Coal plant retirements, gas switching help with PSCo compliance

Due to various existing rules, including the state of Colorado’s Clean Air-Clean Jobs Act (CACJA), Public Service Co. of Colorado considers itself in good position to comply with the U.S. Environmental Protection Agency’s new Mercury and Air Toxics Standards (MATS).

PSCo, a unit of Xcel Energy (NYSE: XEL), on April 27 filed a report with the Colorado Public Utilities Commission about its MATS compliance situation. The filing was part of a broad docket that the PUC opened to look at MATS impacts in Colorado.

The utility noted that MATS will apply to Cherokee Units 3-4; Valmont Unit 5; Pawnee; Hayden Units 1-2; and Comanche Units 1-3. It will not apply to: Cherokee Unit 2, which was retired in 2011; Cherokee Unit 1, due to retire in May 2012; Arapahoe Unit 3, to retire in 2013; or Arapahoe Unit 4, due to switch from coal to gas in 2013.

At Cherokee, Hayden and Valmont, all units not to be retired under the CACJA plan are currently equipped with lime spray dryers and baghouses for control of acid gases and non-mercury metals, respectively. These units also burn a low-mercury Colorado bituminous coal that keeps them below the MATS threshold. Under CACJA, Cherokee Unit 3 and Valmont Unit 5 will retire in 2016 and 2017, respectively, while Cherokee Unit 4 will switch to natural gas by the end of 2017. Since these units already meet the MATS rule, there will only need to be some minor recordkeeping done to comply with MATS from the MATS implementation deadline of April 2015 until the units are retired or fuel switched.

At Comanche, Units 1-2 got new emissions controls as part of the permitting for the recently-built Unit 3. All three of these coal units now have lime spray dryers, baghouses and sorbent injection, so they won’t need new controls to meet the MATS rule.

At Pawnee Unit 1, there is already a baghouse array and sorbent injection in place. A lime spray dryer is due to be installed by the end of 2014, which will get it into MATS compliance by the April 2015 deadline.

The company said its reliance on off-system, coal-fired power impacted by MATS is limited. It buys coal-fired power from resource pools with Tri-State Generation and Transmission Association and Basin Electric Power Cooperative and gets firm energy from the PacifiCorp system delivered at the coal-fired Craig and Hayden plants. The Tri-State and Basin deliveries can be curtailed on a pro rata basis based on outages of resources in the pool. The PacifiCorp deliveries can only be curtailed by force majeure events.

PSCo jointly owns Craig 1-2 and Hayden and said that the Craig units are apparently now in compliance with MATS and Hayden will be once planned new emissions controls are installed. The utility said it has no information right now on Craig Unit 3 compliance or compliance at Basin’s coal-fired Laramie River Station, but indicated that the worst-case impact of any compliance problems at each of those facilities would be minimal.

PSCo said it does from time to time make “opportunity” purchases of coal-fired power for its system, but said that those purchases can be easily curtailed.

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.