PacifiCorp’s latest air plan includes Bridger SCR projects

PacifiCorp, through its Rocky Mountain Power division, plans to install selective catalytic reduction (SCR) systems on Units 3 and 4 of the coal-fired Jim Bridger plant in Wyoming primarily to meet regional haze reduction needs.

PacifiCorp filed Aug. 7 at the Wyoming Public Service Commission for a certificate of public convenience and necessity for these projects. The projects are required to operate Unit 3 beyond Dec. 31, 2015, and Unit 4 beyond Dec. 31, 2016, to comply with environmental requirements.

Chad Teply, vice president of resource development and construction for PacifiCorp Energy, said in testimony that the retrofits are driven by the U.S. Environmental Protection Agency’s proposed action on Wyoming’s Regional Haze State Implementation Plan (SIP) as it pertains to NOx. EPA recommends approval of the SCR and low NOx burner installations on Jim Bridger Units 3 and 4 as Best Available Retrofit Technology (BART). EPA’s proposed action on Wyoming’s Regional Haze SIP related to SO2 recommends approval of the state’s SIP in this regard, which incorporates the established emissions limits assigned to the Jim Bridger Units 3 and 4 scrubbers.

An overall cost estimate for the SCR projects could not be found in the redacted testimony.

PacifiCorp believes that its emissions reduction projects completed to date on Jim Bridger Units 3 and 4 are consistent with the EPA’s Mercury and Air Toxics Standards (MATS). The company will be required to take additional actions to reduce mercury emissions through the installation of controls and use of reagent injection at Jim Bridger 3 and 4 to otherwise comply with the final rule’s standards. Budgeted costs for these additional actions have been incorporated into the financial analyses supporting this CPCN application.

PacifiCorp designing Bridger SCRs to allow PRB coal burn

The Jim Bridger plant consists of four coal units which are two-thirds owned by PacifiCorp and one-third co-owned by Idaho Power. The plant is operated by PacifiCorp Energy. Unit 3 began operation in 1976 and Unit 4 followed in 1979. Unit 3 and Unit 4 have nominal net generation capacities of 523 MW and 530 MW respectively, of which the corresponding PacifiCorp two-thirds shares are 349 MW and 353 MW.

Both units are configured with Alstom (formerly Combustion Engineering) controlled circulation, tangentially fired, pulverized coal boilers and General Electric steam turbine-generators. Both units are configured with closed loop circulating water cooling systems that include mechanical draft cooling towers and electrostatic precipitators (ESPs). Unit 4 was originally equipped with a sodium-based wet flue gas desulfurization (FGD) system, and Unit 3 was retrofitted in 1985 with a sodium-based wet FGD.

The plant is adjacent to PacifiCorp’s and Idaho Power’s co-owned Jim Bridger mines, which supply about 6 million tons per year of sub-bituminous coal to the plant along a 2.4-mile long, 42-inch wide overland belt conveyor. An additional approximately 3 million tons per year of sub-bituminous coal is delivered to the plant from other mines in southwestern Wyoming via rail or truck.

Since the Jim Bridger plant is primarily a mine-mouth facility, fuel supply design flexibility has been focused on potential fuel quality ranges from the mine. In addition to existing primary and secondary coal sources, a point of major import to the coal industry is that PacifiCorp is incorporating design parameters into the Jim Bridger SCR systems to accommodate Power River Basin (PRB) coals to allow future PRB coal switching to remain a viable long-term planning alternative with limited modifications required to the SCR systems.

Each of the planned SCR systems for Units 3 and 4 would be comprised of two separate universal reactors, with multiple catalyst levels; inlet and outlet ductwork; a shared ammonia reagent system; an economizer upgrade; structural reinforcement of the boiler and flue gas path ductwork and equipment; and extension of the existing plant distributed control system (DCS), Teply noted. An induced draft (ID) fan upgrade and an associated auxiliary power system variable frequency drive (VFD) insertion is required on Unit 4 only.

To benefit from competitive market pricing and establish an accurate project critical path schedule aligned with the planned major maintenance outage schedule for Jim Bridger 3, the company initiated a competitive procurement process for the Jim Bridger Units 3 and 4 SCR project in January. The company will negotiate with requests for proposal respondents toward establishing a contract for engineering, procurement, and construction (EPC) of the project, Teply wrote. Delayed receipt of CPCN approval could result in higher costs for these projects, he said.

PacifiCorp has a number of new air projects in the works

Teply said the Jim Bridger Units 3 and 4 emissions projects are part of an overall, constantly evolving PacifiCorp air compliance plan. The company wholly-owns or has partial ownership share in 26 coal units in Wyoming, Utah, Arizona, Colorado and Montana. The company maintains operational responsibility for 19 of those units.

