The Arizona Department of Environmental Quality plans an Oct. 27 hearing on a new report that tracks the department’s progress in complying with the U.S. Environmental Protection Agency’s regional haze mandates; and also charts the gradual loss of coal-fired power in the state due in large part to this rule.
The haze rule requires each state to provide the EPA Administrator with a report every five years evaluating progress towards the Reasonabhle Progress Goals (RPGs) for each mandatory Class I area. 16 States must submit the progress report to EPA for review within five years from submittal date of its initial implementation plan, regardless if the state plan received EPA approval. EPA uses the progress reports as a checkpoint to evaluate the effectiveness of a state’s current strategy to determine if improvement or change is necessary, thereby ensuring continued progress towards visibility improvement in the Class I areas.
Part of the report deals with several emissions sources, including coal-fired power plants, subject to the Best Available Control Technology (BART) standard. The rule requires statesto identify a stationary source as BART-eligible if: it falls within one of twenty-six source categories; it began operation between 1962 and 1977; and has the potential to emit 250 tons per year of any air pollutant.
The Arizona regional haze plan includes ADEQ’s approved BART determinations, as well as additional determinations imposed through the Federal Implementation Plan (FIP) promulgated by EPA. Arizona has seven facilities total that are currently in operation with one or more units requiring BART emission control measures. As for coal facilities:
Arizona Electric Cooperative
Arizona Electric Power Cooperative‘s (AEPCO) Apache Generating Station. There are three subject-to-BART emission units at Apache: Units 1, 2, and 3. These units are subject to “BART alternative” (also known as “better-than-BART”) control requirements included in the facility’s permit revision issued in 2014 and approved into the Arizona State Implementation Plan (SIP) in April of this year. The facility’s permit lists the control measures and stipulates that they will go into effect according to the SIP compliance dates.
- Apache Unit 1 includes Steam Unit 1 (75 MW) and Gas Turbine 1 (10.51 MW). As outlined in its air quality permit, the BART Alternative limits for Apache Unit 1 are that Steam Unit 1 shall combust only pipeline natural gas, with no coal.
- Apache Unit 2 (also known as Steam Unit 2) is a 194.7 MW unit which combusts coal as a primary fuel with the ability to supplement with natural gas as needed. Apache Unit 3 (also known as Steam Unit 3) is a 194.7 MW unit which combusts coal as a primary fuel with the ability to supplement with natural gas as needed. As outlined in its permit, Apache Units 2 and 3 have individual emission limits and control measure requirements, with an optional set of limits, which apply to both units collectively.
- Effective Dec. 5, 2017, Steam Unit 2 shall burn only pipeline quality natural gas except in the event of an emergency.
- The individual BART Alternative requirements for Unit 3 are: Effective Dec. 5, 2016, Steam Unit 3 shall not emit SO2 in excess of 0.15 lb/MMBTU heat input, averaged over 30 boiler operating days and shall not emit PM10 in excess of 0.03 lb/MMBTU heat input (filterable only), averaged over 30 boiler operating days. Effective no later than Dec. 5, 2017, Steam Unit 3 shall install, operate and maintain low NOx burners, overfire air, and selective non-catalytic reduction (SNCR) technology. The SNCR shall operate at all times that Steam Unit 3 is in operation and exhaust gas temperatures equal or exceed the manufacturer’s recommended minimum temperature for operation of the SNCR technology. Effective Dec. 5, 2017, Steam Unit 3 shall not emit NOx in excess of 0.23 lb/MMBTU heat input, averaged over 30 boiler operating days.
- BART Alternative limits for combined operation of Apache Units 2 and 3 are such that effective Dec. 5, 2017, in lieu of the individual limits set forth for NOx above, the combined NOx emissions of Steam Unit 2 and 3, averaged over 30 boiler-operating days, shall not exceed the limit established in an equation.
Arizona Public Service
Arizona Public Service‘s (APS) Cholla Generating Station. There are three emission units located at Cholla with BART requirements, referred to herein as Cholla Units 2, 3, and 4. Cholla Units 2 and 3 are 305 MW coal-fired steam boilers. Cholla Unit 4 is a 425-MW coal-fired steam boiler. All of the units have the same BART determinations for all three visibility-impairing pollutants. The PM10 and SO2 control measures are part of the Arizona SIP, while the NOx control measures are included in the FIP.
