees, then the NSPS should be set lower than the 25 ppm guarantee and instead reflect actual performance. NO x limits for large natural-gas fired turbines (p.8319) if some manufacturers guarantee performance at 9 ppm, then the standard should be set to reflect that figure, rather than 15 ppm. B. Output-based Standards STAPPA and ALAPCO agree with EPA s proposal to use output-based standards since they encourage efficiency. C. NO x Limits for Landfill Gas and Digesters In its Turbines NSPS Proposal (p.8319), EPA seeks comment on whether special consideration should be given to turbines that use landfill, digester or other waste gases. The use of waste gases in a turbine should encouraged, since otherwise these gases would simply be vented to the atmosphere, or flared off. As EPA notes, landfill and digester gases have considerably lower heating values than natural gas, making it more difficult to comply with an output-based standard (Id.). STAPPA and ALAPCO suggest that EPA consider setting an output-based limit for turbines using waste gases that provides an adjustment factor based upon thermal efficiency. EPA should 5 According to an from EPA, the limits in EPA s Turbines NSPS Proposal translate to ppm figures as follows: 9 ppm for simple cycle turbines above 30 MW, 25 ppm for simple cycle turbines below 30 MW and 15 ppm for combined cycle turbines. 6 For example, Wisconsin limits NO x emissions from natural gas-fired turbines of 25 MW or greater to 3 ppm, which assumes the use of SCR. See Wisconsin NR (2)(g). North Carolina s NO x limits for combined cycle gas-fired turbines are lb/mmbtu and ppm, which assume the use of SCR. North Carolina s NO x limits for simple cycle gas-fired turbines are lb/mmbtu and ppm, which assume the use of low NO x burners. 3

4 consider different treatment for turbines that are replacing a flare, since these turbines are using gases that are otherwise being burned. We refer EPA to the work of the Regulatory Assistance Project and its model rule for distributed generation, as it addresses flared gases. D. Sulfur Dioxide Limits for Turbines As EPA notes in the Turbines NSPS Proposal on p. 8319, very few turbines sold today are primarily distillate oil-fired, but many units that primarily fire natural gas can also fire distillate oil. The limits EPA sets for distillate oil-fired turbines should not create an incentive for the use of distillate oil over the use of natural gas, since natural gas is an inherently cleaner fuel. EPA in the Turbines NSPS Proposal sets a SO 2 limit that corresponds to a 500 parts per million by weight (ppmw) sulfur fuel content for distillate oil fuel (p.8320). As EPA notes, this low sulfur fuel (500 ppmw sulfur content) is widely available because of EPA requirements for diesel fuels used for highway and nonroad vehicles. As EPA also notes, ultra low sulfur diesel fuel (15 ppmw or less sulfur fuel content) will become available over the next few years, beginning in 2006, because of recently enacted EPA requirements for diesel highway and nonroad vehicles. This requirement has affected recent permitting decisions; for example, Georgia has issued several Prevention of Significant Determination permits to gas- and oil-fired combustion turbines in recent years that require the combustion of ultra low sulfur fuel beginning in This additional year provides time for setting up distribution facilities for delivering ultra low sulfur fuel oil to combustion turbine facilities. STAPPA and ALAPCO recognize that there may be supply issues with ultra low sulfur diesel fuel in the early years of implementation of EPA s new diesel vehicle requirements, if all new distillate oil-fired turbines are required to use this fuel in addition to highway and nonroad vehicles. If there are supply issues, highway and nonroad vehicles should take precedence. Accordingly, STAPPA and ALAPCO recommend that EPA set a two-tiered SO 2 standard: one that applies through December 31, 2006 that corresponds to a 500 ppmw sulfur fuel content for distillate oil, and one that applies beginning in January 1, 2007 that corresponds to a 15 ppmw sulfur fuel content for distillate oil, assuming EPA determines that adequate supplies of ultra low sulfur diesel fuel exist for vehicles and for turbines. If EPA determines adequate supplies do not exist, it should revisit the supply issue each following year until it can make such a determination. E. Carbon Monoxide Limits for Turbines STAPPA and ALAPCO believe that EPA should set carbon monoxide (CO) limits for combustion turbines. CO limits are fairly common in permit determinations and are readily achievable. 7 CO limits for combined cycle combustion turbines should reflect the use of catalytic oxidation (approximately 3 ppm). 7 See National Turbine Spreadsheet, compiled by EPA Region 4 staff, available at 4

5 F. Monitoring Requirements STAPPA and ALAPCO believe that EPA should craft monitoring requirements that are consistent with good practices, and continuous emissions monitoring systems (CEMS) provide the best data. Accordingly, we recommend the following: CEMS for NO x should be required for all turbines equal to or greater than 30 MW, instead of providing for water/steam to fuel ratio monitoring as EPA proposes; 8 and CEMS for CO should be required. We thank EPA for the opportunity to comment on the Turbines NSPS Proposal. If you have any questions about these comments, please contact either of us or Amy Royden-Bloom of the STAPPA/ALAPCO Secretariat at Sincerely, Brock Nicholson STAPPA Chair Criteria Pollutants Committee Lynne A. Liddington ALAPCO Chair Criteria Pollutants Committee 8 For example, Georgia has required all large combustion turbines it has permitted in recent years to have CEMS for NO x. 5