EPA’s proposed action on Wyoming’s Regional Haze SIP as it pertains to SO2, recommends approval of the state’s SIP. EPA’s proposed action on Wyoming’s Regional Haze SIP as it pertains to NOx is to partially approve and partially disapprove the state’s SIP and issue a Federal Implementation Plan (FIP) for those portions proposed to be disapproved. The EPA’s action proposes to accelerate the installation of SCRs currently required at the company’s Jim Bridger Units 1 and 2 from 2022 and 2021 to 2017, but the agency agreed to accept comment on maintaining the schedule as the state determined in its SIP.

In addition, the EPA proposes to reject the SIP for the coal-fired Wyodak facility and Dave Johnston Unit 3 and require the installation of additional controls, namely a selective non-catalytic reduction system (SNCR), within five years, as well as requiring the installation of low-NOx burners and overfire air at Dave Johnston 1 and 2 by July 31, 2018. The EPA held public hearings on its proposed disapproval on June 26 and 28 and the comment period closed Aug. 3.

In other states PacifiCorp serves:

  • The EPA’s proposed action on Utah’s Regional Haze SIP as it pertains to SO2 recommends approval of the state’s SIP. The Utah SIP utilizes the same trading program utilized by Wyoming. The EPA’s proposed action on Utah’s Regional Haze SIP as it pertains to NOx and particulate matter (PM) is to partially approve and partially disapprove the state’s SIP and request five factor analyses of NOx controls be completed by the state. The company is assisting Utah in that regard. The EPA has indicated that its action on Utah’s SIP may involve requirements for the installation of additional NOX controls, namely SCR, none of which are required by the state of Utah.
  • The EPA’s proposed action on Arizona’s Regional Haze SIP as it pertains to NOx is to partially approve and partially disapprove the state’s SIP and issue a FIP for those portions proposed to be disapproved.
  • The EPA’s proposed action on Colorado’s Regional Haze SIP as it pertains to NOx recommends approval of the state’s SIP. The Colorado SIP requires SCR to be installed on Hayden Units 1 and 2 and Craig Unit 2, all by year-end 2016, with PacifiCorp having partial ownership of each of those units. In addition, the Colorado SIP requires installation of SNCR on Craig Unit 1, in which the company also has partial ownership, by year-end 2017.

A table of planned emissions controls project provided by Teply shows no new wet or dry scrubbers planned for the future, only a 2014 upgrade to an existing wet scrubber at Hunter Unit 1 in Utah. There are a number of SCRs planned in future years, including one for Craig Unit 2 in 2016, Hayden Unit 1 in 2015 and Hayden Unit 2 in 2016. The only SNCR is Craig 1 in 2017. There are no ESPs in the plan, with the only baghouse installation shown in 2014 at Hunter 1. There are a number of installations planned for mercury control, including sorbent injection and coal oxidizers.

Naughton Unit 3 coal-to-gas conversion factors don’t apply in this case

Earlier this year, PacifiCorp gave up on commission approval for new emissions controls coal-fired Naughton Unit 3 in Wyoming and now plans to convert that unit to natural gas. Rick Link, Director, Structuring & Pricing for PacifiCorp, said in Aug. 7 testimony that in the case of Naughton 3, one of the primary drivers favoring gas conversion is the difference between the up-front environmental investment cost that would have been required to continue operating Naughton Unit 3 as a coal-fueled facility beyond 2015 as compared to the up-front investment cost for gas conversion.

Link also laid out an extensive, heavily-redacted analysis on how coal production costs would rise at the Bridger coal mines (both a surface and deep mine are in operation there) if one or more Jim Bridger power plant units was shut or converted to natural gas.

Link also noted that the costs of the Naughton 3 conversion to gas could be eased by diverting coal contracted for that unit to Jim Bridger. “The economic analysis supporting the Company’s decision to convert Naughton Unit 3 to natural gas included potential take-or-pay costs identified in coal supply agreements put in place to fuel the Naughton facility,” he wrote. “That analysis assumed minimum coal contract volumes would be taken at Naughton, and approximately one million tons would be delivered to the Jim Bridger plant in 2015 and 2016. Given that the Jim Bridger fueling plan includes market based deliveries with the expiration of a third party coal supply agreement at the end of 2014, any deliveries from Naughton could be used to fill that open position. All costs inclusive of handling and transport above delivered market prices for any shipments from Naughton to Jim Bridger would be charged to the Naughton plant and not affect coal costs at Jim Bridger. Moreover, given the SCR for Jim Bridger Unit 3 must be installed prior to December 31, 2015 and the SCR at Jim Bridger Unit 4 must be installed by December 31, 2016, any deliveries from Naughton to Jim Bridger in 2015 could be made regardless of the SCR investment decision.”

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.