The U.S. Environmental Protection Agency is reissuing its final approval of the Colorado regional haze State Implementation Plan (SIP) revision submitted in May 2011 with respect to the state’s best available retrofit technology (BART) determination for the coal-fired Comanche Generating Station located near Pueblo, Colorado.
EPA originally finalized its approval of the Colorado regional haze SIP in December 2012. In response to a petition for review of that final action in the U.S. Court of Appeals for the Tenth Circuit, EPA successfully moved for a voluntary remand, without vacatur, to more adequately respond to public comments concerning Comanche. EPA is providing new responses to those comments in a rulemaking notice to be published in the May 26 Federal Register. This final rule will be effective 30 days after date of publication in the Federal Register.
In March 2012, EPA proposed to approve the Colorado regional haze SIP. Among the components of the SIP was a NOx BART determination for Units 1 and 2 at Comanche, which is owned by the Public Service Co. of Colorado subsidiary of Xcel Energy (NYSE: XEL). As with several other facilities, the state submitted a BART analysis for Comanche that took into account the five factors required by the regional haze rule. The state determined that the existing emission controls at Comanche Units 1 and 2, low-NOX burners with over-fire air (LNB/OFA), are BART. EPA proposed to approve the state’s NOx BART determination for Comanche.
EPA received several adverse comments on its proposed approval, including comments from WildEarth Guardians and the National Parks Conservation Association (NPCA). In December 2012, EPA published a notice of its final approval of the Colorado regional haze SIP. That final action included an approval of the Comanche NOx BART determination.
In February 2013, NPCA and Guardians filed petitions seeking the Tenth Circuit’s review of EPA’s final approval of the Colorado regional haze SIP. Guardians challenged EPA’s approval of Colorado’s BART determinations for Units 1 and 2 of the coal-fired Craig Station; Units 1 and 2 of the Comanche Station; and Boilers 4 and 5 of the Colorado Energy Nations Co. (CENC) LLP facility at the Coors Brewery. Guardians also challenged EPA’s approval of Colorado’s reasonable progress determination for Craig Unit 3, and the deadlines for compliance with emission limits for the units at all three facilities. NPCA challenged only EPA’s approval of Colorado’s BART and reasonable progress determinations for Craig Units 1, 2, and 3.
After the court consolidated the cases for review, EPA reached a settlement with NPCA and Guardians concerning their claims related to the Craig Station, and Guardians elected not to pursue its claims regarding CENC/Coors. Guardians’ claims concerning the Comanche Station are still active. In response to these claims, EPA moved the court for a partial voluntary remand of its 2012 final approval without vacatur so as to provide a more detailed and complete response to some of the adverse comments on the proposed approval. The court granted EPA’s motion.
EPA is now reissuing its final approval of the Colorado regional haze SIP with respect to Comanche to provide more detailed and clearer responses to the Comanche-related adverse comments.
An example comment and response is one where a commenter asserted that the state failed to appropriately assess the cost of more expensive selective catalytic reduction (SCR), by assuming that SCR would achieve an emission rate of 0.07 lb/MMBtu on an annual average basis. But, according to the commenter, EPA has noted that SCR can achieve emission rates as low as 0.04 lb/MMBtu on an annual basis, and a 0.05 lb/MMBtu emission rate on an annual average basis is a more appropriate benchmark from which to assess the cost-effectiveness of SCR.
“We disagree with this comment,” said EPA. “We have reviewed the information in the administrative record for this action again, and we find that our previous conclusion is still correct. We agree that SCR can achieve annual NOX emission rates of 0.05 lb/MMBtu, and that ideally Colorado would have used this value when assessing the SCR control option. But if the State had done so, the marginally lower emissions would not have caused the State to reach a different conclusion as to what technology is BART.”
Comanche is a 1,410-MW plant made up of three coal units: Unit 1 (325 MW), Unit 2 (335 MW) and Unit 3 (750 MW). Unit 3 is a new facility completed in 2010 and equipped already with SCR, and is not subject to the haze issue.