Navajo coal plant work group suggests minor haze changes to EPA

A Technical Work Group (TWG) established to identify emission reduction alternatives for the coal-fired Navajo plant has submitted comments supporting the U.S. Environmental Protection Agency’s supplemental Best Available Retrofit Technology (BART) proposal for the Arizona power plant.

The Salt River Project, on behalf of the group, said in a Jan. 7 statement that in October 2013, EPA published a Supplemental Proposal that incorporates in large part a BART alternative that was submitted by the TWG three months earlier. EPA requested public input on the Supplemental Proposal, as well as its Original Proposal, held a series of public hearings and established Jan. 6 as the deadline for public comment.

The TWG includes the Central Arizona Water Conservation District, the Environmental Defense Fund, the Gila River Indian Community, the Navajo Nation, the Salt River Project (SRP), the U.S. Department of the Interior and Western Resource Advocates.

“The TWG appreciates that EPA recognized the significance of the TWG Agreement and the collaborative efforts undertaken by the stakeholders to reach an approach that carefully balances a variety of environmental and economic considerations,” said the Jan. 7 statement. “The TWG supports the EPA’s proposed adoption of the TWG BART Alternative, and recommends EPA adopt a final BART rule for NGS that is based on its October 2013 Supplemental Proposal, with the minor modifications described in their comments. The group will continue to work together on these important issues.”

Navajo is a 2,250-MW, coal-fired power plant located just outside of Page on the Navajo Reservation. The plant is operated by SRP. The other plant participants include the U.S. Bureau of Reclamation, Arizona Public Service, Los Angeles Department of Water and Power, Tucson Electric Power and NV Energy.

EPA’s February 2013 proposal for the plant to meet regional haze goals would require expensive selective catalytic reduction (SCR) to be installed and operational on all three Navajo units within five years of publication of a final rule. EPA also proposed an alternative, based on the fact that this plant and its supplying coal mine are key economic drivers in this region, that would give the plant participants credit for early installation of Low-NOx Burners and Separated Overfire Air (LNB/SOFA), and allow SCR to be installed on a delayed schedule of one unit per year between 2021 and 2023.

In response, the TWG was assembled to develop a supplemental proposal for submittal to EPA. The TWG Alternative is comprised of two scenarios, Alternative A and Alternative B, both of which achieve greater emission reductions than the EPA’s February 2013 proposal. To ensure that the alternatives meet EPA’s “better than BART” criteria, the NGS owners agreed to maintain emissions below a total 2009-2044 NOx emissions cap delineated under EPA’s February 2013 proposal as the “BART threshold” or “BART benchmark” against which alternatives would be compared.

The 2009-2044 NOx cap was calculated based on an annual emission rate of 0.055 lb/MMBtu, which is the emission rate assumed by EPA in its February 2013 proposal.

The TWG alternative outlines the operating scenarios that would be required based on various future developments, including LADWP’s and NV Energy’s planned sales of their stakes in the power plant. The alternatives mostly entail shutdown of one 750-MW unit by the end of 2019, or the curtailment of plant operations by at least 561 MW by the end of 2019, and retrofit for NOX control with SCR and other technologies of surviving capacity. LADWP owns about 477 MW of Navajo, while NV Energy owns about 254 MW. The sum of their shares is 731 MW, which is 19 MW short of one 750-MW unit at the plant.

Part of Four Corners coal plant has been shut under haze program

A similar situation over regional haze compliance at a major coal-fired power plant is currently playing out in the same region. Arizona Public Service completed on Dec. 30, 2013, its purchase of Southern California Edison’s ownership in Units 4 and 5 of the coal-fired Four Corners plant located near Farmington, N.M. APS said that as of the end of 2013 it has permanently closed the plant’s older, less efficient Units 1, 2 and 3, and will install additional emission controls on the remaining cleaner, more efficient units.

With the closing of the APS-owned Units 1-3, capacity at Four Corners has been reduced from 2,100 MW to 1,540 MW. Acquiring SCE’s 48% interest in the larger Units 4 and 5 will increase APS’s total Four Corners capacity from 791 MW to 970 MW. APS now owns 63% of Units 4 and 5, which are the units that will stay in operation over the long term.

Due to this action, emissions of particulates are expected to decline by 43%, NOx by 36%, CO2 by 30%, mercury by 61% and SO2 by 24%. Closure of the three older units by Jan. 1, 2014, and the installation of SCR on Units 4 and 5 by July 31, 2018, will satisfy BART requirements for the plant issued by EPA in August 2012 under its regional haze program.

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.