Southwestern Electric Power Co. (SWEPCO) on Feb. 8 asked the Arkansas Public Service Commission for a declaratory order approving installation of $408.7m worth of new emissions controls on the coal-fired Flint Creek power plant.
The planned controls include: dry flue gas desulfurization (DFGD) equipment for SO2 control; activated carbon injection (ACI) for mercury; and Low NOx burners and over-fired air facilities for NOx control. The DFGD system selected by the project engineers will also include a pulse jet fabric filter, commonly called a baghouse. SWEPCO is a unit of American Electric Power (NYSE:AEP).
SWEPCO is currently planning on commencing site construction activities on or about Jan. 1, 2014, predicated upon a finding by the commission that it would be in the public interest to proceed, and upon the issuance of the required air permit by Arkansas regulators by that date. This schedule will permit construction of the facilities to be completed and placed in service by June 30, 2016. This schedule will require that Flint Creek be taken out of service for approximately three months, because compliance with the the U.S. Environmental Protection Agency’s new MATS Rule for air toxics emissions is required by the first quarter of 2016 and the plant cannot continue to operate until compliance is achieved.
Flint Creek is a jointly-owned plant located in Benton County, Ark., near the town of Gentry. Arkansas Electric Cooperative Corp. is the co-owner of the plant on a 50/50 net output and cost basis. Flint Creek is a single-unit, pulverized coal-fired plant with a net capacity of 528 MW and was placed in service in 1978. SWEPCO’s ownership portion of this unit is 264 MW net, and it is responsible for operating and maintaining the plant.
Christian Beam, Managing Director-Projects and Construction at American Electric Power Service Corp., said in Feb. 8 testimony that the emissions control project is currently in Phase I. The project has been initiated and the project planning and conceptual engineering required to support this filing have been completed. A project plan will be developed which will include a detailed execution strategy for the engineering, design, procurement, permitting, construction, startup and commissioning of the DFGD and ACI systems.
A variety of SO2 control processes and technologies are in use within the industry, but two commercialized processes emerged for comparative study on Flint Creek, Beam testified. Technical and economic evaluations were performed to compare and contrast the wet FGD (WFGD) and DFGD technology options that may be applied while burning 0.8 lb sulfur/mmBtu coal out of the Powder River Basin. Flint Creek currently burns low-sulfur Powder River Basin coal.
Considering equivalent SO2 removal efficiencies among the evaluated FGD technology options, a proprietary DFGD technology is the favored FGD technology based on factors like: lowest total evaluated cost on 30-year (2011-2040) cumulative present worth basis (capital and O&M); lowest water consumption, which is a major consideration given that Flint Creek is considered to be water limited; and lowest auxiliary power usage.
NID system picked for SO2 control
The technical and economic evaluation of the FGD technologies shows that the proprietary NID DFGD technology is the preferred technology for Flint Creek. While the NID technology has all of the benefits of the typical DFGD technologies, it also has significant benefits over other DFGD technologies, including the previous SDA technology that was proposed for the Flint Creek plant prior to the suspension of the project. That previous DFGD project was planned a few years ago under EPA’s Clean Air Interstate Rule, but suspended when a federal court threw out the rule.
NID technology can attain higher levels of SO2 reduction, with vendor guarantee removal rates of 98% compared to maximum removal rates of 95% for SDA and other DFGD technologies. The higher removal rate for NID allows for greater fuel flexibility for the Flint Creek site to meet environmental compliance limits. The DFGD system that is proposed for installation at Flint Creek will remove 95% of the SO2 in the flue gas to meet anticipated emission limits for the design basis fuel. However, NID technology provides greater flexibility for increased SO2 removal rates, if required in the future, Beam wrote.
Selective catalytic reduction (SCR), the best but most expensive technology for deep NOx reductions, is not required for the current compliance strategy. However, there is a potential for the addition of an SCR at Flint Creek in the future, Beam noted.
SWEPCO’s cost of the DFGD system and associated environmental controls project installations, excluding allowance for funds used during construction and company overheads, is currently estimated at $408.7m. Flint Creek is already equipped with electrostatic precipitators for fly ash control.
Beam said AEP has experience with DFGD technology, since it is currently installing a DFGD system at the new John W. Turk plant in Fulton, Ark. The company has also applied for approvals from the Indiana Utility Regulatory Commission and the Kentucky Public Service Commission for the installation of DFGD technology at both the Rockport plant in Indiana and the Big Sandy plant in eastern Kentucky. “DFGD is a proven and viable technology for SO2 reduction for coal-fired power plants, Beam added. “AEP has a proven track record of successfully managing the design and construction of many major environmental projects and it is expected that the DFGD installation at Flint Creek will be another success.”
SWEPCO says replacement gas not viable
Said SWEPCO in its Feb. 8 petition: “In this filing SWEPCO is requesting a declaratory order of the commission finding that the installation of environmental controls at Flint Creek is in the public interest. As discussed in greater detail below, and in the testimony and exhibits supporting this petition, certain [EPA] regulations will require that environmental controls be installed at Flint Creek as a condition of continued operation. Otherwise, the baseload generating capacity provided by the plant will have to be replaced to enable SWEPCO to meet customer demand for electricity and Southwest Power Pool, Inc. (‘SPP’) reserve margin requirements.”
SWEPCO conducted a comprehensive economic analysis of the cost of retrofitting Flint Creek with the required environmental controls compared to the cost of various natural gas alternatives. SWEPCO also retained consultant ICF International to conduct an independent economic analysis of the cost of natural gas alternatives compared to the cost of coal-fired generation from Flint Creek after the installation of emissions controls. The analyses conducted by SWEPCO and ICF evaluated a broad range of assumptions regarding commodity prices, emission allowances and the impact of future greenhouse gas regulation. In each scenario considered by SWEPCO, and in all but one scenario considered by ICF, extending the life of the coal-fired Flint Creek plant was more economic than the natural gas alternatives, SWEPCO said.
The SWEPCO analysis examined three alternatives for replacement capacity in the event Flint Creek is retired: repowering Flint Creek with natural gas; replacing Flint Creek with a natural gas combined cycle plant constructed on-site; and replacing Flint Creek with a generically sited natural gas combined cycle plant located within the Southwest Power Pool footprint. Each of these alternatives was evaluated using a range of assumptions regarding prices for natural gas, coal, emissions allowances and the impact of CO2 regulation.