EPA issues proposal allowing SCR for NOx control at Navajo plant

The U.S. Environmental Protection Agency said Jan. 18 that it is proposing air pollution limits for the coal-fired Navajo Generating Station, one of the largest sources of harmful NOx emissions in the country.

The 2,250-MW plant is located on the Navajo Nation, less than 20 miles from the Grand Canyon, near Page, Ariz., and the Utah state line.

“Today’s action aims to improve visibility, as required by Congress under the Clean Air Act, at 11 national parks and wilderness areas in the Southwest,” EPA said in a Jan. 18 statement. “Each year, more than 4 million people visit the Grand Canyon. However, many visitors cannot fully appreciate the spectacular vistas because of the veil of white or brown haze that hangs in the air, reducing visibility and dulling the natural beauty. Today’s proposal would reduce the visibility impact from Navajo Generating Station (NGS) by an average 73% at the national parks and wilderness areas. It will also help protect public health – NOx reacts with other chemicals in the air to form ozone and fine particles, both associated with asthma, bronchitis, emphysema, and even premature death.”

“By reducing emissions 84%, we will be able to breathe cleaner, healthier air and preserve the visibility essential to the economic vitality of the region,” said Jared Blumenfeld, EPA’s Regional Administrator for the Pacific Southwest. “The millions of tourists who visit national parks in Arizona and Utah every year will now be able see vistas once marred by pollution.”

EPA’s proposed emission limit can be achieved by installing selective catalytic reduction (SCR), which, in combination with the existing low-NOx burners the facility voluntarily installed between 2009 and 2011, would reduce emissions by 84%, or a total of 28,500 tons per year, by 2018.

EPA is proposing to give the plant an additional five years, until 2023, to install new controls to achieve the emission limit. This flexibility recognizes the importance of NGS to numerous tribes, and the environmental benefits provided by the early installation of low-NOx burners in 2009, the agency said. EPA is also requesting comments on other options that could set longer timeframes for installing pollution controls if the facility can achieve additional emission reductions.

EPA said it is prepared to issue a supplemental proposal if other approaches satisfy the Clean Air Act requirements and meet the stakeholders’ needs. EPA said it has engaged extensively with local tribes, the Salt River Project, the Central Arizona Project, the agricultural community and other stakeholders regarding impacts on power and water costs.

Earlier in January, a joint statement signed by the EPA, U.S. Department of the Interior and U.S. Department of Energy commits each agency to helping develop “clean, affordable and reliable power, affordable and sustainable water supplies, and sustainable economic development, while minimizing negative impacts on those who currently obtain significant benefits from NGS, including tribal nations.”

EPA is proposing that best available retrofit technology (BART) under the regional haze program is a plant-wide emission limit for NOx of 0.055 lb/MMBtu by 2018. This can be achieved with SCR in combination with the existing LNB/SOFA (low-NOx burners) that the owners of NGS voluntarily installed between 2009 and 2011.

NGS is co-owned by several entities: the U.S. Bureau of Reclamation (24% share), Salt River Project, Los Angeles Dept. of Water & Power, Arizona Public Service, Nevada Power and Tucson Electric Power. Los Angeles has said it is working to divest its share of the plant, and to convert the coal-fired Intermountain plant in Utah to natural gas, to meet California greenhouse gas standards.

A 90-day public comment period will begin upon publication of the notice in the Federal Register. During this time, EPA will hold public hearings in Arizona about this SCR program.

The Navajo plant’s coal comes via train from the Kayenta strip mine in Arizona of Peabody Energy (NYSE: BTU).

U.S. House Natural Resources Committee Chairman Doc Hastings, R-Wash., long a critic of EPA policies, said in a Jan. 18 statement that EPA is imposing “onerous regulations” at the Navajo plant, which employs hundreds of Navajo and Hopi tribal members and provides affordable electricity and water to millions of Americans.

“This proposed regulation by President Obama’s EPA is just another step in his Administration’s war on coal that has already resulted in lost jobs and American families paying more when they can least afford it,” said Hastings. “The Natural Resources Committee plans to hold oversight hearings to examine the impact of this latest EPA effort that will reduce jobs, negatively impact Indian Tribes, and increase water and power rates on millions of customers.” 

Three other Arizona coal plants also getting SCR mandates

The Navajo SCR installation program is not the only SCR project that EPA is pushing in Arizona. EPA said in a December 2012 Federal Register notice that it is taking final action to approve in part and disapprove in part a portion of Arizona’s State Implementation Plan (SIP) for regional haze and to promulgate a Federal Implementation Plan (FIP) for the disapproved elements of the SIP related to three other coal-fired power plants.

The state and federal plans are to implement the regional haze program in Arizona for the first planning period through 2018. This final rule, published in the Dec. 5, 2012, Federal Register, addresses only the portion of the SIP related to Arizona’s determination of BART to control emissions from eight units at three coal-fired plants: Apache, Cholla and Coronado.

EPA approves in this final rule the state’s determination that the three sources are subject to BART, and approves the state’s emissions limits for SO2 and particulate matter less than or equal to 10 micrometers (PM10) at all the units, but disapproves Arizona’s BART emissions limits for NOX at the coal-fired units of the three power plants. The FIP contains new emissions limits for NOX at these coal-fired units and compliance schedules for implementation of BART.

The affected plants are: Arizona Electric Power’s Apache Units 1, 2 and 3; Arizona Public Service’s Cholla Units 2, 3 and 4; and Salt River Project’s Coronado Units 1 and 2. EPA had proposed to disapprove Arizona’s BART emissions limits for NOX at all of the coal-fired BART units (i.e., all of the BART units except for Apache Unit 1). The proposed FIP contained BART emissions limits for NOX at all of the coal-fired BART units.

Most notably, and with the exception of Apache Unit 1, the FIP includes NOX emission limits for all the units that are achievable with SCR, EPA said. EPA said it encourages the state of Arizona to submit a revised SIP to replace all portions of the FIP, and that it is ready to work with the state to develop a revised plan.

The FIP requirements for NOx by plant are:

Apache Units 2 and 3: The final emissions limit for NOX is 0.07 lbs/MMBtu, determined as an average of the two units, based on a rolling 30-boiler-operating- day average. Compared to the proposed emissions limit of 0.05 lb/ MMBtu on each unit, this higher limit and the addition of a two-unit average provides an extra margin of compliance to account for periods of startup and shutdown as well as additional operational flexibility for Apache given AEPCO’s status as a small entity. The final compliance date for this NOX limit remains five years from the date of publication of this final rule.

Cholla Units 2, 3 and 4: The final emissions limit for NOX is 0.055 lb/MMBtu determined as an average of the three units, based on a rolling 30-boiler-operating-day average. Compared to the proposed emissions limit of 0.050 lb/MMBtu on each unit, the higher limit and three-unit average provide an extra margin of compliance to account for periods of startup and shutdown. As proposed, the final compliance date to install and operate controls is five years from the date of publication of this final rule.

Coronado Units 1 and 2: The final emissions limit for NOX is 0.065 lb/MMBtu determined as an average of the two units, based on a rolling 30-boiler-operating- day average. Compared to the proposed emissions limits of 0.050 on Unit 1 and 0.080 on Unit 2, this new limit based on a two-unit average provides an extra margin of compliance to account for startup and shutdown. The final compliance date for the two units is five years from the date of publication of this final rule.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.