EPA issues final NOx limits for coal-fired Centralia power plant

The U.S. Environmental Protection Agency said in a Dec. 6 Federal Register notice that it is taking final action to approve the Best Available Retrofit Technology (BART) determination for NOX for the TransAlta Centralia Generation LLC coal-fired power plant in Centralia, Wash.

The Washington State Department of Ecology (Ecology) submitted its Regional Haze State Implementation Plan (SIP) in December 2010. In December 2011, Ecology submitted an update to the SIP containing a revised and updated BART determination for Centralia, the state’s only coal-fired power plant. On May 23, EPA proposed to approve the portion of the revised SIP containing the BART determination for TransAlta. EPA said it plans to act on the remaining Regional Haze SIP elements for Washington in the near future.

Centralia is a two-unit, coal-fired power plant, with the units rated at 702.5 MW each when burning coal from the Centralia coalfield as originally designed. That local mine was shut several years ago. The units now burn coal from the Powder River Basin (PRB) and are rated at 670 MW each.

The Regional Haze SIP revision imposes as BART a NOX emission limit of 0.21 lb/MMBtu for each unit based on the installation of selective non-catalytic reduction on both coal-fired units plus Flex Fuel. It also requires a one-year performance optimization study and lowering the emission limits based on the study results. Also, the BART determination requires one unit to cease burning coal by Dec. 31, 2020, and the second unit by Dec. 31, 2025, unless Ecology determines that state or federal law requires selective catalytic reduction to be installed on either unit.

Centralia coal units haven’t been running hard lately

TransAlta Centralian Generation parent TransAlta Corp. (TSX:TA) has been running the coal units, called Centralia Thermal, a bit less in 2012 as it buys cheaper replacement power off the grid. That was among the points made by TransAlta in an Oct. 26 financial report for the third quarter that it filed with Canadian regulators. Centralia Gas, located at the same site, is a 248-MW gas-fired facility.

On July 25, TransAlta announced that it had entered into an 11-year agreement to provide electricity from the Centralia Thermal to Puget Sound Energy (PSE). The contract begins in 2014 and runs until 2025 when the plant is scheduled to be shut down under a greenhouse gas-reduction deal with the state of Washington. Under the agreement, PSE will buy 180 MW of firm, baseload power starting in December 2014. In December 2015, the contract increases to 280 MW, and from December 2016 to December 2024 the contract is for 380 MW. In the last year of the contract, the contracted volume is 300 MW.

In 2011, the TransAlta Energy Bill was signed into law in the state of Washington. The bill, and a memorandum of agreement signed on Dec. 23, 2011, which is part of the bill, provide a framework to transition from coal-fired energy produced at Centralia Thermal by 2025. The bill and memorandum of agreement include key elements regarding, among other things, the timing of the shut down of the units and the removal of restrictions on the terms of power contracts that TransAlta can enter into.

U.S. Energy Information Administration data shows that coal suppliers to Centralia this year have included the Rawhide mine in the Wyoming PRB of Peabody Energy (NYSE: BTU) and the Spring Creek mine in the Montana end of the PRB of Cloud Peak Energy (NYSE: CLD).

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.