Idaho Power applied June 28 at the Idaho Public Utilities Commission for approval for new selective catalytic reduction installations at two units of the Jim Bridger coal plant in Wyoming to meet new regional haze requirements.
The utility owns one-third of the Jim Bridger plant (the other owner is PacifiCorp), which is located near Rock Springs, Wyo. The Jim Bridger plant consists of four units and is the “workhorse” of ldaho Power’s thermal fleet. After adjustment for scheduled maintenance periods and estimated forced outages, the annual energy generating capability of ldaho Power’s share of Jim Bridger is about 625 MW average. Of ldaho Power’s entire thermal generation fleet, it has the lowest dispatch cost and the lowest installed cost of nameplate capacity to operate.
Idaho Power requests that the commission issue a certificate of public convenience and necessity (CPCN) authorizing it to invest in and construct SCR systems and associated ancillary equipment for Jim Bridger Units 3 and 4. Each SCR system 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.
An induced draft fan upgrade and an associated auxiliary power system variable frequency drive insertion are required on Unit 4 only.
The Best Available Retrofit Technology (BART) appeal settlement agreement with the state of Wyoming, and also the Wyoming Regional Haze State lmplementation Plan, require the installation of SCR on Unit 3 by the end of 2015 and on Unit 4 by the end of 2016. On May 23, the U.S. Environmental Protection Agency recommended approval of the Wyoming Regional Haze SIP for installation of SCR on Jim Bridger Units 3 and 4. The EPA has indicated it will sign a notice of final rulemaking on Nov. 21, 2013, making these emission reduction mandates at Units 3 and 4 federally enforceable as well.
If the environmental upgrades are not installed within the time frame given by the state of Wyoming or the EPA, ldaho Power said it would be forced to stop generating from these units.
In August 2012, PacifiCorp filed a CPCN with the Wyoming Public Service Commission to construct these SCR systems, as well as a voluntary request to construct the SCRs with the Public Service Commission of Utah. On May 10, the Utah commission issued its final report and order approving the SCRs. On May 29, the Wyoming commission approved a CPCN for the SCRs.
Switches of Jim Bridger and North Valmy to natural gas were looked at
To determine the economic viability of installing the Jim Bridger SCRs, ldaho Power prepared the Coal Unit Environmental lnvestment Analysis. This so-called “Coal Study” analyzed the SCR investment at Jim Bridger Units 3 and 4 as part of a larger analysis conducted for all four units at the Jim Bridger plant and the two units at the North Valmy coal plant in Nevada, where Idaho Power owns a minority stake.
The methodology used in the Coal Study examined future investments required or reasonably anticipated for environmental compliance for the existing coal units. Those investments were then compared to the costs of two alternatives: replace such units with combined-cycle combustion turbines; or convert the existing coal-fired units to natural gas. For the complete evaluation, Idaho Power said it used a combination of third-party analysis, input from the operating partners of each coal plant, and a final economic dispatch analysis conducted by the company.
The Coal Study supports upgrading Jim Bridger Units 3 and 4 with emissions control equipment to allow ongoing coal-fueled production from this plant through the Coal Study period as the least-cost, least risk outcome for customers. The planning case (planning case carbon/planning case natural gas) results indicate that the cumulative net present value power costs associated with the upgrade option is $254m less than the next least-cost compliance alternative for Unit 3, and $237m less than the next least-cost compliance alternative for Unit 4.
As part of the development of the company’s 2013 integrated resource plan (IRP), the company included four resource planning portfolios that explored options for reducing the amount of coal-fired generation in Idaho Power’s portfolio. The options included replacement with natural gas-fired generation, increased demand-side measures including demand response, changing the fuel at the North Valmy plant to natural gas, and the Boardman-to-Hemingway transmission line.
Two of the evaluated portfolios specifically ceased coal-fired operations at Jim Bridger and North Valmy (the Boardman coal plant in Oregon, where again the utility owns a minority stake, ceases coal-fired operations at year-end 2O2O in all resource portfolios). Because those two portfolios ranked as the two highest cost portfolios of the nine portfolios analyzed, the company’s preferred portfolio includes continued operations at the Jim Bridger and North Valmy coal plants.
The total cost of the SCR project before Allowance for Funds Used During Construction (AFUDC) is $353.8m. ldaho Power’s share of that amount is one-third, or $117.9m.
Because of the scope of the project, the extended period of time it takes to plan, permit, engineer, procure, and construct SCR systems, and the uncertainty of the EPA’s final ruling approving the portion of the Wyoming Regional Haze SIP that addresses the SCRs at Jim Bridger Units 3 and 4, a Limited Notice to Proceed contract was signed with the successful Engineering, Procurement, and Construction bidder on May 31.