Under the FIP, Cholla Units 2, 3, and 4 are subject to a NOx limit of 0.055 lb/BBMtu, determined as an average of the three units and based on a rolling 30-boiler-operating-day average. Under the SIP, the PM10 controls require each unit to use a fabric filter with an associated emission limit of 0.015 lb/MMBtu. In addition, the SO2 controls require each unit to use wet Flue Gas Desulfurization (FGD) with an emission limit of 0.15 lb/MMBtu on a 30-day rolling average. The FIP later imposed an additional requirement of 95% SO2 removal efficiency for the control equipment. Cholla’s current air quality permit contains the BART requirements.
At the time of this report was ADEQ was working with Cholla ownership on a BART Reassessment and permit revision, but the EPA had not yet published an approval. The Cholla SIP Reassessment requires NOx controls that include the complete shutdown of operations at Unit 2. In addition, Units 3 and 4 must meet a 0.22 lb/MMBtu emission limit and halt coal-burning activities with the option to switch to natural gas by 2025.
Salt River Project
Salt River Project’s (SRP) Coronado Generating Station. There are two BART emission units at Coronado, referred to herein as Coronado Units 1 and 2. Both Coronado Units are 456-MW coal-fired steam boilers and both are subject to the same requirements for all three of the visibility-impairing pollutants. The FIP provides the requirements for NOx controls, while the SIP provides the mandates for PM10 and SO2 controls.
- The NOx control is an emission limit of 0.065 lb/MMBtu, which is determined as an average of the two units and based on a rolling 30-boiler-operating-day average.
- No further emissions control technology is required for PM10, but both units must comply with a 0.03lb/MMBtu emission limit.
- In addition, the SO2 BART controls require both units to implement Wet Flue Gas Desulfurization with an associated emission rate of 0.080 lb/MMBtu on a 30-day rolling average.
Coronado’s 2011 operating permit, which was in effect at the time of this report, includes the BART requirements described above for PM10 and SO2. As of June 1, 2014, Coronado Unit 1 was required to comply with a NOx emission rate of 0.080 lb/MMBtu. The facility is currently required to comply with the above-stated NOx BART requirements by Dec. 5, 2017. Coronado is in compliance with its permit and has no violations observed by ADEQ.
On March 31, 2015, EPA published a notice of proposed rulemaking proposing to revise the NOx BART requirements imposed on the Coronado Generating Station in the FIP. If finalized, the revision will require Unit 1 to meet a 0.065lb/MMBtu emission limit. In addition, Unit 2 will comply with an emission limit prescribed in a consent decree of 0.080 lb/MMBtu based on a 30-boiler-operating-day basis.
Tucson Electric Power
Tucson Electric Power‘s (TEP) Sundt Generating Station. Sundt has one emission unit that must comply with certain BART determinations, referred to herein as Sundt Unit 4. EPA disapproved ADEQ’s initial determination that Unit 4 was not BART-eligible and later promulgated requirements for NOX, PM10 and SO2 in the FIP.
- To control NOx emissions, Unit 4 must comply with a of 0.36 lb/MMBtu emission limit, which is consistent with the use of SNCR paired with the existing Low-NOx Burners.
- Sundt Unit 4 must also comply with a PM10 filterable emission limit of 0.030 lb/MMBtu and an SO2 emission limit of 0.23 lb/MMBtu on a 30-boiler-operating-day average.
Alternatively, TEP may elect to switch Sundt Unit 4 to natural gas, in which case it would have meet a NOX emission limit of 0.25 lb/MMbtu and an SO2 emission limit of 0.00064 lb/MMbtu (both on a 30-boiler-operating-day average). The PM10 limit would be based on the results of initial performance test following the switch to gas. TEP must inform EPA of its choice of compliance option by March 31, 2017. If TEP chooses to switch to gas, it must meet the alternative emission limits by Dec. 31, 2017.