Indianapolis wants to build new gas plant, convert two coal units to gas

Indianapolis Power & Light is seeking a Certificate of Public Convenience and Necessity (CPCN) from the Indiana Utility Regulatory Commission to build a new gas-fired combined cycle gas turbine (CCGT) facility at its Eagle Valley power plant.

In an April 29 filing at the commission, the utility said this new CCGT capacity, with a range of 550 MW to 725 MW in size, would help it meet a forecasted need for additional generating capacity of approximately 744 MW by 2016 growing to 797 MW by 2020. IPL is a unit of AES Corp. (NYSE: AES).

In the April 29 application, IPL requested that the commission approve various things, including:

  • grant to IPL a CPCN to construct a 550-725 MW CCGT at IPL’s Eagle Valley Generating Station located in Morgan County Ind.;
  • grant to IPL a CPCN to convert the coal-fired Units 5 and 6 at the Harding Street Generation Station located in Marion County, Ind., to natural gas;
  • approve the construction of transmission, pipeline and other facilities associated with the Eagle Valley CCGT and Harding Street 5 and 6 refueling; and
  • grant to IPL a necessity certificate to engage in the transportation of gas within Indiana for use by IPL in the operation of the CCGT.

Said the utility: “These projects fit appropriately from an operational standpoint within IPL’s electric generating portfolio, particularly when compared to other supply-side and demand side options available to IPL. The projects will help IPL provide generating capacity and system reliability on an efficient and economical basis. IPL has examined other options and determined that the proposed Eagle Valley CCGT and Harding Street 5 & 6 Refueling constitute the reasonable, least cost option available to IPL at the present time to meet the need for electricity within its service area. Thus, IPL represents that the public convenience and necessity require or will require the issuance of the CPCNs approving the construction of the proposed Eagle Valley CCGT and Harding Street 5 & 6 Refueling. IPL cannot continue to operate Units 5 and 6 at its Harding Street station beyond April 16, 2016 without investments to enable the emissions to comply with the MATS Rule.”

IPL has a total owned capacity of about 3,316 MW (net summer) located at four primary sites: Georgetown (Northwest Indianapolis), Harding Street (Southwest Indianapolis), Eagle Valley (Martinsville, Ind.) and Petersburg (Petersburg, Ind.). Distributed among these sites are 28 generating units. This includes IPL’s 11 coal-fired units, which account for the majority of the total energy produced in recent years. IPL also has four oil-fired steam units, which are all over 60 years old. IPL has about 300 MW of wind generation secured under long term Power Purchase Agreements approved by the commission. In addition to this wind energy, IPL said it has recently contracted to purchase about 100 MW of energy from solar facilities located throughout its service territory.

Six old coal units to get shut or converted to gas

Kevin Crawford, employed by IPL as Senior Vice President, Power Supply, said in supporting testimony that the new CCGT will help compensate for the shutdown or refueling of up to six older coal units and five associated oil/diesel-fired units. In addition to new air emissions rules, unit obsolescence and falling natural gas and market prices have contributed to the decision to retire these units. In total, these 11 units comprise 607 MW of capacity (Midwest ISO installed capability rating). The five associated units are oil-fired boilers and one small diesel generator. These oil- and diesel-fired units are not staffed separately from their “sister” coal units and it would not be cost-effective to staff them separately once the six coal units are retired.

Each of these six targeted coal-fired units is covered by an extension under the Mercury and Air Toxics Standards (MATS) granted by the Indiana Department of Environmental Management which allows them to operate until April 2016 at which point they must be shut down or retrofitted to burn another fuel. IPL determined that it was not economical to retrofit these smaller units.

There is a need to replace this retiring capacity since NERC and MISO resource adequacy rules require IPL to secure capacity to meet its projected peak load plus a minimum planning reserve margin of about 14%. Absent the addition of replacement capacity, the retirement of these units in 2016 results in a capacity deficit of 744 MW in 2016 growing to 797 MW by 2020. The 200 MW represented by the Harding Street 5 and 6 refueling project in 2016 and the 683 MW represented by the Eagle Valley CCGT in 2017 are needed to meet the future needs of IPL’s retail customers.

