Texas nears approval for combined-cycle conversion of DeCordova project

The Texas Commission on Environmental Quality said in a July 26 notice, posted to its website on Aug. 1, that it is ready to approve permitting for DeCordova II Power Co. LLC that would allow combined-cycle operation of a simple-cycle plant in Hood County.

The company is seeking a Greenhouse Gas (GHG) Prevention of Significant Deterioration (PSD) Air Quality Permit, which would authorize a modification to add combined-cycle optionality for the simple cycle combustion turbines at Units 5 and 6, located at 4950 Power Plant Court, Granbury, Hood County. This application was submitted to the TCEQ on December 2014.

The TCEQ’s executive director has determined that the emissions of air contaminants from the existing facility which are subject to PSD review will not violate any state or federal air quality regulations and will not have any significant adverse impact on soils, vegetation, or visibility. All air contaminants have been evaluated, and best available control technology will be used for the control of these contaminants. The executive director has completed the technical review of the application and prepared a draft permit which, if approved, would establish the conditions under which the facility must operate.

DeCordova II Power owns the DeCordova Steam Electric Station, which currently consists of two combustion turbines (CTGs) authorized to operate in simple cycle. The simple-cycle operations were authorized in August 2013. The CTGs will be one of two options: General Electric or Siemens.

DeCordova is seeking to augment the electrical generating capability of the DeCordova Station by adding combined cycle operations. The new project will include an increase in the annual hours of operation for the CTGs, the installation of two duct burner (DB) fired heat recover steam generators (HRSGs), a steam turbine, an auxiliary boiler, an emergency generator, and a firewater pump.

The DeCordova Station, upon completion of this project, will consist of two natural gas-fired CTGs each equipped with a supplementary DB fired HRSG to operate in either simple cycle or combined cycle modes. The addition of combined cycle capabilities will result in an increase in the annual operating hours. There will be no increase in the currently authorized operating hours for the simple cycle operations.

The CTGs will be one of the following model options:

  • two General Electric Model 7FA CTGs each rated at a nominal gross capability of 210 MW. Each CTG will have a DB fired HRSG with a maximum heat input of 349.2 million British thermal units per hour (MMBtu/hr); or
  • two Siemens Model SGT6-5000F each rated at a nominal gross capability of 231 MW. Each CTG will have a DB fired HRSG with a maximum heat input of 500 MMBtu/hr.

The project also includes:

  • Auxiliary Boiler – The natural gas-fired auxiliary boiler will have a maximum heat input of 73.3 MMBtu/hr. The boiler will provide steam for CTG startups.
  • Emergency Equipment – The emergency generator and firewater pump are each limited to 100 hours per year (hr/yr) of non-emergency operation per calendar year.
  • Storage Tanks – The emergency equipment will be serviced by two diesel storage tanks.
  • Natural Gas Piping Fugitives – Natural gas will be delivered to the site via pipeline and then metered and piped to the combustion turbines. The piping and fittings associated with the pipeline will be sources of fugitive emissions.

A project contact is: DeCordova II Power Co. LLC, Paul Coon, Air Permitting Manager, Environmental Services, (214) 875-8376.

This is one of several projects that bankrupt Luminant might build

The Luminant unit of Energy Future Holdings has filed for and received air permits from the TCEQ to build two natural gas combustion turbine generation units totaling 420 MW to 460 MW at each of Luminant’s existing DeCordova, Tradinghouse and Lake Creek generation facilities. In a May 1 disclosure statement filed at its bankruptcy court, Energy Future Holdings also said that in 2014 and 2015, Luminant filed air permit applications with the TCEQ to build two natural gas combustion turbine generation units totaling 420 MW to 460 MW at each of its existing Valley and Permian Basin facilities. In 2014 and 2015, Luminant filed air permit applications with the TCEQ to build a combined cycle natural gas generation unit totaling 730 MW to 810 MW at each of its existing Eagle Mountain and DeCordova generation facilities.

In 2015, Luminant filed air permit applications with the TCEQ to build two combined cycle natural gas generation units totaling 1,460 MW to 1,620 MW at its existing Tradinghouse generation facility. The proposed combined cycle natural gas generation units would be alternatives to the natural gas combustion turbine generation units at Luminant’s DeCordova and Tradinghouse generation facilities.

The company noted: “We believe current market conditions do not provide adequate economic returns for the development or construction of these facilities; however, we believe additional generation resources will be needed in the future to support electricity demand growth and reliability in the ERCOT market.”

These new permits cover as of May 1:

  • DeCordova, Combustion Turbine, two units, 420 MW to 460 MW, Air Permits Granted
  • DeCordova, Combined Cycle, one unit, 730 MW to 810 MW, Air Permits Pending
  • Eagle Mountain, Combined Cycle, one unit, 730 MW to 810 MW, Air Permits Pending
  • Lake Creek, Combustion Turbine, two units, 420 MW to 460 MW, Air Permits Granted
  • Permian Basin, Combustion Turbine, two units, 420 MW to 460 MW, Air Permits Granted
  • Tradinghouse, Combustion Turbine, two units, 420 MW to 460 MW, Air Permits Granted
  • Tradinghouse, Combined Cycle, two units, 1,460 MW to 1,620 MW, Air Permits Pending
  • Valley, Combustion Turbine, two units, 420 MW to 460 MW, Air Permits Granted

The latest action in this bankruptcy case is a plan for Energy Future’s Oncor power delivery unit to be sold to NextEra Energy (NYSE: NEE), while the power plants would be spun off to creditors.

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.