EPA to publish final rule rejecting Utah’s NOx limits for two PacifiCorp coal plants

The U.S. Environmental Protection Agency will publish in the July 5 Federal Register a final rule that partially approves and partially disapproves a State Implementation Plan (SIP) revision submitted by the state of Utah in June 2015 to implement the regional haze program under the Clean Air Act (CAA).

The state’s SIP revisions would establish an alternative to best available retrofit technology (BART) controls that would otherwise be required to control nitrogen oxides (NOx) at PacifiCorp’s coal-fired Hunter and Huntington power plants. The June 2015 SIP revision also includes BART determinations for particulate matter with an aerodynamic diameter of less than 10 micrometers (PM10) at these power plants and provisions for making the NOx and PM10 BART emission limits federally enforceable.

The EPA is finalizing the option in its own Jan. 14, 2016, co-proposal to partially approve and partially disapprove the June 2015 SIP revision and is promulgating a Federal Implementation Plan (FIP) to address the deficiencies identified in its proposed partial disapproval of Utah’s regional haze SIP. The EPA is not taking any final action on a related October 2015 SIP revision. The state retains its authority to submit a revised state plan consistent with CAA and Regional Haze Rule (RHR) requirements.

Rather than installing and operating BART controls for its four subject-to-BART electric generating units (EGUs) at Hunter and Huntington, Utah’s SIP submittal relied on an alternative program, which included: the installation of upgraded combustion controls between 2006 and 2014 at the four BART units plus an additional EGU at PacifiCorp’s Hunter plant; and the shutdown of the coal-fired Carbon plant, a non-BART source, to meet the BART requirements for emissions of NOx. To meet its PM BART requirements, Utah’s SIP submittal included the most stringent control technology at each of the four subject-to-BART EGUs.

Said EPA in the final rule: “After carefully considering the comments on our proposal, we determined that there is only one permissible outcome. Therefore, for the reasons described in our proposal and in this action, we find that the State’s NOx BART Alternative for the power plants is not consistent with the applicable statutory and regulatory requirements. As a result, EPA has determined that final disapproval is the only path that is consistent with the Act.”

For the Hunter and Huntington BART units, EPA found that BART for NOx is selective catalytic reduction (SCR), low-NOx burners (LNB) and separated overfire air (SOFA), represented by an emission limitation of 0.07 lb/MMBtu (30-day rolling average). The BART emission limitation of 0.07 lb/MMBtu allows for a sufficient margin of compliance for a 30-day rolling average limit that would apply at all times, including startup, shutdown, and malfunction, EPA said.

The selection of LNB and SOFA with SCR as BART for the Hunter and Huntington BART units is fully justified, said EPA. For these four units, LNB and SOFA with SCR is very cost-effective, at $2,697/ton to $2,928/ton on an average basis (counting the costs and emission reductions from the combination of the three control technology elements), and at $5,830/ton to $6,632/ton on an incremental basis compared to LNB with SOFA and selective non-catalytic reduction (SNCR). Compared to LNB with SOFA, the incremental cost effectiveness of LNB and SOFA with SCR ranges from $5,206/ton to $5,861/ton.

EPA is finalizing its proposed approval of Utah’s PM10 BART determinations for Hunter Units 1 and 2 and Huntington Units 1 and 2. It has determined that Utah’s PM10 BART determinations, emission limitations, and associated monitoring, recordkeeping and reporting for Hunter Units 1 and 2 and Huntington Units 1 and 2 meet requirements. It considered and rejected comments on the validity of the state’s BART analyses for PM10 and the state’s emission limitation of 0.015 lb/MMBtu on a 30-day rolling basis for the Hunter and Huntington BART units.

PacifiCorp’s Hunter plant is located in Castle Dale and consists of three units. Of the three units, only Units 1 and 2 are subject to BART limits under the regional haze program. Hunter Units 1 and 2 have a nameplate generating capacity of 488.3 MW each. The boilers are tangentially fired pulverized coal boilers, burning bituminous coal.

PacifiCorp’s Huntington plant is located in Huntington City and consists of two units. Huntington Units 1 and 2 have a nameplate generating capacity of 498 MW each. The boilers are tangentially fired pulverized coal boilers, burning bituminous coal.

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.