The six targeted coal-fired units (Eagle Valley Units 3-6 and Harding Street Units 5-6, called the “Small Six”) are smaller than the to-survive Big Five coal units and are not equipped with flue gas desulfurization or selective catalytic reduction. 

Eagle Valley CCGT to run over half of the time

The Eagle Valley CCGT will include duct firing, Crawford noted. Duct-firing increases the steam flow generated by the Heat Recovery Steam Generator (HRSG), which in turn increases the overall power output of the steam turbine-generator during the summer days. During duct firing, some of the natural gas fuel is burned directly in the CT flue gas exhaust flow as it travels through the HRSG.

IPL plans to use the CCGT to replace units which operate on an intermediate duty cycle (units which run frequently, but not necessarily all of the time). IPL anticipates the Eagle Valley CCGT to run about 40% to 70% of the year at currently projected natural-gas prices.

“IPL has had detailed discussions with vendors who manufacturer the CTs and STs used to construct a CCGT, including General Electric (‘GE’), Siemens and Mitsubishi,” Crawford wrote. “The nameplate rating of a CCGT from these vendors ranges in size from approximately 550 to 725 MW. IPL is preparing a detailed solicitation from these vendors and, if the CPCN is granted, will purchase the units which result in the Eagle Valley CCGT having the best combination of cost, reliability and performance characteristics. For purposes of this CPCN application, IPL refers to the CCGT as having a summer, duct-fired capacity of 683 MW.”

The refueled Harding Street units would likely be operated as peakers since IPL needs the capacity at this location, but expects to call upon the energy only for a few hundred hours per year. In addition, operating these units as gas-fired peakers minimizes staffing requirements and reduces air emissions compared to the existing coal-fired units. The existing two coal-fired units were designed by Combustion Engineering (now Alstom) as radiant reheat steam generators, and have been in operation since 1958 and 1961 respectively. Based upon review of the boiler, turbine and balance of plant systems by Sargent and Lundy (S&L) and Alstom, both units are technically good candidates for natural-gas conversion. In addition, natural-gas infrastructure is available at the site at minimal infrastructure cost. It is anticipated that the units would together provide approximately 200 MW-210 MW of capacity after refueling.

The Harding Street Units 5 and 6 refueling has been developed to allow completion of the conversion from burning coal to burning natural gas by April 2016. This will allow the units to meet the April 2016 deadline and integrate into the overall outage schedule at Harding Street Station. This schedule also allows the units to be on-line during the period of peak summer demand.

The schedule for the Eagle Valley CCGT includes about 12 months for engineering and to procure long-lead items and around 24 months of major construction on site. Thus, if the CPCN is issued no later than April 2014, IPL plans for commercial operation of the Eagle Valley CCGT in April 2017.

Eagle Valley CCGT to cost about $631m, with new transmission line needed

The proposed Eagle Valley CCGT will have a generation capacity of 550-725 MW and is estimated to cost approximately $631m, not including allowance for funds used during construction or financing charges. IPL has other generating facilities at this site which will be retired-in-place prior to the commercial operation of the Eagle Valley CCGT.

An additional 138-kV transmission line will need to be built. The proposed transmission line would run approximately 23 miles from the existing Eagle Valley plant and Pritchard substation point of interconnection site to the IPL Franklin Township substation located on the southeast side of Indianapolis. The new transmission line would be built on the spare tower line segment of the existing Petersburg substation to Hanna substation transmission line that runs adjacent to the Eagle Valley site.

The Eagle Valley CCGT includes two advanced and proven CTs and one high-pressure ST. Two HRSGs would capture the hot exhaust from the CTs and use that heat to convert water to steam for powering the single ST. A condenser and cooling tower convert the steam back to water, and the cooling water is recirculated, with additional make-up water being provided from on-site wells.

Air-quality control equipment for the CCGT includes low-NOx burners and selective catalytic reduction (SCR) equipment to control NOx emissions. A carbon monoxide (CO) catalyst is likewise included to reduce the emission of CO and volatile organic compounds.

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.